Pag. 27
SIRIO 2000T
SIRIO 2000T
SIRIO 2000T
SIRIO 2000T
SIRIO 2000T
Electronic Broadcast Equipment
2) Select the "MODE" command menu and select the "STEREO" operating mode. Confirm or change 50
or 75µs preemphasis as required.
Operation with a RDS or SCA Encoder:
1) Wire the BNC-type “Aux” connector to the output of the RDS or SCA Encoder. If the internal optional
stereo-encoder is used, wire the "MODULATION" BNC output to the pilot-tone synchronisation input
of the RDS encoder, if present.
2) Select the "AUX" command menu and push "ENTER" to vary the channel sensitivity. Adjust both
transmitter sensitivity and/or the level of the external generator for the deviation required, as explained
in the previous manual sections. Consider that 0dB modulation reading (not the input level) in this field
means 10% total modulation or 7.5kHz deviation, i.e. the standard pre-setting for a SCA auxiliary
channel. In the case of RDS, a reading of -11.5dB or 2kHz is the correct value of modulation.
3) Total modulation and deviation can be read on the "MPX" display field, plus any other composite signal
available present.
Modulation Adjustment with broadcast signal:
Check the overall modulation level for adequacy, as follows:
1) Select the display menu field "MPX": the total modulation will be displayed, both in dB and as deviation
in kHz. An analog moving bar and a digital peak reading are contemporary shown.
2) Send a pseudo constant level musical signal to the modulator input, check the measure hovers in the
around of 0 dBm (or the chosen value, i.e. +6dB) and moves a bit higher during signal peaks only, and
by no more than 1 or 2 dB. For any other reading, adjust the mixer’s “MASTER” volume until the above
conditions are obtained.
The red “Limiter” alarm LED should not or rarely light up, as this would indicate distortion.
If the limiter is set just above 75 kHz, the red LED will light up above 0dB (or chosen level) and
the modulation measured will never show a much greater value. Factory pre-set is 100 kHz (+2.5 dB).
Check of Pilot tone on Stereophonic Transmission:
In case of internal stereo-encoder, no allowance is externally provided to change the pilot tone level,
which is would internally pre-set for 9-10% of modulation, i.e. -21 ÷ -20dB or 7 ÷ 7.5kHz corresponding
to the standard deviation of . In case the stereo multiplex signal it is provided by a separate external stereo-
encoder, it must be measured in absence of audio modulation and any other auxiliary signal as below:
