Paul,
1) Yes, DSP-driven, adaptable squelch would be so excellent! Alas, I don't
the the skills to program such a thing. I would probably be able to define the
desired parameters & operating modes and be glad to work with someone on that.
What I need to do is hang an audio spectrum analyzer on my different FM radios'
squelch amps to see what that spectrum looks like.
I think there are vendor(s) still offering custom squelch boards using the
Micor squelch chip. So who knows in what vault those chips now reside!
2) To address another message, on CTCSS falsing...that won't happen unless
there's something not quite right about the decoder. PL was designed to NOT
false, that's the whole point.
If the PL decoder's bandpass is the wrong shape, e.g. too peaky, then yes, you
could have falsing on random noise. It's Q is then too high & it becomes prone
to "ringing" on transients just like a vy narrow CW filter.
Long live analog FM! Some of our ham radio club guys are all gung-ho on
D-Star. I keep pointing out that its system developers are vy clear that it
works properly when A) there's enuf SNR and B) there's no multipath!
--John
--- On Fri, 8/21/09, Paul Plack <pl...@xmission.com> wrote:
From: Paul Plack <pl...@xmission.com>
Subject: Re: [Repeater-Builder] Re: Squelch action on 10 m FM
To: Repeater-Builder@yahoogroups.com
Date: Friday, August 21, 2009, 5:27 PM
Perhaps one the remaining contributions we could make as
amateurs would be working with DSP to combine all these attributes in a
standalone uP module. It would be great to have an adaptive squelch board for
retrofit into repeaters which could account for multipath, propagation
conditions, noise levels, and user priorities.
It will probably fall to us to do it, because we'll no doubt
be the last users of analog NBFM.
Besides...those Micor squelch chips won't last
forever!
73,
Paul, AE4KR
----- Original Message -----
From:
ka1jfy
To: Repeater-Builder@ yahoogroups. com
Sent: Friday, August 21, 2009 5:16
PM
Subject: [Repeater-Builder] Re: Squelch
action on 10 m FM
Because CTCSS falses on the random noise.
Been there, done that, gave
away the t-shirt.
WalterH
--- In Repeater-Builder@ yahoogroups. com,
n...@... wrote:
>
> At 8/20/2009 23:17, you wrote:
>
>
> >John, how's this for an experiment.. .
>
>
> >Configure a repeater with two receivers, one built for +/- 5
kHz
> >deviation, the other for +/- 15, feed them from a splitter,
use audio from
> >the narrow one, but allow a DTMF command to select
the wider receiver's
> >COS when conditions warrant. (Obviously,
those conditions would have to
> >include no adjacent channel
signal...)
>
> If noise squelch is so problematic in severe
multipath conditions, why not
> do away with it entirely & use
straight CTCSS squelch? The GE decoders
> that use Versatone chips are
fast enough that you can still almost
> eliminate the squelch tail with
an ADM.
>
> Bob NO6B
>
