User Manual p gigaBERT1400 1400 Mb/s Bit Error Rate Tester Generator and Analyzer 071-0590-00 This document supports firmware version 2.2 and above.
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Table of Contents Safety .................................................................................................. xii Getting Started Features............................................................................................... 1-1 Ordering Information............................................................................ 1-4 gigaBERT comparison chart.................................................................. 1-5 Initial Self-Check Procedure ..........................
Table of Contents Generator ERROR INJECT ............................................................ 2-22 Analyzer INPUT ............................................................................ 2-23 Analyzer Error History.................................................................... 2-24 Analyzer ERROR DETECTION ..................................................... 2-25 Analyzer SYNC Controls ................................................................ 2-25 Burst Mode Option .......
Table of Contents Word Patterns ...................................................................................... 3-5 Basics............................................................................................ 3-5 Creating Word Patterns using front panel controls............................. 3-5 Creating Word Patterns using menus ................................................ 3-7 Creating Word Patterns using remote control....................................
Table of Contents Single-Ended or Differential Operation .................................................. 3-27 Selecting the Reference Data Mode ....................................................... 3-27 Monitor Outputs ................................................................................... 3-28 Error Detection Set-up .......................................................................... 3-29 Display Mode: Totalize, Window or Test...............................................
Table of Contents Test Print (PRINT) ......................................................................... 3-68 Test View Previous (VIEW-PRE).................................................... 3-69 Test View Current (VIEW-CUR) .................................................... 3-70 Window Mode (MODE) ................................................................. 3-71 Window Interval in Bits (BITS).......................................................
Table of Contents List of Figures x 2-1 Example of BERT Application........................................................ 2-2 2-2 Nominal Generator NRZ Data and Clock Output Waveforms ........... 2-3 2-3 & 2-4 Generator (TX) Front & Rear Panels ..................................... 2-4 2-5 & 2-6 Analyzer (RX) Front & Rear Panels ....................................... 2-5 2-7 Generator Display.......................................................................... 2-6 2-8 Analyzer Display .
Table of Contents List of Tables 2-1 Generator Inputs & Outputs............................................................ 2-16 2-2 Analyzer Inputs & Outputs ............................................................. 2-17 3-1 PRBS (2N-1) Test Patterns ............................................................. 3-3 3-2 Output Setup Rules vs. Termination Impedance............................... 3-14 3-3 Data Inhibit Logic .........................................................................
Safety Safety Terms Used in This User's Guide CAUTION! Indicates an operation or practice that could harm the instrument. WARNING! Indicates an operation or practice that could result in personal injury or loss of life.
Table of Contents Do Not Remove Instrument Covers To avoid a shock hazard and to maintain proper air flow, never operate the GB1400 with any of its outside covers removed. Static Sensitive Device Notice GB1400 outputs use a GaAs FET design and therefore are susceptible to damage from externally applied over-voltage or electrostatic discharge. Never apply reverse voltage to DATA or CLOCK outputs or voltages that are outside the range specified in Appendix A of this manual.
Preface This manual describes how to use the Tektronix GB1400 Test Set. The product is also known by the name, gigaBERT1400. This manual is your primary source of information on how to use the GB1400 functions. How This Manual is Organized This manual is divided into four sections: Getting Started, Operating Basics, Reference, and Appendices. Getting Started provides an overview of the GB1400 and describes first time operation.
Preface Related Manuals The following document is also complementary to the GB1400: • GB1400 User Manual The GB700 BER Tester User Manual (Tektronix part number 070-9393-02) describes how to operate the GB700 test set.
Preface xvi GB1400 User Manual
Getting Started
Getting Started GB1400 Pattern Generator and Error Detector Features • Test digital data transmission up to 1400 Mb/s • Set Data Rate with 1 kHz resolution • Vary Clock and Data timing with 5 pS resolution • Phase-Synchronous Clock and Data Edge Tracking • 1-Mbit data pattern memory • Measure Eye-Width at Specific BER Automatically • Auto-Synchronization Rx/Tx Lock-up • Front panel or computer control operation The GB1400 is a general-purpose 1400 Mb/s bit error rate tester (BERT) built to m
Getting Started Symmetrical, Low-Jitter Output Waveforms The GB1400 generates low-jitter, symmetrical waveforms over its entire operating frequency range. The clock and data ports provide both true and inverted output signals. The instrument can drive single-ended or differential ECL inputs. Applications The GB1400 is focused on the research, design, and manufacturing of telecommunication components, modules, or links operating at data rates to 1400 Mb/s.
Getting Started Adjustable Inputs For Maximum Flexibility The clock and data ports on the GB1400 Error Detector accept both true and inverted inputs. Single-ended or differential signals can be internally terminated. Input data delay is adjustable over a 4 ns range to accommodate different clock and data signal path delays. Auto Search For Easy Setup Auto search greatly simplifies the Error Detector setup.
Getting Started Ordering Information gigaBERT GB1400 1400 Mb/s BERT Generator and Detector. Not available in Europe. Includes: Power Cord, Manual. Opt. 02 - 75 Ohm Both Sets. Opt. 05 - BURST Mode Both Sets. Opt. 07 - Positive ECL (Pattern Generator Only). Opt. 08 - 1-Mbit RAM WORD Both Sets & PC Pattern Editor Software. Opt. 2M - Rack Mounts - 2 rackmount kits Opt. A3 - Australian 240 V, 50 Hz. gB1400T 1400 Mb/s BERT Pattern Generator. Opt. 02 - 75 Ohm Pattern Generator Only. Opt.
Getting Started GB Comparison Feature Transmitter Frequency range Internal Clock Source External Clock 1 External Clock w/Burst Mode Freq Resolution CR/LF (Internal Clock) Clock /Data Output Amplitude Clock/Data Output Offset Clock/Data Threshold Resolution Std.
Getting Started GB1400 Instrument Configurations - Standard and Burst Option GB1400 instruments are sold with and without the BURST option. To determine if the burst option is installed in a GB1400, press the F1 key several times until you get to the UTIL menu. Then select the OPTION menu. The OPTIONS menu will tell you if the Burst option is installed in the unit. External indications of the BURST option are unique labels for both transmitter and receiver.
Getting Started Initial Self-Check Procedure You may perform the following procedure as an initial self-check of your GB1400 Generator and Analyzer. It is also a useful introduction to the basic features and operation of the GB1400. The fan openings of the GB1400 needs 2-inches of clearance for proper ventilation. Procedure 1. Make sure both the Generator and Analyzer are equipped with the proper fuse. 2.
Getting Started 9. Set Generator pattern to a 223-1 bit PRBS using controls in the PATTERN box as follows: a. Press PRBS. b. Press the pattern up/down keys until PATTERN is set to PN 23. 10. Verify that the Generator error injection rate is off. If the LED in the error inject RATE key is on, then press RATE one or more times until it turns off. 11. Verify that the Analyzer auto-search function is enabled. If the LED in the AUTO SEARCH key is off, then press AUTO SEARCH one time to turn it on.
Operating Basics
Functional Overview This section describes how to use and navigate through the basic functions of the GB1400, including: • BERT Basics • Controls, indicators and connectors • Display Formats • Outputs and Inputs Also in this section is: GB1400 User Manual • Tutorial - "Understand GB1400 instrument setup for BER testing using PRBS patterns"; • Application Note - Auto Search Synchronization with GB1400; and, • Application Example - GB700/ GB1400 Optical component test.
Functional Overview BERT Basics - GB1400 The GB1400 Generator and Analyzer together comprise a 1400 Mb/s, serial, bit error rate test system or BERT. A BERT is an instrument designed to measure the bit error rate (BER)—or more generally, the error performance—of a digital communications device, module, or system.
Functional Overview Falling edge of CLOCK in middle of DATA "eye" Rising edge of CLOCK Coincident with DATA transitions CLOCK DATA Figure 2-2. Nominal Generator NRZ Data and Clock Output Waveforms The nominal Generator clock/data phase relationship is fixed so that the falling edges of the clock signal occur in the middle of bit time slots of the data signal.
Functional Overview Controls, Indicators and Connectors The first four figures in this section identify the controls, indicators and connectors located on the front and rear panels of the GB1400 Generator (Tx) and GB1400 Analyzer (RX).
Functional Overview gigaBERT 1400 ANALYZER FREQUENCY (kHz) VIEW ANGLE ERROR RATE TOTALIZE ERROR HISTORY SYNC LOSS CLEAR BIT PHASE POWER DELAY/ MEMORY PANEL LOCK PATTERN INPUT DELAY WORD LENGTH F1 PRBS ERROR DETECTION F2 F3 F4 CLEAR DISPLAY CLEAR SET SYNC GPIB ADDR CLK REF WORD LOCAL V-TERM V-THRESH MSB 1 RECALL SAVE 2 BIT 3 AUDIO VOL RATE 4 5 6 7 8 LOCK AUTO SEARCH DISABLE REMOTE ON D-INV EXT DATA OFF POWER DATA REFERENCE DATA CLOCK (1) PATTERN SYNC CLOCK MONIT
Functional Overview Display Formats The normal display format for the Generator and Analyzer are explained below. Note that the "normal" format is simply the format of the display when not in the menu mode. Generator (Tx) Display The Generator has a two-line by 24-character high-contrast liquid crystal display (LCD). The Generator display in its normal (non-menu) mode is illustrated in the figure below. Frequency (kHz) Pattern Output 1405000 PN23 2.00 V AMPL FREQ 0 ERR OFF -1.
Functional Overview Analyzer (RX) Display Like the Generator, the Analyzer has a two-line by 24-character high-contrast liquid crystal display (LCD).The Analyzer display in its normal (non-menu) mode is illustrated in the figure below. Frequency (kHz) Error Rate Totalize 1405000 5.0E-06 2410538 1.2 ns PN23 -0.05 V Delay/ Memory Figure 2-8. Analyzer Display in Its Normal (Non-menu) Mode Like the Generator, the Analyzer has a two-line by 24-character high-contrast liquid crystal display (LCD).
Functional Overview • The bottom left section of the Analyzer display can show the following setup parameters: delay in nanoseconds for the DATA or REF DATA input; the selected input termination (GND, -2V, or AC) for the CLOCK, DATA, or REFERENCE DATA input, or the selected word memory (WORD 0 ... WORD 7), Note that DATA input delay may be set manually by the user, or automatically by the AUTO SEARCH feature.
Functional Overview Outputs and Inputs This section introduces all inputs and outputs of the GB1400 Generator and Analyzer. Unless otherwise indicated, all signal inputs and outputs are equipped with SMA female connectors and have a nominal input or output impedance of 50 ohms. However, a 75 Ohm Option is available for both the Generator and Analyzer which changes nominal impedance of key inputs and outputs to 75 ohms. Note: The same term can be expressed three different ways.
Functional Overview installed) when not in use—that is, when the Generator is driving singleended inputs. • CLOCK/4 [output]: This is a clock signal at one quarter the frequency of CLOCK. This output may be useful when observing generator outputs using an oscilloscope that does not have the bandwidth to trigger on the CLOCK output. • PATTERN SYNC [output]: This is a pulse that occurs once per pattern frame.
Functional Overview Generator OUTPUT Section The controls shown below are used to set up the Generator's clock and data outputs. OUTPUT CLOCK DATA OFFSET AMPLITUDE INVERT DATA (D-INV) GB1400 User Manual • CLOCK: Use this key to select clock amplitude and offset set up mode. • DATA: Use this key to select data amplitude and offset set up mode. • AMPLITUDE (↑ ↑ ,↓ ): Use these up/down keys to adjust clock or data output amplitude.
Functional Overview Generator Rear Panel The rear-panel of the Generator contains the auxiliary signals, remote control, and AC-power inputs shown below. See the appendix for instruction on how to set up the RS-232 and GPIB ports, and general information on using external controllers with the Generator. PHASE A PHASE B CLOCK/2 ERROR INJECT DATA INHIBIT • PHASE A: An SMA connector provides signal output for DATA Phase A. This phase-shifted data pattern provides signals suitable for MUX/DEMUX testing.
Functional Overview Analyzer INPUT Section The INPUT section of the Analyzer front panel contains the test signal NRZ data and clock inputs shown below. DATA • DATA REFERENCE DATA CLOCK CLOCK CLOCK and DATA [inputs]: These inputs comprise the main test signal input to the Analyzer. DATA is the main NRZ data input to the Analyzer pattern detector and CLOCK is its corresponding clock signal. Both inputs have selectable input terminations.
Functional Overview Analyzer MONITOR Section The MONITOR section of the Analyzer front panel contains the auxiliary outputs shown below. These outputs may be used to monitor the test signal as seen by the Analyzer. PATTERN SYNC MONITOR CLOCK DATA 50 Ohm SOURCE 2-14 • CLOCK [output]: A buffered copy of the clock signal received by the Analyzer. • DATA [output]: A regenerated (re-clocked) version of the data signal received by the Analyzer.
Functional Overview Analyzer Rear Panel The rear-panel of the Analyzer contains the auxiliary signal, remote control, printer, and AC-power inputs shown below. See the appendix for instruction on how to set up the RS-232 and GPIB ports, and general information on using printers and external controllers with the Analyzer. DATA ERROR INHIBIT THRESHOLD RZ ERROR OUTPUT RS-232C PRINTER GPIB • DATA THRESHOLD OUTPUT: The programmed DATA threshold voltage is set via the front panel.
Functional Overview Connectors, Terminations, and Levels Tables 2-1 and 2-2 below summarize the physical interface characteristics of all GB1400 Generator and Analyzer inputs and outputs. Table 2-1.
Functional Overview Table 2-2. Analyzer (RX) Inputs and Outputs Connector Label Signal Type Section Connector Type Impedance, threshold, and delay DATA/DATA BAR Input INPUT SMA, female 50 Ohm, see NOTE 1, variable threshold and delay. Selectable termination: GND, -2 V, AC CLOCK/CLOCK BAR Input INPUT SMA, female 50 Ohm, see NOTE 1, fixed threshold.
Functional Overview Controls and Indicators All of the controls, indicators, inputs, and outputs found on the Generator or Analyzer front or rear panels are discussed in the following section. Power Switches The ON/OFF power switch is located on the left side of the test instrument below the LCD screen. The power switch switches the 120/240 VAC to the system power supply. When off, a Battery backup circuit powers the non-volatile RAM.
Functional Overview GPIB Section Controls There are two keys in the GPIB section: • ADDR: Key used to set GPIB address in the range 0 to 30. • LOCAL: The LED in this key indicates whether the instrument is in the local mode (LED off) or remote mode (LED on). If the LED is on, you can return the instrument to local mode by pressing the LOCAL key. Note that these two keys are used only when operating the instrument via its GPIB port.
Functional Overview Pattern Controls and Function Keys The PATTERN section of both the Analyzer and Generator front panels contains two basic types or groups of controls: "pattern" and "function". The four function or "soft" keys —F1, F2, F3, and F4— have different functions depending on the current mode of the instrument. A primary function of these controls is to access and navigate the menu system.
Functional Overview Function (Soft) Keys (F1, F2, F3, and F4) Menu Functions: The primary use of the function keys in the Generator and Analyzer is to access and navigate each instrument's menu system. F1 may be thought of as the main menu key. Pressing F1 will display the instrument's first level menu. Once inside the menu system, you may use the F1, F2, F3, and F4 keys to select different menus, or to make choices within a selected menu.
Functional Overview Generator ERROR INJECT Section Controls in the ERROR INJECT section are used to set up the Generator's error injection function. ERROR INJECT RATE SINGLE 2-22 • RATE: Press this control one or more times to select an internal error inject rate, or the external error inject mode. • SINGLE: When the error inject function is set to single (ERR OFF), press this key to inject single errors.
Functional Overview Analyzer INPUT Section The controls shown below are used to set up the Analyzer clock and data inputs. INPUT DELAY V-TERM V-THRESH D-INV EXT DATA REFERENCE DATA DATA (1) 50 Ohm, 2V MAX CLOCK CLOCK (1) (2) 50 Ohm, 1.5V MAX • DELAY: Press this key to add delay to the DATA or REF DATA inputs to adjust the clock/data phase relationship.
Functional Overview Analyzer Error History Section SYNC LOSS BIT PHASE POWER 2-24 CLEAR SYNC LOSS The SYNC LOSS LED is lit when the unit is not synchronized, it will remain lit until cleared by the user. BIT The BIT LED is lit when bit errors occurs, and remains lit until it is cleared by the user. PHASE The PHASE LED is lit when the guaranteed setup or hold time of the GB1400 input decision circuit is violated.
Functional Overview Analyzer ERROR DETECTION Section The ERROR DETECTION section contains test setup and display controls. ERROR DETECTION DISPLAY CLEAR AUDIO VOL RATE SYNC LOCK AUTO SEARCH DISABLE DISPLAY SELECT: Use this control to select which results are displayed in the Bit Error Rate (BER) fields. The options are Window, Totalize, or Test. • CLEAR: Press this key to clear previous results and to start/stop timed tests.
Functional Overview Burst Mode Option The standard GB1400 operates over a clock frequency range of 1 Mbit/s to 1400 Mbit/s. The GB1400 Tx has an internal clock source that has a range of 1 MHz to 1400 MHz. It also has a provision for using an external clock source of the same frequency range. When using the external clock source, it must be applied continuously without interruption.
Functional Overview Burst Mode Usage The Burst Mode option of the GB1400 will find usage in applications where traditional BERTs cannot operate. Traditional BERTs require a continuous CLOCK and DATA signal with no interruption. Should interruptions occur, the RX will resynchronize or indicate errors that actually did not occur due to the asynchronous re-start. The BURST MODE allows operation with a noncontinuous clock.
Functional Overview Undefined Time Undefined Time Ext Clk In ……………….. ……………….. Clk Out ……………….. ……………….. Data Out ……………….. ……………….. Data Value 1 0 1 1 0 0 Figure 2-9. Transmitter Burst Mode Option [ Sync Time ][ Measurement A DATA Sync Attained B Undefined Time |------| Sync Attained | DATA [Msmt ] [ Sync ] [Measurement Start Resync ] C DATA [Msmt ] [Measurement ] [Msmt ] Figure 2-10.
Functional Overview PECL Option for GB1400 Tx The PECL option is available for the GB1400 Tx only. The PECL option for the GB1400 Tx is a modification that allows for an increased OFFSET RANGE for the clock and data outputs, so that the user will be able to generate PECL levels for testing in a PECL environment. PECL is defined as ECL operating +5.0 V above ground. Example: ECL Levels PECL Levels VOH ≈ -.9V VOH ≈ +4.1V VOL ≈ -1.8V VOL ≈ +3.2V VBB ≈ -1.35V VBB ≈ +3.65V VTT ≈ -2.0V VTT ≈ +3.
Tutorial Basic BERT testing with the GB1400 A critical element in digital transmission systems is how error-free its transmissions are. This measurement is made by a bit-error-rate tester (BERT). The GB1400 Generator (Tx) and Analyzer (Rx) are designed to operate at bit rates up to 1400 Mb/s. These portable instruments provide PRBS or User Defined Patterns (up to 1Mbit deep) for high speed BERT testing. Objective of Tutorial Understand GB1400 instrument setup for BER testing using PRBS patterns.
Tutorial Instrument Connections and Controls Data Threshold connection (required for single-ended signals) GB1400 Analyzer (Receiver) DATA CLOCK GB1400 Generator (Transmitter) CLOCK CLOCK 1. DATA DATA Setup units with default settings Note: Resetting the unit to factory defaults is used infrequently. It helps simplify instructions on this beginners lab. A customer would not normally do this as they would lose their stored setups.
Tutorial 2. Connect the Generator to the Analyzer. Connect the generator and analyzer as shown below. The generator CLOCK output connects to the analyzer CLOCK input. The generator DATA output connects to the analyzer DATA input. The rear panel THRESHOLD output on the Rx connects to the Receiver NOT-DATA input on the front panel. Terminate the generator NOT_CLOCK and NOT_DATA signals with the 50Ω terminators located on the front panel of the generator.
Tutorial B. Locate the controls in the PATTERN box of the Generator. Make sure the PRBS button is enabled (the LED inside this switch should be ON). Set the Generator pattern to a 223 -1 bit PRBS as follows: Set this parameter PRBS type …to this value PN 23 …using this procedure. Press pattern up/down arrow keys until PATTERN is set to PN 23 C. Locate the controls in the ERROR INJECT box of the Generator. Verify that the Generator ERROR RATE GENERATOR is OFF (the LED within the switch should be OFF).
Tutorial 5. Change the PRBS pattern type These steps demonstrate one of the many benefits of our Full-Featured AutoSearch algorithm - automatic synchronization to the incoming signal by selecting the correct PRBS test pattern. A. Locate the controls in the PATTERN box of the Generator. Make sure the PRBS button is enabled (the LED inside this switch should be ON). Set the Generator pattern to a 2 7 PRBS as follows: Set this parameter PRBS type …to this value PN 7 …using this procedure.
Tutorial B. Locate the controls in the OUTPUT box of the Generator. Adjust the Data amplitude and offset as follows: Caution: Adjust only the DATA signal. Do not change the CLOCK signal. Set this parameter DATA amplitude. …to this value 0.50 volts …using this procedure. Press the DATA key. The LED within the switch should be lit. Press AMPLITUDE up/down keys until data amplitude is set to 0.50V. DATA baseline offset -0.
Tutorial Set DATA THRESHOLD to this value Verify these results on the Analyzer Press the ERROR DETECTION and ERROR HISTORY “ CLEAR KEYS” , then confirm: -0.50 volts SYNC LOSS and BIT LED’s are ON Comments Data signal not detected. Selected threshold is below the minimum level of your data signal. SYNC LOCK LED is OFF ERROR RATE display shows “NO DATA” or a 50% Error Rate. Approximately -0.
Tutorial D. Locate the controls in the SYNC box of the Analyzer. Verify that the function is ENABLED. The LED in the AUTO SEARCH key should be ON. If the LED is OFF, press the AUTO SEARCH function one time to turn the ON. At this point, verify that the green LOCK LED is ON. AUTO SEARCH The Analyzer will now search and calculate a new data threshold.
Applications Application Note Method For Very Fast Automatic Receiver Synchronization And Eye Width Measurement Two Auto Search Synchronization Methods This application note describes two Auto Search synchronization methods used in the GB1400 Bit Error Rate test set - a FAST method and a BER method. The criteria and sequence of events for the two methods are compared and the differences are described.
Application Note - Auto Search Synchronization PHASE This is a unique and very fast method of determining where the edge of a data bit is in relation with the clock. The determination of phase errors is done by monitoring the logic value of a data bit at the selected threshold voltage and delay at two slightly different times. If the logic value is the same at the two different times, then a phase error has not occurred.
Application Note - Auto Search Synchronization 2-40 GB1400 User Manual
Application Note - Auto Search Synchronization I. Auto Search Algorithm – “Fast” Method Auto Search will determine the Data V- Threshold, Data Delay, Data Pattern and Polarity automatically. The so called “FAST” method has been given its name because of the speed with which it determines the threshold voltage setting, delay, data pattern and polarity. This is the default method used by the GB1400 Receiver.
Application Note - Auto Search Synchronization Auto Search will find the DATA PATTERN and POLARITY. 1. The receiver then attempts to SYNC on each data pattern and Polarity (10 possibilities). If sync is found, STOP. 2. Attempt the previous step ten times. If the pattern is not found after ten times, go back to "Find Data V-Threshold". II. AUTO SEARCH Algorithm – BER Method Like the “FAST” method of Auto Search, the “BER” method will also determine the V-Threshold, data delay, data pattern and polarity.
Application Note - Auto Search Synchronization 3. If unsuccessful, it will then try the following data delays in the previous step1/4 per, 3/4 per, 1/8 per, 5/8 per, 3/8 per, 7/8 per. 4. If sync is still not found, go back to the first section Find Data V-Threshold. Auto Search will determine the Data Delay. 1. Initially the entire delay range (0nS to 3.99 nS) in steps of 70pS will be sampled for 20mS each for error rate.
Application Note - Auto Search Synchronization If the error rate is above the Threshold, the next point toward the Data Eye Center will be examined, and so on, until the error rate transitions to below the Threshold. The first point below the Threshold will be the TRUE transition point. 6. After the new transition points are re-examined and the TRUE transition points are found, the delay will be set as follows: For Case 1, the delay will be set to the middle of the two TRU transition points (point C).
Application Note - Auto Search Synchronization Consideration In Determining The Eye Data Width In most circumstances a test signal data eye displayed on an oscilloscope will appear to be larger than that reported by the GB1400 Receiver. This is expected and is due to several factors. One is that low error rates are virtually impossible to see on an oscilloscope.
Application Example GB700/ GB1400 Optical Component Test gB-Series Tx gB-Series Rx Clock Clock Data Fiber Optic Data Clock Recovery and Retiming Fiber Optic Link Test Example A typical BERT application is measuring the error performance of the electricalto-optical (E/O) and optical-to-electrical (O/E) output modules of a fiber optic transmission system, as shown in the diagram above. Not all fiber optic links are designed for extremely high speed.
Application Example Fibre Channel Link Testing Parallel and High-speed Serial gigaBERT (Serial) Tx Parallel stimulus Rx Parallel results Rx O/E Serial - BUS BUS - Serial Rx Tx Fiber BUS Interface BUS Interface Interface Under Test gigaBERT (Serial) E/O Tx 2-47 GB1400 User Manual
Application Example Application Example Testing QPSK Modems, I & Q I-Channel BERT GB700/1400 Rx data clock GB700/1400 Tx DATA CLOCK CLOCK I I QPSK Mod /Demod up to 1400 Mb/s data rate Q Q-Channel BERT GB700/1400 Rx data clock Q GB700/1400 Tx EXT CLOCK INPUT DATA CLOCK 2-48 GB1400 User Manual
Application Note Application Example QPSK BER Testing using PRBS Data for 2-Channel I & Q I-Channel BERT GB700/1400 Rx data clock GB700/1400 Tx I DATA I Q-Channel BERT GB700/1400 Rx QPSK Mod / Demod DATA Delay line or long coax cable Q data clock Q CLOCK CLOCK Delay line can simulate a PRBS pattern with an offset of n-clock bits. Both I and Q channels running PRBS data (but offset by n-clocks).
Application Example 2-50 GB1400 User Manual
Reference
Reference Menu Overview A wide range of "auxiliary" setup functions is provided in the GB1400 Generator and Analyzer Menu systems. To enter the Generator or Analyzer Menu system, simply press the instrument's F1 key. At this point the format of the display will change to show the first page of the top level Menu. The top level Menu in both the Generator and Analyzer contains other Menus and various setup parameters. Once inside the Menu system, you use the functions keys, F1 ...
Reference Recalling the Default Setup The default setup of the Generator and Analyzer are shown in the Appendix. To return the Generator or Analyzer to this setup, use the following procedure: 1. Turn instrument power off. 2. While holding down the VIEW ANGLE, MSB 1, and (PATTERN) CLEAR keys simultaneously, turn instrument power back on. 3. After you see the message Default Settings appear in the display, release the three keys.
Reference The PRBS patterns generated and analyzed by the GB1400 are listed below. Table 3-1. PRBS (2 n-1) Test Patterns n Label Used in Generator and Analyzer Displays 7 15 17 20 23 PN 7 PN 15 PN 17 PN 20 PN 23 Length (2n -1 bits) 127 32767 131,071 1048575 8388607 Maximum Number of Contiguous 0s 6 14 16 19 22 Word Patterns Word patterns are programmable by the user.
Reference Selecting (RECALLing) a Saved Word Pattern You can recall a WORD pattern using the Generator or Analyzer RECALL function: 8/16 bit WORD patterns are available on all instruments. Long-WORD (>16bits) are available only in units equipped with the 1-Mbit Option. Use the following procedure to select (recall) a WORD pattern: Press the WORD key to place instrument in WORD mode. Press the RECALL key. Press the pattern up/down keys until the desired WORD or desired mark density pattern is displayed.
Reference Word Patterns This section explains how to create, edit, save, and recall WORD patterns using front panel controls or the Menu system. Basics You may create and save up to ten WORD patterns in battery-backed memory locations WORD 0 through WORD 9. In addition, the current WORD pattern is stored in battery-backed memory. In standard units, each of the saved WORDs and the current WORD can contain up to 16 bits.
Reference 3. If you need to change WORD length, press the WORD LENGTH key and then the pattern up or down key to toggle WORD length between 8 and 16 bits. When the desired WORD length is displayed, press the WORD key to return to the WORD editing mode. 4. To select the first or second byte in a 16-bit pattern, press the up or down key. The selected byte will be indicated in the display by an arrow located between the two bytes.
Reference Creating Word Patterns Using Menus The Menu functions used to create or edit WORD patterns are: LENGTH FILL EDIT and ORDER. These functions are located in the WORD Menu. Note that ORDER is a standard function while the LENGTH, FILL, and EDIT functions are added to the WORD Menu as part of the 1-Mbit Option. Therefore in standard units, all WORD editing procedures, except for bit order, are performed using front panel controls.
Reference When done, exit the EDIT Menu by pressing either F4 to lock in these changes or F1 to "escape" without making any setup changes. 7. You now may want to access the ORDER and Pattern Sync Menus by pressing F1 (MORE). The ORDER Menu determines the bit transmission/analysis order of each byte in the pattern, that is MSB or LSB first. The Pattern Sync Menu determines the byte location of the pattern sync pulse in long WORD patterns.
Reference argument of -2 tells the instrument to discard the pattern in scratchpad memory and not to update the front panel. An argument of -1 tells the instrument to copy the pattern in scratchpad memory to the current WORD memory location and to update the front panel. Arguments 0 to +9 tell the instrument to copy the pattern in scratchpad memory to the indicated (save) memory location without updating the front panel.
Reference Generator (TX) Functions This section defines key functions of the GB1400 Generator and how to set up these functions using front panel controls. Clock Source and Frequency The Generator can operate using its internal clock, or an external clock source. The CLOCK section of the Generator front panel is used to select clock mode (internal or external), set internal clock frequency, and store or recall userdefined frequencies.
Reference 3. Press the clock section up/down keys to increment or decrement the current frequency using the previously selected step size. Note that the underscore position indicates a step size, not which digit will be edited. For example if displayed frequency is 622.950, and the cursor is under the "9", then step size is 100 kHz and pressing the up (↑) key one time will change frequency to 623.050 MHz.
Reference Data and Clock Outputs This section explains how to set up the Generator's clock and data outputs as well as related pattern sync. and clock/4 outputs. Overview The OUTPUT section of the Generator front panel contains the instrument's main NRZ (clock + data) outputs: DATA DATA-BAR CLOCK CLOCK-BAR Note: The same term can be expressed three different ways. = CLOCK BAR = NOT CLOCK CLOCK = DATA BAR = NOT DATA DATA DATA and CLOCK are the non-inverted test pattern outputs of the GB1400 Generator.
Reference V top (clock ) C LO CK CLOC K Amplitude (pk -pk ) CLOC K Bas eline Offse t S ame amplitude a s C LOCK C LOC K Sa me offs et as CLOC K V top (da ta) DA TA D A TA A mplitude (pk-pk) DA TA Bas eline Offse t V top DA TA Sa me amplitude a s D A TA Same offset as D ATA Figure 3-1. Nominal Generator Clock and Data Waveforms Showing Amplitude, Baseline Offset, and Vtop.
Reference Amplitude and Baseline Offset The rules governing the setup of clock and data amplitude and baseline offset are as follows: RULE 1: When terminated by 50 Ohms to ground, the amplitude adjustment range of clock and data outputs is 0 to 2 V peak-to-peak . However, the absolute voltage of the pulse top cannot exceed +2.0 VDC, that is: Vamplitude p-p + Voffset ≤ 2.
Reference The following controls are used to set clock and data output amplitude and baseline offset: CLOCK : DATA: AMPLITUDE (↑ ↑ ,↓ ): BASELINE OFFSET (↑ ↑ ,↓ ): Note that when the CLOCK key is pressed, its LED turns on and the display shows clock output amplitude and offset. Similarly, when the DATA key is pressed, its LED will turn on and the display shows data output amplitude and offset. The general procedure for setting data and clock output amplitude and baseline offset is shown below. 1.
Reference Single-ended or Differential Operation DATA-BAR and CLOCK-BAR are complimentary outputs to DATA and CLOCK respectively. Therefore, to drive a single-ended clock or data input simply connect appropriate true output (CLOCK or DATA) while terminating its compliment (CLOCK-BAR or DATA-BAR) with 50 Ohms to ground.
Reference Error Injection The GB1400 Generator can inject bit errors, also known as logic errors, into the output data pattern. One use of error generation is to self-test the GB1400 Generator/Analyzer system. Or, when generating WORD patterns containing simulated framed signals, for example a SONET signal, error generation can be used to determine the ability of the terminal under test to detect errors or to stay in-frame in the presence of high error rates.
Reference Procedure to Control Error Injection Mode 1. Press the RATE key one or more times to select the desired error injection mode. Note that the LED in the RATE key will turn on except when mode is set to ERR OFF. Available selections are: ERR OFF: Single error injection. ERR 1E-7: Generate errors at rate of 10-7. ERR 1E-6: Generate errors at rate of 10-6. ERR 1E-5: Generate errors at rate of 10-5. ERR 1E-4: Generate errors at rate of 10-4. ERR 1E-3: Generate errors at rate of 10-3.
Reference Analyzer (RX) Functions This section explains how to enable or disable Analyzer automatic synchronization functions. It further shows how to manually set Analyzer input parameters and error detection functions, and how to start tests, view results, and print results. The section also defines all results calculated by the Analyzer. Automatic Setup Functions (SYNC ) This section explains how to use the following "SYNC" controls and indicator in the ERROR DETECTION section: AUTO SEARCH key.
Reference LOCK Indicator and Actions Taken by the Analyzer if Synchronization (Lock) is Lost The LOCK LED indicates whether or not BER is above or below the current synchronization threshold. The LOCK indicator will turn on while BER is below the current synchronization threshold, and off while BER is above this threshold. The setup actions taken by the Analyzer when BER crosses the synchronization threshold will depend on the state of the AUTO SEARCH and DISABLE keys, as shown in the table below.
Reference AUTO SEARCH with "Non-PRBS" Patterns In cases where you need to use a WORD or other type pattern for testing, you can still use AUTO SEARCH to set DATA and CLOCK threshold, and DATA input delay and threshold as follows: 1. Set up the Generator to transmit a PRBS pattern. 2. Enable Analyzer AUTO SEARCH as follows: EXT (ref. data input control), off SYNC DISABLE, off AUTO SEARCH, on 3. After the Analyzer LOCK LED turns on, disable AUTO SEARCH by pressing the AUTO SEARCH key.
