User`s guide

224 Agilent X-Series Signal Generators User’s Guide

Basic Digital Operation (Option 653/655/656/657)

Setting the Real-Time Modulation Filter

The real- time modulation filter effectively compresses a single carrier I/Q waveform down to just the

I/Q constellation points and then controls the transitions similar to the modulation filter in Arb

Custom modulation. The key difference is that this filter is applied as the waveform plays, rather

than in the waveform data itself. The real- time modulation filter is only available for Dual ARB

waveforms.

When the real- time modulation filter is on, the sample clock rate acts as the symbol rate. The sample

clock rate must be set to one half of the sample rate for the real- time Arb modulation filter feature

to be turned on. The sample rate is determined by the Option 65x baseband generator.

CAUTION Because the Arb format only supports rectangular I/Q data for defining the symbol

decision points, constant envelope modulation, which should be specified as magnitude

and phase, are not supported. (Examples of constant envelope modulation are MSK and

FSK.)

The carrier frequency must be the same for all frequencies used (i.e. only single carrier

applications work with arb real- time modulation filters).

Figure 8-26 Real-Time Modulation Filter Softkeys for the Dual ARB Player

page 214

The settings in this menu

can be stored to the file

header, see page 155.

For details on each key, use key help

as described on page 44.

Mode > Dual ARB > Arb

Setup > More

These are the available

real-time modulation filters that

can be applied to a waveform.