User and Service Guide Agilent 83446A/B Lightwave Clock/Data Receiver
Agilent part number: 83446-90018 Edition 1 Printed in USA March 2000 1400 Fountaingrove Parkway, Santa Rosa, CA 95403-1799, USA Notice. The information contained in this document is subject to change without notice. Agilent Technologies makes no warranty of any kind with regard to this material, including but not limited to, the implied warranties of merchantability and tness for a particular purpose.
Printing History Agilent Part Number Edition 83446-90004 83446-90011 83446-90018 Date Edition 1 October 1994 Edition 1 June 1995 Edition 1 March 2000 iii
Safety Symbols CAUTION WARNING The following safety symbols are used throughout this manual. Familiarize yourself with each of the symbols and its meaning before operating this instrument. The caution sign denotes a hazard to the instrument. It calls attention to a procedure which, if not correctly performed or adhered to, could result in damage to or destruction of the instrument. Do not proceed beyond a caution sign until the indicated conditions are fully understood and met.
General Safety Considerations WARNING WARNING WARNING WARNING This is a Safety Class I product (provided with a protective earthing ground incorporated in the power cord). The mains plug shall only be inserted in a socket outlet provided with a protective earth contact. Any interruption of the protective conductor inside or outside of the instrument is likely to make the instrument dangerous. Intentional interruption is prohibited.
Certi cation and Assistance Agilent Technologies certi es that this product met its published speci cations at the time of shipment from the factory. Agilent Technologies further certi es that its calibration measurements are traceable to the United States National Institute of Standards and Technology (NIST), to the extent allowed by the Institute's calibration facility, and to the calibration facilities of other International Standards Organization members.
Declaration of Conformity vii
Warranty This Agilent Technologies instrument product is warranted against defects in material and workmanship for a period of one year from date of shipment. During the warranty period, Agilent Technologies will, at its option, either repair or replace products which prove to be defective. For warranty service or repair, this product must be returned to a service facility designated by Agilent Technologies.
Contents 1. General Information 2. Installation and Preparation for Use 3. Description of the Agilent 83446A/B . . . . . . . Front-panel features . . . . . . . . . . . . . Rear panel features . . . . . . . . . . . . . Agilent 83446A/B Speci cations and Characteristics Electrostatic Discharge Information . . . . . . . Reducing ESD damage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Installing the Agilent 83446A/B . . . . . . . . . . . . Step 1. Inspect the shipment . . . . . . . . .
Replaceable parts Example of optimizing laser extinction ratio . . . . . Waveform Test . . . . . . . . . . . . . . . . . . . . . Example of measuring eye diagram using recovered clock signal . . . . . . . . . . . . . . . . . . . . . 4. Servicing the Agilent 83446A/B General information . . . . . . . . . . . . . . . . . Troubleshooting . . . . . . . . . . . . . . . . . . . Adjustment Procedures . . . . . . . . . . . . . . . Power supply adjustment procedure . . . . . . . . .
Figures 1-1. 1-2. 1-3. 1-4. 2-1. 2-2. 2-3. 2-4. 3-1. 3-2. 3-3. 3-4. 4-1. 4-2. 4-3. 4-4. 4-5. 4-6. 4-7. Agilent 83446A/B block diagram. . . . . . . . . . . . . . The Agilent 83446A/B front-panel. . . . . . . . . . . . . The Agilent 83446A/B rear panel. . . . . . . . . . . . . . Example of a static-safe work station. . . . . . . . . . . . Opening the fuse holder door. . . . . . . . . . . . . . . Selecting the line voltage value and checking the fuse. . . . AC power cables available. . . . . . . . . . . . .
Tables 1-1. 1-2. 2-1. 2-2. 3-1. 4-1. 4-2. 4-3. 4-4. 4-5. 4-6. 4-7. 4-8. 4-9. 4-10. 4-11. Agilent 83446A/B Speci cations and Characteristics . Static-Safe Accessories . . . . . . . . . . . . . . Agilent 83446A/B Power Requirements . . . . . . Agilent Technologies Service Numbers . . . . . . . Average Gating Period to Achieve 100 Errors . . . . Required Tools . . . . . . . . . . . . . . . . . Voltages on the DC Power Supply Terminals . . . . Required Test Equipment . . . . . . . . . . . . .
1 General Information
General Information What you'll nd in this chapter 1-2 A brief description of the Agilent 83446A/B lightwave clock/data receiver. A list of options and accessories available. Agilent 83446A/B speci cations and characteristics. Information about the lightwave receiver's serial number label. Information about avoiding damage to the instrument from electrostatic discharge.
