Agilent N4962A Serial BERT 12.
Notices © Agilent Technologies, Inc. 2012 No part of this manual may be reproduced in any form or by any means (including electronic storage and retrieval or translation into a foreign language) without prior agreement and written consent from Agilent Technologies, Inc. as governed by United States and international copyright laws. Manual Part Number N4962-91021 Edition Fourth edition, April 2014 Agilent Technologies, Deutschland GmbH Herrenberger Str.
Safety Summary General Safety Precautions 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. Agilent Technologies Inc. assumes no liability for the customer's failure to comply with these requirements.
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Environmental Information This product complies with the WEEE Directive (2002/96/EC) marketing requirements. The affixed label indicates that you must not discard this electrical/electronic product in domestic household waste. Product category: With reference to the equipment types in the WEEE Directive Annexure I, this product is classed as a “Monitoring and Control instrumentation” product. Do not dispose in domestic household waste.
Contents 1 Getting Started ......................................................................................................... 9 1.1 General .............................................................................................................. 9 1.1.1 1.1.2 1.1.3 1.1.4 1.1.5 1.1.6 1.1.7 1.2 N4962A Operation Overview ....................................................................... 11 1.3 Getting Started with the N4962A Serial BERT 12.5 Gb/s ...................... 12 1.3.1 1.3.2 1.
3.6 4 Data Path ........................................................................................................ 32 Operation ................................................................................................................. 33 4.1 General Information ...................................................................................... 33 4.1.1 4.1.2 4.2 Front Panel Interface .................................................................................... 35 4.2.1 4.2.2 4.2.
Getting Started 1 Getting Started 1.1 General The N4962A serial BERT 12.5 Gb/s operates from 500 Mb/s – 12.5 Gb/s referencing an external clock, and from 9.85 – 11.35 Gb/s with the programmable internal clock. The N4962A includes: • Internal clock system • PRBS generator • Error detector 1.1.
Getting Started 1.1.3 PRBS generator • • Selectable PRBS patterns: o Lengths: 27-1, 210-1, 215-1, 223-1, 231-1 o Mark densities: 1/2, 1/4, 1/8 Adjustable PRBS amplitude: o Voltage: 0.3 - 1.8 V pp per output o Step size: 10 mV 1.1.
Getting Started 1.2 N4962A Operation Overview The Agilent Technologies N4962A is a cost-effective serial BERT 12.5 Gb/s, consisting of an internal clock system, PRBS generator, and error detector. It is designed for automated production-line testing, manufacturing, characterization, and R&D lab use. The N4962A features high-UI jitter injection and programmable output amplitude. Figure 1.
Getting Started 1.3 Getting Started with the N4962A Serial BERT 12.5 Gb/s 1.3.1 Unpacking and Installation The N4962A serial BERT 12.5 Gb/s is shipped with all the accessories required for the self-test mode and verification. The contents includes: • N4962A serial BERT 12.5 Gb/s • Two coax cables to connect rear-panel clocks (TX CKO, RX CKO to TX CKI, RX CKI) • Two phase balanced 50 Ω coaxial cables for self-test mode (IN, ¯¯ IN to OUT, OUT ¯¯¯) • Four 2.
Getting Started 1.3.2 Safety and Regulatory This product has been designed and tested in accordance with accepted industry standards, and has been supplied in a safe condition. The documentation contains information and warnings that must be followed by the user to ensure safe operation and to maintain the product in a safe condition. Do not remove instrument covers. There are no user serviceable parts within.
Getting Started 1.3.5 Performance Recommendations • • • • • • When using differential-mode connections, ensure the cables are phase balanced Differential connectors may be used single-ended if unused ports are terminated in 50 Ω Use high quality cables and connector savers (or adaptors) Keep cable lengths short and minimize number of cable bends Use a 7-10 in-lbs torque wrench when attaching connectors Terminate all unused RF connectors with 50 Ω terminations 1.
