The DX-394 can be readily adapted to have a 3rd IF at 12kHz to feed a
computer sound card with which free software can decode DRM transmissions.
Jan Terpstra has designed a two transistor 455kHz-to-12kHz "quick and dirty"
converter that he and I have built. Today I successfully received DRM
transmissions from Sackville using the DX-394 with the converter and the
free DReaM software running on a Celeron 450MHz computer.

The DReaM software is intriguing in its own right and is capable of doing AM
and SSB demodulation from the 12kHz IF using DSP. Remarkably, I think it
excels the stock AM demodulator at very weak signal reception and provides
selectable bandwidth in 1kHz steps from 1 to 15 kHz.

For more on DRM on the DX-394 visit/join
http://groups.yahoo.com/group/RADIOSHACKDX394/ .

Tom

"Tom Holden" wrote in message
. ..
AM demodulator at very weak signal reception and provides
selectable bandwidth in 1kHz steps from 1 to 15 kHz.
Tom

Tom, how are you adjusting the bandwidth in 1kHz steps with the software?

Thanks.

Al KA5JGV
San Antonio, Tx.

----- Original Message -----
From: "Al - KA5JGV"
Tom, how are you adjusting the bandwidth in 1kHz steps with the software?

The software does more than DRM. The bandwidth selection is in AM mode not
DRM.

In the AM mode, the Evaluation page of the DReaM software has 15
radiobuttons to select bandwidth. Under the spectral display, a red bar
shows the bandwidth selected relative to the demodulator centre frequency,
which you set by clicking on the display. For example, if you have tuned the
radio toan AM station so that the carrier is at 12 kHz, you see a spike in
the display at that frequency. Clicking on the spike centres the DSP filter
on it. Then you can vary the filter bandwidth. It's all done in the math in
the software.

You can also select USB or LSB, thus shifting the filter to one side of the
carrier. Works great on AM with carrier to suppress interference that's one
sided. Just think of it as a 3rd IF with variable bandwidth and passband
tuning with an AM demod and a product detector - yes you can demodulate
suppressed carrier AM too.

73, Tom

"Tom Holden" wrote in message
...
The software does more than DRM. The bandwidth selection is in AM mode not
73, Tom

Tom, thanks for the detailed information. I have used this program many
times for DRM and never realized there was an AM option to it. You're right,
it's quite impressive what all can be done with this mode. I have a Ten-Tex
RX-350 so all the DSP options are already there, but for a radio without
these features, this program is great. All interested in DRM or DSP that
have a 12kHz IF should try it.

Al KA5JGV