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Tektronix 071-0590-00 QPSK BER Testing using PRBS Data for 2-Channel I & Q

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Application Note

GB1400 User Manual 2-49

Application Example

QPSK BER Testing using PRBS Data for 2-Channel I & Q

QPSK Mod / Demod

Delay line

or long

coax cable

GB700/1400 Tx

DATA

CLOCK

DATA

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).

GB700/1400 Rx

data clock

GB700/1400 Rx

data clock

I-Channel BERT

Q-Channel BERT

Contents

Main Page WARRANTY Page Table of Contents Page Page Page Appendices List of Figures List of Tables Safety Page Preface How This Manual is Organized Conventions Page Page Page Getting Started GB1400 Pattern Generator and Error Detector Features Symmetrical, Low-Jitter Output Waveforms Applications PRBS Or User-Defined Test Patterns Adjustable Inputs For Maximum Flexibility Auto Search For Easy Setup Powerful Analysis And Reporting Functions Front Panel Or Automated Operation Burst Mode Ordering Information Getting Started GB Comparison Feature GB660/CSA907A Tx and Rx GB1400 Tx and Rx GB700 Tx and Rx Page Initial Self-Check Procedure Procedure Page Page Functional Overview BERT Basics - GB1400 Page 2-4GB1400 User Manual Controls, Indicators and Connectors BIT (2) (1) OUTPUT AC-LINE Figure 2-5. Front Panel, GB1400 Analyzer (RX) Figure 2-6. Rear Panel, GB1400 Analyzer (RX) Display Formats Generator (Tx) Display 1405000 PN23 2.00 V AMPL FREQ 0 ERR OFF -1.00 V OFFS PN23 INV Analyzer (RX) Display 1405000 5.0E-06 2410538 1.2 ns PN23 -0.05 V Page Outputs and Inputs Generator OUTPUT Connectors Section Generator CLOCK Section Generator OUTPUT Section Generator Rear Panel Changing the Line Fuse Analyzer INPUT Section Analyzer MONITOR Section Analyzer Rear Panel Changing the Line Fuse Connectors, Terminations, and Levels Note 1: A 75-Ohm version of the GB1400 is an option. Controls and Indicators Power Switches Unit Mounting Unit Cooling View Angle and Panel Lock Keys GPIB Section Controls Pattern Controls and Function Keys Function (Soft) Keys (F1, F2, F3, and F4) Generator ERROR INJECT Section Analyzer INPUT Section Analyzer Error History Section Analyzer ERROR DETECTION Section Analyzer SYNC Controls Burst Mode Option Burst Mode Usage Page PECL Option for GB1400 Tx Tutorial Basic BERT testing with the GB1400 Instrument Connections and Controls Page Page Page Page Page Note - Common Setup Problems This Concludes the Tutorial. Applications Method For Very Fast Automatic Receiver Synchronization And Eye Width Measurement Two Auto Search Synchronization Methods Page Page I. Auto Search Algorithm Fast Method II. AUTO SEARCH Algorithm BER Method Page Page Consideration In Determining The Eye Data Width Consideration In Determining The Data Eye Center Delay Specifications GB700/ GB1400 Optical Component Test Fiber Optic Link Test Example Fibre Channel Link Testing Parallel and High-speed Serial 2-48 GB1400 User Manual Testing QPSK Modems, I & Q Application Note GB1400 User Manual 2-49 QPSK BER Testing using PRBS Data for 2-Channel I & Q Page Page Reference Menu Overview Functions Common to Generator (TX) and Analyzer (RX) AC Power Selecting 115 VAC or 230 VAC Operation Selecting a Pattern Pattern Definitions Selecting the Active Pattern Selecting PRBS Patterns Selecting the Current Word Pattern Selecting (RECALLing) a Saved Word Pattern Word