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Agilent Technologies 71612 Quick Reference

Agilent Technologies 71612 Quick Reference

Error performance analyzer
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Agilent 71612 Error Performance Analyzer
This booklet is intended as a handy reminder of the fundamen-
tals of BER measurement and of how to use the Agilent
71612 Error Performance Analyzer for BER measurements.
Full details of all the steps and procedures are given in the
71612 Operating and Programming Manual. We recommend
that you read the full manual before using this booklet.
Tab
Intro to the 71612 Agilent 71612 12.5 Gb/s Error
Front/Rear Cabling Front and Rear Panel Cabling
Pat Editor Operation Pattern Editor Operation
BER - What is it?
Quick Reference (71612-90017)
Contents
Title
Performance Analyzer
The Front Panel
Initial Switch-on
Measurements
Disk Operation
General Functions
The Menus
and Residual BER
Data Rate
Page
5
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  • Page 1: Table Of Contents

    71612 Operating and Programming Manual. We recommend that you read the full manual before using this booklet. Contents Title Page Intro to the 71612 Agilent 71612 12.5 Gb/s Error Performance Analyzer The Front Panel Front/Rear Cabling Front and Rear Panel Cabling Initial Switch-on...
  • Page 2 Intro to the 71612 CAUTION All of the 71612 data and clock outputs are dc-coupled. DO NOT APPLY ANY EXTERNAL VOLTAGE TO THESE OUTPUTS. This will damage the internal amplifiers. Take particular care when using a bias tee to connect it the correct way.
  • Page 3 Intro to the 71612...
  • Page 4 Agilent 71612 Intro to the 12.5 Gb/s Error Performance Analyzer 71612...
  • Page 5 The Front Panel The 70004A Display serves as the front panel for instruments in the 71612 Series, and as your window for viewing current system configuration and measurement results. Instrument Hardkeys gain instant access to primary instrum ent hardkeys instrument functions such as data output or result pages.
  • Page 6 Instrument Softkeys Intro to the softkeys select instrument functions. The functions are 71612 organized in groups, called softkey menus. NOTE Softkeys that are selected are displayed in inverse video or are underlined. Some softkeys switch between two states, such as .
  • Page 7 Parameter Control Keys Display knob Use the display RPG knob to change parameters and select operating values. Numeric keypad Use the numeric keypad to enter numeric values. Use the two step keys to change parameters up or down. Intro to the 71612...
  • Page 8 Front and Rear Panel Cabling Front/Rear Cabling System Back-to-Back Connection...
  • Page 9 HP-MSIB Cabling, rear panel Front/Rear Cabling...

  • Page 10: Initial Switch-On

    Initial Switch-on 1. For a back-to-back system check, connect up the front panel as shown on page 9. Otherwise, connect up as appropriate to your application. 2. Connect the 70843 and 70004A rear-panel HP-MSIB ports as shown on page 10. If not, the red HP-MSIB LED on the display will light up.

  • Page 11: Pattern Generator Setup

    Pattern Generator Setup Set Up Clock Output Select and setup the clock source clock output frequency using the SIG GEN FREQ FREQ STEP softkeys. SIG GEN AMPLTD SIG GEN ON OFF Setup the internal clock parameters using the available softkeys. The CLOCK and CLOCK OUT ports can be set to be independent, , or track together,...

  • Page 12: Pat Gen Setup

    Select Pattern Generator Trigger Output Pulse The TRIGGER OUTPUT port gives an electrical trigger for use with an oscilloscope or other test equipment. Pattern or clock triggers are provided. Clock trigger is a square wave at 1/8 or 1/32 of clock rate. Pattern trigger is synchronized to repetitions of the output pattern.

  • Page 13: Error Det Setup

    Error Detector Setup Set Up Data Input Ensure the Error Detector is cabled correctly. Select then setup input polarity, termination input & eye and delay using the available softkeys. Perform clock-data alignment to ensure the Error Detector samples in the middle of the date eye as follows: Select 0/1 THR AUTOMAN input &...
  • Page 14 Note that the sync softkeys are disabled (greyed out) when BURST GATING (on gating menu) is selected. Errors Output Port Produces a pulse that is the logical OR of errors in a 32-bit segment of data. Pulse length switchable - RZ or stretched (200 ns).

