Linux-Hams archive - August 1999: Re: soundmodem on SBPro

Re: soundmodem on SBPro

Thomas Sailer (rdpkqid@cotse.net)
Wed, 04 Aug 1999 16:40:26 +0200


Tomi Manninen OH2BNS wrote:
>
> On Wed, 4 Aug 1999, Hamish Moffatt wrote:

> > Do you think it is a problem to operate with the squelch open always?
> > The soundmodem seems to do a pretty good carrier detect anyway.
>
> As far as I can see, using squelch with soundmodem can only make things
> worse. It _will_ make carrier detection slower and possibly also receiver
> recovery (from tx). Both are very important factors for efficient channel
> usage. False carrier detection is much less dangerous. CPU usage might be
> slightly lower with squelch but I doubt you can even notice that.

On the other hand, if a hardware squelch decides wrongly, the packet is
trashed. If the software squelch (or rather carrier detect) errs,
the packet reception is not affected.

So it depends. If you have a very fast hardware squelch (preferably
that operates on the RF power level), then use it, but I doubt that
most FM rigs have anything but an extremely slow squelch.

Tom