N5161A/62A/81A/82A/83A MXG Signal Generators User's Guide

Basic Digital Operation (Option 651/652/654)Setting the Real-Time Modulation FilterSetting the Real-Time Modulation FilterThe real- time modulation filter effectively compresses a single carrier I/Q waveform down to just theI/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. The sampleclock rate must be set to one half of the sample rate for the real- time Arb modulation filter featureto be turned on. The sample rate is determined by the Option 65x loaded inCAUTIONBecause the Arb format only supports rectangular I/Q data for defining the symboldecision points, constant envelope modulation, which should be specified as magnitudeand phase, are not supported. (Examples of constant envelope modulation are MSK andFSK.)The carrier frequency must be the same for all frequencies used (i.e. only single carrierapplications work with arb real- time modulation filters).Figure 8-26 Real-Time Modulation Filter Softkey for the Dual ARB PlayerMode > Dual ARB > ArbSetup > MoreThe settings in this menucan be stored to the fileheader, see page 149.page 207These are the availablereal-time modulation filters thatcan be applied to a waveform.For details on each key, use key helpas described on page 42.Agilent N5161A/62A/81A/82A/83A MXG Signal Generators User’s Guide 217