:CRECovery:JSANalysis:SPECtrum

Command Syntax

:CRECovery{1:8}:JSANalysis:SPECtrum  {INPut | MEASured | EMULated}

Where the {1:8} specifier identifies a slot number. The slot number is associated with the N1060A, N1076A/B, N1077A, N1078A, or 86108B module with Option JSA. When an 86108B module is used, the slot number is always 1.

Query Syntax

:CRECovery{1:8}:JSANalysis:SPECtrum?

Query Response

{INP | MEAS | EMUL}

Description

Selects the input signal's location in the clock-recovery circuit from which to construct the jitter spectrum and perform the Jitter Spectrum Analysis (JSA). The following arguments are available.

INPut

In Oscilloscope or Eye/Mask mode, selects to view all of the low- frequency jitter on the input signal. This is the recovered clock with the effects of the clock recovery PLL de-embedded. This selection is not available in Jitter Mode. Use the :CRECovery:JSANalysis:OPTimize:INPut command to set the 86108A/B's hardware clock-recovery loop bandwidth to a minimum value which results in optimum input spectrum fidelity. If the loop can not establish lock, you can manually adjust these settings using the :CRECovery:CLBandwidth and :CRECovery:LSELect commands.

The INPut argument is not available in Jitter Mode.

MEASured

Available in Oscilloscope, Eye/Mask, and Jitter modes. The Measured spectrum type complements Jitter Mode by showing the distribution of low-frequency jitter. It enables you to discover the root cause of jitter in your device. (Jitter Mode integrates jitter over a larger spectrum resulting in larger RJ measurements.) Use the :CRECovery:CLBandwidth command to configure the 86108A/B clock-recovery loop bandwidth to the bandwidth specified in the applicable standard. Use the :CRECovery:LSELect command to set the Type Two Loop Transition Frequency (Peaking) to the recommended setting in the applicable standard.

EMULated

Available in Oscilloscope, Eye/Mask, and Jitter modes. Emulated allows you to view low-frequency jitter response to a wide variety of user-specified clock recovery (PLL) configurations. While using the 86108A/B's hardware clock recovery, clock recovery emulation (CRE) is used to measure the incoming signal relative to an ideal software clock-recovery response. In Jitter mode, the effect of this spectrum on Jitter Mode's RJ measurement can be toggled on and off with the :CRECovery:JSANalysis:RJCorrection command. To configure the CRE PLL, use the :CRECovery:JSANalysis:PLL:ORDER command and its eight siblings. After configuring the Clock Recovery Emulation PLL, use the :CRECovery:JSANalysis:OPTimize:EMBedded command to obtain the optimum CRE spectrum fidelity by automatically matching, as closely as possible, the hardware CDR parameters to the CRE PLL settings. You can manually configure these settings using the :CRECovery:CLBandwidth and :CRECovery:LSELect commands.

Use the :CRECovery1:JSANalysis:INTegrate:F command to set the upper and lower frequency integration limits for the jitter spectrum. Use the :CRECovery1:JSANalysis:FFTMagnitude:SMOothing command to apply smoothing to the jitter spectrum.

To turn on Jitter Spectrum Analysis (JSA) and clock recovery emulation, use the :CRECovery1:JSANalysis:ACQuire command.

Command Compatibility

• N1060A Option JSA
• 86108A/B Option JSA
• N107X-series Option JSA

Example Command Sequence

:CRECovery{1:8}:JSANalysis:SPECtrum EMBedded

Child Commands

• :ASCii:YDATa Returns comma-separated ASCII values.
• :DOUBle:YDATa Returns 64-bit floating point values.
• :FLOat:YDATa Returns 32-bit floating point values.
• :PEAKs Returns a comma-separated ASCII list of the identified JSA spectrum peaks.
• :PEAKs:ALL
• :POINts Returns the number of data points.
• :XINCrement Returns frequency spacing between the data points.
• :XORigin Returns the frequency value of the first data point.