Nautel VS1, Operation And Maintenance Manual

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VS1 Operations and Maintenance Manual Operating the transmitter
Issue 3.1 2013-10-01 Page 2-65
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AGC Limiter:
If Enabled, when the modulation level exceeds the AGC Limit, the gain of the
audio input will instantly decrease in order to reduce the modulation level below the AGC
limit threshold. Recovery from this audio gain reduction is dependent on the Time Constant
delay (fast attack, slow recovery). The input signal is briefly distorted by the audio gain
reduction when the threshold is exceeded. Select Enabled or Disabled. If Enabled, enter:
– AGC Limit: enter value between 0 and 160% (default is 120%)
– Time Constant: enter value between 0 and 1000 ms (default is 300 ms)
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Two Slope Limiter:
If Enabled , when the modulation level exceeds the Threshold , the gain of
the audio input will instantly change according to the gain percentage setting (percentage of
the initial gain, which is below the threshold). The input signal is distorted by the audio gain
change.
– Threshold: enter value between 0 and 160% (default is 160%)
– Gain: enter value between 0 and 100% (default is 50%)
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L/R Limiter:
This look-ahead limiter can be applied to the signal immediately before the ste-
reo generator in the exciter. It has a fixed attack-time (and corresponding delay) of approxi-
mately 1 s. It can be configured to reduce the signal, if the gain setting is 0 dB or less, or can
be used to perform an AGC function and boost quiet sections of the audio if a positive gain
setting is used. If
Enabled , enter the following parameters:
– Max Gain: enter value between -30 and 30 dB (default is 12 dB)
– Decay Time: enter value between 0 and 60 s (default is 5 s)
– Hold Time: enter value between 0 and 60 s (default is 5 s)
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MPX Power Limiter:
If Enabled , enter MPX RMS Limit. This limit allows the broadcast sig-
nal to remain in compliance with the MPX power limits as suggested in ITU-R BS.412-9.
While the limiter will keep the transmitter in compliance, it is recommended that adjustment
to the processing be made in such a way to minimize the reductions performed by the lim-
iter. Otherwise the signal will not take advantage of the peak modulation capability available.
– MPX RMS Limit: enter value between -12 and 12 dBr (default is 0 dBr)