Getting Started 1.6 Align Clock and Data • • • • Press the Data Path > PRBS ¯¯¯¯ button only if the DUT is inverting o When on, the PRBS will generate an inverted output signal Press the Display > Scroll ↓ button and select Ø Press the Adjust > Config State + button to auto-set the detector phase Observe the Error ε light o The light indicates errors are being measured by the error detector, if the light is on, no error-free sampling point could be found 1.
Getting Started 16 Serial BERT 12.
N4962A System Overview 2 N4962A System Overview The N4962A consists of three functional blocks: • Internal/external clock system with analog jitter injection • PRBS generator (TX) with variable output amplitude control • Error detector (RX) with electronic clock phase adjustment The N4962A is controlled by front-panel buttons and remote GPIB (IEEE 488.2) commands; information is conveyed with LED indicators and a display on the front panel, along with GPIB data communication. Figure 2.
N4962A System Overview The PRBS generator creates a continuous bit stream triggered by the input clock rate, configured by the selectable pattern length, mark space density, data inversion, and error injection settings. The output is amplified by a programmable gain stage. The error detector compares the input to an automatically-synchronized bit stream generated with the same system settings. The clock input features an electronic phase adjuster to correctly align the clock and data sampling point.
N4962A System Overview Controls Local (button & light) – indicates local (vs.
N4962A System Overview Table 1. Configuration state details (shown on display panel, default in BOLD) Config State Description Options PAT 2E31 PRBS generator pattern length 2E31, 2E23, 2E15, 2E10, 2E7 MS 0.500 PRBS generator mark space density 0.500 (1/2), 0.250 (1/4), 0.
N4962A System Overview 2.2 Rear Panel Quick Reference Figure 4. N4962A rear panel Connectors DataThru ¯¯¯¯¯¯ , DataThru (SMA) – connected to ¯¯, IN IN when ‘thru’ data path selected.
N4962A System Overview 2.3 Connector Care Refer to the N4960-90030 N495xA through N498xA Connector Care Reference Guide at www.agilent.com/find/N4962A. Inspect the connectors for the following: • Worn or damaged threads • Scratches to mating surface • Burrs and loose metal particles • Dust or foreign material in the space surrounding the center pin (type K only) • Ensure that female contacts are straight and aligned Clean the connectors as described in the following procedure.
System Details and Performance Specifications 3 System Details and Performance Specifications Specifications describe the instrument’s warranted performance. Nonwarranted values are stated as typical. All specifications are valid in a range from 10°C to 40°C ambient temperature after a 30 minute warm-up phase. If not otherwise stated, all unused RF inputs and outputs must be terminated with the included 50 Ω-terminated connectors. 3.1 General Table 2.
System Details and Performance Specifications 3.2 Safety and Regulatory Do not remove instrument covers. There are no user serviceable parts within. Operation of the instrument in a manner not specified by Agilent Technologies may result in personal injury or loss of life. To prevent electrical shock, disconnect instrument from mains before cleaning. Use a dry cloth or one slightly dampened with water to clean the external case parts. Do not attempt to clean internally.
System Details and Performance Specifications Figure 5. N4962A block diagram – internal clock system The internal LF 1/16th-rate clock can be phase locked to an external source in order to synchronize the N4962A with the external device. To synchronize the clocks, follow the procedure detailed below. The internal or external LF clock is available from the buffered LF TrigO connector. To ensure phase lock of an external LF clock applied to the ExtCKI port, the following procedure must be used: 1. 2. 3. 4.
System Details and Performance Specifications Table 3. Parameters for N4962A internal low-frequency clock (LF TrigO, Ext CKI) Frequency 615.625 to 709.375 MHz Max input amplitude Ext CKI: 2.0 Vpp (+10 dBm) Output power LF TrigO, 0.5 V pp typical Connector Female SMA, single-ended, AC coupled, 50 Ω impedance The LF 1/16th rate clock must phase lock to the data rate clock.
