232 Keysight EXG and MXG X-Series Signal Generators User’s GuideBasic Digital Operation for N5172B/82B with Options 653/655/656/657Setting the Real-Time Modulation FilterSetting the Real-Time Modulation FilterThe real-time modulation filter effectively compresses a single carrier I/Q waveform down to justthe I/Q constellation points and then controls the transitions similar to the modulation filter in ArbCustom modulation. The key difference is that this filter is applied as the waveform plays, ratherthan in the waveform data itself. The real-time modulation filter is only available for Dual ARBwaveforms.When the real-time modulation filter is on, the sample clock rate acts as the symbol rate. Thesample clock rate must be set to one half of the sample rate for the real-time Arb modulation filterfeature to be turned on. The sample rate is determined by the Option 65x baseband generator.Figure 8-26 Real-Time Modulation Filter Softkeys for the Dual ARB PlayerBecause the Arb format only supports rectangular I/Q data for defining thesymbol decision points, constant envelope modulation, which should bespecified as magnitude and phase, are not supported. (Examples ofconstant envelope modulation are MSK and FSK.)The carrier frequency must be the same for all frequencies used (i.e. onlysingle carrier applications work with arb real-time modulation filters).page 219The settings in this menucan be stored to the fileheader, see page 163.For details on each key, use key helpas described on page 56.Mode > Dual ARB > ArbSetup > MoreThese are the availablereal-time modulation filters thatcan be applied to a waveform.
