Getting Started with the Agilent J-BERT N4903A High-Performance Serial BERT You only need a few minutes to get started with the J-BERT. This Getting Started Brochure helps you to quickly understand the operating principles and set up your first BER test. If you need more detailed information on the J-BERT, check out the Online Help. The Help also offers printable versions of the User Guide and the Programming Guide.
Safety Summary Notice Copyright General Safety Precautions © Agilent Technologies, Inc. 2006. The following general safety precautions must be observed during all phases of operation of this instrument. Failure to comply with these precautions or with specific warnings elsewhere in this manual violates safety standards of design, manufacture, and intended use of the instrument. Revision Revision 2.
Installing the Agilent J-BERT Inspect Shipment Check if the J-BERT shipping container contains the following standard deliverables: If the contents are incomplete, if there is mechanical damage, or if the instrument does not work within its specifications, notify the nearest Agilent office. The Agilent office will arrange for repair or replacement without awaiting settlement.
Operating the Agilent J-BERT Now that the instrument is running, let’s take a look at its front panel elements: Instrument Setup Controls Accumulation Controls Keypad and Front Panel Knob PG Connectors Power Switch and Earth Terminal Preset Local USB PG Controls ED Controls ED Connectors The Agilent J-BERT is available in different versions. Depending on your version, some of the hardware and functionality described in this brochure may not be available.
Operating the Agilent J-BERT Changing Parameters With the touchscreen, your finger is the mouse. Tipping an item with your finger is like clicking it with the mouse. You can use the numeric keypad to enter values by hand, or the large knob to adjust values. You can also use the knobs at the bottom of the instrument to change certain frequently used values in run-time.
Preparing the Test What Are We Testing? The quickest way to familiarize yourself with the instrument is to set up a short test. You can test the BER on a cable. All you need for this test is an APC/RPC cable for the data port connection and an APC/RPC-SMA adapter cable to connect the PG clock output to the ED clock input. Setting up the Pattern Generator First we need to set up the pattern generator. To keep things simple, let's set up LVDS logic levels for both the data and clock output.
Setting Up the Instrument Set the Bit Rate Now we want to set the pattern generator's bit rate. For now, we will use the instrument's internal clock: 1 Switch to the Bit Rate Setup. 2 Keep the Internal Clock Source. Select the Pattern Now select the data pattern to be used for the test: 1 3 Select 1.06250 Gb/s Ethernet from the list. You can easily add your favorite frequencies to the list. Press the Pattern Setup button to switch to the pattern editor. 2 Open the Pattern Select dialog box.
Setting up the Instrument Setting up the Error Detector The next step is to set up the error detector’s inputs. 1 Press the PG/ED Setup button twice to switch to the error detector setup. 2 Click the Edit button. 3 Set the Input to Normal. This means, we need only one cable that will be connected between the pattern generator and the data input port. 4 Enter the termination voltage that matches the output termination of the DUT, in our case equal to the pattern generator’s data output.
Setting Up the Instrument Synchronizing the Pattern Now make sure that the error detector automatically syncs to the data pattern: 1 Open the Pattern Sync Setup dialog box. 2 Make sure that Normal Sync Mode and Automatic Sync are selected. With this setting, the error detector starts synchronizing when the BER exceeds a certain threshold value. You can see when it has synchronized when the Sync Loss indicator goes off. If sync fails, the sampling point is probably outside of the eye.
Modifying the Test Setup Adjusting the Sampling Point You can adjust the sampling point manually, for example, to test the performance of your DUT closer to the edge of the eye: 1 Use the Decision Threshold knob to move the sampling point vertically. 2 Use the Data In Delay knob to move the sampling point horizontally. You can see how the BER increases when measuring at the edge of the eye.
Modifying the Test Setup Inserting Errors You can add a single bit error to the data stream by pressing the Error Add button. You could also loosen the data cable and wiggle it carefully. Watch how the BER changes. The pattern generator can also be set up to insert a specified BER in the data stream. This can, for example, be used for testing error correction algorithms.
Installing Hardware Options Installing the J20 Option To install the J20 Interference Channel: 1 Perform the regular shutdown procedure provided by the operating system. 2 Disconnect the instrument from mains. Caution Never plug in or remove a module while the instrument is connected to mains power. 3 Unscrew and remove the slot cover. 5 Press the lever until the 6 Insert and tighten 4 Insert the module module rests firmly in place, the front plate aligned with the Error Detector’s front panel.
