Thanks for the files.

The problem that I see right off is that the PDF says that the worse case s/n ratio for that design is 23dB. That's quite reasonable for working with DTMF signals off a phone line, but not a source picked up using an AM shortwave radio.

You guys have just about convinced me that any scheme using a plain digital PIC isn't gonna fly.

There are lots of DTMF decoder chips, but I expect that they require a s/n ratio similar to that normally found on a phone line i.e. pretty good. Plus, hacking them to do 100 and 1000Hz might be a big problem seeing as how they were designed from the ground up to do DTMF.

Other than the NE567s already in use, does anyone have any other ideas? Suggestions on development tools for DSP PICs that don't have a huge learning curve?

Thanks again,

Mike