[FedCom] Odds and Ends - federal

[Steven Donnell]

Ken wrote:s
 Not sure technically how analog intermod could go through digital repeaters,
perhaps someone else on the list could comment.

 I needed to expain this to one of the folks that I "play" w/ recently: A
repeater needs to be specifically designed/enabled to pass P25 through it. This
would require it to be set for a specific NAC/NID, although there is a
"universal" NAC that a repeater can be set for so that it will recognise all
valid NACs. Note: This is a different NAC from the universal NAC used in
NAC-selectable receivers. In addition, the repeater can(if desired) still be set
to recognise certain CTCSS/DCS codes too, in order to pass analog signals. I
dont know how well a P25 signal could pass through an analog repeater if the
tone deocde function was disabled. I suspect this would depend on the extent the
audio was filtered, the data "polarity" of the retransmitted signal. Not too
well I suspect, plus you would not get any advantage of error correction of the
received audio before its retransmitted.

>
> >
> > Random honks in the Boston MA area seem to be on
> > 163.775 - 170.775 - 172.775 - anyone see a pattern
> > here? :-)

163.775 had quite a bit of problems when it was first put in service, mostly
intermod from paging and an FM Brodcast freq., but it has since gotten much
better. If I recall it uses DCS on the output, when Ive heard it w/ the
intermod. This permits it to be used  in "mixed mode" (analog or dig). This
might be a trend w/ other users in this band...

> Steve
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