Nautel NV7.5, Operation And Maintenance Manual

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NV10/NV7.5 Operations and Maintenance Manual Operating the transmitter
Issue 3.4 2016-08-03 Page 2-65
– AGC Limiter:
select
Enabled
, then enter
AGC Limit
percentage
(allowable range is 0-160%, defaulted to 120%) and
Time Constant
(allowable range is 0-1000 ms, defaulted to 0 ms). 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.
– 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, that which is below the threshold). The input signal is distorted
by the audio gain change.
–Threshold
(allowable range is 0-160%, defaulted to 120%).
–Gain
(allowable range is 0-100%, defaulted to 56.2%).
– L/R Limiter:
this look-ahead limiter can be applied to the signal
immediately before the stereo generator in the exciter. It has a fixed
attack time (and corresponding delay) of approximately 1 ms. 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
(allowable range is -20 to 20 dB, defaulted to 0 dB).
–
Decay Time
(allowable range is 0 to 60 s, defaulted to 0 s).
–
Hold Time
(allowable range is 0 to 60 s, defaulted to 0 s).
–
MPX Power Limiter:
if
Enabled
, enter MPX RMS Limit . This limit
allows the broadcast signal 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 as to minimize
the reductions performed by the limiter. Otherwise, the signal will
not take advantage of the peak modulation capability available.
–
MPX RMS Limit
(allowable range is -12 to 12 dBr, defaulted to 0 s).