Reference Synchronization (LOCK) Threshold The current synchronization threshold depends on pattern, and the setup of the SYNC Menu, as summarized in the table below: Table 3-5. Synchronization Threshold Pattern Type PRBS All WORD patterns (up to 16 bits) when 1-Mbit Option not installed. All WORD, mark density, or other ROM patterns with 1-Mbit Option installed. Threshold 1,024 errors in 4,096 bits (BER = 2.5 E-01) 128 errors in 4,096 bits (BER = 3.
Reference Clock, Data, and Reference Data Inputs This section explains how to set up Analyzer clock, data, and reference data inputs using front panel controls and Menus. Overview The Analyzer CLOCK, DATA, and REF DATA inputs are designed to accommodate a wide range of output logic levels and circuit designs. An equivalent circuit diagram of the Analyzer input section is shown in the following figure. Input Comp 50 Ω -2Vdc AC GND Figure 3-3.
Reference Controls The INPUT section controls that are used to set up input parameters are: DELAY key V-TERM key V-THRESH key INPUT (↑, ↓) Keys D-INV key In addition, the state of the F2 and F3 function keys determines the action of the INPUT up/down keys as shown in the table below. Note that this function of the F2 and F3 keys does not apply while the Analyzer is in the Menu mode. Table 3-6.
Reference AUTO SEARCH parameter. Therefore, you should normally turn off AUTO SEARCH if you want to fix delay at a specific value. Input Termination The input termination can be independently selected for the CLOCK, DATA, and REF DATA inputs. Note that the termination selected for CLOCK and DATA also applies to the CLOCK-BAR and DATA-BAR inputs. Available input terminations are shown in table below. Table 3-7. Input Terminations for CLOCK, DATA, and REF DATA Label Termination GND 50 Ohms to ground.
Reference Input Decision Threshold The input decision thresholds of the DATA, and REF DATA inputs can be independently adjusted. However, it is important to note that input threshold adjustment applies only for single-ended operation. When operating Analyzer data inputs in the differential mode, their input decision threshold effectively becomes the average of the positive peak and negative peak voltage levels and is not adjustable by the user.
Reference Singled-ended or Differential Operation Analyzer clock and data inputs can be operated in a singled-ended or differential mode. Differential operation provides greater immunity to ground noise and EMI. Note that threshold setup applies to the clock and data inputs only when they are operated in the singled-ended mode.
Reference Monitor Outputs The MONITOR CLOCK and DATA outputs are provided so that you can monitor the test signal as seen by the Analyzer. This allows you to attach an error logging device, for example, to record the exact times that errors occur. Or, you may attach another type of instrument to make specialized calculations. MONITOR DATA is an NRZ output signal with the same bit sequence as that recovered by the Analyzer front end circuit. MONITOR CLOCK is the corresponding clock signal.
Reference Error Detection Set Up Overview The GB1400 Analyzer calculates error results using three different methods: Window, Test, and Totalize. These three methods are independent of each other and can operate simultaneously. Window results are used to view current or "real-time" performance. Totalize results are generally used to view performance over long intervals. Test results are used to measure error performance over specified time intervals.
Reference How TOTALIZE Results are Measured Totalize results are measured continuously by the Analyzer. Totalize results can be cleared by the user (by pressing the CLEAR key when Totalize results are displayed). However, Totalize result accumulation is a continuous background process of the Analyzer and cannot be suspended by the user. The Totalize measurement process is illustrated in the figure below.
Reference CLEAR WINDOW interval "W" is set in terms of bits or time in using WINDOW menu. W W W Slip time "S" is effectively 200 ms in display or 1 sec. in End-of-Window reports S W W Figure 3-5. The WINDOW Measurement Process How TEST Results Are Measured Unlike Totalize and Window results, the accumulation of Test results can be started or stopped by pressing the CLEAR key. That is, the CLEAR key in effect becomes a test start/stop key.
Reference As shown in the next figure, Test results may be calculated using one of three timing modes: Timed, Untimed, or Repeat. T EST Measurement Process C LEAR U ntimed Measurement Interval U ntimed T EST Process: Intervals started and stopped manually by operator. TEST interval "T" set in terms of time (hrs:min:sec) in TEST menu. C LEAR Timed TEST Pr ocess: Interv als started by operator, stopped automatically at end of interval T.
Reference Display Mode: Totalize, Window, or Test When the Analyzer is not in the Menu mode, you can select a display mode using the SELECT DISPLAY key. The display mode determines which BER and Bit Error results are shown in the main display. BER results are shown in the top, middle field of the display, while Bit Error results are shown in the top right field. Display mode also determines which results will be cleared when you press the ERROR DETECTION CLEAR key.
Reference Window Process Set Up The Window measurement process may be configured using the four parameters in the WINDOW Menu: MODE: Defines window length in terms of "bits" or "seconds". BITS: Window length in bits. SECOND: Window length in terms of hours, minutes, and seconds. REPORT: Turns end-of-window reports on or off. If you want to measure Window results, you must set the MODE parameter, and depending on your MODE selection, either the BITS or SECOND parameter.
Reference Test Process Set Up The TEST Menu contains the following six selections: LENGTH: Test length: hours, minutes, seconds. MODE: Test timing mode: Timed, Untimed, or Repeat. REPORT: Test reporting mode: None, Print On Error, or Both. THRESH: Threshold for the TES (threshold errored second) result. SQUEL: On Error report squelch after 10 consecutive seconds: yes or no. PRINT: Use this function to print current Test results immediately.
Reference Viewing Results BER and bit error results are shown in the normal display mode. However to view the complete list of Test results, you must use the TEST Menu VIEW-CUR or VIEW-PRE functions. BER and Bit Errors The Analyzer calculates BER and bit errors using all three measurement methods (Totalize, Window, and Test). The current display mode determines which BER/bit error result pair is shown in the display.
Reference Printing Results (Reports) A serial or parallel printer may be connected to the Analyzer's RS-232-C or PRINTER ports respectively. Note that you cannot connect a GPIB printer directly to the GPIB port; but you may "print" results to a GPIB controller, which can store reports for later viewing or printing. Basic Report Setup Procedure The following initial setup procedure must be performed in order to generate any type of Analyzer report. 1.
Reference Analyzer Setup Report Press the F4 key at any time to print an immediate report listing the current setup of the Analyzer. This function is not available while the Analyzer is in the Menu mode. An example Setup Report is shown below. Example Analyzer Setup Report **** Tektronix, Inc. GB-1400 Jun/14/99 02:14:29 AUTO_SET AUTO DATA_DELAY 1.800E-9 DATA_THRES 0.05 RDATA_DELAY 0.000E-9 RDATA_THRES -1.
Reference End-of-Test Reports When End-of-Test reports are enabled, one End-of-Test report will be generated each time the end of a Test interval is reached. This can occur automatically, when timing mode is set to Timed or Repeat, or manually when the user stops an Untimed test by pressing the CLEAR key. Use the REPORT parameter in the TEST Menu to enable or disable End-of-Test reports. An example End-of-Test report is shown below.
Reference End-of-Window Reports When enabled, an End-of-Window report will occur once every second. The results of an End-of-Window report are based on a sliding interval T, where T is set in terms of bits or time (hours:minutes:seconds). Use the REPORT parameter in the WINDOW Menu to enable or disable End-of-Window reports. Use the MODE, BITS, and SECOND parameters in the WINDOW Menu to set window length T. An example End-of-Window report is shown below.
Reference On-Error Reports When enabled, On-Error reports are generated for each second in which error rate is above the current THRES threshold. Note that On-Error reports can be squelched after reports are generated on 10 consecutive seconds, by enabling the SQUEL feature. This is recommended for unattended operation since On-Error reports can generate a lot of paper. An example On-Error report is shown below.
Reference Result Definitions The following section defines all results calculated by the Analyzer. BER and Bit Errors The following two results are calculated by all three Analyzer measurement processes (Totalize, Window, and Test): Bit Errors : The total number of bit (logic) errors counted in the measurement interval. May be based on Totalize, Window, or Test measurement intervals. Bit Error Rate (BER): Also known as "bit error ratio". May be based on Totalize, Window, or Test measurement intervals.
Reference Errored Seconds (ES): The number of seconds in the measurement interval containing one or more errors. The GB1400 measures asynchronous errored seconds—that is one second intervals based on the instrument's internal clock rather than the detection of an error. Errored seconds are not counted during unavailable time (see below). However, the errored second count does include both severely errored seconds and non-severely errored seconds.
Reference TES: Threshold Errored Seconds: The number of seconds in the measurement interval in which BER exceeds the threshold set by the THRES parameter in the TEST Menu, minus the number of unavailable seconds. Available threshold values are 1E-n, where n = 2, 3, ... 16. TES = (seconds with BER ≥ Threshold) - US US = unavailable seconds in the current interval Degraded Minutes (DM): The number of 60 second intervals in the current interval in which the BER exceeds the current test threshold (THRES).
Reference CLEAR Control Pressing the CLEAR key will reset all active history indicators. Note that when you start a test, you must clear test results and history indicators by pressing the ERROR DETECTION CLEAR and ERROR HISTORY CLEAR keys respectively. Audio (Beeper) Function The Analyzer may be set up to "beep" each time a second is detected in which BER is above a specified threshold. The AUDIO VOL and RATE controls are used to configure this function. Procedure To Set Up the Audio Alert Function 1.
Reference Starting and Stopping Measurements The following section explains how to start and stop TEST measurements, and how to initialize or "re-start" WINDOW and TOTALIZE measurements. The TEST measurement process has two states: started and stopped . In the started or active state, new "current" results are accumulated while all results from the previous TEST interval are saved in memory.
Reference mode is selected, TEST intervals must be started and stopped manually by the user. When the Timed mode is selected, TEST intervals are started manually, but stopped automatically after an interval determined by the LENGTH parameter in the TEST Menu. When the Repeat timing mode is selected, once the TEST process has been started by the user, new TEST intervals are stopped and then restarted automatically, at intervals determined by the LENGTH parameter.
Reference Menus This chapter explains how to use the GB1400 Menu system. It includes basic rules, an overview of the Generator and Analyzer Menu structures, and a description of each Menu function. Functions Performed Using the Menu System The GB1400 Menu system is used to perform two types of functions: setup and immediate. Menu setup functions are used to set up instrument parameters such as test mode (untimed, timed, or repeat), of test duration, and window length.
Reference F1 F2 F3 F4 MORE LENGTH MODE REPORT 3. Press F2 and you will see the LENGTH function: F1:ESC F2<- ->F3 F4:SET TEST LENGTH = 01:00:00 NOTE: Your display may show a different value. 4. The TEST LENGTH function allows you to set the length of timed tests in terms of hours, minutes, and seconds. Notice that either the hours, minutes, or seconds field will be flashing. To change the value of the flashing field, press the pattern up/down keys.
Reference F1:ESC F4:SET TEST MODE = TIMED 8. As before, to lock in this setup change and return to the TEST Menu, press the F4 key and see: F1 F2 F3 F4 MORE LENGTH MODE REPORT 9. The last function we'll perform in this example is to enable End-of-Test and On-Error reports. To do this select the REPORT function by pressing F4 and see: F1:ESC F4:SET REPORTS ON = NONE 10. Now press the pattern up key three times to select EOT/ERROR which will enable both End-of-Test and On-Error reports.
Reference At this point you could perform a 30 minute timed test by: 1. Selecting the TEST display mode (press DISPLAY SELECT until a "T" appears in front of the BER field) and 2. Pressing the ERROR DETECTION CLEAR key to start a timed test interval. General Rules for Using the Menu System Operation of the GB1400 Analyzer and Generator Menu systems can be summed up by the following rules: 1. From the normal display mode, press F1 to enter the Menu system. 2.
Reference Menu Summaries The GB1400 Generator and Analyzer Menu system may be thought of as a top level or "main" Menu plus a series of sub-Menus, with each sub-Menu containing a group of related functions. In this section you will find: 1. A brief description of each Menu found in the GB1400 Menu system. 2. An overall view of the Analyzer Menu system. 3. An overall view of the Generator Menu system.
Reference Table 3-11.
Reference Table 3-12. Generator Menu System Overview Menu Page F1 F2 F3 F4 MAIN 1 2 RS232 UTIL GPIB WORD RS232 1 2 BAUD EOL PARITY XON/XOFF SIZE ECHO WORD 1 2 MORE EXIT (to Normal mode) MORE ESC (to MAIN Menu) MORE* ESC (to MAIN Menu) ESC (to MAIN Menu) EDIT* ORDER3 LENGTH* BUFFER FILL* -- OPTION VER -- UTIL 1 NOTES: 3-54 1. Menu names appear in bold typeface. 2. Functions included only in instruments equipped with the 1-Mbit Option are marked with an asterisk (*). 3.
Reference Menu Function Definitions This section describes each Menu function included in the GB1400 Menu system.
Reference Word Edit (EDIT) Format: F1:ESC F2<- ->F3 F4:SET WORD AT ddddd = bbbbbbbb Menu: WORD Function Name: EDIT Instruments: Analyzer and Generator Options: Requires the 1-Mbit Option. Application: Use this function to create new WORD patterns or edit the current WORD pattern. Parameters: Byte Location (ddddd): Set this parameter to the location (in decimal) of the byte you want to edit in the current WORD.
Reference Word Length (LENGTH) Format: F1:ESC F2<- ->F3 F4:SET LEN:mmmmm BYTES + n BITS Menu: WORD Function Name: LENGTH Instruments: Analyzer and Generator Options: Requires the 1-Mbit Option. Application: Use this function to set the length of the current WORD pattern. Parameters: Bytes (mmmmm): Set this parameter to the number of whole bytes in the pattern length. That is, if length is M bytes + N bits, set this parameter to M.
Reference Word Fill (FILL) Format: F1:ESC F4:SET FILL WORD MEMORY WITH:hh Menu: WORD Function Name: FILL Instruments: Analyzer and Generator Options: Requires the 1-Mbit Option. Application: Use this function to fill all bytes in the current WORD with the same 8-bit pattern. Parameters: Fill Byte (hh): Enter the hex value for the fill byte Range: 00 to FF.
Reference Word Order (ORDER) Format: F1:ESC F4:SET WORD ORDER = ccc FIRST Menu: WORD Function Name: ORDER Instruments Analyzer and Generator Options: Requires the 1-Mbit Option. Application Use this function to change the transmit or analysis bit order (MSB first or LSB first) of the current WORD pattern. Parameters: Word Order (ccc): May be set to LSB or MSB. Note: Word order also applies to the fractional end-byte in patterns that do not contain an exact multiple of eight bits.
Reference Word Synchronization Threshold (SYNC) Format: F1:ESC F4:SET WORD SYNC THRES LEVEL= d Menu: WORD Function Name: SYNC Instruments: Analyzer only Options: Requires the 1-Mbit Option. Application: This function is used to set the BER synchronization threshold used by the Analyzer for long WORD patterns. This function does not affect the sync. thresholds for PRBS or short WORD patterns, which are fixed.
Reference Buffer Format: F1: ESC WORD MEM: 0 Menu: WORD àMORE à BUFFER Function Name: BUFFER Instruments: Generator and Analyzer Options: 0 segments 1 Mbit 1 segment 512 kbits 3 segments 256 kbits 6 segments 128 kbits 10 segments 64kbits F4: SET 1M BUFFERS Application: Selecting memory locations Parameters: Ten possible WORD memory selections are WORD 0 thorugh WORD 9.
Reference AUTO Format: F1: ESC F4: SET AUTO SEARCH MODE Menu: Main Menu àF4 à AUTO Function Name: AUTO Instruments: Analyzer only Options: FAST - So-called because of the speed which it determines the threshold voltage setting, delay, data pattern and polarity. BER - This method requires the user to set criteria pertaining to Bit Error Rate threshold and sample size that is used to determine the size and center of the data eye.
Reference Test Length (LENGTH) Format: F1:ESC F2<- ->F3 F4:SET TEST LENGTH = hh:mm:ss Menu: TEST Function Name: LENGTH Instruments: Analyzer only Options: None required. This is a standard feature. Application: Use this function to set the duration of timed tests and the repeat interval of repeat timed tests. Parameters: Hours (hh): Set from 00 to 23. Minutes (mm): Set from 00 to 59. Seconds (ss): Set from 00 to 59.
Reference Test Mode (MODE) Format: F1:ESC F4:SET TEST MODE = ccccccc Menu: TEST Function Name: MODE Instruments: Analyzer only Options: None required. This is a standard feature. Application: Use this function to select a test timing mode. Parameters: Test Timing Mode (ccccccc): May be set to TIMED, REPEAT, or UNTIMED Notes: This function applies only to the TEST measurement process and has no impact on either the TOTALIZE or WINDOW measurement processes.
Reference Test Reports (REPORT) Format: F1:ESC F4:SET REPORTS ON = ccccccccc Menu: TEST Function Name: REPORT Instruments: Analyzer only Options: None required. This is a standard feature. Application: Use this function to enable or disable End-of-Test and OnError reports. Parameters: Reports On (ccccccccc): May be set to: NONE: All test reports are disabled. END OF TEST: Only EOT reports enabled. ON ERROR: Only On Error reports enabled. EOT/ERROR: Both EOT and On Error reports enabled.
Reference Test Threshold (THRES) Format: F1:ESC F4:SET ERROR THRESHOLD = eeeee Menu: TEST Function Name: THRES Instruments: Analyzer only Options: None required. This is a standard feature. Application: Use this function to set the value of the test threshold. Parameters: Test Threshold (eeeee): Set from 1E-03 to 1E-16. Notes: The test threshold affects On-Error reports and the TES (threshold errored second) result.
Reference Test Squelch (SQUEL) Format: F1:ESC F4:SET ON ERROR SQUELCH = ccc Menu: TEST Function Name: SQUEL Instruments: Analyzer only Options: None required. This is a standard feature. Application: Use this function to enable or disable squelching of On-Error reports.