System Details and Performance Specifications The TX clock, available from the buffered HF TrigO and TX CKO connectors, features the optional addition of an external jitter signal. To add jitter to the PRBS clock, and therefore to the PRBS output signal, switch into jitter-injection mode by changing the Config State “Jitter” setting to 1, and apply a DC to 100 MHz sinusoid to the JitterI connector.
System Details and Performance Specifications Figure 6. N4962A block diagram – PRBS generator The PRBS output bit stream is amplified by an adjustable gain stage. The output amplitude ranges from 300 mV pp to 1800 mV pp per output (0.6 V pp to 3.6 V pp differential) in 10 mV pp increments. The amplified PRBS output signal is available from the single-ended or differential 2.92 mm K-connector OUT/OUT ¯¯¯connectors on the front panel.
System Details and Performance Specifications The PRBS bit stream consists of data generated by one of five patterns, listed in Table 7. The pattern length is a system configuration setting, selected by changing the Config State “PAT xxxx” setting, detailed in Section 4.2.3. Table 7. N4962A PRBS generator patterns Pattern Config State Polynomial 231 – 1 2E31 X31 + X28 + 1 = 0 4.67 Hz ITU-T 0.150 223 – 1 2E23 X23 + X18 + 1 = 0 1.19 kHz ITU-T 0.150 2 –1 2E15 X + X + 1 = 0 305 kHz ITU-T 0.
System Details and Performance Specifications Figure 7. N4962A block diagram – error detector The error detector compares the sampled input bit stream to a separate internal PRBS signal generated with the same configuration settings as the PRBS generator. The error detector automatically synchronizes its internal PRBS with the incoming bit stream, in a process called ‘training’. The error detector is in training mode when off, and switches to error-counting mode when the detector is turned on.
System Details and Performance Specifications Table 8. Parameters for N4962A error detector (IN, ¯¯) IN Data rate 0.5 to 12.5 Gb/s PRBS patterns 2n – 1, n=7, 10, 15, 23, 31 Data input sensitivity (single ended) 0.1 V pp typical Data input voltage range 2 Vpp max (single-ended) ± 0.5 V DC common mode voltage max Data input phase adjust 0 to 360° Data input phase adjust resolution 2° for data rates ≥ 5 Gb/s 90° for data rates < 5 Gb/s Data input external interface Differential.
System Details and Performance Specifications 3.6 Data Path The N4962A can operate in one of three data path configurations. The data path can be set from the front panel, detailed in Section 4.2.2, or through GPIB remote commands. The current data path is indicated with the front panel lights. One of the three lights will be lit. The lights are labeled Disabled, Enabled, and Thru.
Operation 4 Operation The following section provides detailed information regarding the use of the N4962A serial BERT 12.5 Gb/s. Please refer to the front and rear panel quick reference, in Section 2, for abbreviated information. 4.1 General Information The N4962A serial BERT 12.5 Gb/s should be used in accordance with the following: • Read and follow operating instructions; do not exceed min/max specifications.
Operation 4.1.1 Performance Recommendations Follow the following recommendations for best performance: • When using differential mode connection for IN/IN ¯¯, OUT/OUT ¯¯¯, or DataThru/DataThru ¯¯¯¯¯¯ , ensure the cables are phase balanced. If the electrical length of one cable is a significant fraction of a unit interval longer than the other, the quality of the differential signal will be degraded and BER will increase. • Keep cable lengths short and minimize number of cable bends.
Operation 4.2 Front Panel Interface Figure 8. N4962A front panel The N4962A front panel indicates system configuration, and can be used for local operation of the instrument. The front panel contains three groupings of buttons and lights (local, receiver, and data path controls; configuration adjustment controls; and display selection controls), a display panel and error light, and the PRBS generator (SOURCE) and error detector (RECEIVER) connectors. The PRBS generator connectors, labeled SOURCE, are 2.
