R.V.R. Elettronica SDC20, Technical Manual

Page: 19 / 44

SDC20 Stereo Digital Coder
R.V.R. Elettronica S.r.l. (Bo) Pag. 19
SECTION 3
INSTALLATION PROCEDURES
3.1 CONNECTIONS
Verify that SDC20 coder is switch off. Connect the output connector
of the mixer or of the last transmitter to R and L input connectors. The
SDC20 coder input is balanced and can be of XLR type or socket type.
Respect pins position showed in technical specifications of the
connectors (Fig.5). SDC20 has SCA and RDS inputs; the technical
caracteristics of these inputs are mentioned in Table A.
It's important don't connect any audio signals not codified because will
be mixed with MPX signal on the MPX output.
3.2 INSTALLATION
The SDC20 coder is setted ex factory to obtain max stereo separation
through a measuring professional decoder. This setting is just sufficient
for the most part of the FM station.
However it's possible, to obtain max. performance for each transmitting
system, adjust again on pilot tone phase to compensate possible FM
transmitter phase delays.
So that this adjustment is precise, it's necessary to use a measureing
professional decoder.
In absence of measuring instruments, an approximative adjustment can be
executed in the following way:
1) Put into L and R inputs of the coder a 1 KHz sinusoidal signal.
2) Switch off the Preenphasis command.
3) Adjust input level to read on led meter a signal of 0 dBm (yellow
led).
4) Adjust output level for a level that entails a deviation of 75 KHz
(100%) on the tranmsitter meter.
5) Connect an oscilloscope to low frequency output of left channel of
a good quality tuner.
6) Switch off left channel on the coder and adjust the phase on the
oscilloscope to obtain a minimum residual of signal.
7) Now, connect the oscilloscope on low frequency output of the tuner
right channel and disconnect coder right channel inserting again
left channel.