Reference Test Print (PRINT) Format: F1:ESC F4:SET F4 TO PRINT TEST RESULTS Menu: TEST Function Name: PRINT Instruments: Analyzer only Options: None required. This is a standard feature. Application: Use this function to print a test summary report based on current test results (if a test is in progress) or previous test results (if a test is not in progress). Parameters: None. This is an immediate function.
Reference Test View Previous (VIEW-PRE) Format: F1:ESC F4:SET (result name)(count) (%) Menu: TEST Function Name: VIEW-PRE Instruments: Analyzer only Options: None required. This is a standard feature. Application: Use this function to view results from the last completed test. Parameters: This is an immediate function. After selecting VIEW-PRE use the pattern up/down keys to scroll through the results shown below.
Reference Test View Current (VIEW-CUR) Format: F1:ESC F4:SET (result name)(count) (%) Menu: TEST Function Name: VIEW-CUR Instruments: Analyzer only Options: None required. This is a standard feature. Application: Use this function to view current test results. In effect this function takes a snap shot of the latest results from a test in progress. Parameters: None. This is an immediate function. Use pattern up/down keys to scroll through results.
Reference Window Mode (MODE) Format: F1:ESC F4:SET WINDOW MODE = ccccccc Menu: WINDOW Function Name: MODE Instruments: Analyzer only Options: None required. This is a standard feature. Application: Use this function to set window length equal to the number of bits specified by the WINDOW BITS function, or the time specified by the WINDOW SECOND function. Parameters: Window Mode (ccccccc): May be set to BITS or SECONDS.
Reference Window Interval in Bits (BITS) Format: F1:ESC F4:SET WINDOW LEN = 1.0eEE BITS Menu: WINDOW Function Name: BITS Instruments: Analyzer only Options: None required. This is a standard feature. Application: When WINDOW MODE is set to BITS, use this function to set window duration in terms of bits. Parameters: Window Length (EE): May be set from 1.0e08 to 1.
Reference Window Interval in Hrs:Min:Sec (SECOND) Format: F1:ESC F2<- ->F3 F4:SET WINDOW LEN = hh:mm:ss Menu: WINDOW Function Name: SECOND Instruments: Analyzer only Options: None required. This is a standard feature. Application: When WINDOW MODE is set to SECONDS, use this function to set window duration in terms of hours, minutes, and seconds.
Reference Window Reports (REPORT) Format: F1:ESC F4:SET END OF WINDOW PRINT = ccc Menu: WINDOW Function Name: REPORT Instruments: Analyzer only Options: None required. This is a standard feature. Application: Use this function to enable or disable End-of-Window reports. Parameters: End-of-Window Print (ccc): May be set to ON or OFF. Notes: To print End-of-Window reports, be sure ON/OFF parameter in PRINT Menu is set to ON.
Reference RS-232 Baud Rate (BAUD) Format: F1:ESC F4:SET BAUD = dddd Menu: RS232 Function Name: BAUD Instruments: Analyzer and Generator Options: None required. This is a standard feature. Application: Use this function to set the baud rate of the serial (RS-232C) port. Parameters: Baud rate (dddd): May be set to 300, 600, 1200, 2400, 4800, or 9600.
Reference RS-232 Parity (PARITY) Format: F1:ESC F4:SET PARITY = cccc Menu: RS-232 Function Name: PARITY Instruments: Analyzer and Generator Options: None required. This is a standard feature. Application: Use this function to set parity for the serial port.
Reference RS-232 Data Bits (SIZE) Format: F1:ESC SIZE = F4:SET d Menu: RS232 Function Name: SIZE Instruments: Analyzer and Generator Options: None required. This is a standard feature. Application: Use this function to set the number of data bits per character for the RS-232 (serial) port. Parameters: Number of Data Bits (d): May be set to 7 or 8.
Reference RS-232 End-of-Line Char. (EOL) Format: F1:ESC F4:SET EOL = ccccc Menu: RS232 Function Name: EOL Instruments: Analyzer and Generator Options: None required. This is a standard feature. Application: Use this function to select an end-of-line terminator. This character or pair of characters will be added to the end of every line in reports sent to the RS-232 port. Parameters: End-of-Line Terminator (ccccc): May be set to CR/LF, LF/CR, CR, or LF.
Reference RS-232 Xon/Xoff (XON/XOFF) Format: F1:ESC F4:SET XON/XOFF ENABLE = ccc Menu: RS-232 Function Name: XON/XOFF Instruments: Analyzer and Generator Options: None required. This is a standard feature. Application: Use this function to enable or disable Xon/Xoff flow control. Parameters: Xon/Xoff Flow Control (ccc): May be set to ON (enabled) or OFF (disabled).
Reference RS-232 Echo (ECHO) Format: F1:ESC F4:SET RS232 ECHO ENABLE = ccc Menu: RS232 Function Name: ECHO Instruments: Analyzer and Generator Options: None required. This is a standard feature. Application: Use this function to enable or disable character echo on the RS-232 port. When enabled, the instrument will "echo" (that is, transmit back to the controller) each character that it receives on the RS-232 port. Parameters: RS-232 Echo Enable (ccc): May be set to ON or OFF.
Reference GPIB Format: F1:ESC F4:SET TERMINATOR = cccccc Menu: Selected from "main" Menu. Function Name: GPIB Instruments: Analyzer and Generator Options: None required. This is a standard feature. Application: Use to select the GPIB end-of-line termination character or characters. Parameters: GPIB End-of-Line Terminator (cccccc): May be set to EOI or EOI/LF.
Reference Utility Option (OPTION) Format: F1:ESC (options listed here) Menu: UTIL Function Name: OPTION Instruments: Analyzer and Generator Options: None required. This is a standard feature. Application: Use this function to see which options are installed in your Analyzer or Generator. Parameters: None. This is an immediate function.
Reference Utility Version (VER) Format: F1:ESC (software version listed here) Menu: UTIL Function Name: VER Instruments: Analyzer and Generator Options: None required. This is a standard feature. Application: Use this function to see the software version installed in your unit. Parameters: None. This is an immediate function.
Reference Time Option (DATE) Format: F1:ESC F2<- ->F3 F4:SET DATE = mmm dd yy Menu: Selected from main Menu. Function Name: DATE Instruments: Analyzer only Options: None required. This is a standard feature. Application: Use to set the Analyzer's internal date function. Parameters: Month (mmm): Set in range JAN, FEB, ..., DEC Day (dd): Set in range 01, 02, ..., 31 Year (yy): Set in range 93, ..., 99 Notes: End-of-Test reports are date and time stamped.
Reference Time Option (TIME) Format: F1:ESC F2<- ->F3 F4:SET TIME = hh:mm:ss Menu: Selected from main Menu. Function Name: TIME Instruments: Analyzer only Options: None required. This is a standard feature. Application: Use this function to set the instrument's 24-hour internal clock. Parameters: Hours (hh): Set in range 00 - 23 Minutes (mm): Set in range 00 - 59 Seconds (ss): Set in range 00 - 59 Notes: The Analyzer clock uses a 24-hour format.
Reference 3-86 GB1400 User Manual
Appendices
Specifications This appendix details the Specifications of the GB1400 Generator (TX) and GB1400 Analyzer (RX). Note: The same term can be expressed three different ways. CLOCK DATA = CLOCK BAR = DATA BAR = NOT CLOCK = NOT DATA GB1400 Generator (TX) Internal Clock Source Frequency Range 1 MHz to 1400 MHz Step Size Range 0.01,0.
Specifications Data Patterns Format NRZ-L, Normal and Complement Type PRBS or WORD (User-programmable) PRBS Patterns 2n-1; n=7,15,17,20,23 WORD Lengths 8 and 16-bit only, 1 Mbit memory (with optional memory) PRBS Phase Tap Information The Pseudo-Random data patterns used in the GB1400 TX are generated by shift-register and exclusive-OR feedback technique. The pattern is dependent on which feedback taps (shift register outputs) are selected.
Specifications Clock Output (True and Complement) Amplitude Variable, 0.5V to 2.0V, 50 mV steps Baseline Offset Variable, -2.0V to +1.0V, 50 mV steps -2.0V to +1.8V, 50 mV steps, with PECL option Pulse Top Limit +2.0V into 50 Ohms, +4V open load +2.8V into 50 Ohms, with PECL option Rise/Fall Time 150 pS, typical (20-80%) at 1V amplitude Jitter: 100 pS, peak-to-peak Max.
Specifications RS-232 and GPIB Interfaces Controlled functions Remote control of all front panel functions except POWER and PANEL LOCK. Read-back functions Read-back of ten clock frequencies and ten data patterns stored in non-volatile memory, unit operating frequency, clock source status, pattern select.
Specifications GB1400 Analyzer Clock Input Frequency Range 1MHz to 1400 MHz Input Level 0.5V to 2.0Vp-p,. Single Ended or Differential Impedance 50 Ohms, AC coupled (50 Ohm ECL to -2V with BURST MODE option) Input Threshold Non-programmable (fixed threshold levels) Connector SMA Burst Mode (option) 150 kHz to 1400 Mhz (ECL Levels) Data Input Format NRZ-L, True or inverted, differential or single-ended Data Rate 1 to 1400 Mb/s (Burst Mode option 150 kbps to 1400 Mbps) Input Threshold -1.
Specifications Data Patterns Format NRZ-L Type PRBS or WORD (User-programmable) PRSB Patterns 2n-1 where n =7,15,17,20,23 WORD Length 8- and 16-bit only, 1 Mbit with optional memory PRBS Phase Tap Information The Pseudo-Random data patterns used in the GB1400 RX are generated by shift-register and exclusive-OR feedback technique. The pattern is dependent on which feedback taps (shift register outputs) are selected.
Specifications Auxiliary Signals: Pattern Sync, Clock, Data, Error and Threshold Level 250 mVp-p into 50 Ohms, 500 mV into Hi-Z Impedance 50 Ohms Data Monitor Latched Input Data Clock Monitor Buffered Input Clock Pattern SYNC 1-bit wide pulse per frame Error Inhibit Rear panel, ECL Error Output Rear panel, ECL AUX Rear panel, Data Threshold output Note: Connect this output to DATA BAR (Not DATA) for single-ended operation.
Specifications SYNC thresholds PRBS mode 25% (1024 erros/4096 bits) WORD mode 3.1% (128 errors/ 4096 bits) Optional 1 Mbit WORD thresholds, programmable Level BER Ratio (Errors/bits) 1 3.1E-2 256/8192 2 7.8E-3 256/32768 3 1.9E-3 256/131072 4 9.7E-4 256/262144 5 4.8E-4 256/524288 6 2.4E-4 256/1048576 7 1.2E-4 256/2097152 8 6.1E-5 256/4194304 9 3.0E-5 256/8388608 Measurements BER Measurements Three simultaneous BER measurements (Totalize, Window and Test) displayed as: BER 9.
Specifications RS-232 and GPIB Interfaces Controlled functions Remote control of all front panel functions except POWER and PANEL LOCK. Read-back functions Read-back of ten data patterns stored in non-volatile memory - unit operating frequency, bit error rate information, sync and history status, pattern select.
Specifications A-10 GB1400 User Manual
BERT Primer/ Technical Articles Section Table of Contents • BERT Primer, see page B-2 Technical Articles GB1400 User Manual • BERT - First and last measurement tool for transmission device design acceptability, see page B-13 • Ensure Accuracy of Bit Error Rate Tests, see page B-21 • Measure Error Rates Quickly and Accurately, see page B-32 B-1
BERT Primer BERT Definition A critical element in digital transmission systems is how error-free its transmissions are. This measurement is made by a bit-error-rate test set (BERTs). BERTs are not focused or geared to any particular transmission format or protocol (although they may be capable of emulating a number of such formats); and are not confined to any specific data rates within their operating range.
BERT Primer BERT Pattern Generation Almost all BERT generators include some type of pseudo-random patterns generation. These “PRBS” patterns are used to stimulate a “Device Under Test” (DUT) for the purpose of comparing actual received data with the “reference” data available to the receiver. These PRBS patterns are described below. PRBS Patterns A type of data pattern used by most BERTs is called “PRBS” - pseudo-random binary sequence.
BERT Primer The Tektronix PB200 provides capabilities to invert data on both transmit and receive. This provides full flexibility to adjust the PRBS signal to the user's exact requirements. Table B-1 identifies the PB200 polynomial and shift register feedback taps used to generate PRBS data.
BERT Primer PRBS Generation Circuits - A few sample diagrams PRBS generators are named after the number of combinations they generate; thus the 28 -1 PRBS is generated from 255 unique 8-bit combinations, each producing one bit in the output stream. The all-zero state is excluded (accounting for the -1), because it would generate itself and no other combination.
BERT Primer D Q1 D Q2 D Q3 D Q4 D Q5 D Q6 D Q7 output CLK 7 Figure B-3. Seven-stage PRBS generator (2 -1 PRBS) with taps at 6 and 7 The serial patterns generated by the four stage 24 -1 PRBS generator (figure B-4 on previous page) is listed below. 4 Table B-3.
BERT Primer BERT Clock A clock source is necessary to provide the timing for generation of the BERT digital output, and to provide the logic strobe for acquisition of the data by the receiver. The Clock must provide clean, sharp logic transitions and needs to be delayable to account for time the signals from the BERT take to propagate through the DUT. Most BERTs have an internal clock source. All BERTs have the ability to operate using an External Clock.
BERT Primer Received Data Pattern Reference If the transmitter is using some other known standard pattern, such as a particular Mark-Space Density pattern, a copy of that pattern must also be generated by the receiver. The BER reference data may be a User Defined pattern. The same pattern used by the transmitter must be loaded into the analyzer's memory.
BERT Primer Confidence Level in BER Measurement At first glance, one might think that the BER is known after receiving just one bit error. It would be expressed as 1 over the total number of bits received. But how do we know what the “true” BER is? After all, the first errored bit could have been just a freak “glitch”. In reality, from a statistical confidence point of view, we must measure long enough to get many errors. This could take a very long time.
BERT Primer Other BERT Features In addition to measuring Bit Error Rate, BERTs may have additional features which enhance ease of use or expand test capabilities.
BERT Primer Pattern Lock Before a BER measurement can be made, the BERT Transmitter and Receiver must be using the same test pattern. This may be guaranteed if they use the same PRBS or fixed word pattern and are running at the same clock rate, but there is still the issue of having the bit comparison begin at the same point in the pattern. All of our general purpose BERTs have the ability to do an “auto search” for pattern lock.
BERT Primer Jitter Generation Some BERTs have the ability to generate and impose jitter on the internal clock. A jittered External Clock input is the means for adding jitter to the Tx source on GB700 and GB1400 BERT instruments.
Technical note BERT - first and last measurement tool for transmission device design acceptability Bit error rate testers (BERTs) are the basic tool for testing the quality of transmission systems and circuit elements. The job of the BERT is simple - to feed test patterns bit-by-bit through the transmission path or device-under-test (DUT), and confirm that the error rate is sufficiently low. Typical acceptable error rates might be one in one billion bits or lower. Under the hood, BERTs are all 1s and 0s.
BERT Technical Articles SESs for which the previous two seconds were also SESs. Some BERTs will graph these and other errors over time to illustrate clumping or mark events. How long is long enough? Every time the BERT detects an error, it logs another check mark in the error column and updates the other various measurements it makes.
BERT Technical Articles 10 1 2 10 10 BER 10 10 10 10 10 3 4 5 6 7 8 10 9 10 10 10 10 10 11 12 13 10 14 10 10 15 16 7 8 9 10 11 12 13 14 15 16 17 18 SNR (dB) Figure 1.
BERT Technical Articles ISI errors are caused when particular patterns (symbols) of data interfere with each other, leading to blurring and smearing of signals. An example of ISI can be illustrated by following a square wave (1010....). When the signal leaves the transmitter, the corners of the square wave are sharply defined. As the signal travels a couple of miles over a transmission medium, attenuation (a function of distance) sets in.
BERT Technical Articles Stressing through pattern generation One common stress test employs a pseudorandom binary sequence (PRBS) generator to create test data. The PRBS generator is seeded with a nonzero pattern of n bits. Using a shift register with XOR feedback, the PRBS will cycle endlessly through every combination of n-bits (except for the all-zero state), with no repeats until every combination has been generated (see Figure 3 and Table 2 for the 24 -1 PRBS). XOR A B C D Figure 3.
BERT Technical Articles PRBS generators are named after the number of combinations they generate; thus the 28 -1 PRBS is generated from 255 unique 8-bit combinations, each producing one bit in the output stream. The all-zero state is excluded (accounting for the -1 in 28 -1", above), because it would generate itself and no other combination. The purpose of a PRBS is to stress a system by testing possible combinations of data that could pass through the device, bringing out different types of problems.
BERT Technical Articles For example, you could use a saved pattern to create an ATM header and a generated pattern to populate the packet with random data, allowing you to build test data that looks more like "live traffic". If you are testing an error-correcting circuit on a modem, the transmitted pattern could have parity errors that the modem should correct.
BERT Technical Articles B-20 GB1400 User Manual
BERT Technical Articles Technical Article from 5/9/91 Electronic Design magazine Ensure Accuracy Of Bit-Error Rate Tests By Dan Wolaver and James Hanley, Tektronix ========== To properly evaluate digital transmission systems, users must understand their BER tester’s specifications. ========== A critical element in a digital transmission system is how error-free its transmissions are.