Operation 4.2.2 Front Panel – Display Panel Figure 9. N4962A front panel – display panel Table 11. N4962A front panel – display panel Text Error ε Type Description light The error light is lit for a short period of N/A time when the error detector identifies a bit error. If the error light is solid red, many errors are being detected. display panel 36 Default The eight-character display shows the current configuration option selected by using the Display->Scroll UP and DOWN buttons.
Operation 4.2.3 Front Panel – Local, Receiver, and Data Path Controls Figure 10. N4962A front panel – local, receiver, and data path controls Table 12. N4962A front panel – local, receiver, and data path controls Text Local Receiver -> On Type Description button & light Light indicates local control: • ON when front-panel control is enabled; ON • OFF when remote GPIB interface is in use. Button switches to local control.
Operation Data Path -> PRBS ¯¯¯¯ Invert button & light Light indicates inverted PRBS generator output: • OFF when PRBS bit stream is not inverted; • ON when PRBS bit stream is inverted. Button toggles the output inversion ON and OFF. OFF Inverting the bit stream after training and turning on the detector will result in a BER measurement approaching 1E0.
Operation 4.2.3 Front Panel – Configuration Adjustment Controls Figure 11. N4962A front panel – configuration adjustment controls Table 13. N4962A front panel – configuration adjustment controls Text Type Description Default Buttons adjust internal clock frequency by 0.01 GHz: • UP increases frequency (max 11.35 GHz); • DOWN decreases frequency (min 9.85 GHz). Adjust -> Freq Adjust -> Ampl UP and DOWN buttons UP and DOWN buttons Serial BERT 12.
Operation Text Adjust -> Ø Type Description Default UP and DOWN buttons Buttons adjust BER clock phase by 2 degrees from 5 to 12.5 GHz, and in 90-degree increments below 5 GHz: • UP increases phase offset (max 358, min 0) 0 degrees • DOWN decreases phase offset Display will briefly show new clock phase setting after pressing either button, and then switches back to previously-displayed setting.
Operation Text Type Description Default JitterI port. • Synth 1 o options: 0, 1 Internal clock setting: 0 = use external clock (internal clock turned off); 1 = use internal clock. • Err00000 Five-digit error detector error counter, included for low BER applications, or for testing external error injection. The counter accumulates errors since the detector was reset, and wraps around 99999. This counter should not be used as the authoritative number of errors counted.
Operation Text Type Description Default sequence. When the source is used with the error detector, this value should be set to 1. This helps with a condition when all zeros are loaded into the error detector’s input, which can erroneously cause bad error rate numbers. This should be set to 0 when using a different manufacturer’s pattern generator, or a known good signal is used with the N4962A source.
Operation Text Type Description Default measurement depth (BER) is: CI = 1 − e − Freq (GHz )×time ( s )×MeasDepth ( BER ) • 1234R111 o options: none This is the serial number and firmware revision code of the instrument (only the last four digits of the serial number are shown on the front panel display). Table 14. ErAd settings and expected BER measurements for 10 Gb/s operation ErAd Setting Expected BER Expected BER (added errors (10 GHz clock; (12.
Operation 4.2.5 Front Panel – Display Selection Controls Figure 12. N4962A front panel – display selection controls Table 15. N4962A front panel – display selection controls Text Type Description Default Buttons select the measurement or configuration option to display on the display panel: • UP selects the previous display item; • DOWN selects the next display item.
Operation Text Type Description Default • ε time (sec) Displays the elapsed time of the BER measurement, in seconds. If the error detector is on, the elapsed time will increment in real time. If the error detector is off, the elapsed time shown is from the previous session. • Ampl (V) Displays the single-ended PRBS output amplitude, in volts. This voltage is per side, multiply by 2 when the output is used differentially. • Freq (GHz) Displays the internal clock frequency, in GHz.