Description of the Agilent 83446A/B The Agilent 83446A/B lightwave clock/data receivers are designed to extract clock and data information from digitally modulated lightwave signals. They operate at the following SONET/SDH rates: Agilent 83446A : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 2.48832 Gb/s Agilent 83446B : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 622.
General Information Description of the Agilent 83446A/B For more information on using the lightwave clock/data receiver refer to Chapter 3. Learning the inside story . . . The block diagram for the Agilent 83446A/B is shown in Figure 1-1. The optical-to-electrical conversion is performed by a sensitive APD photodetector which covers the 1310 and 1550 nm wavelength ranges. The optical input uses 50 m multimode ber for compatability with either single-mode or multimode ber inputs.
General Information Description of the Agilent 83446A/B Accessories supplied The Agilent 83446A/B lightwave clock/data receiver is shipped with: Power cable (refer to Figure 2-3) FC/PC front-panel connector interfaces Agilent 83446A/B Lightwave Clock/Data Receiver User and Service Guide.
General Information Description of the Agilent 83446A/B Front-panel features Figure 1-2. The Agilent 83446A/B front-panel.
General Information Description of the Agilent 83446A/B 1. Line switch. 2. Powerline LED. 3. CLOCK OUT connector. Output is nominally 2.48832 GHz (622.08 MHz for Agilent 83446B). When the SYNC LOSS indicator is extinguished this output is synchronized with the bit rate of the input signal. When not synchronized to an input signal the output free-runs near the nominal clock frequency. 4. SYNC LOSS indicator. This LED is o whenever the clock output is synchronized to the bit rate of the input signal.
General Information Description of the Agilent 83446A/B Rear panel features Figure 1-3. The Agilent 83446A/B rear panel. 1. Power line module. 2. CLOCK RECOVERY INPUT connector. Use to recover clock and data from an electrical signal. 3. CLOCK RECOVERY INPUT SELECT switch. Use to select between front optical input and rear electrical input.
Agilent 83446A/B Speci cations and Characteristics Table 1-1 lists speci cation, characteristics, typical performance, and nominal values. The distinction between these terms is described as follows: Speci cations describe warranted performance over the temperature range 0 C to +55 C (unless otherwise noted). All speci cations apply after the instrument's temperature has been stabilized after 30 minutes of continuous operation.
General Information Agilent 83446A/B Speci cations and Characteristics Table 1-1. Agilent 83446A/B Speci cations and Characteristics Speci cations1 Agilent 83446A Data rate Sensitivity234 Data amplitude5 Clock amplitude Maximum operating input power2 Input optical return loss6 Characteristics Wavelength range Maximum safe, continuous optical input power Output electrical return loss (all electrical outputs) at 1.0 GHz at 2.0 GHz at 2.
General Information Agilent 83446A/B Speci cations and Characteristics Table 1-1. Agilent 83446A/B Speci cations and Characteristics, continued GENERAL SPECIFICATIONS Temperature Range 0 C to +55 C 040 C to +75 C Maximum relative humidity 80% for temperatures up to 31 C., decreasing linearly to 50% relative humidity at 40 C. Altitude up to 15,000 feet (4,572 meters). Conducted and radiated emissions meet the requirements of CISPR Publication 11 and EN 55011 Group 1, Class A.
Electrostatic Discharge Information Electrostatic discharge (ESD) can damage or destroy electronic components. All work on electronic assemblies should be performed at a static-safe work station. Figure 1-4 shows an example of a static-safe work station using two types of ESD protection: Conductive table-mat and wrist-strap combination. Conductive oor-mat and heel-strap combination. Both types, when used together, provide a signi cant level of ESD protection.
General Information Electrostatic Discharge Information Figure 1-4. Example of a static-safe work station.
General Information Electrostatic Discharge Information Reducing ESD damage The following suggestions may help reduce ESD damage that occurs during testing and servicing operations. Before connecting any coaxial cable to an instrument connector for the rst time each day, momentarily ground the center and outer conductors of the cable. Personnel should be grounded with a resistor-isolated wrist-strap before touching the center pin of any connector and before removing any assembly from the unit.
2 Installation and Preparation for Use
Installation and Preparation for Use What you'll nd in this chapter Installing the Agilent 83446A/B. Connecting the Agilent 83446A/B lightwave clock/data receiver to a bit-error-ratio tester. How to perform a quick con dence check of the Agilent 83446A/B. How to return the Agilent 83446A/B for service. Cleaning connections for accurate measurements.
Installing the Agilent 83446A/B CAUTION CAUTION VENTILATION REQUIREMENTS: When installing the instrument in a cabinet, the convection into and out of the instrument must not be restricted. The ambient temperature (outside the cabinet) must be less than the maximum operating temperature of the instrument by 4 C for every 100 watts dissipated in the cabinet. If the total power dissipated in the cabinet is greater than 800 watts, then forced convection must be used.
Installation and Preparation for Use Installing the Agilent 83446A/B or return it to Agilent Technologies for service. Refer to \How to Return the Agilent 83446A/B for Service".
Installation and Preparation for Use Installing the Agilent 83446A/B Step 2. Set the line voltage selector Use the following procedure to set the lightwave clock/data receiver's voltage selector to the voltage range (100, 120, 220, or 240V) corresponding to the available ac voltage. CAUTION Before connecting the lightwave receiver to the power source, you must set the rear-panel voltage selector correctly to adapt the lightwave receiver to the power source.
Installation and Preparation for Use Installing the Agilent 83446A/B Step 3. Check the fuse The recommended fuse is listed below: For a 100/120V operation: T 0.315A, 250V, time delay, Agilent part number 2110-0449. For a 220/240V operation: T 0.16A, 250V, time delay, Agilent part number 2110-0448. WARNING For continued protection against re hazard, replace line fuse only with same type and ratings. The use of other fuses or materials is prohibited.
Installation and Preparation for Use Installing the Agilent 83446A/B Step 4. Connect the Agilent 83446A/B to a power source CAUTION The lightwave clock/data receiver is a portable instrument and requires no physical installation other than connection to a power source. Do not connect ac power until you have veri ed that the line voltage is correct, the proper fuse is installed, and the line voltage selector switch is properly positioned, as described in the following paragraphs.
Installation and Preparation for Use Installing the Agilent 83446A/B CAUTION di erent areas. Figure 2-3 lists the available ac power cables, illustrates the plug con gurations, and identi es the geographic area in which each cable is appropriate. Always use the three-prong ac power cord supplied with this instrument. Failure to ensure adequate earth grounding by not using this cord may cause instrument damage.
Installation and Preparation for Use Installing the Agilent 83446A/B Figure 2-3. AC power cables available.
Installation and Preparation for Use Installing the Agilent 83446A/B Step 5. Turn on the Agilent 83446A/B With the power cable inserted into the line module, turn the lightwave receiver on by pressing the line switch. The green light-emitting diode (LED) should light. If the LED should fail to light, refer to \Performing a Quick Con dence Check" in this chapter.
Connecting the Agilent 83446A/B to a BitError-Ratio Test Set The following procedure describes how to connect the lightwave clock/data receiver to a bit error ratio test set (BERT). Refer to Figure 2-4. Figure 2-4. Connecting the Agilent 83446A/B to a bit error ratio test system. 1. Turn the lightwave clock/data receiver on. Let it warm up for 30 minutes. 2. Turn the BERT on and let it warm up according to its speci cations. 3. Perform any calibrations indicated in the documentaion for the BERT.
Installation and Preparation for Use Connecting the Agilent 83446A/B to a Bit-Error-Ratio Test Set CAUTION 4. Connect a cable from the CLOCK OUT connector on the receiver to the clock input connector of the BERT. An adapter may be necessary. 5. Connect a cable from the DATA OUT connector on the receiver to the data input connector on the BERT. An adapter may be necessary. 6. Clean the end of the receiver's OPTICAL INPUT glass ber and the end of the glass ber in the laser output cable.
Performing a Quick Con dence Check To verify the basic functionality of the clock/data receiver, use the following procedure. (Clean all optical interfaces as described in \Cleaning Connections for Accurate Measurements", before making measurements.) 1. Turn on the clock/data receiver and observe the SYNC LOSS LED lights. 2. Connect the optical source 1200{1600 nm >027 dBm with modulation at 2.48832 Gb/s rate to optical input. (Use a 622.08 Mb/s rate at >028 dBm with Agilent 83446B instruments.) 3.
Installation and Preparation for Use Performing a Quick Con dence Check 6. Review the procedure for the test being performed when the problem appeared. Are all the settings correct? 7. Are the connectors clean? Refer to \Cleaning Connections for Accurate Measurements" for more information about cleaning the connectors. If the clock/data receiver still fails, you have two options: Return the lightwave receiver to Agilent Technologies for repair.
How to Return the Agilent 83446A/B for Service When an instrument is returned to a Agilent Technologies service o ce for servicing, it must be adequately packaged and have a complete description of the failure symptoms attached. When describing the failure, please be as speci c as possible about the nature of the problem. Include copies of additional failure information (such as instrument failure settings, data related to instrument failure, and error messages) along with the instrument being returned.
