Friday, May 06, 2005

Why I'd like a digital IF output on my Orion

What could you do with a digital IF output from the Orion transceiver connected to your PC? I have a few ideas. Maybe you can add more.
  • Custom IF DSP filters in your PC - like an optimized RTTY filter. (The Sharc DSPs are efficient for DSP, but modern PCs should be plenty fast enough to process a 20 kHz band.)
  • Support interesting modulation modes (ISB, synchronous AM, DRM, PSK31, and all the other strange modes). Avoid the compromises of audio soundcard interfaces.
  • Detect multiple data streams simultaneously
  • Record your IF for later playback and analysis
  • Real time spectral display.
If you had a digital IF input for Tx, you could generate interesting modulations in your PC, multiple audio/data streams (ISB or multiple SSB, digital audio) - FCC permitting.

The programmers among us would be able to enhance Orion's "software defined radio". Eventually there will be killer signal software for general use on everyone's PC.


Lee said...

You missed the most important, the ability to upgrade at will, as new technology comes online, independant of Ten Tec's marketing ideas.

A second is to off-load significant portions of the processing duties to the PC therefore making the whole system more efficient. Not exactly dual processing but in that ball park.

If you can remove some of the processing duties off rig you can turn off a lot of the "processing" that is going on, so for example you could actually do 100wpm QSK, because the processor is not interupted making a side tone etc.

The other major thing lacking is a high speed low overhead data connection between the rig and the PC, or maybe even 2 of these, and a command language that is more than just a subset of the I/O functions.

Ten Tec has the best front end in the business period. So all that is left is to maximize the rear end.

Martin Ewing said...

A few responses to Lee.

My view is that we have to let TenTec be TenTec. That is, we can't expect TT to change their firmware as we'd like. In particular, "100 wpm QSK" is probably not in the cards because the T/R changeover logic (antenna switching, etc.) is always going to be TT's domain - and it's probably not capable of working much faster than it does now.

It's debatable whether your PC is a "better" place to do DSP. The dedicated SHARC chips in the Orion are highly tuned for this application. Unfortunately, they are controlled by TT's firmware, and there's little hope of making them programmable by the end user. Off-loading the SHARCs probably would not help the overloaded Dragonball control processor. The reason to use the PC is flexibility and user programmability for those who can put up with the extra complications.

I think TT missed a bet by not providing this digital IF interface. It would have given them a lot of visibility among the "QEX types" (or GNUradio types?) who would have built lots of software by now. And that would sell more radios.