Patterns Basics Creating Word Patterns Using Front Panel Controls Page Creating Word Patterns Using Menus Creating Word Patterns Under Remote Control Saving Word Patterns (1-Mbit Memory Option) Recalling Word Patterns (1-Mbit Memory Option) Generator (TX) Functions Clock Source and Frequency External Clock Input Clock Source Step Size and Frequency Saving a Frequency Recalling a Frequency Data and Clock Outputs Reference GB1400 User Manual 3-13 Figure 3-2. Generator Clock and Data Output Equivalent Circuits Amplitude and Baseline Offset Logically Inverting Output Data (D-INV) Single-ended or Differential Operation Pattern Sync and CLOCK/4 Outputs Error Injection Selecting an Error Inject Mode ERROR INJECT Input Analyzer (RX) Functions Automatic Setup Functions (SYNC ) AUTO SEARCH With PRBS Patterns AUTO SEARCH with "Non-PRBS" Patterns How to DISABLE Automatic Pattern Resynchronization Relationship between AUTO SEARCH and DISABLE Synchronization (LOCK) Threshold Clock, Data, and Reference Data Inputs Input Data Delay Input Termination Input Decision Threshold Logically Inverting Input Data Singled-ended or Differential Operation Selecting the Reference Data Mode Monitor Outputs Error Detection Set Up Page Page Page Display Mode: Totalize, Window, or Test Clearing Results and Starting Tests Totalize Process Set Up Window Process Set Up Test Process Set Up Viewing Results Printing Results (Reports) Reference 3-38 GB1400 User Manual Page Page Page Result Definitions Page Error History Indicators CLEAR Control Audio (Beeper) Function Analyzer Error Messages Starting and Stopping Measurements Page Menus Functions Performed Using the Menu System Menu and Function "Pages" F1 F2 F3 F4 MORE TEST WINDOW WORD Page Page General Rules for Using the Menu System Menu Summaries Page Page Menu Function Definitions Word Edit (EDIT) WORD AT ddddd = bbbbbbbb Word Length (LENGTH) LEN:mmmmm BYTES + n BITS Word Fill (FILL) FILL WORD MEMORY WITH:hh Word Order (ORDER) WORD ORDER = ccc FIRST Word Synchronization Threshold (SYNC) WORD SYNC THRES LEVEL= d Buffer WORD MEM: 0 1M BUFFERS AUTO AUTO SEARCH MODE Test Length (LENGTH) TEST LENGTH = hh:mm:ss Test Mode (MODE) TEST MODE = ccccccc Test Reports (REPORT) REPORTS ON = ccccccccc Page Test Squelch (SQUEL) ON ERROR SQUELCH = ccc Test Print (PRINT) F4 TO PRINT TEST RESULTS Test View Previous (VIEW-PRE) (result name)(count) (%) Test View Current (VIEW-CUR) (result name)(count) (%) Page Page Window Interval in Hrs:Min:Sec (SECOND) WINDOW LEN = hh:mm:ss Page Page Page Page RS-232 End-of-Line Char. (EOL) EOL = ccccc Page RS-232 Echo (ECHO) RS232 ECHO ENABLE = ccc Page Page Page Time Option (DATE) DATE = mmm dd yy Time Option (TIME) TIME = hh:mm:ss Page Page Specifications GB1400 Generator (TX) Page Page Page GB1400 Analyzer Page Page Page Page Page Page BERT Primer BERT Definition BERT used to test physical layer BERT Building Blocks BERT Pattern Generation PRBS Patterns BERT Primer PRBS Generation Circuits - A few sample diagrams output Other Tx Patterns BERT Clock Output Amplifiers Data Coding, NRZ BERT Receiver or "Error Analyzer" Components Received Data Pattern Reference Data Input Amplifier(s) Error Comparator BER Computation Other BER Measurements Confidence Level in BER Measurement Confidence Requires Collecting Many Errors Additional Reading Stress Testing Other BERT Features Eye Width Measurement Auto-Synch Pattern Lock