Suppose that for the sake of miniaturization, I want to receive
a typical IR remote control signal (~35kHz carrier, on/off modulated
with minimum on/off times on the order of 1ms) using a bare photodiode
running into a PIC A-D converter (or similar) and doing all the signal
processing in software.  It seems like that should be about possible.

The signal I receive at the A-D is going to be a sum of ambient
illumination plus noise sources (60Hz illumination, mostly) plus
the signal I'm actually interested in.  Plus maybe other competing
signals at slightly different carrier frequencies that I'd rather
not see...

1) If I know the carrier frequency I'm interested in, and I know
    that I'm interested in on/off modulation, how do I pick the
    minimum sample frequency I can get away with?  Presumably I
    don't want an exact multiple of the carrier frequency.

2) Does anyone care to point to a suitable DSP algorithm, hopefully
    implementable on a typical integer microcontroller, that will do
    the rest of the work I'm interested in?  This IS the sort of
    thing that DSP algorithms can do, right?  If I need multiplies
    and divides, can I pick a carrier frequency so that those end
    up being shifts?

Thanks
Bill W
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