BERT Technical Articles A clock source produces a clock signal, C, that times the occurrence of each bit in the digital signal. A driver, which may be a power amplifier, a laser diode, an RF modulator, or a tape head, prepares the signal for the system under test. The system under test can be a transmission line with repeaters, or an optical fiber link, microwave radio link, or digital tape recorder.
BERT Technical Articles BERT receiver Data Source Driver System under test Line receiver H’ H F Clock Source Data pattern generator Decision circuit Error monitor G C D’ Data pattern generator BERT transmitter Clock recovery (a) Data pattern generator BERT receiver F Clock Source Data Source Driver System under test Line receiver H’ H Decision circuit Error monitor G Clock Source C’ Data pattern generator D’ (b) Clock recovery G’ Clock recovery BERT transmitter Jitter genera
BERT Technical Articles Likewise, the BERT’s clock-recovery circuit must tolerate at least as much jitter as the system’s recovery circuit without causing errors. Although the BERT clock source should be essentially jitter-free to test the digital transmission system under normal conditions, users may wish to stress the system at times. In that case, the BERT must generate controlled jitter. To do so, some BERTs have a jitter generator that can sinusoidally modulate the phase of the clock source.
BERT Technical Articles 0.1 µ F D’ C R 50 (a) D’ Avergage = -0.5 Average = 0.5 1 Time -1 Pattern A Pattern B 1 Pattern A (b) F 2 1 -1 Time RC 0.5 0.5 (c) Figure 3. (a) Most transmission systems use AC coupling. (b) Consequently, a bit-error-rate tester can measure the system's noise margin by generating signal patterns with an unbalanced number of 1s and 0s. (c) The result is baseline wander, which reduces the margin between the received signal, F, and the threshold.
BERT Technical Articles To stress the noise margin continuously, the tester alternates between 10001000 (pattern A) and 11101110 (pattern B) at a frequency below the AC coupling circuit’s cutoff frequency. Each pattern continues long enough for the circuit’s transient to die out. A duration of 3.14 time constants, or πRC, is sufficient. Therefore, the complete fixed pattern stored in memory has a period of at least 2πRC.
BERT Technical Articles The simplest fixed pattern with a 50% transition density is again 11001100. The patterns in Table 1 that stress noise margin by varying the balance of 1s and 0s also maintain a 50% transition density. Similarly, patterns that stress the clock-recovery circuit by varying transition density should keep the 1s and 0s in balance (see the following table). Table 2.
BERT Technical Articles To stress the noise margin, the PRBS spectrum must have components below the coupling circuit’s cutoff frequency, fL . For example, a 23-stage PRBS generator with a bit rate, fc, of 44.7 Mbits/s has a pattern length of 223 -1=8,388,607 bits. The fundamental frequency, fF, is fc/8,388,607=5.33 Hz. If fL =32 kHz, thousands of the pattern’s spectral components are removed.
BERT Technical Articles If the transmitter clock source has phase jitter θi , the received data signal, F, has the same jitter. But the eye pattern does not display this jitter because the scope is synchronized to the data. In general, θo , which is the phase of the recovered clock signal, G, cannot track θi , exactly, so some phase error (θe=θi -θo) exists between the clock and the data. With the oscilloscope synchronized to the data, this error is seen as a broadening of the recovered clock’s trace.
BERT Technical Articles Jitter Tolerance In general, the noise and imperfect equalization of the transmission system itself introduce much more jitter than the clock source does. If the jitter, qi , of the received data exceeds the receiver’s jitter tolerance, the receiver will begin making errors. When the BERT is recovering its own clock, the instrument receiver’s jitter tolerance must be greater than the system receiver’s for all waveforms. Otherwise, the BERT will report an incorrectly high error rate.
BERT Technical Articles A BERT designed to measure jitter has a phase demodulator connected to the covered clock. The range of fm is from f1 =10 Hz to f4 ; the amplitude depends on fm. The BERT’s jitter generation and jitter measurements specifications should be somewhat higher than the maximum jitter that a system can typically tolerate. As a result, a BERT with jitter generation can find a receiver’s θe max by setting f m=f4 and increasing A until the receiver begins to make errors.
BERT Technical Articles Technical article from 5/95 issue of Electronic Design Magazine Measure Error Rates Quickly and Accurately By Dan H. Wolaver, Tektronix, Inc. Abstract The accurate measurement of the error rate of a digital communication system requires that a good number of errors be recorded. We show that if n errors are counted, then the inaccuracy is about 1/ n . For example, by recording 400 errors, the inaccuracy is 5%.
BERT Technical Articles If a BERT such as the Tektronix GB700/ GB1400 is used to measure the error rate, the current BER is continually calculated and displayed according to the formulas r' = n / T (2) and BER' = r' / fb = (n / T) / fb , (3) where r' and BER' are the measured estimates of the actual r and BER, T is the elapsed measurement time, and n is the number of errors counted during T. The variation of r' as T increases is shown in Figure 2.
BERT Technical Articles That is, n is within n of the expected count most of the time (68% of the time). If we take the inaccuracy of the measurement to be σ as a fraction of n, then Inaccuracy68% = σ / n ≈ 1/ n . (7a) This relationship is plotted in Figure 3 (the curve for 68% confidence). Inaccuracy in % 30 95% Confidence 20 68% Confidence 10 0 10 100 1000 10000 Number of errors measured n Figure 3. Inaccuracy error-rate measurement can be expressed as a function of the number of errors measured.
BERT Technical Articles Testing for an Upper Limit on Error Rate If a communication system is required to have a BER less than 10–9, the system design usually provides a couple dB of margin. This margin can make the nominal error rate on the order of 10–12 , which is an average of only one error a week for fb = 1.544 Mbit/s! It is clearly impractical to measure such a low error rate accurately. But accuracy is not needed here––only some confidence that the error rate is less than 10–9.
BERT Technical Articles Standard Mathematical Tables published by the Chemical Rubber Co, or use the software product Mathcad produced by MathSoft. It is usually convenient to measure signal strength and noise in dB. Let the signal-to-noise ratio in dB be defined as SNR = 20 log(S / Nrms). (12) Then with Equation (11) we can find BER as a function of SNR. This is plotted in Figure 4. In Figure 4a the BER axis is a log scale.
BERT Technical Articles BER vs. Attenuation appears as a straight line because the BER scale is again distorted. The line here is for the case SNR0 = 18 dB. For other values of SNR0, the plot would fall parallel to the line in Figure 5. Remember that we are talking about electrical attenuation here; 1 dB of optical attenuation is worth 2 dB of electrical attenuation. 10 10 2 3 BER 10 10 10 10 10 4 5 6 7 8 9 10 10 10 10 10 12 14 10 16 0 1 2 3 4 5 6 7 8 9 10 11 Attenuation (dB) Figure 5.
BERT Technical Articles Example 1 A 44.736-Mbit/s system seems to have a very low error rate; in a five-minute test no errors occurred. It is decided to use stress to estimate the BER with no stress. When 5 dB of electrical attenuation is placed in the signal path, 13,400 errors are measured in one second––a BER of 13400 / 44736000 = 3×10−4. Using graph paper like that provided at the end of this article, plot a point at Attenuation = 5 dB and BER = 3× 10 −4, as in Figure 6.
BERT Technical Articles Note that the line through the points in Figure 6 has about the same slope as the dashed lines. This indicates the noise is about Gaussian. As the slope of the plotted line is closer to that of the dashed lines, the noise process is closer to Gaussian, and the extrapolation is more reliable.
BERT Technical Articles confidence that the stressed error rate is less than 10−5. By extrapolation, we are 95% confident the unstressed BER is less than 10−9. 10 4 BER 10 10 10 10 10 10 10 Example 3 5 6 Example 4 7 8 9 10 12 0 0 1 0.5 2 1 3 1.5 Attenuation (dB) 4 2 5 (elec) 2.5 (opt) -9 Figure 7. This plot determines the attenuation necessary to turn a test for BER=10 with no stress -5 -9 into a test for BER=10 with stress (the third example in text).
BERT Technical Articles Make a plot of BER versus Attenuation for SNR0 = 10 −10 by starting at BER = 10−10 for Attenuation = 0, and draw a straight line parallel to the dashed lines, as in Figure 7. We will use a smaller stress than in Example 3. An optical attenuation of 1 dB (equivalent to 2 dB of electrical attenuation) would raise the BER to 2×10−7 , or a stressed error rate of rs = 51840000 × 2×10−7 = 10.37 errors per second.
BERT Technical Articles Sidebar article to Measure Error Rates Quickly and Accurately Poisson Error Process A Poisson process is one in which events are not dependent on each other, and conditions causing the events don't change with time. Raindrops hitting a skylight is an example of a Poisson process. The impact of one raindrop doesn't affect the arrival time of another. If we know the average rate r of a Poisson error process, then we have completely characterized it.
BERT Technical Articles (µ − σ) / T < r' < (µ + σ) / T or r − r / T < r'< r + r / T . These two "bounds" are shown by the two curves in Figure S-2. The measured error rate r' is seen to lie between them most of the time. As T increases, the bounds get closer to r = 5 / hr, but there will always be some deviation of r' from r. Therefore the "actual" error rate r can never be known in practice; it would take an infinite time to measure r. The standard deviation of the error measurement n is σ = µ = rT .
BERT Technical Articles Biography Dan Wolaver is director of research and development at Tektronix/BTT, Inc. He received a PhD in electrical engineering from MIT in 1969. For ten years he worked for Bell Labs on digital communications systems, and he taught at Worcester Polytechnic Institute for eleven years. He is the author of Phase-Locked Loop Circuit Design.
Remote Commands This chapter explains the syntax used by the GB1400 remote command language, and defines all set and query commands. In addition, commands are listed and briefly described in both alphabetical and functional order.
Remote Commands Overview This section defines the GB1400 command syntax including command types, parameter types, delimiters used between command elements, and terminators used at the end of command lines. Symbols The table below shows the symbols used in this chapter to describe GB1400 commands and responses. Symbol Carriage return (ASCII decimal 13). Line Feed (ASCII decimal 10). End or Identify, a message terminator signal specified in ANSI/IEEE Std. 488.
Remote Commands Command Types: Set and Query There two basic types of GB1400 commands: set commands and query commands. Set commands are used to make setup changes or to cause a status change, for example to start or stop a test. Query commands ask the instrument to respond with the contents of a status register or the value of a given setup parameter. GB1400 commands may have only a query form or only a set form, however most commands have both.
Remote Commands Command Line Rules The following rules summarize the basic syntax of GB1400 commands: Command Lines: A given command line may contain one or multiple commands. If a command line contains multiple commands, commands will be separated by a ";" (semicolon). Command Line Terminator RS-232C Interface: Command lines issued to the instrument should be terminated by a simple carriage return (CR).
Remote Commands Setting Arguments Outside of Legal Ranges If you issue a set command with an argument value that is outside the allowed range for that argument, then the instrument will reject the command. Numeric Responses If the response to a query command is a number, then it will be specified as one of the following types: Type Description decimal integer (e.g., 8) decimal real number without exponent (e.g., 2.00) decimal real number with exponent (e.g., 700.
Remote Commands Command Examples The following are some typical GB1400 set and query command examples: Command C-6 Action or Response clock_freq? Returns the current output clock frequency setup of the Generator or the measured input clock frequency of the Analyzer word_memory? Returns the saved word patterns in all 10 word memory locations. word_memory? 7 Returns the saved word pattern in word memory location 7.
Remote Commands Command Summary – Alphabetical The following is a listing of all GB1400 Generator and Analyzer commands and the page number of their full description. Page *cls......................................................................................................C-12 *ese [n]................................................................................................C-12 *ese? ...................................................................................................C-13 *esr?....
Remote Commands byte_length? .........................................................................................C-94 byte_mode ...........................................................................................C-95 byte_sync [n] (Analyzer only)...............................................................C-96 byte_sync? (Analyzer only) ................................................................C-96 clock_amp_dn .............................................................................
Remote Commands date ["yyyy-mm-dd"] .............................................................................C-86 date?....................................................................................................C-86 disp_select [total | window | test] ...........................................................C-67 disp_select?..........................................................................................C-67 edit_begin [n] ..............................................................
Remote Commands recall_word [m] ....................................................................................C-21 res_bits? ..............................................................................................C-45 res_cur_rate?.......................................................................................C-45 res_dm? ...............................................................................................C-46 res_dm_per? .........................................................
Remote Commands test_thres? ...........................................................................................C-76 time [s] ................................................................................................C-87 time?....................................................................................................C-87 total_bits?.............................................................................................C-52 total_error? ..............................................
Remote Commands Command Descriptions The following section defines each GB1400 set and query command. Unless noted otherwise, the following conventions will be followed in the command descriptions in later sections of this chapter: Command Headers: Command headers will be shown using the entire command name in lower case. For legal abbreviations, see the Command Summary – Alphabetical section earlier in this Chapter.
Remote Commands *ese? Event Status Enable (Query). Returns a decimal number in the range 0 to 255 corresponding to the contents of the Event Status Enable Register (ESER). Min. Abbr. *ese? Returns where is a decimal number from 0 to 255. Example *ese? 255 (command) (response) *esr? Event Status Register (Query). Returns a decimal number in the range 0 to 255 corresponding to the contents of the Standard Event Status Register (SESR). Min. Abbr.
Remote Commands *lrn? Learn (Query). Returns a character string listing the instrument's current setup, except for: q information on the remote ports, q calibration values, q stored frequencies, or q stored words The returned string will consist of a series of commands (headers plus parameters). These commands may be stored by the controller and used to restore the instrument to the same setup at a later time. Min. Abbr. *lrn Example: lrn? AUDIO_RATE 4 AUDIO_VOL 0 AUTO_SEARCH AUTO BYTE_LENGTH 8,0 ....
Remote Commands *rst Reset. This command causes the instrument to return to its factory default settings and to enter a known operation state. Specifically *rst does the following: q puts the instrument into the Operation Complete Command Idle State. q puts the instrument into the Operation Complete Query Idle State. q returns most setup parameters to their factory default settings (Appendix B). However *rst does not impact any of the following: q the setup of the RS-232 or GPIB ports. q GPIB address.
Remote Commands *sre? Service Request Enable (Query). This query command returns a decimal number in the range 0 to 255 corresponding to the contents of the Service Request Enable Register, where bit 6 is ignored. Min. Abbr. *sre? Returns where is a decimal number in the range 0 to 255, where Bit 6 is ignored. Example *sre? (command) 32 (response) (Indicates that the SRE contains 00100000 binary). *stb? Status Byte (Query).
Remote Commands *tst? Self Test. Causes the instrument to perform a self test and return the result. A result of 0 means the self test was successful. A return of any other value means the self test was not successful. The GB1400 self test is limited in scope. Min. Abbr. *tst? Returns 0 Example *tst? 0 (if successful) (command) (indicates successful self test) *wai Wait. This command forces the instrument to stop processing any additional commands until all pending operations are completed. Min.
Remote Commands tsr? (Analyzer Only) Test Status Register Query. This command returns a decimal number representing the current contents of the Test Status Register (TSR). C-18 Min. Abbr. tsr? Returns , in the range 0 to 255.
Remote Commands Commands Shared by the Generator and Analyzer Except where noted, the following commands are found in both the Generator and Analyzer command sets. Pattern and Word Commands Use these commands to select a pattern, enable or disable pattern inversion, create and save word patterns, and perform related pattern functions. data_invert [on|off] Data Inversion. Returns current status of Output Data Polarity.
Remote Commands Example data_pattern prbs data_pattern? Data Pattern Query. Returns a character string indicating the current Generator or Analyzer data pattern mode. Min. Abbr. data_p? Returns [prbs|word] [prbs|word|rdata] (Generator) (Analyzer) Example data_pattern? DATA_PATTERN PRBS (command) (response) prbs_length [v] PRBS Length. Selects the current PRBS pattern which becomes the current active pattern if and only if pattern "mode" is set to PRBS (see data_pattern command).
Remote Commands recall_word [m] Recall Word. Causes the instrument to recall the word pattern saved at location "m" and make this pattern the current word pattern and the active pattern. Min. Abbr. recall_w Arguments m: Example recall_word 5 0, 1, ..., 9 save_word [m] Save Word. Causes the instrument to save the current word pattern to word memory location "m". Min. Abbr. save_w Arguments m: Example save_word 5 0, 1, ..., 9 word_bits [l], [b1 | b2] Word Bits.
Remote Commands word_bits? Word Bits Query. The response will be in the form [n] [byte 1] [byte 2], where n is either 8 or 16 (the current word length) and byte 1 and byte 2 are hex, octal, or binary representations of the first and second bytes in the pattern. Note that byte 2 will be included only if pattern length is 16. Min. Abbr.
Remote Commands word_mem_ord [m], [msb | lsb] Word Memory Order. Sets the bit order of the word saved at location m to either "msb" (most significant bit first) or "lsb" (least significant bit first). Min. Abbr. word_mem_o Arguments m: msb: lsb: Example word_mem_ord 9, msb 0, 1, ..., 9 most significant bit first least significant bit first (selects the most significant bit first order for word memory location 9) word_mem_ord? Word Memory Order Query (All).
Remote Commands word_memory [m], [l], [b1], [b2] Word Memory. Stores into word memory m the word pattern of length l, with a bit sequence represented by b1 and b2. Min. Abbr. word_memo Arguments m: l: b1: decimal in range 0 to 9. 8 or 16 #00 to #FF #Q000 to #Q377 #B00000000 to #B11111111 b2: same as b1. However, b2 is allowed only if l (length) is set to 16. Example (hexadecimal) (octal) (binary) word_memory 3, 16, #HC4, #HF0 Stores the 16-bit sequence C4F0 (hex) into word memory 3.
Remote Commands word_order [msb | lsb] Word Order. Sets the bit order of the current word to MSB or LSB. The unit will start the transmission with the MSB of the first byte or the LSB of the first byte (MSB/LSB). After the MSB (or LSB), the bits would be transmitted continuing with the bits of the first byte until the LSB (or MSB) is reached, then proceeding with the next byte in the same order. Min. Abbr.
Remote Commands edit_end 1 Example #2 - To edit memory location 6 and save into memory location 8 without affecting the current pattern or location 6. edit_begin 6 word_order msb byte_block 12,16,#H24,#H23 edit_end 8 If the data pattern to be programmed is not of the same WORD ORDER as that associated with the pattern memory location being used, the WORD ORDER must be specified prior to any editing or downloading.
Remote Commands When changing the BUFFER MODE, the stored patterns and the current pattern may be lost. When transitioning from a smaller mode to a larger mode, some of the stored patterns will be lost. When going from larger to smaller, those patterns (including the current pattern) which have lengths greater than the allowed length will be initialized. Memory allocation for Word Memory storage 1M ………………………….. ** 512K WORD0……………………………. 256k WORD0………….WORD1………..WORD2……. 128k WORD0..WORD1..WORD2..
Remote Commands word_memory? Word Memory Query. Returns the all ten programmable WORD memories. The response will be ten message units separated by semi-colons ";", and each will contain the memory location, length and data bytes of each memory.
Remote Commands GPIB and RS-232 Commands gpib_address [v] GPIB Address. This command sets the instrument's GPIB address to v. It may only be issued via the instrument's RS-232C port. Min. Abbr. gpib_a Arguments v: Example gpib_address 15 0, 1, ..., 30. gpib_address? GPIB Address Query. This command returns a decimal number indicating the instrument's GPIB address. It may only be issued over the RS-232C port. Min. Abbr.
Remote Commands gpib_bus? GPIB Bus Mode Query. Returns a character string indicating the current GPIB bus mode. May be used only over the RS-232C port . Min. Abbr. gpib_b? Returns [off_bus | talk_listen] Example gpib_bus? GPIB_BUS TALK_LISTEN (command) (response) rs_echo [on|off] RS-232C Echo. Enables or disables character echo on the RS-232C (serial) port. Min. Abbr. rs_e Arguments on: Enables ECHO mode, instrument will echo back each character received.
Remote Commands Arguments on: off: EOL terminator added to end of prompt (OAH) no terminator added to prompt. Example rs_pmt_lf on rs_pmt_lf? RS-232C Prompt Line Feed Query. Returns a character string indicating whether RS-232C prompt line feed (OAH) is enabled (on) or disabled (off). Min. Abbr. rs_pm Returns [on|off] Example rs_pmt_lf? RS_PMT_LF ON rs_prompt [s] RS-232C Prompt. This command sets the prompt on the RS-232C port to the character string contained in the quoted string s.
Remote Commands rs_xon_xoff? RS-232C Xon/Xoff Query. This command returns a character string indicating whether RS-232C port Xon/Xoff flow control is enabled or disabled. C-32 Min. Abbr.
Remote Commands Misc. Shared Commands all_mem? All Memory (Generator). Returns a character string indicating the current Generator clock source (INT or EXT), the contents of all 10 Generator frequency memories, and the contents of all 10 Generator word memories. Min. Abbr. all_? Returns , , , Example all_mem? (command) CLOCK_SOURCE INT; (response) CLOCK_MEMORY 0, 500.000E+6; CLOCK_MEMORY 1, 550.000E+6; ... CLOCK_MEM 9, 700.
Remote Commands header [on | off] Header. Tells the instrument whether or not to include headers (command names) in responses. Min. Abbr. he Arguments on: off: Example header on include headers do not include headers header? Header Query. Returns a character string indicating the instrument's header status. Min. Abbr. he? Returns [on | off] Example header? HEADER ON (command) (response) logo? Logo Query.
Remote Commands options? Options Query. Returns a character string listing all of the options installed in the instrument, or returns the character string NONE indicating that no options are installed. Min. Abbr. op? Returns , , etc. where possible strings are: 1 MB Indicates 1 MB Option installed PROM Indicates PROM Option installed 75 OHM Indicates 75 ohm Option installed BURST Indicates BURST Mode installed PECL Indicates PECL Mode installed. NONE Indicates no options are installed.
Remote Commands Generator Commands The following commands are found only in the Generator command set. Clock Source and Frequency Setup Commands clock_freq [v] Clock Frequency. Sets the clock frequency to a value [v], specified in Hz, over the range of 1 MHz to 1405 MHz in steps of 1kHz. Min. Abbr. clock_f Arguments v , in the range 1.000E+6 to 1405.000E+6 in steps of 0.001E+6. Example clock_freq 622.000E+6. clock_freq? Clock Frequency Query.
Remote Commands clock_memory [m], [f] Clock Memory. Sets the frequency saved at frequency memory location [m] to a specified value [f], in the range 1 MHz to 1405 MHz, in steps of 1 kHz. Min. Abbr. clock_m Arguments m: , in the range 0, 1, ..., 9 f: , in the range 1.000E+6 to 1405.000E+6 in steps of 0.001E+6 Example clock_memory 9, 100.000E+6 clock_memory? [m] Clock Memory Query. Returns the frequency saved at frequency memory location [m].
Remote Commands clock_step [v] Clock Step. Sets the clock frequency increment/decrement default step size 10 kHz, 100 kHz, 1 MHz, 10 MHz, 100 MHz, or 1000 MHz. Min. Abbr. clock_ste Arguments v: Example clock_step 1.000E+6 , in the range: 0.010E+6, 0.100E+6, 1.000E+6, 10.000E+6, 100.000E+6 or 1000.000E+6 clock_step? Clock Step Query. Returns the current clock frequency step size. Min. Abbr. clock_ste? Returns Example clock_step? CLOCK_STEP 1.
Remote Commands recall_freq [m] Recall Frequency. This command recalls a previously saved frequency from memory location [m]. The recalled frequency becomes the current frequency of the Generator internal clock. Min. Abbr. recall_f Arguments m: Example recall_freq 5 , in the range 0, 1, ..., 9. save_freq [m] Save Frequency. This command saves the current Generator internal clock frequency to memory location [m], Min. Abbr.
Remote Commands Output (Clock and Data) Setup Commands amplitude [v] Amplitude. This command sets both Data and Clock amplitudes to the same voltage [v]. Min. Abbr. am Arguments v: Example amplitude 1.50 , in the range 0.50 to 2.00 in steps of 0.05. amplitude? Amplitude Query. Returns two message units, the first indicating the clock amplitude setting and the second indicating the data amplitude setting. Min. Abbr. am? Returns , Example amplitude? (command) CLOCK_AMPL 1.
Remote Commands clock_amp_up [v] and clock_amp_dn [v] Clock Amplitude Up/Down. This command pair is used to increment or decrement the current clock amplitude by specified amount of [v] volts. Min. Abbr. clock_amp_u clock_amp_d Arguments v: Example clock_amp_up 0.05 clock_amp_dn 0.05. , in range 0.05 to 1.50 in steps of 0.05. clock_ampl [v] Clock Amplitude. This command sets the output clock amplitude to [v] volts. Min. Abbr. clock_ampl Arguments v Example clock_amplitude 2.
Remote Commands Examples clock_off_up clock_off_dn clock_off_up [v] and clock_off_dn [v] Clock Offset Up, Clock Offset Down. This command pair is used to increment or decrement the current output clock signal baseline offset by a specified amount [v] volts. Min. Abbr. clock_off_u clock_off_d Arguments v: , in the range 0.05 to 3.00 in 0.05 v steps. in the range 0.05 to 3.80 in 0.05 v steps (PECL option) Example clock_off_up 0.10 clock_off_dn 0.10 clock_offset [v] Clock Offset.
Remote Commands Min. Abbr. data_amp_u data_amp_d Arguments none Example data_amp_dn data_amp_up [v] and data_amp_dn [v] Data Amplitude Up, Data Amplitude Down. This command pair is used to increment or decrement the current amplitude of the Generator data output by a specified step size of [v] volts. Min. Abbr. data_amp_u data_amp_d Arguments v: Example data_amp_up 1.00 , in the range 0.05 to 1.50, in steps of 0.05. data_ampl [v] Data Amplitude.
Remote Commands Min. Abbr. data_off_u data_off_d Arguments none Example data_off_up data_off_up [v] and data_off_dn [v] Data Offset Up, Data Offset Down. This command pair is used to increment or decrement the current baseline offset of the Generator data output by a specified step size of [v] volts. Min. Abbr. data_off_u data_off_d Arguments v: , in the range 0.05 to 3.00, in steps of 0.05. in the range 0.05 to 3.80 in 0.05 v steps (PECL option) Example data_off_up 0.
Remote Commands offset [v] Offset. This command sets the Generator clock and data baseline offset to the same specified value of [v] volts. Min. Abbr. off Arguments v: , in the range -2.00 to 1.00 in steps of 0.05. in the range -2.00 to 1.80 in 0.05 v steps (PECL option) Example offset 1.50 offset? Offset Query. Returns two message units, the first containing the Generator clock output baseline offset and the second containing the Generator data output baseline offset. Min. Abbr.
Remote Commands Error Injection Commands error_rate [off|ext|rate_3|rate_4|rate_5|rate_6|rate_7] Error Rate. Sets the Generator output bit error injection rate to "off", "external", or one of the following specified values: 10-3, 10-4, 10-5, 10-6, or 10-7. Min. Abbr. error_r Arguments off: ext: rate_3 rate_4 rate_5 rate_6 rate_7 Example error_rate rate_6 turns error injection off. selects the external error injection mode. sets bit error injection rate to 10-3. sets bit error injection rate to 10-4.
Remote Commands Analyzer Commands The following commands are found only in the Analyzer command set. Results Retrieve Commands Analyzer results commands are used to query the Analyzer for Test, Window, and Totalize interval results. Note that Analyzer numeric results are returned in one three basic formats:. q or integer results, which include various counts such as bits or bit errors, up to a maximum of 16 digits. Examples: 0, 1, 15, 45959, 1234567890123456.
Remote Commands clock_freq? Clock Frequency. Returns the CLOCK input frequency in Hz that is measured by the Analyzer. Min. Abbr. clock_f Returns , in format ddd.ddE+6 Example clock_freq? CLOCK_FREQ 700.00E+6 (command) (response) res_bits? Results Bits Query. This command returns the number of bits counted, either in the current interval so far or the previous test interval, depending on the setup of TEST PREV and the current test state. Min. Abbr.
Remote Commands res_dm? Results Degraded Minutes Query. This command returns the number of degraded minutes counted, either in the current interval so far or in the previous test interval, depending on the setup of TEST PREV and the current test state. Min. Abbr. res_dm? Returns Example res_dm? RES_DM 12 (command) (response) res_dm_per? Results Degraded Minutes Query.
Remote Commands res_efs_per? Results Error-Free Seconds. This command returns the percentage of error free seconds calculated, either in the current test interval so far or in the previous test interval, depending on the setup of TEST PREV and the current test state. Min. Abbr. res_efs_? Returns Example res_efs_per? RES_EFS_PER 100.00 (command) (response) res_elapsed? Results Elapsed (Time).
Remote Commands res_es? Results Errored Seconds. This command returns the total number of errored seconds counted, either in the current test interval so far or in the previous test interval, depending on the setup of TEST PREV and the current test state. Min. Abbr. res_es? Returns Example res_es? RES_ES 384 (command) (response) res_es_per? Results Error-Free Seconds Percentage.
Remote Commands res_pha_es? Results Phase Errored Seconds. This command returns the total number of phase errored seconds counted, either in the current test interval so far or in the previous test interval, depending on the setup of TEST PREV and the current test state. Min. Abbr. res_p? Returns Example res_pha_es? RES_PHA_ES 591 (command) (response) res_ses? Results Severely Errored Seconds.
Remote Commands res_start? Results Start (Time). This command returns a quoted string indicating the start time, either of the current test interval or the previous test interval, depending on the setup of TEST PREV and the current test state. Min. Abbr. res_sta? Returns , in the format: yy/mm/dd "hh:mm:ss.th" where yy = year, mmm = month (JAN, FEB, ..., DEC), dd = day, hh = hours, mm = minutes, ss = seconds, th = tenths and hundreds of seconds.
Remote Commands res_tes? Results Threshold Errored Seconds. This command returns the total number of threshold errored seconds counted, either in the current test interval so far or in the previous test interval, depending on the setup of TEST PREV and the current test state. Min. Abbr. res_tes? Returns Example res_tes? RES_TES 9823 (command) (response) res_tes_per? Results Threshold Errored Seconds Percentage.
Remote Commands res_us? Results Unavailable Seconds. This command returns the total number of unavailable seconds counted, either in the current test interval so far or in the previous test interval, depending on the setup of TEST PREV and the current test state. Min. Abbr. res_us? Returns Example res_us? RES_US 120 (command) (response) res_us_per? Results Unavailable Seconds Percentage.
Remote Commands total_error? Totalize Error Query. Returns the number of bit errors counted so far in the current Totalize measurement interval. The Totalize error count is zeroed at the start of each new Totalize measurement interval, that is at power-up and after a error reset. Min. Abbr. total_e? Returns Example total_error? TOTAL_ERROR 20984 (command) (response) total_rate? Totalize (Bit Error) Rate Query.
Remote Commands Input Setup Commands clock_term [neg_2v | gnd | ac] Clock Termination. Sets the Analyzer clock input termination voltage to "v". Min. Abbr. clock_ter Arguments neg_2v gnd ac Example 50 ohms to -2 volts. 50 ohms to ground. 50 ohms via 0.01 µF capacitor to ground. clock_term gnd clock_term? Clock Termination Query. Returns a character string indicating the current Analyzer clock input termination setup voltage. Min. Abbr.
Remote Commands data_del_up and data_del_dn Data Delay Up/Down (Default). This command pair is used to increment (data_del_up) or decrement (data_del_dn) the current DATA input delay by the default amount, 0.005 nSec. C-58 Min. Abbr.
Remote Commands data_del_up [v] and data_del_dn [v] Data Delay Up/Down. This command pair is used to increment (data_del_up) or decrement (data_del_dn) the current DATA input delay by v seconds. Note that v is expressed as a real number with an exponent and is in the range of 0.1 to 3.99 nSec in 0.005 nSec steps. Min. Abbr. data_del_u data_del_d Argument v Example data_del_up 0.02E-9 data_del_dn 0.10E-9 , 0.1E-9 to 3.99E-9 in 0.005E-9 steps data_delay [v] Data Delay.
Remote Commands data_term [neg_2v | gnd | ac] Data Termination. Sets the Analyzer data input termination voltage to "v". Min. Abbr. data_te Arguments neg_2v: gnd ac Example 50 ohms to -2 volts. 50 ohms to ground. 50 ohms via 0.01 µF capacitor to ground. data_term ac data_term? Data Termination Query. Returns a character string indicating the current Analyzer data input termination setup. C-60 Min. Abbr.
Remote Commands data_thr_up and data_thr_dn Data Threshold Up/Down (Default). This pair of commands increments (data_thr_up) or decrements (data_thr_dn) the current Analyzer DATA input threshold by the default increment of 0.05 volts. Min. Abbr. data_thr_u data_thr_d Arguments none Examples data_thr_up data_thr_dn (increments threshold by 0.05 volts) (decrements threshold by 0.05 volts) data_thr_up [v] and data_thr_dn [v] Data Threshold Up/Down.
Remote Commands data_thres? Data Threshold Query. Returns the current threshold voltage for the Analyzer DATA input. Min. Abbr. data_thre? Returns Example data_thres? DATA_THRES -1.50 (command) (response) rdata_del_up and rdata_del_dn Reference Data Delay Up/Down (Default). This command pair is used to increment (rdata_del_up) or decrement (rdata_del_dn) the current REF DATA delay by the default increment of 0.1 nSec. Min. Abbr.
Remote Commands rdata_delay [v] Reference Data Delay. Sets the Analyzer REF DATA input delay to v, where v may be set in the range 0.0 nSec to 3.99 nSec in 0.1 or 0.2 nSec steps. v is expressed as a real number with an exponent of -9. Min. Abbr. rdata_dela Argument v: Example rdata_delay 1.10E-9 0.00E-9 to 3.99E-9, in steps of 0.10E-9 or 0.2E-9 rdata_delay? Reference Data Delay Query. Returns the current Analyzer REF DATA input delay. Min. Abbr.
Remote Commands rdata_thr_up and rdata_thr_dn Reference Data Threshold Up/Down (Default). This command pair is used to increment (rdata_thr_up) or decrement (rdata_thr_dn) the current REF DATA threshold by the default increment of 0.05 volts. Min. Abbr. rdata_thr_u rdata_thr_d Argument none Examples rdata_thr_up rdata_thr_dn rdata_thr_up [v] and rdata_thr_dn [v] Reference Data Threshold Up/Down.
Remote Commands rdata_thres? Reference Data Threshold Query. Returns the current threshold voltage for the Analyzer REF DATA input. Min. Abbr. rdata_thre Returns Example rdata_thres? RDATA_THRES 1.
Remote Commands Error Detector and History Setup Commands auto_search [auto | off | disab] Auto_Search. Enables or disables the Auto Search and Automatic pattern re-alignment functions. Min. Abbr. auto_s Arguments auto: off: disab Example auto_search auto Auto Search on, pattern re-alignment enabled Auto Search off, pattern re-alignment enabled :Auto Search off, pattern re-alignment disabled auto_search? Auto_Search Query.
Remote Commands auto_mode [ber, fast] Auto_Mode. Sets the Auto Search mode for finding the Data Delay. Arguments ber: fast Example Uses the Bit Error Rate to find the Data Eye Crossing Uses the Clock to Data Phase to quickly find the Data Crossing auto_mode ber auto_mode? Returns the Auto Search Data Delay mode.
Remote Commands auto_sample [n] Auto_Sample. Sets the number of Data Bits to Sample when Auto Search is in BER mode. This is the exponent for the number of Bits accumulated at the Delay Settings, in terms of 10E+n: Arguments n: Example auto_sample 4 4 to 11 auto_sample? Returns the exponent of the number of Data Delay Sampling Bits.
Remote Commands auto_thresh [n] Auto_Thresh. Sets the Error Rate Threshold used when Auto Search is in BER mode. This the exponent for the error rate used for the Delay settings, in terms of 10E-n Arguments n: 3 to 10 Example auto_thresh 3 auto_thresh? Returns the exponent of the number used as the Data Delay Error Rate Threshold. Response auto_width? Returns the Width of the Data Eye as determined by Auto Search, in either mode. These values are in terms of seconds.
Remote Commands disp_select [total | window | test] Display Select. Selects the total, window, or test display mode. The display mode determines which BER and bit error results are shown in the top-middle, and top-right fields respectively of the display. Min. Abbr.
Remote Commands histry_bits? History Bits Query. Returns a character string indicating the state of the BIT error history indicator. Min. Abbr. histry_b? Returns [on | off] Example histry_bits? HISTRY_BITS OFF (command) (response) histry_clear History Clear. This command clears (resets) all four Analyzer history LEDs: Sync Loss, Bit Error, Phase Error, and Power Loss. Min. Abbr.
Remote Commands histry_phase? History Phase. Returns a character string indicating the state of the PHASE error history indicator. Min. Abbr. histry_ph? Returns [on | off] Example histry_phase? HISTRY_PHASE ON (command) (response) histry_power? History Power. Returns a character string indicating the state of the POWER Loss history indicator. Min. Abbr. histry_po? Returns [on | off] Example histry_power? HISTORY_POWER OFF (command) (response) histry_stat? History Status Query.
Remote Commands histry_sync? History Sync Indicator Query. Returns a character string indicating the state of the SYNC Loss history indicator. Min. Abbr. histry_sy? Returns [on | off] Example histry_sync? HISTRY_SYNC OFF (command) (response) sync? Synchronization Query. Returns a character string indicating whether the Analyzer synchronization LOCK LED is on or off. If it is on, then the Analyzer is in pattern synchronization. If it is off, then the Analyzer is out of pattern synchronization. Min.
Remote Commands TEST Setup Commands test_discard Test Discard. This command discards all results from the previous test interval, making previous results unavailable until the next test state RUN to STOP transition occurs. Min. Abbr. test_d Arguments none Example test_discard test_length [t] Test Length. Sets the test length to the time specified in the string "s". The string will be in 24-hour format "HH:MM:SS" enclosed in single or double quotes. This command sets the timed test interval.
Remote Commands test_mode [untimed|timed|repeat] Test Mode. Sets the test timing mode. The test once started, will stop and start according to the mode. Min. Abbr. test_m Arguments untimed: after test start, a test interval will continue until a test stop command is received, or the test is stopped manually from the front panel, or power loss. timed: after a test start, a test interval will stop automatically after test length has elapsed, front panel key, remote command or power loss.
Remote Commands test_prev? Test Previous Query. Returns the current state of the test_prev command. Min. Abbr. test_pre? Returns [current|previous] Example test_prev? TEST_PREV CURRENT (command) (response) test_print Test Print. This command causes the Analyzer to print a Test Summary report. This report has the same basic format and contents as an End-of-Test report. If a test is in progress, the report will be based on current interval results.
Remote Commands test_report? Test Report Query. Returns a character string indicating the current setup of the test report parameter. Min. Abbr. test_r Returns [eot|on_error|both|none] Example test_report? TEST_REPORT BOTH (command) (response) test_squelch [on|off] Test Squelch. Enables or disables squelching of On-Error reports. Min. Abbr.
Remote Commands test_state [run|stop] Test State. This command is used to start or stop the test measurement process. Min. Abbr. test_st Arguments run: stop: Example starts the test measurement process. Will initiate an untimed, timed, or repeat test depending on the setup of test mode. Stops the test measurement process. Will terminate untimed or repeat tests. Will also prematurely end timed tests before "test length" has elapsed. test_state run test_state? Test State Query.
Remote Commands test_thres [v] Test Threshold. Used to set the test error rate threshold to the value: 1 x 10-v. This threshold determines which seconds are counted as Threshold Errored Seconds (TES). It also determines when On-Error reports are generated. Min. Abbr. test_t Arguments v Example test_thres 12 , in the range 2, 3, ..., 16. That is the test error rate threshold may be set in the range 10-2 to 10-16. test_thres? Test Threshold Query.
Remote Commands WINDOW Setup Commands win_bit_len [v] Windows Bit Length. Sets BER window bit length parameter to 1 x 10v bits. This parameter determines window length when WIN_MODE is set to BITS. Min. Abbr. win_bit_ Arguments v Example win_bit_len 15 , in the range 8, 9, ..., 16. win_bit_len? Windows Bit Length Query. Returns the value v, indicating that the BER window bit length parameter is set to 1 x 10v bits. Min. Abbr.
Remote Commands win_mode [bits|sec] Windows Mode. Determines whether BER window length is determined by the windows bits (pattern length) parameter or the windows seconds (time length) parameter. Min. Abbr. win_m Arguments bits: sec: Example win_mode bits selects the windows bits length parameter selects the windows seconds length parameter. win_mode? Windows Mode Query. Returns the current BER window length mode. Min. Abbr.
Remote Commands win_rate? Window Rate Query. Returns the BER measured in either the current window interval so far, or the previous window interval, depending on the setup of WIN_PREV. Min. Abbr. win_ra? Returns Example win_report [on|off] Windows Report. This command enables or disables End-of-Window reports. Min. Abbr. win_re Arguments on off Example win_report on enables End-of-Window reports. disables End-of-Window reports. win_report? Windows Report Query.
Remote Commands win_sec_len [s] Windows Seconds Length. Sets the BER window seconds length parameter to the duration indicated by the quoted string s. Min. Abbr. win_s Arguments s , in format "hh:mm:ss", where hh = hours (00 to 23), mm = minutes (00 to 59), and ss = seconds (00 to 59). Example win_sec_len 00:30:00 win_sec_len? Windows Seconds Length Query. Returns a quoted string indicating the value of the BER window seconds length parameter. Min. Abbr.
Remote Commands PRINT Setup Commands print_enable [on|| off] Print Enable. This command turns the "master" Analyzer Print Enable parameter on or off. When Print Enable is off, then no reports will be printed. When Print Enable is on, then all enabled reports will be printed. Remember that individual reports will not print unless they are enabled individually and Print Enable has been set to "on". Min. Abbr. print_e Arguments on off Example print_enable on enabled reports will print.
Remote Commands print_port? Print Port Query. Returns the currently selected printer port. Min. Abbr. print_p? Returns [ parallel | gpib | serial ] Example print_port? PRINT_PORT PARALLEL (command) (response) print_string ["s"] Print String. This command prints a character string s to the currently selected printer port. Min. Abbr. print_s Arguments "s" Example print_string "This is a test" GB1400 User Manual a character string enclosed in quotes.
Remote Commands Audio Beeper Setup Commands audio_rat_up and audio_rat_dn Audio Rate Up/Down (Default). This command pair is used to increment (audio_rat_up) or decrement (audio_rat_dn) by one the exponent of the current error rate threshold of the BER beeper. Min. Abbr. audio_rat_u audio_rat_d Arguments none Example audio_rat_up This command adds one to the exponent of the beeper BER threshold. audio_rat_up [v] and audio_rat_dn [v] Audio Rate Up/Down.
Remote Commands audio_rate? Audio Rate Query. Returns the current error beeper BER threshold. Returns Example audio_rate? AUDIO_RATE 9 (command) (response) audio_vol [v] Audio Volume. Sets the volume of the error beeper to v, where v can range from 0 (off) to 4 (maximum volume). Min. Abbr. audio_vol Arguments v: Example audio_vol 4 0, 1, 2, 3, or 4 audio_vol? Audio Volume Query. Returns a decimal number in the range 0, 1, 2, 3, or 4, that represents the current error beeper . Min. Abbr.
Remote Commands audio_vol_up and audio_vol_dn Audio Volume Up/Down (Default). This command pair is used to increment (audio_vol_up) or decrement (audio_vol_dn) the current error beeper volume by one level. Min. Abbr. audio_vol_u audio_vol_d Argument none Example audio_vol_up audio_vol_dn audio_vol_up [v] and audio_vol_dn [v] Audio Volume Up/Down. This command pair is used to increment (audio_vol_up) or decrement (audio_vol_dn) the current error beeper volume by "v" levels. C-88 Min. Abbr.
Remote Commands Misc. Analyzer Commands date ["yyyy-mm-dd"] Date. Sets the current date in year-month-day format. Note that the argument is a quoted character string. Min. Abbr. date Arguments yyyy mm dd Example date "2001-03-21" year (NOTE: may be above 2000) month (1, 2, ..., 12) day (1, 2, ..., 31) date? Date Query. Returns a quoted string that indicates the current date setup of the Analyzer in year-month-day format. Min. Abbr.
Remote Commands time [s] Time. Used to set the instrument's time of day clock. Min. Abbr. ti Arguments s Examples time 16:30:02 , in the format "hh:mm:ss". where hh = hours (00 ... 23), mm = minutes (00 ... 59), and ss = seconds (00 ... 59). time? Time Query. Returns a quoted string indicating the current setting of the instrument's time of day clock. C-90 Min. Abbr. ti? Returns Example time? TIME "16:30:11.
Remote Commands 1 MB Option Commands The following section identifies commands that are modified or added when the 1 MB Option is installed. Modified Commands When the 1 MB Option is installed, the All_mem command will operate as before except that it will not return any saved word patterns.
Remote Commands byte_block [a], [i], [b1], ..., [bn] Byte Block. This command overwrites a block of i bits in the edit pattern, beginning at address a, with the overwrite pattern indicated by bytes b1 through bn. Min. Abbr. Arguments Example byte_b a , the following ranges indicate the starting address of the overwrite block.
Remote Commands byte_block? [a] Byte Block Query. Returns the hex., octal, or binary representation of the 80 bit section of the edit pattern beginning with the bit at address a. Note that if there is no editing session in progress, this command will return the indicated 80 bit section from the current word pattern. "a" 0 to 131071 (1M mode) 0 to 65535 (512K mode) 0 to 32767 (256K mode) 0 to 16,383 (128K mode) 0 to 8191 (64K mode) Min. Abbr. byte_b? Response [a], [i], [b1], ...
Remote Commands byte_delete [a], [i] Byte Delete. This command deletes i bits from the edit pattern starting with bit a. Min. Abbr. Arguments byte_d a , in the range "a", the block of bits to be deleted begins at this address. 0 to 131071 (1M mode) 0 to 65535 (512K mode) 0 to 32767 (256K mode) 0 to 16,383 (128K mode) 0 to 8191 i Example (64K mode) , in the range 8 to 80, in steps of 8, this is the number of bits to delete.
Remote Commands byte_edit [a], [b1] Byte Edit. This command is similar to byte_block except that it can overwrite (edit) only one byte at a time. The command overwrites 8 bits starting at address a. Min. Abbr. Arguments byte_e a , in the range "a", the address of the overwrite byte. 0 to 131071 (1M mode) 0 to 65535 (512K mode) 0 to 32767 (256K mode) 0 to 16,383 (128K mode) 0 to 8191 b1 Example (64K mode) indicates the overwrite byte pattern.
Remote Commands byte_fill [i], [b1], [b2], ..., [bn] Byte Fill. This command fills the entire edit pattern with a repeating i-bit pattern, b1, b2, b3, ..., bn. Min. Abbr. Arguments byte_f i , in the range 8 to 80, in steps of 8, indicates the number of bits in the fill pattern. b1, ..., bn indicating the contents of the fill pattern. Each byte may be in the range: #H00 to #HFF (hex), #Q000 to #Q377 (octal), or #B00000000 to #B11111111 (binary).
Remote Commands byte_length [m], [n] Byte Length. This command sets the length of the edit pattern to m bytes plus n bits. Min. Abbr. byte_l Arguments m , in the range: 0 to 131072 (1M mode) 0 to 65536 (512K mode) 0 to 32768 (256K mode) 0 to 16,384 (128K mode) 0 to 8192 (64K mode) n Example , in the range 0 to 7. byte_length 16384, 0 NOTE: If the number of whole bytes (m) is greater than 2047, then the number of added bits (n) must be set to 0.
Remote Commands byte_mode [n] Byte_Mode. Controls the WORD storage mode. There will always be a Current Word Buffer. In addition to that, there is 0 to 10 memory storage buffers. In different modes, the buffers permit patterns of different lengths.
Remote Commands byte_sync [n] (Analyzer only) Byte Synchronization. This command sets the long-word pattern synchronization threshold. This threshold does not apply to short-word patterns, or PRBS patterns. The long-word synchronization threshold is set in terms of an integer, n, which corresponds to a BER threshold. In the table below, the ratios of errors to bits corrrespond to the window examined and the maximum errors for the threshold. Level BER Ratio (errors/bits) 1 3.1E-2 (256/8192) 2 7.
Remote Commands edit_begin [n] Edit Begin. You must issue this command to the instrument before starting an editing session. In effect this command loads the contents of a word memory location specified by n into a scratch pad memory location. Once in the scratch pad memory it can be edited, uploaded to the controller, or saved to the same or a different memory location. You also must issue the edit_begin command before downloading a word pattern to the instrument. Min. Abbr.
Remote Commands edit_cntrl? Edit Control Query. This command returns a character string that indicates whether or not a long-word (1 MB Option) editing session is in progress and if that session is under local or remote control. Min. Abbr.
Remote Commands C-102 GB1400 User Manual
Using GPIB, RS-232 Interfaces This chapter describes the use of the GB1400 Bit Error Rate Tester Remote Interfaces. Since the remote interfaces enable automatic testing, the user does not have to complete any of the manual procedures necessary for front panel operation. However, the user can write programs to conduct the test sessions. Using the GPIB Interface The GB1400 supports remote control through the GPIB interface bus connector on the rear panel.
Using GPIB, RS-232 Interface Functions The GB1400 is configured as a talker/listener. No controller functions are implemented.
Using GPIB, RS-232 query command. The GB1400 responses commands will be either character mnemonics (for example, INT or EXT) or numerics (Example: 200.0).
Using GPIB, RS-232 Service Request Enable Different conditions for a service request can be individually enabled. The Service Request Enable byte contains the enabling bits for the status byte. For a service request to occur, either the TSB, MAV or ESB bit must be enabled. Each time the GB1400 is powered on, this byte is RESET so that no bits are enabled. The bit definition is the same as the status byte, except bit 7 is undefined.
Using GPIB, RS-232 Standard Event Status Enable Register Different conditions within the Standard Event Status Register can be individually enabled or disabled. The Standard Event Status Enable Register contains enabling bits. Each time one of the event conditions or one of the enabling bits change, the status of the ESB bit is re-evaluated. If any status bit is set and its corresponding enable bit is set, the ESB bit is set also.
Using GPIB, RS-232 GPIB Common Commands The following commands are provided to use with GPIB status reporting, as defined by IEEE 488.2 for service request: *STB? *SRE *SRE? *ESR? *ESE *ESE? *CLS Additional SRQ GPIB Commands (Rx only) The following commands are provided to use with the Test Status SRQ feature: TSE TSE? TSR? IEEE-488.
Using GPIB, RS-232 Functional Elements The IEEE 488.2 standard requires a list of the functional elements which are used by the GB1400 receiver. These are the functional elements used in constructing the remote commands that control the receiver. For more information, see the IEEE 488.2 standard, sections 4.3, 7.1.1, and 7.3.3. From Tables 4.2 and 4.3 of the IEEE 488.
Using GPIB, RS-232 Using the RS-232 Interface Option The GB1400 supports remote control through the RS-232C connector on the rear panel The unit can be operated from the front panel and over the remote interface simultaneously. Any unit changes made remotely are displayed on the front panel. All of the front panel functions can be controlled over the RS-232C interface, except “POWER.
Using GPIB, RS-232 RS-232 Interface Hardware/ Handshaking Considerations The remote interface consists of a 25-pin female D-type connector on the rear panel. When using the RS-232C interface, connect the controller to the GB1400 with an appropriate 25-pin cable. The GB1400 is configured as an RS-232C DCE (Data Circuit terminating Equipment). For a local (direct) connection to a DTE device (most RS-232C controllers), connect the controller to the GB1400 with a straight (non-null modem) cable.
Using GPIB, RS-232 Programming RS-232C Remote Commands There are two types of remote commands for the GB1400: • Set commands (commands) • Queries commands (queries The set commands force the GB1400 to take a specific action. The query commands direct the GB1400 to return status information. Commands are entered one line at a time. Errors may be corrected while entering a line, with the backspace key.
Using GPIB, RS-232 RS-232C Error Messages All RS-232C remote commands received by the GB1400 are checked for command validity and appropriate parameters (parameters listed with commands within brackets [ ]). All valid command strings are executed.
