A07A2200S
By modulating the transmitter through the nominal level input signals and with fixed tone (i.e..
400Hz), the deviation must not exceed 75KHz (COMP) and the input signal level must not exceed
100%. But if a music signal is available at the input, indication can also exceed this value and the
exact rules for this check will be seen in the screen shot 11.
Besides, if the automatic audio gain control is off, the 75KHz deviation value is equivalent to 100%
of the input signal values. On the opposite, if the AGC is on 75KHz deviation can be obtained by an
input signal which is variable, as level, from half to the double of the nominal value.
4.6.14 By entering PAGE UP the following screen shot will appear:
In this screen shot it’s possible to enter, if installed, the option of the modulation level automatic
control due to the audio signals: when the AGC is on, the maximum modulation value is checked at
75KHz varying the audio amplifiers gain; the dynamic is ±6dB and this is useful when the input
signal level is not sure.
For a wider explanation about the AGC operating see paragraph 4.4.
There is also a control on the modulation presence, since everywhere it isn’t allowed to transmit by
unmodulated carrier; after two minutes of modulation absence an alarm can be given and the power
can be disabled. When the modulation returns to the normal value, the alarm stops and the usual
operation is restored; in case of stereophonic transmission, the threshold for the modulation absence
is 10KHz, because of the subcarrier value.
4.6.15 By entering PAGE UP the following screen shot appear :
380 221 R02 Pag. 23
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