Operation Text Type Description Default will remain on the Config State display item. For example, the first state shown is the PAT 2Exx, and the Config State light is lit. Pressing Scroll DOWN selects the MS 0.xxx state, and the Config State light remains lit. The Config State currently selected is indicated by the display text. There is no indicator for the different states. States are described in Table 13, and detailed in Section 4.2.3. 4.3 Rear Panel Interface Figure 13.
Operation The Pat TrigO connector is an output pattern trigger from the PRBS generator. The Pat TrigO signal changes state after 32 complete PRBS bit streams have been generated. Pat TrigO has a frequency equal to (clock_rate) / (32 * bit_pattern_length); With a clock speed of 10 GHz, the Pat TrigO frequency is 2.4 MHz with a pattern length of 27-1, and 0.15 Hz with a pattern length of 231-1. TX CKI and RX CKI are the transmit (PRBS generator) and receiver (error detector) clock inputs.
Operation 4.4 Power-On State The power-on state of the N4962A is set after turning the rear Power switch on. The internal clock is active and generates a 10.0 GHz clock. The PRBS generator is off. The error detector is off, in training mode, and will not accumulate errors. The error detector light may indicate errors if the default sampling position is incompatible with the cable length, or if the OUT/OUT ¯¯¯ port(s) are not connected to the IN/IN ¯¯port(s). Table 16.
Operation 4.5 System Verification When first using the N4962A and before using the machine to test an external DUT, first confirm that the system is generating a PRBS bit stream and can detect bit errors. 4.5.
Operation 4.5.2 Error Free Test When the error detector clock phase is correctly adjusted, the default settings will result in error-free operation. The Error ε light will be off, and the measured BER will be zero. Check the error-free operation as follows: • Put the system in self test mode, described in Section 4.5.1.
Operation 4.5.4 Low BER Test To verify that the error detector can correctly count a small number of errors, use the PRBS error injection capability to insert a known number of errors into the bit stream, as follows: • Put the system in self test mode, described in Section 4.5.1.
Operation If the sampling point occurs near the PRBS transition point, the sampled value is uncertain and many bit errors will be measured by the detector. Adjusting the phase away from the transition point will optimally position the sampling point and allow the best chance of measuring error-free operation. The N4962A can automatically detect and set the detector clock phase for the best sampling point. It requires that the system settings and data path allow error-free operation.
Operation • • • Record the second phase value; the optimum point is halfway between the two values Press the Adjust > Ø - button and adjust the phase offset to the optimal point Observe the Error ε light (should remain off, indicating no errors detected) Depending on the DUT characteristics, the optimal sampling point may occur at different detector phase adjustment values.
Operation • • • • • • • 54 Press the Display > Scroll ↓ button and select Ø Press the Adjust > Config State + button to auto-select the detector phase Observe the Error ε light (should remain off, indicating no errors detected) Press the Receiver > On button and ensure the light is on Press the Display > Scroll ↑ button and select ε time (sec) (should be increasing) Press the Display > Scroll ↑ button and select BER Press the Receiver > On button and ensure the light is off when complete Serial BERT 12.
Remote GPIB Interface 5 Remote GPIB Interface The N4962A can be controlled and queried with the rear-panel GPIB interface. The GPIB interface complies with IEEE standard 488.2-1992. To learn more about the GPIB interface, consult the following books from the IEEE: • • The International Institute of Electrical and Electronic Engineers. IEEE Standard 488.1-1987, IEEE Standard Digital Interface for Programmable Instrumentation. New York, NY, 1987. .
Remote GPIB Interface 5.1 GPIB Capabilities The GPIB interface capabilities are described in Table 17. Table 17.
5.2 GPIB Command Syntax The N4962A can be controlled through the GPIB interface using commands and queries. The commands and queries are documented in the Backus-Naur Form notation, detailed in Table 18. Table 18. N4962A GPIB command and query syntax Symbol Meaning <> Defined element (eg: ) ::= Is defined as (eg: ::= argument) | Exclusive OR {} One of this group is required [] Optional item … Previous elements may be repeated Serial BERT 12.
