Subject: [NEXTEL-1] Digital Carrier Squelch

From: Marcel <[email-masked]>
Date: Fri, 25 Apr 2003 11:40:02 -0400

-------- Original Message --------
From: Mark Hollingsworth <[email-masked]>
Subject: [project25] Digital Carrier Squelch

I have found some interesting information on the
'Digital Carrier Squelch' in Motorla radios. I have
not tested the Racal to see what it does.

In all of our systems presently, we are in carrier
squelch for portables and mobiles and most bases
(analog). We don't have any problems running like
this, it works just fine, and since we have a lot of
very old equipment, there is some good reasons to do
so. Perhaps not a good reason with all new stuff,
but...

Anyway, I found with the XTS3000 (and Spectra Astro)
you can pick 'digital carrier squelch' for the squelch
type, and it will open the receiver on any viable NAC.
The problem is, to change the TX NAC, you must change
it to 'Normal Squelch' (or at leat off of carrier). No
problem, I thought, I'll just leave the RX NAC at 293
(I have always been told this is digital carrier
squelch). But in testing, I found it will only open on
293, nothing else!

Here is the problem, the original plan was to 'slave'
the repeaters to TX the same NAC as it operates on.
That way, we could find which repeater is working, and
which isn't really easily. But since the radios must
'see' a common NAC to unsquelch, then all the
repeaters will have to TX a common NAC (I set it to
293).
I see no way to put an 'ID' of any kind on the
repeater, and I guess that would defeat the whole ID
idea, since it would strip the ID of the
Portable/mobile (the ADI probably does this!).

I called Motorola, and they said I had it programmed
incorrectly- so I sent in a codeplug of the Quantar
and the XTS. I didn't do anything incorrect, and they
found out I was right, 293 is NOT carrier squelch.

I have just recently found that the Racal uses $F7E or
$F7F for carrier squelch, and Daniels has a couple of
neat NACs for various features (I think the same
codes).
Perhaps Motorola just is using something different,
but nobody there knew about it, or a way around it.

I always thought this was part of the P-25 specs, but
of course, we have been given a LOT of misinformation
(like it will have better coverage, yeah, sure...).

Anyway, all that to ask for others experiences, or
ideas.

Mark

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