NF FRA51602, Instruction Manual

Page: 183 / 286

5.7 Amplitude compression
5
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27
FRA 51602
The internal operation of this instrument for amplitude compression is described below.
1) Measurement is performed once with the oscillator output voltage at the value that is currently set.
2) The amplitude measured at the reference channel [REF CHANNEL] is compared with the target
amplitude [REF LEVEL] . If the result is within the permissible error [TOLERANCE] , the
measurement at the current frequency is ended.
3) If the permissible error is exceeded, a new oscillator amplitude is calculated from the error. (The
amplitude setting is changed.)
4) The measurement is performed again and the results are compared with the target amplitude. If the
permissible error is exceeded, the amplitude setting is reset again and the measurement is repeated.
5) If the maximum number of retries [RETRY TIMES] is exceeded, it is treated as an error and the
measurement at the current frequency is ended.
6) The measurement result is output.
To protect the equipment under test when the oscillator output voltage is changed in the step three above, it
is possible to set the maximum amplitude [OUTPUT LIMIT] (voltage control).
Figure 5-14 Operation for amplitude
The amplitude setting is done with
【
OSC
】 –
[Amplitude Compression]
.
[FUNCTION]
: Set to ON to use the amplitude compression function.
[REF CHANNEL]
: Set the channel for amplitude monitoring (reference channel).
[REF LEVEL]
: This is the target for amplitude control. Amplitude control is performed so
CH1
CH2
Reference channel
compression
＋
－
Target amplitude
×
Correction factor
＋
＋
Limiter
Voltage limitation
～
OSC
DFT
DFT