Remote GPIB Interface 5.2.1 Command Structure The GPIB interface allows commands, which tell the instrument to take a specific action, and queries, which ask the instrument to return information. Commands are composed of syntactic elements: • • • • Header – the command name; if it ends with a question mark, the command is a query. Delimiter – a space, colon (:), comma (,), or semi-colon (;) which breaks the message into segments for the instrument to process. Link – a command sub-function.
5.3 IEEE Common Commands The IEEE 488.2 standard has a list of reserved commands that must be implemented by all instruments using the standard. The N4962A implements all of the required commands, listed in Table 19. Table 19.
Remote GPIB Interface 5.4 SCPI Mandated Commands The N4962A also conforms to the Standard Commands for Programmable Instrumentation (SCPI 1999.0) command set. Two SCPI mandated commands are implemented, listed in Table 20. Table 20. N4962A SCPI mandated commands Command Function :SYSTEM:ERROR? Returns event/error number and message from error queue :SYSTEM:VERSION? Returns SCPI protocol version number (1999.0) 5.5 N4962A Device Commands The N4962A device commands are summarized in Table 21.
Command Parameters / Results :SOURce:VOLTage:[LEVel]:[AMPLitude] {? | {300 <= value <= 1800}} :MODe {? | NORMal | THRU | OFF} :SENSe:NOData {? | ON | OFF} :SYSTem:STATus? {BITERROR | NODATA | NORXCLK} :SENSe:APTime {? | {1 <= value <= 5000}} :SENSe:ROSCillator:PHASe {? | AUTO | {0 <= value <= 360}} :SENSe:SWEep:TIME {? | 0.001 <= value <= 4194303.
Remote GPIB Interface Command :SOURce:ROSCillator:SOURce {INTernal | EXTernal} Type Command Description Selects the low-frequency clock to be used. INTernal selects and powers the internally-generated clock, EXTernal selects the external clock connected to Ext CKI, and powers down the internal clock.
Command :SOURce:ROSCillator:[INTernal]:FREQuency {9850 <= value <= 11350} Type Command Description Sets the frequency of the internal high-frequency clock, in MHz. The internal clock source must be selected for this feature to work.
Remote GPIB Interface Command :SOURce:ROSCillator:JITTer {ON| OFF} Type Command Description Sets the jitter injection mode. If 1, the high-jitter mode will be enabled and the jitter input signal JitterI will be FM modulated onto the TX CKO and HF TrigO outputs. This feature requires the internal clock be selected. On Jitter 0, a low bandwidth modulator mode is selected, lowering the noise floor, and filtering jitter above 100 kHz.
5.5.2 PRBS Pattern Commands Command :SOURce:PATTern? Type Query Description Returns the current PRBS pattern length. Results PRBS{7 | 10 | 15 | 23 | 31} Example See below Command :SOURce:PATTern {PRBS{7 | 10 | 15 | 23 | 31}} Type Command Description Sets PRBS pattern length to the value indicated in the command line. PRBSn selects a pattern with length 2^n-1.
Remote GPIB Interface Command :SOURce:PRBS:MARKspace? Type Query Description Returns the current PRBS pattern mark space density. Results MS{2 | 4 | 8} Example See below Command :SOURce:PRBS:MARKspace {MS{2 | 4 | 8}} Type Command Description Sets PRBS pattern mark space density to the value indicated in the command line. MSn selects a pattern with mark space density of 1/n.
Command :SOURce:PRBS:INVert? Type Query Description Returns the current PRBS invert setting. Results {ON | OFF} Example See below Command :SOURce:PRBS:INVert {ON | OFF} Type Command Description Sets PRBS invert setting to the value indicated in the command line. If ON, the PRBS signal is inverted. Parameters {ON | OFF} Example OUTPUT 725; ":SOUR:PRBS:INV ON" OUTPUT 725; ":SOUR:PRBS:INV?" ENTER 725; value$ PRINT value$ ! should be “ON” Serial BERT 12.
