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SIELCO srl
- Via Toscana, 57/59 - 20090 BUCCINASCO (Mi) - ITALY - tel. 02 - 45713300 - www.sielco.org
EXC/RTX19 - USER & MAINTENANCE MANUAL - rev.1.5 - 05/16
Page 30
MPX 75.0kHz + 0.0dB
Nom.input = + 6.0dBm
AUX 2.0kHz -31.5dB
Nom.input = + 0.0dBm
MPX limiter + 7.1dB
ON
Field #24: LF Modulation Input level setup
This field permits to vary the main LF input channels sensitivity, i.e. multiplex, left and right
channel. Take present that the multiplex and the right signals share the same circuitry and the
sensitivity is set to the same value for both right (or multiplex) and left channel, with a negligible
differential error (<0.2dB) at any level. Allowed range is -3.5 ÷ +12.5 dBm.
The first line of the display shows the actual modulation, while the bottom line shows the nominal
input level for 100% modulation. Increasing the nominal input level will accordingly decrease the
modulation, if a steady state test signal is applied on the inputs.
Field #25: Auxiliary channel Input level setup
As the previous one, this field permits to preset the auxiliary channels input sensitivity. Allowed
range is -12 ÷ +4 dBm to produce 10% modulation, i.e. 7.5kHz deviation or 0dB in the upper line
of the display.
The bottom line shows the nominal value at which this occurs, in dBm.
Field #26: Limiter setup
This field permits to set the limiter action. They may be separately adjusted the threshold level
and the enabling or disabling of the circuit.
Based on local regulations, the limiter may be preset at the maximum allowed modulation level,
internationally set to 75kHz-peak deviation (or 0dB), so that the transmitter effectively limits
modulation signals which slightly trespass this value. If the regulation is more tolerant, the limiting
value may be slightly higher to allow for some dynamical room to occasional modulation peaks:
a valid level may be +2.5dB, which corresponds to 100kHz-peak deviation.