Installation and Preparation for Use How to Return the Agilent 83446A/B for Service Instrument shipping preparation procedure CAUTION 1. Write a complete description of the failure and attach it to the instrument. Include any speci c performance details related to the problem. The following information should be returned with the instrument. Type of service required. Description of the problem: Whether problem is constant or intermittent. Whether instrument is temperature-sensitive.
Installation and Preparation for Use How to Return the Agilent 83446A/B for Service from Sealed Air Corporation (Commerce, California 90001). Air CapTM looks like a plastic sheet lled with air bubbles. Use the pink (antistatic) Air CapTM to reduce static electricity. Wrapping the instrument several times in this material will protect the instrument and prevent it from moving in the carton. 3. Seal the carton with strong nylon adhesive tape. 4. Mark the carton \FRAGILE, HANDLE WITH CARE". 5.
Installation and Preparation for Use How to Return the Agilent 83446A/B for Service Table 2-2. Agilent Technologies Service Numbers Austria Belgium Brazil China Denmark Finland France Germany India Italy Ireland Japan Korea Mexico Netherlands Norway Russia Spain Sweden Switzerland United Kingdom United States and Canada 2-18 01/25125-7171 32-2-778.37.71 (11) 7297-8600 86 10 6261 3819 45 99 12 88 358-10-855-2360 01.69.82.66.
Cleaning Connections for Accurate Measurements CAUTION Accurate and repeatable measurements require clean connections. Use the following guidelines to achieve the best possible performance when making measurements on a ber-optic system: Keep connectors covered when not in use. Use dry connections whenever possible. Use the cleaning methods described in this section. Use care in handling all ber-optic connectors.
Installation and Preparation for Use Cleaning Connections for Accurate Measurements Dust Caps Provided with Lightwave Instruments Item Laser shutter cap FC/PC dust cap Biconic dust cap DIN dust cap HMS10 dust cap ST dust cap Inspecting Fiber-Optic Cables Agilent Part Number 08145-64521 08154-44102 08154-44105 5040-9364 5040-9361 5040-9366 Consistent measurements with your lightwave equipment are a good indication that you have good connections.
Installation and Preparation for Use Cleaning Connections for Accurate Measurements WARNING Always remove both ends of ber-optic cables from any instrument, system, or device before visually inspecting the ber ends. Disable all optical sources before disconnecting ber-optic cables. Failure to do so may result in permanent injury to your eyes. To clean a non-lensed connector CAUTION Do not use any type of foam swab to clean optical ber ends.
Installation and Preparation for Use Cleaning Connections for Accurate Measurements CAUTION Do not shake, tip, or invert compressed air canisters, because this releases particles in the can into the air. Refer to instructions provided on the compressed air canister. 7. As soon as the connector is dry, connect or cover it for later use. To clean an adapter 1. Apply isopropyl alcohol to a clean foam swab. Cotton swabs can be used as long as no cotton bers remain after cleaning.
Installation and Preparation for Use Cleaning Connections for Accurate Measurements To test insertion loss Use an appropriate lightwave source and a compatible lightwave receiver to test insertion loss. Examples of test equipment con gurations include the following equipment: Agilent 71450A or Agilent 71451A optical spectrum analyzers with Option 002 built-in white light source.
Installation and Preparation for Use Cleaning Connections for Accurate Measurements
3 Using the Agilent 83446A/B
Using the Agilent 83446A/B What you'll nd in this chapter 3-2 Example of measuring dispersion power penalty of an optical ber. Example of optimizing the bias on a laser for lowest bit error ratio. Example of generating oscilloscope eye diagrams when a separate clock trigger is not available.
Bit-Error-Ratio Test Optical ber su ers from chromatic dispersion, which causes light at di erent wavelengths to travel through the ber at slightly di erent velocities. Since the linewidth of a laser is not in nitesimally narrow, the di erent wavelength components will not all arrive at the end of a long length of ber at the same time. This tends to atten and spread out fast risetime pulses, leading to intersymbol interference.
Using the Agilent 83446A/B Bit-Error-Ratio Test System sensitivity calibration System sensitivity without dispersion is determined by connecting the laser output through an optical attenuator and directly to the clock/data receiver. To nd sensitivity for 1210010 BER: 1. Connect the equipment as shown in Figure 3-1. Set the optical attenuator so the input power to the clock/data receiver is approximately {20 dBm.
Using the Agilent 83446A/B Bit-Error-Ratio Test Clock Frequency (Agilent 83446B) : : : : : : : : : : : : : : : : : : : : : : : : : : 622.
Using the Agilent 83446A/B Bit-Error-Ratio Test d. Reconnect splitter output A to the input of the clock/data receiver and splitter output B to the optical power meter. e. Keeping the attenuator set as determined in step 3c, calculate the calibration factor necessary for the power meter to read 027.0 dBm (028.0 dBm for Agilent 83446B). This calibration factor is then applied to all subsequent power meter readings to determine the input power to the clock/data receiver. 4.
Using the Agilent 83446A/B Bit-Error-Ratio Test Determining dispersion power penalty To determine dispersion power penalty: 1. Connect the equipment as shown in Figure 3-2. Fiber length should be representative of length anticipated under normal operation. Figure 3-2. Setup to measure dispersion power penalty of single-mode ber. 2.
Using the Agilent 83446A/B Bit-Error-Ratio Test Gating Period : : : : : : : : : : : : : : : : As necessary to capture at least 100 errors 3-8
Using the Agilent 83446A/B Bit-Error-Ratio Test 3. Do a preliminary scan of the sensitivity by stepping the variable attenuator through a range of values and observing the delta error ratio on BERT. Record the power level into the clock/data receiver that gives roughly 1210010 BER. Leaving the attenuator at this setting, press RUN GATING key on the BERT to initiate a gating cycle. Record the error ratio indicated at the conclusion of the cycle. 4.
Bit-Error-Ratio Test Digital optical transmission systems send data by intensity modulating the optical source. In principle, a logical one is represented by a time interval of full-intensity light while a logical zero is represented by an interval of no light. This ideal case produces the maximum intensity di erence between a one and a zero, yielding the best signal-to-noise ratio and lowest possible bit-error-ratio.
Using the Agilent 83446A/B Bit-Error-Ratio Test Example of optimizing laser extinction ratio The clock/data receiver can be used to determine the laser bias point that produces the lowest bit-error-ratio. This is determined by adjusting laser bias for the minimum error ratio while monitoring real-time error performance on a BERT. NOTE Because of ber dispersion, the optimum bias point through a short length of ber may not be the same as through a long ber.
Using the Agilent 83446A/B Bit-Error-Ratio Test Figure 3-3. Setup for optimizing laser extinction ratio. 3. Observe the delta-error-ratio on the BERT. Set the attenuator to an attenuation level high enough to cause a measurable error ratio in the range of 1006 to 1009 . 4. While observing the delta-error-ratio on the BERT, slowly adjust the laser bias in the direction that causes the error ratio to improve.
Waveform Test Eye diagrams are important tools for characterizing the waveform performance of a laser source. An eye diagram is generated on an oscilloscope by observing the data output from the laser while triggering the oscilloscope from a separate signal at the clock frequency. Example of measuring eye diagram using recovered clock signal In many cases a separate clock signal is not readily accessible.
Using the Agilent 83446A/B Waveform Test Figure 3-4. Setup for measuring eye diagram by triggering from recovered clock. 2. Adjust the trigger level on the oscilloscope to achieve reliable triggering. 3. Set the oscilloscope TIME/DIV to 100 ps. Adjust the vertical scale on the oscilloscope to obtain a convenient signal level on the display. The displayed eye diagram now accurately represents the contributions of all possible bit combinations.
4 Servicing the Agilent 83446A/B
Servicing the Agilent 83446A/B What you'll nd in this chapter WARNING WARNING WARNING WARNING WARNING General information Troubleshooting Adjustment procedure Replacement procedures Replaceable parts These servicing instructions are for use by quali ed personnel only. To avoid electrical shock, do not perform any servicing unless you are quali ed to do so. The opening of covers or removal of parts is likely to expose dangerous voltages.
General information NOTE Clean the cabinet using a damp cloth only. Serial-number information Whenever you contact Agilent Technologies about your lightwave receiver, have the complete serial number and option designation available. This will ensure you obtain accurate service information. Refer to \Description of the Agilent 83446A/B" in Chapter 1 for more information.
Servicing the Agilent 83446A/B General information Reliability considerations The lightwave receiver input circuitry can be damaged by power levels that exceed the maximum safe input-level speci cations. Refer to Table 1-1 for the input speci cations. To prevent input damage, these speci ed levels must not be exceeded. Protection from electrostatic discharge Electrostatic discharge (ESD) can damage or destroy electronic components.
Troubleshooting The main functional blocks of the clock/data receiver are the power supply and the photodetector/clock/data recovery unit. Figure 4-1. Agilent 83446A/B block diagram. WARNING WARNING The opening of covers or removal of parts is likely to expose dangerous voltages. Disconnect the instrument from all voltage sources while it is being opened. The power cord is connected to internal capacitors that may remain live for ve seconds after disconnecting the plug from its power supply.