  • Page 15: Meas Gating

    Measurement Gating Start or Stop Gating Start or stop gating at any time using R UN G ATIN G STOP GATING If your Display does not have a hardkey panel, select and use the gating RUN GATING M EN U STOP GATING Note the green Gate flag at top right of the display during the measurement period.

  • Page 16: Measurements

    Measurements Basic BER Measurement Press to start measurement. R UN G ATIN G Press to end measurement; view results STOP GATING on display. Data Eye Measurement Select 0/1 THR AUTOMAN input & eye EYE EDG THRSHLD CLK-DAT ALIGN result pages EYE RESULTS On input signals with an unequal mark-density, perform a 0/1 threshold center operation.
  • Page 17 Block BER Select - use BLOCK BER BLOCK START error location display knob or numeric keypad to select BLOCK START address, select , enter block length (must be BLOCK LENGTH a multiple of 32). Press R UN G ATIN G result pages view results on page at end of...
  • Page 18 Pattern Editor Operation Select a Pattern Select then choose from one of five fixed pure pattern patterns, or a ram-based prbs zero sub mark density user pattern Edit User Patterns Select pattern edit ram user edit disk user . Select INTERNL PATT DISK PATT toggle screen...
  • Page 19 Save a Block of Data Define a block of data within the current editor user pattern memory, then save the block to any pattern store large enough to hold the pattern. The current pattern store contents are overwritten by the new data being saved. Select pattern edit ram user...

  • Page 20: Disk Operation

    Disk Operation Format a New Disk Select pattern disk utils format disk FORMAT YES Delete a Disk Pattern Store Select , then pattern disk utils delete diskpat select the store to be deleted. DISK PATT Disk Operation...

  • Page 21: General Functions

    General Functions Set Keyboard Lock Set Error Detector Real Time Clock Update Firmware Perform Self Test General Functions For all of the above, select and select the misc M EN U appropriate softkeys. Save/Recall Instrument setups Select then recall setup trigger &...

  • Page 22: The Menus

    The Menus The display instrument hardkey panel (when fitted) and the softkeys displayed when the key is selected are M EN U used to select all major instrument functions. The following menu maps illustrate the softkey choices for each function or group of functions. The boxes shown on the charts represent actual key presses and illustrate the sequence of key presses required to perform individual functions.
  • Page 23 Main Menu Menus Notes:...
  • Page 24 Pattern Notes: Menus...
  • Page 25 Pattern - PRBS Menus Notes:...
  • Page 26 Pattern - Zerosub Notes: Menus...
  • Page 27 Pattern - Markdensity Menus Notes:...
  • Page 28 Pattern - Ram User Notes: Menus...
  • Page 29 Pattern - Disk User Pattern Menus Notes:...
  • Page 30 Pattern - Edit Ram User Notes: Menus...
  • Page 31 Pattern - Edit Disk User Menus Notes:...
  • Page 32 Pattern - Edit User Notes: Menus...
  • Page 33 Data Output Menus Notes:...
  • Page 34 Clock Output Notes: Menus...
  • Page 35 Error Add Menus Notes:...
  • Page 36 Trigger & Setup Menus...
  • Page 37 Result Pages Menus Notes:...
  • Page 38 Input & Eye Notes: Menus...
  • Page 39 Sync & Audio Menus Notes:...
  • Page 40 Gating Notes: Menus...
  • Page 41 Error Location Menus Notes:...

  • Page 42: Ber Basics

    BER Basics Bit Error Ratio (BER) is the most fundamental measure of system performance - how well bits are transferred end-to- end. While this performance is affected by factors such as signal-to-noise and distortion, ultimately it is the ability to receive information error-free that defines the quality of the link.
  • Page 43 BER - What is it?

  • Page 44: Bert Decision Threshold

    BERT Decision Threshold The decision threshold is the point above which voltages are counted as a one, and below which it is counted as a zero. This decision is made on every incoming bit, turning an analog value into a digital stream of ones and zeros. For both test instruments and network equipment, the key to accurately representing the incoming signal is in getting the position of this decision point correct.