Remote GPIB Interface Command :SOURce:PRBS:IERR:RATe? Type Query Description Returns the current error injection rate Results {OFF | ERR1E{0 <= value <= 7}} Example See below Command :SOURce:PRBS:IERR:RATe {OFF | ERR1E{0 <= value <= 7}} Type Command Description Sets the digital error injection rate to 10^n errors injected per second. If OFF, no errors are injected.
Command :SOURce:VOLTage:AMPLitude? Type Query Description Returns the current single-ended PRBS output amplitude, in mVpp per side. (double this number for differential) Results {300 <= value <= 1800} Example See below Command :SOURce:VOLTage:AMPLitude {300 <= value <= 1800} Type Command Description Sets the single-ended PRBS output amplitude, in mVpp per side.
Remote GPIB Interface 5.5.3 Measurement Commands Command :MODe? Type Query Description Returns the current data path. Results {NORM | THRU | OFF} Example See below Command :MODe {NORMal | THRU | OFF} Type Command Description Sets the instrument data path: NORMal Normal operation, IN/IN ¯¯connected to error detector, PRBS generator enabled. THRU Input through, IN/IN ¯¯ connected to DataThru/DataThru ¯¯¯¯¯¯ PRBS generator enabled.
Command :SENSe:NOData? Type Query Description Returns the state of the data sense option. Results {ON | OFF} Example See below Command :SENSe:NOData {ON | OFF} Type Command Description Sets the NoData sense function. When used with the N4962A source, helps to detect all-zeros' data. Parameters {ON | OFF} Example OUTPUT 725; ":SENS:NOData OFF" OUTPUT 725; ":SENS:NOData?" ENTER 725; value$ PRINT value$ ! should be “OFF” Serial BERT 12.
Remote GPIB Interface Command :SYSTem:STATus? {BITERROR | NODATA | NORXCLK} Type Query Description Returns the state of the output indicator: BITERROR Indicates the current status of the BERT error light; the light is lit when errors are counted; the query returns 0 when the light is lit NODATA Indicates the current status of the NoData flag determined by the instrument (only if NODATA is turned on, see above); the query returns 0 when the NoData condition is met NORXCLK Indicates the current status o
Command :SENSe:APTime {1 <= value <= 5000} Type Command Description Sets the desired autophase measurement time, in 1/10ths of a millisecond. The lowest number is 1 (0.1 ms). The highest number is 5000 (500 ms). Parameters {1 <= value <= 5000} Example OUTPUT 725; ":SENS:APT 300" OUTPUT 725; ":SENS:APT?" ENTER 725; value$ PRINT value$ ! should be “300” Command :SENSe:ROSCillator:PHASe? Type Query Description Returns the error detector clock phase.
Remote GPIB Interface Command :SENSe:ROSCillator:PHASe {AUTO | {0 <= value <= 360}} Type Command Description Sets the error detector clock phase for sampling point. If AUTO, the N4962A will automatically determine the optimum phase for best sampling point once, and set the phase to that value. For data rates less than 5 GHz, the phase detector is limited to 0, 90, 180, or 270 degree increments.
Command :SENSe:SWEep:TIME {0.001 <= value <= 4194303.999} Type Command Description Sets the desired measurement time, in seconds. The lowest number is 0.001 seconds. The highest number is 4194303.999 seconds. Parameters {0.001 <= value <= 4194303.
Remote GPIB Interface Command :SENSe:TRAIn {10 <= value <= 6500} Type Command Description Sets the desired training delay time, in 1/10ths of a microsecond. The lowest number is 10 (1 us). The highest number is 6500 (650 us). Parameters {10 <= value <= 6500} Example OUTPUT 725; ":SENS:TRAI 120" OUTPUT 725; ":SENS:TRAI?" ENTER 725; value$ PRINT value$ ! should be “120” Command :STATus:OPERation:MEASurement:CONDition? Type Query Description Returns 1 if measurement is in progress.
