3 VMA Mode
3.1 Digital Demod Measurement
If Adaptive is set to run, the instrument uses the results of the current measurement
to update the filter coefficients for the next measurement. The instrument chooses
coefficients that produce a modulation quality metric that is less impacted by the
presence of linear distortion.
If Adaptive is set to hold, the instrument does not update the filter coefficients.
Instead, the instrument uses the last updated coefficients before selecting hold.
You can select run or hold at any time to continue or stop updating filter
coefficients.
Note that the instrument does not redefine the equalization filter to have a unit
impulse response when you select run or when you turn the equalization filter off
and then on; instead, the instrument uses the last updated filter coefficients.
Equalization is applied to time-domain data. For best results, make sure you select a
frequency span that contains all the energy of your signal. If significant energy from
your signal falls outside of the displayed frequency span, equalization will not work
on your signal.
You can define the length of the equalization filter (in symbols) and set the
convergence (convergence determines the size of the steps used to reshape the
equalization filter). For additional details about these parameters,
see"Convergence" on page 343 and "Filter Length" on page 342.
The following parameters affect measurement speed when using adaptive
equalization:
–
meas interval
–
filter length (for the equalization filter)
–
points/symbol
Remote
Command
[:SENSe]:DDEMod:SEGMent1|…|6:EQUalization:STATe OFF | ON | 0 | 1
[:SENSe]:DDEMod:SEGMent1|…|6:EQUalization:STATe?
Example
:DDEM:SEGM1:EQU:STAT ON
:DDEM:SEGM1:EQU:STAT?
Preset
OFF
State Saved Yes
Backwards
Compatibility
SCPI
[:SENSe]:DDEMod:EQUalization:STATe
Filter Length
Sets the length (in symbols) for the instrument's equalization filter.
Vector Modulation Analyzer Mode User's &Programmer's Reference 342
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