[Linrad] Re: Running Linrad on 2 computers through a network : Help

[attglobal.net; radio1@xxxxxxxxxxxxxxxx>]

For  what it worth, FM squelsh works on quieting so is always less 
sensitive than the receiver.  We would rather squelsh on subaudible tone 
or some digital pattern.  These are not available in the standard ssb 
signal. I once worked for Harris RF, they had an ssb (reduced carrier) 
squelsh that worked on the recovered carrier, again not available here.

73, John K1vbm

---- Original Message ----

From: Leif Asbrink <leif@xxxxxxxxxx>
To: linrad@xxxxxxxxxxxxxxxx
Cc: 
Subject: [Linrad] Re: Running Linrad on 2 computers through a network : 
Help
Date: Wed, June 10, 2009, 14:24:00


Hi Gaëtan,

> About the squelch, I'm interested in monitoring a particular channel
> (SSB) without hearing all the time the noise hiss, though I admit this
> is a bit wasting the WB rx capabilities of Linrad.
Ok. You need the wideband for good noise blanking so it is no waste:-)

The standard procedure would be to have AGC enabled and to
turn the volume bar in the baseband graph down to make the
noise hiss rather weak.

The problem with SSB squelch is that the SSB signal is likely to
be off frequency and that auto tuning is very difficult in SSB mode.
(An unprocessed voice is fairly easy, but when a good speech
processor has been used it is difficult. I have tried and failed...)

> I guess it is
> difficult to implement for a particular channel (or the sampling BW
> has to be limited to a few kHz around that channel). The easiest would
> be to define a threshold below which the receiver is muted but at 96
> or 192 kHz sampling, there would always be some birdies (eventually
> not removed by the autospur) triggering the squelch.
A squelch would operate on whatever comes out from the baseband
filter and it would be possible to set a threshold for average power
below which the output would be muted. Very easy, but there has
to be some kind of user interface with yet another control bar....

Comments from others?


73

Leif





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