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and 255, which is the decimal equivalent of a binary number with the following bit-
significance:
Bit 0
X channel output overload (> ±300 %FS)
Bit 1
Y channel output overload (> ±300 %FS)
Bit 2
X2 channel output overload (> ±300 %FS)
Bit 3
Y2 channel output overload (> ±300 %FS)
Bit 4
CH1 output overload
Bit 5
CH2 output overload
Bit 6
CH3 output overload
Bit 7
CH4 output overload
NC
New curve
Initializes the curve storage memory and status variables. All record of previously
taken curves is removed.
NHZ.
Causes the lock-in amplifier to respond with the square root of the noise spectral
density measured at the Y channel output, expressed in volt/Hz or amps/Hz
referred to the input. This measurement assumes that the Y channel output is
Gaussian with zero mean. (Section 3.3.16). The command is only available in
floating point mode.
NN[.]
Noise output
In fixed point mode causes the lock-in amplifier to respond with the mean absolute
value of the Y channel output in the range 0 to 12000, full-scale being 10000. If the
mean value of the Y channel output is zero, this is a measure of the output noise.
In floating point mode causes the lock-in amplifier to respond in volts.
NNBUF [n]
Noise Buffer Length control
The value of n sets the noise buffer length according to the following table:
n
Function
0
Noise buffer off
1
1 second noise buffer
2
2 second noise buffer
3
3 second noise buffer
4
4 second noise buffer
NOISEMODE [n] Noise Measurement Mode control
The value of n sets the noise measurement mode according to the following table:
n
Function
0
Noise measurement mode off
1
Noise measurement mode on.
When the noise measurement mode is turned on, the output filter time constant is
automatically adjusted until it lies in the range 500 µs to 10 ms inclusive, the
synchronous time constant control is turned off, the fast analog output mode is
turned on (FASTMODE 1), and the output filter slope is set to 12 dB/octave if it had
previously been 18 or 24 dB/octave.
OA[.] [n]
Oscillator amplitude control
In fixed point mode n sets the oscillator amplitude in mV. The range of n is 0 to
Appendix F, ALPHABETICAL LISTING OF COMMANDS
F-17
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