Servicing the Agilent 83446A/B Troubleshooting Photodetector and clock/data recovery assembly Modulated light enters the InGaAs avalanche photodetector diode (APD) through a multimode ber front panel connector. The APD converts the modulated light to a current replica of the modulation. The APD is biased in the 40 to 100V range by a thermally compensated high voltage bias supply. The APD output signal is converted to a voltage and ampli ed by a low noise preamp stage.
Servicing the Agilent 83446A/B Troubleshooting The 012 V power supply is not used. The voltages on the power supply terminals are described in Table 4-2. Table 4-2. Voltages on the DC Power Supply Terminals Terminal E2, 0OUT E2, +OUT E1, 0OUT E1, COM E1, +OUT Description 05.2V power supply Common ground 012 V power supply Common ground +12 V power supply Voltage 05.32 Vdc 610 mV 0 Vdc 012 Vdc (approximate) 0 Vdc +12.
Adjustment Procedures Power supply adjustment procedure WARNING The clock/data receiver has several adjustments, two of which are on the power supply. To adjust the power supply, use an Agilent 3456A digital multimeter (or equivalent) to measure the dc output voltage at the power supply terminals. If the dc output voltage is not within tolerance, adjust the power supply. Only trained service personnel should perform measurements inside the instrument chassis. Use extreme care.
Servicing the Agilent 83446A/B Adjustment Procedures 5. Measure the power supply output voltage. The voltage reading should be +12.12 Vdc 610 mV. 6. If the voltage is not +12.12 Vdc, adjust the +12V ADJ for a reading of +12.12 Vdc 610 mV.
Servicing the Agilent 83446A/B Adjustment Procedures Photodetector/clock/data recovery assembly adjustment procedure There are three adjustments on the photodetector/clock/data recovery assembly. The R50 +VAPD adjust sets the APD bias for optimum sensitivity. The R82 Threshold Adjust sets the CDR detection threshold for optimum sensitivity. The R78 High Input Limit Set sets maximum operating power for the speci ed error rate.
Performance Tests The performance tests in this section require the following test equipment: Table 4-3.
Servicing the Agilent 83446A/B Performance Tests Setting up and biasing the laser transmitter 1. Connect equipment as in Figure 4-2. a. Connect the pattern generator output to the laser analog modulation input. b. Connect the laser output to attenuator input. c. Connect the attenuator output to the O/E converter input. d. Connect the O/E output to the scope input. e. Initialize the instruments. Figure 4-2. Laser transmitter setup. 2. Set the test equipment to the settings shown in Table 4-4.
Servicing the Agilent 83446A/B Performance Tests Table 4-4. Laser Transmitter Setup Pattern Generator Error Detector Clock Source 223 01 pattern 1.00 Vpp data amplitude 0.000V data high level (0V term.) normal polarity, clock trigger trigger mode clock/32 23 zeroes trigger pattern 223 01 pattern auto 0/1 threshold positive clock edge normal data polarity auto clock-data alignment gating manual gating OFF 2.48832 GHz frequency (Agilent 83446A), 622.
Servicing the Agilent 83446A/B Performance Tests 4. Turn on the laser and observe the eye pattern on the digitizing oscilloscope. Set a time window of 10% of the eye, centered in the eye pattern. 5. Use voltage histograms to measure the mean \1" level and the mean \0" level of V1 and V0. 6. Turn o the laser and measure the o set level (Vo ). 7. Calculate the extinction ratio (V1 0 Vo ) / (V0 0 Vo ). 8. Adjust the pattern generator output level, if necessary, for an extinction ratio of between 6.6 and 7.
Servicing the Agilent 83446A/B Performance Tests Test 1. Sensitivity NOTE Allow the Agilent 83446A/B and test equipment to warm up for at least 30 minutes. Procedure 1. Connect equipment as in Figure 4-3. 2. Initialize the test equipment as shown in Table 4-5. 3. Turn on the Agilent 83446A/B. Initiate an auto clock/data alignment on the error detector. The error detector should synchronize and the error ag should disappear. An eye diagram should appear on the oscilloscope. 4.
Servicing the Agilent 83446A/B Performance Tests Figure 4-3. Agilent 83446A/B test equipment setup.
Servicing the Agilent 83446A/B Performance Tests Table 4-5. Sensitivity Test Setup Pattern Generator Error Detector Clock Source Laser Transmitter (both 1310/1550 nm) 0ptical Attenuator Optical Power Meter Digitalizing Oscilloscope 223 01 pattern data amplitude set for 6.6:1 extinction ratio on transmitter 0.000V data high level (0V term.
