Nautel GV3.5, Operation & Maintenance Manual, Page: 90 / 251

GV5/GV3.5 OPERATIONS & MAINTENANCE MANUAL OPERATING THE TRANSMITTER
VERSION 0.2 2014-07-23 PAGE 3.2.73
 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).