R.V.R. Elettronica PTRL-NV/S3, Техническое руководство

Страница: 47 / 171

R.V.R. ELETTRONICA S.r.l. (BO) Pag. 45
PTRLNV/S3 - Technical and Maintenance Manual
6.3 MEASUREMENT OF RECEIVER'S 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/
20 KHz 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 (Fig.9) to make MONO
measurement.
SETUP B1 / Fig.9
2) Generate an R.F. carrier at operating frequency and -67 dBm;
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 (Fig.10) to make
the STEREO measurement.
5) Adjust the signal generator output for a level of 1mV (the carrier
and deviation will remain constant).