[TenTec] Pegasus DSP project

[Mark Erbaugh]

I'm investigating a potential software project for use with my Pegasus.

There is a mod for the Jupiter to extract the 12 kHz IF for external
processing.  Take a look at:

http://kd4dcy.net/jupiter/mod_ifout/mod_ifout.shtml

The mod is intended to facilitate Digital Radio Mondiale (DRM) decoding, but
can probably be used for other things.  From the photos, it looks like this
the same board is used in both the Jupiter and Pegasus and I've made this
mod to my Pegasus.

>From the schematics, it looks like this is the Receive IF signal just prior
to being fed to the DSP processor.

Since the signal is at 12 kHz, it's possible to feed this into a computer
soundcard (that's what you would - with appropriate software) to decode DRM
broadcasts. The soundcard could digitize the signal and once digitized, any
kind of demodulation could be done. Essentially you are replacing the DSP
processing done in the Pegasus / Jupiter with DSP processing done in your
PC.

Given the advancement of PC hardware, there is now more processing
horsepower available in the PC than in the DSP chip in the Pegasus, thus it
seems likely that features could be added that wouldn't be possible within
the limitations of the Pegasus DSP.

Some of the things that I think should be possible to do:

1) DRM reception (already available from other sources)

2) Narrower / sharper filters. It should be possible to have a 25 or 50 Hz
filter with a 1.1 or better shape factor.

3) Syncronous AM reception

4) 12 kHz spectrum scope with live receive audio

5) Up to band wide spectrum scope with no receive audio with greater
resolution than with the current sweep.

6) Binaural CW reception (does anyone really find this useful)?

7) Manual notch filter / Improved Auto notch

8) Additional NR algorithms / adjustable NR level.

9) Programmable AGC

Note: this is going to require a more powerful PC than to just run the
Pegasus, but these features should be doable with a 1 GHz Pentium.

I do most of my programming in Borland Delphi and have already done some DSP
work with Delphi for the FlexRadio SDR-1000. I plan on using Delphi for this
project.

I'm open to suggestions for features, but I'm really more interested in
disucssing the the technical details with others.  I'm a newbie when it
comes to DSP.  I'm trying to learn what I can, but being able to discuss DSP
programming with someone else would be helpful.

73,
Mark, N8ME