Using GPIB, RS-232 D-12 GB1400 User Manual
p Customer Acceptance Test For GB1400 Generator & Analyzer NOTICE TO ALL PERSONS RECEIVING THIS DOCUMENT THIS DOCUMENT IS ONLY CONDITIONALLY ISSUED, AND NEITHER RECEIPT NOR POSSESSION THEREOF CONFERS OR TRANSFERS ANY RIGHT IN, OR LICENSE TO USE, THE SUBJECT MATTER OF THE DOCUMENT OR ANY DESIGN OR TECHNICAL INFORMATION SHOWN THEREON, NOR ANY RIGHT TO REPRODUCE THIS DOCUMENT OR ANY PART THEREOF, EXCEPT FOR MANUFACTURE BY VENDORS FOR TEKTRONIX AND FOR MANUFACTURE UNDER THE CORPORATION’S WRITTEN LICENSE, NO RI
Performance Verification Performance Verification The following tests verify that the GB1400 Generator & Analyzer achieve their specified performance. These instruments are not user-adjustable. If the GB1400 needs repair, return it to Tektronix. Recommended Test Equipment The recommended test equipment needed to verify performance is listed below.
Performance Verification Functional Test To functionally test the GB1400, connect the Generator to the Analyzer and confirm their correct operation as described below. Note In these procedures, the Generator and Analyzer are returned to their default settings. The word memories will be reset. If you have entered word patterns that you do not want to lose, use a GPIB or RS-232C controller to save them before beginning these procedures.
Performance Verification gigaBERT-1400 TRANSMITTER Data OUTPUT Not Data Clock Not Clock DATA THRESHOLD (on rear panel) gigaBERT-1400 RECEIVER Not Clock Clock Data Not Data Figure 1 -- Setup for Functional Test of Standard Instrument q Step 4: At the Generator, verify that PRBS is selected (the PRBS LED light, in the PATTERN, section, should be on.) If not, press the ‘PRBS’ key to select it.
Performance Verification Confirmation of Frequency Function q Step 6: In the Generator CLOCK section, the FREQUENCY LED should be on. If it is not, press the ‘FREQUENCY’ key to select it. q Step 7: Use the Generator CLOCK up/down keys to change the output frequency. q Step 8: Check that the frequency displayed by the Analyzer matches the Generator output to within ± 0.1 MHz. (Note that the resolution of the Analyzer is 0.01 MHz and that the resolution of the Generator is 0.001 MHz.
Performance Verification Confirmation of Generator Output Data Level Change In this part of the functional test procedure, you will verify that the Analyzer threshold responds correctly to the sample values of baseline offset and amplitude in the Generator output. The sample values and threshold limits are summarized in the following Data Levels table. Repeat steps 21 through 27 for each row of the Data Levels table.
Performance Verification Confirmation of Error Injection Rates q Step 29: In the Analyzer ERROR DETECTION section, press the ‘DISPLAY SELECT’ key until there is an ∞ (infinity) symbol on the display preceding the error rate. q Step 30: At the Analyzer, press the ‘CLEAR’ key in the ERROR HISTORY section, and press the ‘CLEAR’ key in the ERROR DETECTION section to clear the history LEDs and error rate display.
Performance Verification keys in the input section of the Analyzer until the PHASE light in the ERROR HISTORY section illuminates. Manually return the Analyzer delay setting to that recorded above. Verify that the PHASE light can be extinguished by the ‘CLEAR’ key. Confirmation of Selectable Analyzer Terminations q Step 41: Set the Generator and Analyzer to Factory Default Settings. Confirm that the Analyzer F2 LED is not lighted.
Performance Verification GB1400 Acceptance Test E-9
Performance Verification Confirmation of Buttons and Indicators q Step 49: Reset both the Generator and Analyzer by cycling the power. q Step 50: Verify the following Generator LEDs.
Performance Verification q Step 52: Verify the Analyzer LEDs and buttons operate by toggling the following buttons and observing the LEDs turn ON and OFF.
Default Settings This appendix lists factory default settings for the GB1400 Generator and Analyzer. These are the value for the various operating parameters, when the unit leaves the factory. These settings can be changed by the user, and stored in non-volatile RAM. Should the non-volatile RAM be corrupted (due to battery failure), the unit will reset all settings as listed here and the message 'RAM CORRUPTION' will appear on the display for a few seconds to note that all settings are reset.
Default Settings Generator (TX) Factory Default Settings CLOCK External Clock Source INT Frequency 1405.0 MHz Frequency Memory 0 720 MHz 1 360 MHz 2 180 MHz 3 90 MHz 4 45 MHz 5 1360 MHz 6 680 MHz 7 340 MHz 8 170 MHz 9 85 MHz Frequency Step Size 1000.0 MHz Data Pattern PRBS pattern PN 7 (27-1) Word memory (all ten) AA 55 Programmable Data Pattern AA 55 Current Pattern Setting PRBS Data Invert OFF Word Order LSB CLOCK/ DATA Outputs F-2 Output Clock Amplitude 1.
Default Settings Remote Interfaces Remote mode local GPIB address (Generator) 15 GPIB Bus TALK_LISTEN GPIB terminator EOI/LF RS-232C prompt BERT1400> RS-232C baud rate 9600 RS-232C parity even RS-232C data size 8 bits RS-232C EOL CR/LF RS-232C echo OFF RS-232C prompt line feed OFF MISC.
Default Settings Analyzer (RX) Factory Default Settings Clock, Data, and Reference Data Inputs Input data delay 0 pS Input data threshold 0.00 volts Reference Data Delay 0 pS Reference Data Threshold -1.
Default Settings Time and Date Date 1-1-1999 Time 00:00:00.0 Printer Port parallel Print enable on Current BER Mode Seconds Bits 1.0E+9 Seconds 00:00:01 Previous Remote Status CURRENT Report Enable OFF Test Parameters Test Mode TIMED Test Length 00:00:30 Test Report Enable ON ERROR Test Error Rate Threshold 1.
Default Settings MISC.
Cleaning Instructions Clean the GB1400 often enough to prevent dust and dirt from accumulating. Dirt acts as a thermal insulator, preventing effective heat dissipation, and can also provide high-resistance leakage paths between conductors or components in a humid environment. Cleaning the Exterior Clean the dust from the outside of the instrument with a soft, clean cloth or small brush. A brush is especially useful for removing dust from around the buttons and connectors.
Cleaning Instructions G-2 GB1400 User Manual
Pattern Editor Requirements and Features Version 1.10 (9/13/96) Before You Begin: Before installing this program, it is suggested that you make a copy of this disk and store it away in a safe place. To protect against accidentally overwriting any files on this disk, slide the write protect tab on the back of the disk to the protect position. To Install MLPE: 1) Start Microsoft Windows. 2) In the FILE pulldown menu, choose RUN. 3) Type A:\SETUP or B:\SETUP. 4) Choose the OK button.
Pattern Editing Software Minimum Requirements: Microsoft Windows 3.1 or later running on a 386 or faster machine with 4 Mb of memory, For reasonable speed, a 486 DX or DX2 with at least 8 Mb of memory. At least 2 Mb of free hard disk space. gB700 Tx or Rx with 128K memory. gB1400/1600 Tx or Rx with at least 256K memory. A PB200. One free RS-232 port or a National Instruments GPIB card with associated driver and software. List of Features • Editing capability in excess of 1 Mb.
Pattern Editing Software • The editor uses a proprietary editor and therefore cannot share data with other applications via the Clipboard. • The editor will not work with the GB660. List of Files on this Disk SETUP.EXE SETUP.INS README.DOC MLPE.Z MLPE.INI MLPE.BMP FPGRID10.VBX Please verify that the above files are on this disk. If any are missing, please contact Tektronix.
Pattern Editing Software directory is still there and is not corrupted. If it is not there, copy the MLPE.INI file from the MLPE directory to the WINDOWS directory. See if the program runs properly. If it is there, it may possibly be corrupted. Rename the file that is there to MLPE.SAV and copy the MLPE.INI file from the MLPE directory to the WINDOWS directory. if the program runs properly, delete the MLPE.SAV file from the WINDOWS directory.
Pattern Editing Software Saving patterns If you open an existing saved pattern from disk and make changes to it, you will be reminded to save the changes before you can close the file or exit the program. If you receive a pattern from a gigaBERT to the Tektronix Pattern Editor you must remember to save the file to disk before closing the file or exiting the program. The program will not remind you to do so.
Pattern Editing Software The HELP system indicates that only "filename.pat" files can be opened. This is not true. Although ".pat" is the default extension and should be used for saving all gigaBERT files, there may be different extensions that may be used for the packetBERT200 depending on the version of firmware of the instrument. All possible filename extensions are listed in the "List of File Type" box in the File Open and File Save menus. Consult your packetBERT200 manual for filenames that are valid.
Pattern Editing Software WARNING Read License Agreement Before Opening Tektronix / Microwave Logic Products Copyright Microwave Logic, Inc. All Rights Reserved Part Number 9508-1388 Version 1.0 IMPORTANT READ BEFORE OPENING SEALED WRAPPER This software is provided under license from Microwave Logic, Inc. Retention of this program for more than (30) days, use of the program in any manner, or opening the sealed wrapper surrounding the program constitutes acceptance of the license terms.
Pattern Editing Software TEKTRONIX, MICROWAVE LOGIC PRODUCTS SOFTWARE LICENSE AGREEMENT THE ENCLOSED PROGRAM IS FURNISHED SUBJECT TO THE TERMS AND CONDITIONS OF THIS AGREEMENT, RETENTION OF THE PROGRAM FOR MORE THAN THIRTY DAYS, OPENING THE SEALED WRAPPER, IF ANY, SURROUNDING THE PROGRAM OR USE OF THE PROGRAM IN ANY MANNER WILL BE CONSIDERED ACCEPTANCE OF THE AGREEMENT TERMS.
Pattern Editing Software If the Program is acquired by or for an agency of the U.S. Government, the Program shall be considered computer software developed at private expense and the license granted herein shall be interpreted as granting Customer restricted rights in the Program and related documentation as defined in the applicable acquisition regulation. THE PROGRAM MAY NOT BE USED, COPIED, MODIFIED, MERGED, OR TRANSFERRED TO ANOTHER EXCEPT AS EXPRESSLY PERMITTED BY THESE TERMS AND CONDITIONS.
Pattern Editing Software THIS WARRANTY IS GIVEN BY MICROWAVE LOGIC WITH RESPECT TO THE PROGRAM IN LIEU OF ANY OTHER WARRANTIES, EXPRESS OR IMPLIED. MICROWAVE LOGIC AND ITS VENDORS DISCLAIM ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE., MICROWAVE LOGIC'S RESPONSIBILITY TO REPLACE DEFECTIVE MEDIA, OR REFUND CUSTOMER'S PAYMENT IS THE SOLE AND EXCLUSIVE REMEDY PROVIDED TO THE CUSTOMER FOR BREACH OF THIS WARRANTY.
Theory of Operation See block diagrams of GB1400 TX and GB1400 RX at end of this section. GB1400 Generator (TX) Design Overview The GB1400 TX is designed to generate a programmable WORD of 16-bits , and five PRBS of 2n-1 (n=7, 15, 17, 20, 23), at serial data rates of up to 1400 Mb/s. The unit incorporates a programmable crystal-locked clock source that operates at this bandwidth, and two programmable pulse output amplifiers, for both Clock and Data Output.
Theory of Operation The Error Inject circuitry consists of a chain of decade counters, used to generate a pulse every 10E-n bits (where n=3-7). This pulse generates a single bit error on the output data streams, providing a known error rate for back-to-back tests.
Theory of Operation GB1400 Analyzer (RX) Design Overview The GB1400 RX is designed to receive a differential or single-ended programmable WORD of 16-bits, and five PRBS of 2n-1 (n=7, 15, 17, 20, 23), at serial data rates of up to 1400 Mb/s, compare it to a locally-generated identical data stream and perform Bit Error Rate (BER) analysis upon it. Very high frequency GaAs, ECL and discrete circuitry is incorporated on multilayer controlled impedance pretend circuit boards.
Theory of Operation In PRBS mode, the Pattern Sync circuit detects the start (n, 1, zeros) of the PRBS pattern. This produces a single bit width pulse once per pattern frame. In WORD mode, the shift register detects the programmable WORD load pulse, which occurs once per WORD frame. Error Counter PCB The Error Counter PCB contains the circuitry to count the Bit Errors detected by the Data Generator PCB, and also measures the system clock frequency.
EXT CLK 0.1uf CLOCK/4 OUT AMPL 50 Ohm CLK F/4 CLOCK OUT F CLOCK SYNTHESIZERF CLK CLOCK DIVIDER & DISTRIBUTION _ F CLOCK OUT REAR PANEL OFF PATTERN SYNC PHASE A DATA INHIBIT 4:2 MUX PHASE B DATA INVERT AMPL CLOCK/2 CLK SYNC CLK CLK PRN GEN ERROR INJECT WORD GEN D R DATA OUT Q EXT CLK _ DATA Q OUT EXTERNAL ERROR INJECT CPU BUS OFF FRONT PANEL CPU BUS 2 x 24 LCD DISPLAY AC INPUT CPU NON-VOLATILE RAM BATTERY GB1400 Tx Figure I-1.
Theory of Operation + DATA IN PROGRAM DELAY 50ohm - DATA MONITOR Q D _ ERROR INHIBIT Q CLK 50ohm AC AC -2V DATA INVERT REAR PANEL -2V REF DATA IN + INTERNAL DATA PATTERN _ PROGRAM DELAY Q CLK - REF MODE Q D 50ohm REF THRESHOLD AC -2V GND CLOCK MONITOR CLOCK CLK LOAD NETWORK CLK CLOCK DIST FEED + PROGRAMMABLE ERROR/SYNC THRESHOLD SLIP ERRORS - 50ohm CLOCK BAR MUX 50ohm LOAD NETWORK PATTERN SYNC AC CLK SYNC CLK SYNC SLIP CLK CLK -2V PRN GEN DATA ERROR ERROR
Glossary/ Index
Glossary Address A number specifying a particular user device attachment point... The location of a terminal, a peripheral device, a node, or any other unit or component in a network...A set of numbers than uniquely identifies something - a location in computer memory, a packet of data traveling through a network. Analog-to-Digital Converter A device that converts an analog signal, that is, a signal in the form of a continuously variable voltage or current, to a digital signal, in the form of bits.
Glossary Bit Rate The number of bits of data transmitted over a phone line per second. Byte A unit of 8 bits. Channel A communications path or the signal sent over a channel. Through multiplexing several channels, voice channels can be transmitted over an optical channel. Clock 1. An electronic component that emits consistent signals that paces a computer’s operations. 2. An oscillator-generated signal that provides a timing reference for a transmission link.
Glossary Multi-Channel Cable An optical cable having more than one fiber. Noise Unwanted signals that combine with and hence distort the signal intended for transmission and reception. Residual error rate The error rate remaining after attempts at correction are made. RS-232C A physical layer interface standard for the interconnection of equipment. Rx, Receiver An abbreviation for Receiver A detector and electronic circuitry to change optical signals to electrical signals.
Glossary glossary-4 GB1400 User Manual
Index Index -A- Appendices Analyzer Functions, 3-19 BERT Primer/ Technical Articles, B-1 Analyzer Error Messages, 3-45 Cleaning Instructions, G-1 Audio (Beeper) Function, 3-45 Customer Acceptance Test, E-1 AUTO SEARCH, "Non-PRBS" Patterns, 3-21 PRBS Patterns, 3-20 Default Settings, F-1 Pattern Editing Software, H-1 Remote Commands, C-1 Automatic Setup Func.
Index Nominal Generator Clock, Data Waveforms showing Amplitude, Baseline Offset and Vtop, 3-13 -CControls, Indicators, and Connectors, 2-4 Controls & Indicators, 2-18 Analyzer ERROR DETECTION, 2-25 Nominal Generator NRZ Data and Clock Output Waveforms, 2-3 Analyzer Error History, 2-24 Seven-stage PRBS generator, B-6 Analyzer INPUT, 2-23 TEST Measurement Process, 3-32 Analyzer SYNC Controls, 2-25 Three-stage PRBS generator, B-5 Func (Soft) Keys (F1, F2, F3, F4), 2-21 TOTALIZE Measurement Process,
Index Single-Ended or Differential Operation, 3-16 Utility Option (OPTION), 3-82 Utility Version (VER), 3-83 Step Size and Frequency, 3-10 Window Interval in Bits (BITS), 3-72 Getting Started, 1-1 Window Interval in Hrs:Min:Sec (SECOND), 3-73 -I- Window Mode (MODE), 3-71 Initial Self-Check Procedure, 1-7 Window Reports (REPORT), 3-74 Word Edit (EDIT), 3-56 -M- Word Fill (FILL), 3-58 Menus, 3-48 Word Length (LENGTH), 3-57 Using the Menu System, 3-48 Word Order (ORDER), 3-59 General Rules, 3-5
Index -SSelecting an Active Pattern, 3-3 Selecting (Recalling) a Saved Word Pattern, 3-4 Selecting PRBS Patterns, 3-3 Selecting the Current Word Pattern, 3-3 Selecting a Pattern, 3-2 Pattern Definitions, 3-2 -WWord Patterns, 3-5 Basics, 3-5 Creating Word Patterns using front panel controls, 3-5 Creating Word Patterns using menus, 3-7 PRBS Patterns , 3-2 Creating Word Patterns using remote control, 3-8 Word Patterns, 3-3 Recalling Word Patterns, 3-9 -T- Saving Word Patterns, 3-9 Tables Actions taken
