Mathew,
This is a common problem, especially when users with multiband/multimode
radios use them on FM repeaters, not realizing that they are
overdeviating. I guess it's a mixed blessing that some kind and gentle
listeners will advise a repeater user that his/her signal is "loud and
clear" when the report should have been "overdeviated, distorted, and
almost unreadable." Gotta love these kind and gentle folk!
My solution is to incorporate a hard clipper that will prevent incoming
signals with excessive deviation from being repeated at any more than a
fixed limit. When CTCSS encode is used, as it normally is in my systems,
I set the tone level to about 500 Hz and limit the repeat audio to about
4.3 kHz. In other words, I deliberately cause overdeviated incoming
signals to be distorted so that other users will speak up and complain
about that user's signal.
I know I could use one of a number of "soft AGC" circuits to control the
incoming audio before it is repeated, but that would not prompt the
offending users to mend their ways. I am working on an audio monitor that
will interject the voice warning "average modulation too high" when it
detects that overdeviation of the input signal is present. It is not a
simple project!
73, Eric Lemmon WB6FLY
w9mwq wrote:
> I have set the deviation level of the repeater to 4.5 kHz, which for
> most users is excellent, however I have a few users who, no matter what
> radio they use, always clip well over 6 kHz wide. Is there a way to
> limit this? When these users come in, you have to turn down the volume,
> but then it's difficult to hear the normal voice users of the system.
> Any thoughts?
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