[BC] RE: DRM

[Davis, Jack L. KTXL]

Message: 20

Date: Wed, 8 Feb 2006 14:29:00 -0700

From: "Gary Peterson" <kzerocx at rapidcity.net>

Subject: [BC] DRM?

To: <broadcast at radiolists.net>

Message-ID: <000701c62cf6$c585e020$3b0f22d0 at kzerocx>

Content-Type: text/plain;     charset="iso-8859-1"

 

I've not been able to find the answer to my question elsewhere, so I am
coming to one of the best sources of collective knowlege, about radio, that
I am aware of.

 

On weekends, I have been noticing a broad signal around 7160 kHz that sounds
like a string-trimmer on steroids.  This frequency is often used by
international shortwave broadcast stations.  I'm wondering if there is a
station running DRM or if this is just a jammer.  Can anyone tell me what a
DRM signal sounds like on a product detector?  All I have been able to find
are audio files of properly demodulated DRM.

 

Thanks for any replies.  I'm very curious.

 

Gary, K?CX

 

Gary,

 

That is an excellent description of the sound of a DRM signal.  Add a little
sawmill sound and you are right on the money.  I have been able to decode
some DRM signals here in northern California but for the most part the East
coast has a better shot at it.  There are a lot of signals from the maritime
provinces of Canada and the skip distance is just not good here. I have
modified a couple of SW receivers (A Radio Shack DX-394 and a TenTec) to
interface with a soundcard input on a PC.  There is free software available
that does a good job of decoding and using a spectral display for tuning.
The IF converter converts the 455 KHz IF of the Rat Shack receiver to 22 KHz
for the soundcard, the IF of the TenTec is 22 KHz so it is plug and play.  I
am using the DREAM software that can be found here:

 

http://drm.sourceforge.net/index.html
<http://drm.sourceforge.net/index.html> 

 

There are other sources for compiled versions that can be located with a
Google search.  There is also a lot of information on converters as well as
Winradio products.

 

It takes a bit of fiddling to get it right but once you get a feel for it
life is good!  I really like the way DRM works, too bad it was not a choice
in the US.  There was an item a while back that Harris had been working with
some Mexican broadcasters to roll out DRM so perhaps I can have a better
shot at it.  There are a lot of European signals but they tend to be
directed to other than North American locations.  

 

Try it, you will like it!

 

Jack

K6YC