Command :INITiate:BER Type Command Description Latches data on BERT board; equivalent to turning on the receiver. Results none Example none Command :TRIGger:INITiate Type Command Description Initiates data acquisition (begins testing); equivalent to turning on the receiver. Example See below Command :TRIGger:ABORt Type Command Description Aborts data acquisition (ends testing); equivalent to turning off the receiver. Example See below Serial BERT 12.
Remote GPIB Interface Command :TRIGger:SAMPle Type Command Description Takes sample of current measurement. Does not return any values, but allows the values to be queried by other commands. Example See below Command :SENSe:DATA? [BCOunt | ECOunt | ETIMe | BER | ALL] Type Querry Description Returns the selected parameter from the current instrument sample, or returns all parameters as a vector if ALL or no parameter is specified.
Example OUTPUT 725; ":SENS:SWE:TIME 10" OUTPUT 725; ":TRIG:INIT" WAIT 2 OUTPUT 725; ":TRIG:SAMPLE” OUTPUT 725; ":SENS:DATA? BER” ENTER 725; value$ PRINT value$ ! BER value after 2 seconds Command :FETCh:BER? [BCOunt | ECOunt | ETIMe | BER | ALL] Type Querry Description Returns the selected parameter from the memory stored on the FPGA, or returns all parameters as a vector if ALL or no parameter is specified. Does not require the measurement to currently be running.
Remote GPIB Interface Example OUTPUT 725; ":SENS:SWE:TIME 10" OUTPUT 725; ":TRIG:INIT" WAIT 2 OUTPUT 725; ":TRIG:SAMPLE” OUTPUT 725; ":SENS:DATA? BER” ENTER 725; value$ PRINT value$ ! BER value after 2 seconds WAIT 3 OUTPUT 725; ":TRIG:ABOR" OUTPUT 725; ":FETC:BER?" ENTER 725; result$ PRINT result$ ! BER value after 5 seconds 5.6 Examples The following programming example assumes the user is programming with Agilent BASIC, a simple interpretative language that is convenient for instrument programming.
The next block of code shows how to save the instrument state in one of the save/recall registers (0-9), how to change the value of the internal HF clock, and how to restore the previous instrument state saved in the save/recall register. 50 OUTPUT 725; "*SAV 1" 60 OUTPUT 725; ":SOURCE:ROSC:FREQ 11111" 70 OUTPUT 725; ":SOURCE:ROSC:INT:FREQ?" 80 ENTER 725; freq$ 90 PRINT freq$ 100 OUTPUT 725; "*RCL 1" ! save current inst.
Remote GPIB Interface This block of code shows how to change system configuration settings, such as the PRBS pattern length, PRBS mark space density, internal clock power, and jitter injection mode.
The N4962A has a programmable error injection that can be set from 1error/sec to 1E7 errors/sec in logarithmic steps of 10. This is detailed in Table 14.
Remote GPIB Interface After running for 5 seconds, the program outputs a string with TOTAL-BITS, TOTAL-ERRORS, ELAPSED-SECONDS, BIT-ERROR-RATE. An alternative method of measuring BER is to use the sample command. The SAMPLE command allows the user to "sample" the Bit Error Rate any number of times during a measurement period.
Returning the N4962A Serial BERT to Agilent Technologies 6 Returning the N4962A Serial BERT to Agilent Technologies If the N4962A serial BERT 12.5 Gb/s fails system verification and you cannot correct the problem, return it to Agilent Technologies for repair following the steps shown below. 1. Record all symptoms. 2. Contact Agilent Technologies using the “Request an RMA” form at http://www.agilent.com/find/assist. 3.
Returning the N4962A Serial BERT to Agilent Technologies 86 Serial BERT 12.
© Copyright Agilent Technologies 2012 Fourth edition, April 2014 Printed in Germany
