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Appendix E, ALPHABETICAL LISTING OF COMMANDS
FMVSPAN[.] [n] Oscillator frequency modulation voltage span command
FRQ[.]
FRQ1[.]
FRQ2[.]
FSTART[.] [n]
E-12
mHz. The range of n is 0 to 125,000,000 representing 0 to ± 125 kHz; in floating
point mode n sets the span frequency in Hz. The range of n is 0 to 1.25E5.
Note: The center frequency
limits of the oscillator ( 0 to 250 kHz). Hence the center frequency plus the span
frequency cannot exceed 250.0 kHz and the center frequency must be greater than
or equal to the span frequency. For example, at 125 kHz center frequency the
maximum span frequency is
span frequency is
10 kHz; at 240 kHz center frequency the maximum span
frequency is also
10 kHz. When setting the center frequency and span frequency
under computer control it is recommended to first set the span frequency to zero
followed by the center frequency to the required value and finally the span
frequency to the required value. This will avoid potential problems with the new
center frequency being rejected because it is not a legal value when compared with
the old span frequency.
The value of n sets the oscillator frequency modulation span voltage; in fixed point
mode n is an integer in the range 0 to +10000, corresponding to a range from
0.000 V to 10.000 V, and in floating point mode it is in volts.
NOTE: The span voltage plus the center voltage cannot exceed
Reference frequency meter
If the lock-in amplifier is in the external reference source modes, the FRQ command
causes the lock-in amplifier to respond with 0 if the reference channel is unlocked, or
with the reference input frequency if it is locked.
If the lock-in amplifier is in the internal reference source mode, it responds with the
frequency of the internal oscillator.
In fixed point mode the frequency is in mHz, and in floating point mode the
frequency is in Hz.
Reference frequency meter, reference 1 channel
In dual reference modes, the FRQ command causes the lock-in amplifier to respond
with 0 if the reference 1 channel is unlocked, or with the reference input frequency if
it is locked.
In fixed point mode the frequency is in mHz, and in floating point mode the
frequency is in Hz.
Reference frequency meter, reference 2 channel
In dual reference modes, the FRQ command causes the lock-in amplifier to respond
with 0 if the reference 2 channel is unlocked, or with the reference input frequency if
it is locked.
In fixed point mode the frequency is in mHz, and in floating point mode the
frequency is in Hz.
Oscillator frequency sweep start frequency
Sets the start frequency for a subsequent sweep of the internal oscillator frequency,
in the range 0 to 250 kHz.
In fixed point mode, n is in millihertz, and in floating point mode n is in hertz.
the span frequency must not exceed the frequency
125 kHz; at 10k Hz center frequency the maximum
10.000 V
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