Racal Instruments 3162A/B, User Manual

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User Manual 3162A/B
Using The Instrument 3-40
queries the PLL state and returns “0” (OFF) or “1” (ON)
The query:
PHASe:ADJust?
queries the PLL offset and returns value in degrees or points depending on the
setting of PHASe:STEP.
The query:
PHASe:SOURce?
queries the PLL reference source and returns “EXT”, “TTLT<n>” or “ECLT0”.
Using the Frequency
Counter
In PLL mode, the Model 3162B uses an autoranging counter circuit to measure
the frequency of the reference signal. This built-in counter is available to you,
provided that the signal at the trigger input is valid and the PLL ON LED
illuminates. Frequencies are measured from 100 Hz to 18.75 MHz with 6 digits
of resolution, including decimal point and suffix multiplier.
To measure external frequencies you must first place the model 3162B into
PLL mode and then use the PLL command as described below.
The command:
FREQuency:EXTernal?
queries external frequency and returns a frequency in Hz. A 0.00000e0 reading
indicates that no valid signal is available at the trigger input.
Using the Phase
Modulation Input
The Phase Modulation (PM) function operates in conjunction with the PLL
function. The PM Input accepts signals that phase modulate the main output
frequency (carrier) after it has locked to an external reference.
When the Model 3162B is placed in PLL mode, the phase of the main output
signal may be shifted from the reference phase using the phase modulation
input. Although not very accurate, the phase modulation input provides a way
of phase offsetting the main output to 360
E
or more.
The PM IN is sensitive to voltage levels. Applying 1V to this input generates
a phase offset of 24
°
. Likewise, applying -1V to this input generates a phase
offset of -24
°
. You may apply up to 20V to this input and, depending on the
frequency and number of waveform points, generate a phase offset of 480
°
.
The applied frequency range is DC to 10kHz, depending on the lock frequency
and the number of waveform samples. See Appendix A for a graph of waveform
points vs. maximum PM frequencies.