Servicing the Agilent 83446A/B Performance Tests Table 4-5. Sensitivity Test Setup (continued) Agilent 83446A/B being tested Rear panel switch to FRONT 015 dBm input power clean the optical connectors FC/PC adapter 5. Substitute the 1550 nm laser transmitter in place of the 1310 nm unit. Set the drive level for a 6.6:1 extinction ratio. Recalibrate the optical attenuator. Connect the ber to the Agilent 83446A/B and reduce the power until errors begin.
Servicing the Agilent 83446A/B Performance Tests Detection threshold adjustment 7. This adjustment is marked THRESHOLD on the printed circuit card (R7). Set the optical power for about 10-20 errors per gating cycle. Adjust the THRESHOLD pot for minimum errors. If the errors go to zero during the adjustment, reduce the optical power. The THRESHOLD is optimum at the error null setting. Sensitivity veri cation 8.
Servicing the Agilent 83446A/B Performance Tests Test 2. Maximum operating input power Test Setup The maximum operating input power test requires the same setup as \Test 1. Sensitivity". If sensitivity testing has just been completed, the test equipment is already properly initialized. If not, initialize as instructed in the section titled \Sensitivity" in this chapter. The test may begin with either the 1310 or 1550 nm transmitter. Procedure Set the optical power into the Agilent 83446A/B at 09 dBm.
Servicing the Agilent 83446A/B Performance Tests Test 3. Electrical output signal amplitudes Test setup The electrical output signal amplitude test requires the same setup as shown in Figure 4-3. If the sensitivity and maximum operating input power tests have just been completed, the equipment is already initialized. If not, initialize as instructed in the section \Sensitivity". The following procedure may be done with either the 1310 or 1550 nm transmitter. Procedure 1.
Servicing the Agilent 83446A/B Performance Tests Data high level mean voltage Data low level mean voltage Data high mean value minus low mean value (must be >0.
Servicing the Agilent 83446A/B Performance Tests Test 4. Rear-panel input port veri cation (functional check only) Test setup The rear-panel input port veri cation test requires the same setup as shown in \Test 1. Sensitivity". If the section \Maximum operating input power" has just been completed, the test equipment has already been properly initialized. If not, initialize as instructed in the section \Sensitivity". Procedure 1.
Servicing the Agilent 83446A/B Performance Tests Test 5. Input optical return loss Test equipment Table 4-6.
Servicing the Agilent 83446A/B Performance Tests f. Set the Agilent 81554SM as follows: Averaging time : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 200 ms Lambda : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 1310 nm CAL REF : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 0.18 db g.
Replacement Procedures What you'll nd in this section This section contains the replacement procedures for the following assemblies: CAUTION RF cable and RF connector AC cable assembly Power supply Photodetector/clock/data recovery assembly This instrument contains static-sensitive components. Read the electrostatic discharge information in Chapter 1 before removing any assemblies.
Servicing the Agilent 83446A/B Replacement Procedures Replacing the RF cable or the RF connector When replacing the RF cable or RF output connectors, use the appropriate torque value. Refer to Table 4-7. When disconnecting the cables at the photodetector assembly, use the Suhner removal tool (Table 4-7). CAUTION Avoid bending or distorting any semirigid cables when removing or reinstalling assemblies. Before removing an assembly, always loosen both ends of any semirigid cable attached to the assembly.
Servicing the Agilent 83446A/B Replacement Procedures Replacing the ac cable assembly The ac cable assembly consists of the line module, the line switch, and the cable harness. When replacing the ac cable assembly, unsolder the connections to the dc power supply. Remove the line module. Remove the line switch. Refer to Figure 4-4 and Table 4-8 when installing a new ac cable assembly. Figure 4-4. Wiring diagram for the line module.
Servicing the Agilent 83446A/B Replacement Procedures Table 4-8.
Servicing the Agilent 83446A/B Replacement Procedures Replacing the power supply Unsolder the connections to the dc power supply. Remove the four screws that attach the power supply to the chassis. Refer to Table 4-1, Figure 4-5, Table 4-9, and Table 4-8 when installing a new power supply. Adjust the 5.2V and 12V power supplies to the proper voltages listed in Figure 4-5. Figure 4-5. Wiring Diagram for the power supply terminals. Table 4-9.
