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ECRESO FM 100/300 W, user manual– 06/2015
Page 44
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5.13.
FM limiter parameters
These parameters are available as:
Front panel
FM LIMITER menu
see section 6.3.13
Serial commands
CONF
see section 7.2.4
Engi PC application
AGC/Limiter page
see section 8.2.2
Embedded web site
Transmitter/Modulation/AGC Limiter page
see section 9.4.3
Without the FM Limiter option, the CLIP parameter is the only available parameter.
CLIP
(CONF.DEV.CLIP) – read/write
With this parameter, set the MPX hard clipper to prevent any possibility of overmodulation on the modulator itself.
This process is carried out digitally right before the RF generation, and is therefore enabled on all the inputs. If the
deviation is greater than the configured value (in kHz), the MPX hard clipper is automatically enabled. Unlike FM
limiters/clippers used in audio processing, this clipper cannot be used continuously for it generates a noticeable audio
distortion. It is therefore best to set it at 0, or at the maximum authorized deviation, plus a few kHz to ensure
additional security with the audio processor.
From 0 to 200 kHz
The FM Limiter option includes 3 processing stages:
AGC: The Automatic Gain Control purpose is to compensate level variations applied to the selected audio
input. The algorithm is wide-band for maximum audio fidelity and gated to avoid noise and unwanted
level corrections.
FM LIMITER: The FM Limiter prevents from over-modulation by limiting the audio peaks.
MPX POWER LIMITER: The MPX Power Limiter is based on to the ITU-R 412 standard applied on some FM
markets.
CLIP STATE
(CONF.STATE.CLIP) – read/write
This parameter enables or disables the clipper. Default: off.
Off/On
AGC STATE
(CONF.AGC.STATE) – read/write
This parameter enables or disables the Automatic Gain Control processing stage. Default: off.
Off/On
AGC DRIVE
(CONF.AGC.DRIVE) – read/write
With this parameter, load more or less the AGC input. At 0 dB gain reduction will be applied when the transmitter is
fed by an audio level higher than the input level setting. Increasing the drive will add gain reductions, while low audio
levels will be increased (more processed). Default value: +4 dB.
From 0 to 12 dBu