Amplitude Modulation Commands - Racal Instruments 3151 User Manual

3151 And 3151A User Manual
Amplitude
Modulation
Commands
Arbitrary waveforms stored in memory segments are used as
modulating envelopes in Amplitude Modulation mode. The modulated
carrier is always a sine waveform with its frequency set in points. The
first step in modulating a waveform is to generate an arbitrary
waveform either from the standard function library or by downloading
a waveform from the controller.
The command:
AM <value>
sets the internal modulation depth in percent. Select values from 1%
to 200%. The default setting for AM depth is 50%.
The query:
AM?
queries the modulation depth and returns a value in percent.
The command:
AM:INTernal:FREQuency <value>
sets the frequency of the carrier sine waveform. The frequency of the
carrier wave is programmed in points. Select from 10 to 500 points.
The default setting for the carrier frequency is 100 points. The
frequency of the carrier wave can be computed from the sampling
clock frequency divided by the number of points in the active
segment. Use the FREQ:RAST? command to determine the current
sampling clock frequency. The maximum carrier frequency is the
sampling clock frequency divided by 10 points. The envelope
frequency should be less than the carrier frequency.
The query:
AM:INTernal:FREQuency?
queries the carrier frequency and returns a value in points.
The command:
AM:EXECute
enables amplitude modulation. To ensure proper operation, enable
the amplitude modulation after setting up the other modulation
parameters. Amplitude modulation cannot be turned on and off.
Therefore, ensure that the original arbitrary waveform is available in
another memory segment as a back-up.
Using The Instrument 3-41