[Fwd: {Collins} Audio passband tuning for Collins]

Bob And Bettina Groh rgroh at SWBELL.NET
Thu Jan 19 10:30:30 EST 2006

Bob Stewart posted this on the Collins email list and I hope he won't 
mind if I pass this along to the keepers of the green and the glowing 
tubes fans. I checked out the web site he mentions
and it is one neat and interesting web site. They have a variety of free 
software packages and I wish I had the time to fool with some of them. 
Maybe in a couple of months when I get a little more caught up on 
cleaning up 40 years of 'collecting'.

73 de WA2CKY
Bob Groh

-------- Original Message --------
Subject: 	{Collins} Audio passband tuning for Collins
Date: 	Tue, 10 Jan 2006 17:39:30 -0800 (PST)
From: 	Bob Stewart <bob at evoria.net>
Reply-To: 	bob at evoria.net
To: 	collins at listserve.com

I've been playing with a new freeware program along
with my KWM-2.  Actually, I'm abusing its purpose a
bit.  I'm sure everyone has heard of Software Defined
Radios.  There is free software for it called
SDRadio.exe available at sdradio.org.  The actual
purpose of the software is to take the I and Q outputs
of a quadrature detector, do the software magic, and
turn it into audio.  However, I discovered that the
software will still do most of its magic if it only
has the I input, i.e. the audio output of your
reciever of any vintage.  

What does it provide?  Well, it has 3 levels of noise
limiting, passband tuning, and I just discovered how
to change the audio bandwidth by putting the mouse on
the edge of the blue zone, grabbing it, and moving it.
 I'm sitting here listening to a fairly weak DX signal
with very strong QRM right next to it.  The software
does a good job of eliminating a signal that's 30DB
stronger at the cost of a bit of bandwidth.

My plans are to actually build an IF SDR for my KWM-2
to get the full benefit of this software, but, I'm
going to continue to play with it to see what its
capabilities are with just the I input.  If you try
it, you will get better results by disabling the AGC. 
As a practical matter on my KWM-2, this means backing
off on the RF Gain control till the S-meter stops
bouncing.  Be sure you disable your speaker.  If you
don't, the 1 second delay before it comes out of your
computer speaker will be quite disorienting.

It's not my software, and I have nothing to do with
it, but if you have any questions about what I'm
doing, I'd be glad to give your more info.

Bob - AE6RV
Sponsored by the Collins Collectors Association http://www.collinsradio.org
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