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.