3156B User Manual
WaveCAD 4-24
Racal Instrument © 2005
There are 4 parameters that control standard FM. Point and click on
Carrier Frequency to adjust the frequency of the carrier signal. The
Modulation frequency parameter defines the frequency of the
modulating waveform, which could be one of sine, triangle, ramp or
square waves. Point and click on the Frequency deviation parameter
to program the deviation range. The Marker Frequency defines a
frequency point where the SYNC output on the front panel will output a
marker signal.
The arbitrary FM becomes active when the Arbitrary button is
depressed. When this function is selected, the standard FM
parameters, except the carrier frequency which is common to both
functions, have no effect anymore.
The Arbitrary FM has two parameters: Carrier frequency and FM
SCLK. The carrier frequency is the frequency of the sine waveform
before it is being modulated. The FM SCLK sets the sample clock
frequency of the arbitrary waveform that modulates the carrier. The
arbitrary waveform is built using the FM composer. Not that the
arbitrary FM modulating waveform memory is separate from the main
arbitrary memory and function. The specifications for the FM arbitrary
sample clock and size is given in Appendix A.
To change the arbitrary FM parameters point and click on the Arbitrary
FM parameters. The value that is associated with the lit LED is
displayed on the digital display. You can use the dial, keyboard, or the
[
↑
] [
↓
} keys to adjust the readout to the required setting. After you
modify the reading, press Execute to update the 3156B with the new
reading.
AM
The AM Group has parameters that control the amplitude modulation
function. The carrier frequency is the frequency of the sine waveform
before it is being modulated. Modulation Frequency and Modulation
Depth determine the properties of the modulation envelop.
To change the AM parameters point and click on the AM parameters.
The value that is associated with the lit LED is displayed on the digital
display. You can use the dial, keyboard, or the [
↑
] [
↓
} keys to adjust
the readout to the required setting. After you modify the reading, press
Execute to update the 3156B with the new reading.
Enable
The Enable Group affects the 3156B only when the operate enable
source is set to software (software is the default enable source). If the
output state is on, clicking on the operate Enable button will stimulate
the output. In some cases, the disable can stop the output. The
various options to enable and disable the output waveforms, using the
enable commands are given in Table 3-2. Note that when the 3156B
has not been enabled, the output generates sine waveforms at
frequency value set by the carrier frequency parameter.