  • Page 45: False Sync

    False Sync BER - False sync occurs when the equipment tries to achieve What is it? synchronization, and although the error ratio falls below the sync threshold value set, it is not properly synchronized. This can happen with certain user-based patterns but not with a PRBS.

  • Page 46: Test Time, Confidence Interval

    Test Time, Confidence Interval and Residual BER BER is a statistical measure. It is not possible to predict with certainty when errors will occur. Therefore, how do you know when you have tested error-free for long enough to say that you really have better than 10 performance? When testing systems it is important to test at the full line rate to minimize the test time, without compromising the...

  • Page 47: Q Factor

    Q Factor BER - Q is a measure of the electrical signal-to-noise ratio of the What is it? system at the receiver decision threshold. BER may be estimated from Q when it is impractical to measure using conventional techniques. Q factor is a figure of merit often used in optically amplified systems in which noise from the amplifiers dominates receiver noise.
  • Page 48 The data is separated at the point of minimum error rate for measurable BER's and each set is fitted to an ideal curve assuming Gaussian noise statistics. The equivalent mean and standard deviation are derived from the slope and intercept of the fitted curve. Q factor can also be measured using a digitizing oscilloscope, although this is less accurate;...

  • Page 49: Eye Contour Measurements

    Eye Contour Measurements BER - Eye contours plot the inside of the eye as a function of What is it? BER. They enable a quantitative understanding of the eye diagram and can show degradations such as noise and inter-symbol interference when used with appropriate test patterns.

  • Page 50: Bert Troubleshooting

    BERT Troubleshooting Setting up a Simple BER Measurement Pattern Generator setup Error Detector setup BER - What is it?
  • Page 51 BERT Connected Back-to-Back BER - What is it?
  • Page 52 BERT Connected to DUT BER - What is it?

  • Page 53: Properties Of Prbss

    Properties of PRBSs BER - What is it? Why use PRBSs? • They simulate random data. • The data sequence is deterministic. The pattern repeats and can be predicted to infinity. • Easy to generate and measure them at high speed. •...
  • Page 54 • Gallium Arsenide circuits can suffer from “slow tail” - long runs of zeros or ones allow capacitive charging of the circuit which can cause the first one or zero that comes afterwards to fail to attain a full logic level voltage.
  • Page 55 Properties of PRBSs BER - • Balanced - the number of ones equals the number of What is it? zeros within ±1. • Compare sequence with itself - get 50% error ratio in all positions except exact correlation where it is error free. •...
  • Page 56 PRBS Frequency Spectrum Digital NRZ data has a sin x/x characteristic spectrum. PRBS follows this envelope, with line spectra of a spacing related to the sequence repetition rate. The longer the sequence before it repeats, the narrower the line spacing. The closer to a continuous spectrum produced, the more like an analog noise source the test signal looks.
  • Page 57 Decimation BER - What is it? Demultiplex a PRBS through a demux with 2 ports (2, 4, 8, 16, and so on) and the output of each will be the same PRBS sequence at lower speed with different phases. The same is true for multiplexing - most test equipment will generate multiple streams of PRBS at low speed and combine them at the end into one high speed stream.

  • Page 58: Logic Levels, Terminations And

    Logic Levels, Terminations and Data Rates Logic Levels Family SCFL PECL -0.9 V 4.1 V -0.9 V -1.75 V 3.25 V 900 mV 850 mV 850 mV Termination -2 V +3 V 50 Ω 50 Ω 50 Ω Supply 0/-3.5 V 0/-5.2 V 5/0 V Family...
  • Page 59 Terminations BER - What is it?
  • Page 60 BER - What is it?
  • Page 61 Common Data Rates BER - What is it? Selected Telecom Rates North American European Rate DS 1 1.54 Mb/s DS 3 44.736 Mb/s 2.048 Mb/s 34.368 Mb/s 139.264 Mb/s OC-1 STM-0 51.84 Mb/s OC-3 STM-1 155.520 Mb/s OC-12 STM-4 622.08 Mb/s OC-48 STM-16 2.48832 Gb/s...

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