Realtime Signal Processing for Unix?

Christoph Zrenner asks: "I'm a UK medical student with a serious research interest in "how to interface neurons with computers". We do a major project in our third year and I'm interfacing an eel spinal cord (8 analog inputs, 12 analog outputs) to simulate the eel's movements on a computer. The processing needs to happen in real-time (1ms delay) so that the cord can get feedback from the computer. Having spent two days foraging through the Internet I still haven't come up with a decent solution - does anyone have any experience with this kind of thing? I was hoping to use the Matlab/Linux combination but only found an (expensive!) Realtime Windows Target Toolkit for Matlab!"

Comments

Don't use sigma-delta A/D and D/A convertes.

[geirt]

Many A/D and D/A converters use sigma-delta converters (Look for words like: "one bit converter" or "bit stream", they are variants of this technology). Most sound cards use these sigma-delta converters, so do many A/D and D/A cards for PC, especially those with high dynamic range (many bits ...). These converters have excellent linearity, low distortion, and are inexpensive, but they have a significant time delay, so you might have more than 1 ms delay in the A/D converter alone. No real time OS can work around that.

Be sure that you select A/D and D/A converters with "sub ms" time delay.

Code Composer Studio

[Mechanik]

Disclaimer: I work for Texas Instruments.

I don't know how familiar you are with Code Composer Studio, but it sounds pretty much like what you're looking for. It is TI's debugger for their Digital Signal Processors. You can either run your DSP software on real DSP silicon, or you can run it on a simulator that runs on the host computer. If you needed to capture data or pipe it to another program, you could then stream out blocks of memory to a file. Of course, this all requires you to be able to write DSP code :-)

There is also a free 30 day evaluation copy that you can order. Simulator only, but otherwise fully functional. If you can do all of your work in 30 days, this might be all you need :-)

There is special pricing for universities. They get the software are very reduced rates.

The software listed on the website is for the PC, and runs on Windows. It is not really advertised to the mass market, but there is a version for Solaris as well. If you wanted to get a hold of that, you might be able to, but you'd have to do a lot of pestering. That product is Code Composer Studio for Solaris 1.1

It is not out of the realm of possibility for Linux or HP-UX versions of the software to be released as well, if it is perceived that there is enough interest. If you want it, start pestering people :-)

Mechanik