Servicing the Agilent 83446A/B Replacement Procedures Replacing the PCDR assembly CAUTION 1. Remove the cable assemblies from connectors P1, P2, and P3 on the photodetector/clock/data recovery (PCDR) assembly. 2. Use the Huber Suhner connector tool (refer to Table 4-1) to remove the four coax cable assemblies from the PCDR assembly. These connectors are small and delicate. Failure to use the Huber Suhner connector tool can result in concealed damage that will cause an unreliable connection. 3.
Replaceable parts What you'll nd in this section This section contains information for: identifying and ordering replacement assemblies mechanical parts for the Agilent 83446A/B lightwave receiver Replaceable parts table Table 4-10 lists information for each major assembly and for each major mechanical and electrical part that is not part of a major assembly. Table 4-11 format lists information for the clock/data receiver replaceable hardware.
Servicing the Agilent 83446A/B Replaceable parts Direct mail-order system Within the USA, Agilent Technologies can supply parts through a direct mail-order system. Advantages of using the system are as follows: Direct ordering and shipment from Agilent Technologies. No maximum or minimum on any mail order. (There is a minimum order amount for parts ordered through a local Agilent Technologies o ce when the orders require billing and invoicing.) Prepaid transportation.
Servicing the Agilent 83446A/B Replaceable parts Figure 4-6. Agilent 83446A/B assembly level replaceable parts.
Servicing the Agilent 83446A/B Replaceable parts Table 4-10.
Servicing the Agilent 83446A/B Replaceable parts Figure 4-7. Agilent 83446A/B replaceable hardware.
Servicing the Agilent 83446A/B Replaceable parts Table 4-11. Replaceable Hardware Index Number 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Agilent Part Number 0515-2044 0515-0372 0515-0947 0515-1400 0380-0019 0535-0082 2190-0016 2950-0001 2200-0166 83410-20003 2260-0009 1400-0249 0610-0001 2190-0014 Description SCREW, MACH M4.0 X 10MM FLAT-HD SCREW, MACH M3.0 X 8MM PAN-HD SCREW, MACH M3.5 X 10MM PAN-HD SCREW, MACH M3.
Servicing the Agilent 83446A/B Replaceable parts
Index
Index A B C ac cable assembly, 4-28 accessories, 1-5 ac power cables, 2-8 adjustment procedure, 4-8, 4-10 Agilent maintenance contract, 2-14 Agilent Technologies Sales and Service O ces, 2-17 altitude, 1-10 assembly-level replaceable parts, 4-34 assistance, vi auxiliary out connector, 1-7 avalanche photodetector diode (APD), 4-6 bit-error-ratio test measuring dispersion power, 3-3 Bit-Error-Ratio Test optimizing laser extinction, 3-10 bit-error-ratio test set, 2-11 cabinet, cleaning, 2-2 calibration syst
D E F H I data out connector, 1-7 description Agilent 83446A/B lightwave receiver, 1-3 detection threshold adjustment, 4-19 direct mail-order system, 4-33 direct phone-order system, 4-33 dispersion power penalty, 3-3{9 electrical output signal amplitudes, 4-21 electrostatic discharge (ESD), 1-12 protection, 4-4 reducing damage, 1-14 static-safe work station, 1-13 EMI compatibility, 1-10 error ratio, 3-10 eye diagram measuring from recovered clock signal, 3-13 ber-optic cables cleaning connections, 2-19
L M O P R laser extinction optimizing, 3-10 laser extinction ratio, 3-11 laser transmitter setup, 4-11 lightwave receiver, 1-3 line frequency, 2-7 line fuse, 2-6 line module, 4-28 line voltage range, 2-5 line voltage selector, 2-5 low voltage servicing, 4-6 maximum operating input power adjustment, 4-20 opening the fuse holder door, 2-5 optical in connector, 1-7 options, 1-5 overvoltage servicing, 4-6 packaging, 2-15 part ordering information, 4-32 performance tests, 4-11 photodetector assembly, 4-6 phot
repair options, 2-14 replaceable parts, 4-32 replacement procedures, 4-26 replacing photodetector/clock/data recovery assembly, 4-31 replacing the ac cable assembly, 4-28 replacing the line module servicing, 4-28 replacing the power supply, 4-30 responsivity testing, 2-13 returning for service, 2-15 RF cable or connector servicing, 4-27 S T safety symbols, iv safety considerations, v servicing, 4-3 sales and service o ces, 2-17 sensitivity testing, 4-15 sensitivity veri cation, 4-19 serial numbers, 1-5,
V W +VAPD adjustment, 4-18 VA power requirements, 2-7 ventilation requirements, 2-3 veri cation test failing, 2-13 voltage range, 2-5 voltage tumbler, 2-5 warranty, 2-14 warranty information, viii waveform test measuring eye diagram, 3-13 Index-6