Pattern Loading Software Error Insertion Page BERT - first and last measurement tool for transmission device design acceptability Bit error rate testing How long is long enough? Stressing the transmission system Page Page Stressing through pattern generation A B C D Page Page Page Ensure Accuracy Of Bit-Error Rate Tests Page BERT Technical Articles (b) GB1400 User Manual B-23 Page (b) (c) Page Page + Peak- Peak Ideal pulse position Jitter modulation Superimposed pulses with jitter modulation Page A1 A2 f1 f2 f3 f4 Frequency Amplitude UI peak-to-peak Page Measure Error Rates Quickly and Accurately Example of Error Rate Measurement Time in hours BER Measurement Inaccuracy versus Test Time Nn n Page Testing for an Upper Limit on Error Rate Reduced Test Time by Stressing Page Page Example 1 BER Attenuation (dB) Example 2 Example 3 BER Attenuation (dB) Example 3 Example 4 Example 4 Summary Poisson Error Process p n rT 50 5 e BER Attenuation (dB) (opt) Page Remote Commands Overview Symbols Command Types: Set and Query Command Line Format Command Names (Headers) Command Line Rules Page Remote Commands Command Examples The following are some typical GB1400 set and query command examples: Command Summary Alphabetical Page Page Page Page Command Descriptions Common and Proprietary GPIB Commands *cls *ese [n] *ese? *esr? *idn? *lrn? *opc *opc? *rst *sre [n] *sre? *stb? *tst? *wai tse [v] (Analyzer Only) tse? (Analyzer Only) Page Commands Shared by the Generator and Analyzer Pattern and Word Commands data_invert [on|off] data_invert? data_pattern [prbs | word | rdata] data_pattern? prbs_length [v] prbs_length? recall_word [m] save_word [m] word_bits [l], [b1 | b2] word_bits? word_length [l] word_mem_len [m], [l] word_mem_ord [m], [msb | lsb] word_mem_ord? word_mem_ord? [m] word_memory [m], [l], [b1], [b2] word_memory? [m] word_order [msb | lsb] Page word_order? Page GPIB and RS-232 Commands gpib_address [v] gpib_address? gpib_bus [off_bus || talk_listen ] gpib_bus? rs_echo [on|off] rs_echo? rs_pmt_lf [on|off] rs_pmt_lf? Page Misc. Shared Commands all_mem? header [on || off] header? logo? options? view_angle [v] view_angle? Generator Commands Clock Source and Frequency Setup Commands clock_freq [v] clock_freq? clock_memory? clock_memory [m], [f] clock_memory? [m] clock_source [int|ext] clock_source? clock_step [v] clock_step? clock_stp_up and clock_stp_dn clock_stp_up [v] and clock_stp_dn [v] recall_freq [m] save_freq [m] Output (Clock and Data) Setup Commands amplitude [v] amplitude? clock_amp_up and clock_amp_dn Page Page Page data_off_up [v] and data_off_dn [v] data_offset [v] data_offset? offset [v] offset? Error Injection Commands error_rate [off|ext|rate_3|rate_4|rate_5|rate_6|rate_7] error_rate? error_single Analyzer Commands Results Retrieve Commands clock_freq? res_bits? res_cur_rate? res_dm? res_dm_per? res_efs? res_efs_per? res_elapsed? res_errors? res_es? res_es_per? res_los? res_pha_es? res_ses? res_ses_per? res_start? res_stop? res_sync? res_tes? res_tes_per? res_tot_rate? res_us? res_us_per? total_bits? total_error? total_rate? total_time? Input Setup Commands clock_term [neg_2v | gnd | ac] clock_term? Page data_del_up [v] and data_del_dn [v] data_delay [v] data_delay? data_term [neg_2v | gnd | ac] data_term? Page Page rdata_delay [v] rdata_delay? rdata_term [neg_2v | gnd | ac] rdata_term? rdata_thr_up and rdata_thr_dn rdata_thr_up [v] and rdata_thr_dn [v] rdata_thres [v] Page Error Detector and History Setup Commands auto_search [auto | off | disab] auto_search? Page Page Page disp_select [total || window || test] disp_select? error_reset histry_bits? histry_clear histry_phase? histry_power? histry_stat? histry_sync? sync? TEST Setup Commands test_discard test_length [t] test_length? test_mode [untimed|timed|repeat] test_mode? test_prev [current|previous] test_prev? test_print test_report [eot|on_error|both|none] test_report? test_squelch [on|off] test_squelch? test_state [run|stop] test_state? test_thres [v] test_thres? WINDOW Setup Commands win_bit_len [v] win_bit_len? win_bits? win_error? win_mode [bits|sec] win_mode? win_prev [current|previous] win_prev? win_rate? win_report [on|off] win_report? win_sec_len [s] win_sec_len? win_time? PRINT Setup Commands print_enable [on||off] print_enable? print_port [ parallel || gpib || serial ] Page Audio Beeper Setup Commands audio_rat_up and audio_rat_dn audio_rat_up [v] and audio_rat_dn [v] audio_rate [v] audio_rate? audio_vol [v] audio_vol? Page Misc. Analyzer Commands date ["yyyy-mm-dd"] date? time [s] time? 1 MB Option Commands Modified Commands Replaced Commands Commands specific to I MB Option byte_block [a], [i], [b1], ..., [bn] byte_block? [a] byte_delete [a], [i] byte_edit [a], [b1] byte_edit? [a] byte_fill [i], [b1], [b2], ..., [bn] byte_insert [a], [i], [b1], ..., [bn] byte_length [m], [n] byte_length? byte_mode [n] byte_mode? byte_sync [n] (Analyzer only) byte_sync? (Analyzer only) edit_begin [n] edit_cntrl? edit_end [n] Page Using GPIB, RS-232 Interfaces Using the GPIB Interface GPIB Interface Device Settings Interface Functions GPIB Connector Pin-Outs Programming GPIB Remote Commands GPIB Numeric Responses GPIB Status Reporting Page Page GPIB Common Commands IEEE-488.2 Programming Manual Requirements Functional Elements Using the RS-232 Interface Option RS-232 Interface Device Settings RS-232 Interface Hardware/ Handshaking Considerations RS-232 Interface Testing Programming RS-232C Remote Commands RS-232C Error Messages Page p Performance Verification Functional Test Page Confirmation of Frequency Function Confirmation of Selectable Data Patterns Confirmation of Generator Output Data Level Change Confirmation of Error Injection Rates Confirmation of Selectable Analyzer Terminations Page Confirmation of Buttons and Indicators Page Default Settings Returning to Factory Default Settings How to Recall Factory Default Settings Using Front Panel Controls Via Remote Control Generator (TX) Factory Default Settings CLOCK Data Pattern CLOCK/ DATA Outputs Remote Interfaces Analyzer (RX) Factory Default Settings Clock, Data, and Reference Data Inputs Data Pattern Auto Search/Pattern Synchronization Error Beeper Time and Date Printer Current BER Test Parameters Remote Intefaces Page Cleaning Instructions Page Pattern Editor Requirements and Features What is MLPE? Page Page Page Page Page Page Page Page Page Theory of Operation GB1400 Generator (TX) Design Overview PLL Clock Source PCB Data Generator PCB Data and Clock Output Amplifier PCB GB1400 Analyzer (RX) Design Overview Input Amplifier PCB Data Generator PCB Error Counter PCB Common to both GB1400 TX and GB1400 RX CPU PCB Front Panel PCB GB1400 User Manual I-5 CPU BUS GB1400 Tx Theory of Operation I-6GB1400 User Manual DQ Q Figure I-2. Block Diagram - GB1400 RX _ Page Glossary Page Page Page Index