The Clock Recovery subsystem commands control the clock recovery modules. This includes setting data rates, as well as querying lock status and "signal present" conditions. Be sure to include the module slot number in the command. For the 86108A/B, only slot 1 is allowed. For 83496A/B clock recovery modules, the slot number can be 1 or 3 depending on the location of the module in the DCA-X's module bay. For the N107x-series clock recovery DCA-Ms, the slot number can be 1 through 8.

The JSA commands configure the JSA's clock-recovery emulation. To save JSA data to a file, use the :DISK:JSANalysis:SAVE command. To load a JSA data file into JSA memory, use the :DISK:JSANalysis:RECall command. To use the JSA memory, use the :JSAMemory subsystem commands. Use the :CRECovery1:JSANalysis:ACQuire command to turn on jitter spectrum analysis.

Not all of this subsystem commands apply to every module, as the following table shows. Depending on the module, the data rates can either be set to a specific value or to any value within a range, as listed in the Data Rate Table.

The 86108A and 86108B modules provide two electrical channels for clock recovery. When sending a clock recovery command to the modules, specify slot one (1) for the subsystem, for example :CRECOVERY1:LOCKED?. Do not use :CRECOVERY3:LOCKED? as slot 3 is not a valid selection.

• Send the :CRECovery1:CLBandwidth command to specify a loop bandwidth between 15 kHz to 20 MHz (86108B) or 15 kHz to 10 MHz (86108A).
• Send the :CRECovery1:CRATe command to specify the data rate (unbanded tuning).
• Send the :CRECovery1:LOCKed? query to determine if the module is locked on the signal.
• Sent the :CRECovery1:LSELect command to select the Type-2 PLL loop transition frequency (peaking).
• Send the :CRECovery:PRESets command to load a previously saved or factory provided clock recovery settings.
• Send the :CRECovery1:RELock command to establish lock and to reestablish lock whenever a setup parameter changes (for example input port or trigger on data), the data rate changes, or the signal parameters change (for example, edge density).
• Send the :CRECovery{1:4}:SOURce command to select between multiple module channels.

You can specify loop bandwidth to be based on a fixed value or a data-rate dependent value (based on data rate and data-rate divide ratio) using the :CRECovery1:LBWMode command. With a fixed loop bandwidth selected, specify a loop bandwidth between 15 kHz to 20 MHz (86108B) or 15 kHz to 10 MHz (86108A) with the :CRECovery1:CLBandwidth command. With a data-rate dependent loop bandwidth, use the :CRECovery1:RDIVider command.

The :CRECovery1:ODRatio command can be used to specify the divide ratio that is applied to the module's front-panel Recovered Clock Output.

Example Setup of 86108A/B Module

This sequence of commands shows one method of setting up an 86108A/B module.

:SYSTem:DEFault
*OPC?
:DIFF1:DMODe ON
:CHAN1A:BANDwidth BANDwidth3    //  BW set to 32 GHz
:CHAN2A:BANDwidth BANDwidth3
*OPC?
:CRECovery1:CRATe 1.03125E+10    //  CDR rate set to 10 GHz
:CRECovery1:CLBandwidth 5.00E+5    //  CDR PLL BW to 500 kHz
:CRECovery1:RELock    //  Lock CDR
*OPC?
:PTIMebase1:RSOurce INTernal
:PTIMebase1:STATe ON    //  Turn on precision timebase
:PTIMebase1:RTReference
*OPC?

83496A/B Modules

Keysight 83496A/B modules provide both optical and electrical clock recovery selected by the :CRECovery{1:4}:SOURce command. These modules have continuous, unbanded tuning from 50 Mb/s to 7.10 Gb/s (14.2 Gb/s, Option 200). Specify the data rate with the :CRECovery{1:4}:CRATe command.

Because these modules do not provide automatic locking, you must issue the :CRECovery{1:4}:RELock command to establish lock and to reestablish lock whenever a setup parameter changes (for example input port or trigger on data), the data rate changes, or the signal parameters change (for example, edge density). Use the :CRECovery{1:4}:LOCKed? query to determine if the module is locked on the signal. If the module loses lock, the trigger becomes asynchronous with the data and the instrument will not display a correctly triggered waveform.

On standard 83496A/B modules select the loop bandwidth using the :CRECovery{1:4}:LBANdwidth command. On Option 300 modules, you can specify loop bandwidth to be based on a fixed value or a data-rate dependent value (based on data rate and data-rate divide ratio) using the :CRECovery{1:4}:LBWMode command. With a fixed loop bandwidth selected, specify a loop bandwidth between 30 kHz to 10 MHz with the :CRECovery{1:4}:CLBandwidth command. With a data-rate dependent loop bandwidth, use the :CRECovery{1:4}:RDIVider command.

Use the :CRECovery{1:4}:ODRatio command to specify the divide ratio that is applied to the module's front-panel Recovered Clock Output.