R.V.R. Elettronica RXRL-NV, Техническое руководство

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RXRL-NV Technical and Maintenance Manual
R.V.R. Elettronica S.r.l. (Bo) Pag. 44
6.3 MEASUREMENT OF RECEIVER S/N RATIO
The mono S/N (signal to noise) ratio is measured at the output of
the receiver by feeding it with a 400 Hz modulating signal (±75 KHz
deviation) and comparing the output with the same output, under the same
conditions, in the absence of the modulating signal, across the 30Hz/
20KHz band.
In the case of stereo modulation, the S/N ratio will be measured on single
channels (left and right) decoded and de-emphasized.
Both mono and stereo measurements should be taken having configured the
unit according to SETUP B1 and B2 and carrying out the following
procedure:
1) Connect the instruments as shown in SETUP B1 to make MONO
measurement.
2) Generate an R.F. carrier at operating frequency and -67dBm; modulate
the carrier with a 400 Hz tone with a ±75 KHz deviation. Inject the
resultant R.F. signal into the receiver input.
3) Using the FAM modulation analyzer, check that the S/N ratio of the
RXRL-NV receiver is better than 65 dB, referred to a deviation of
±75 KHz.
4) Connect the instruments as shown in SETUP B2 to make the STEREO
measurement.
5) Adjust the signal generator output for a level of 1mV (the
carrier and deviation will remain constant).
6) Use the modulation analyzer to make the S/N measurement and check
that the figure is better than 60 dB for the RXRL-NV.
SETUP B1