> I tried feeding the pulse train out of a Rohm 3-terminal IR receiver
> chip into a PC's line input. That didn't work too well cuz all u get is
> a splatter of waves with peaks all over the place. Can't pick out the
> 1's & 0's.  I guess coz it's a train square waves with lots of
> harmonics. No good :(

Maybe.  Of course your signal will have lots of harmonics, but it should
still be within the capabilities of an audio card to capture it reasonably
well.  A typical carrier is about 40KHz, but most receiver modules need a
minimum of around 10 carrier cycles per pulse to receive them properly.
That's only the carrier ON pulse, so a complete carrier on/off burst
shouldn't be much less than 20 carrier cycles, or 2KHz.  That leaves
plenty of headroom for the sound card to capture enough harmonics that the
signal should be understandable.

Make sure the sound card is set to a high sample rate, like "CD quality"
or 44.1KHz.  8 bit mono resolution should be fine.  This method should
work, and it is probably useful to undestand why it didn't.  Yous symptom
sounds like the sampling rate was too low.

I am also a bit suspicious what this "cool edit" software might be doing.
You don't want it to edit anything before grabbing the WAV file.  I would
use something as dumb as possible just to record the WAV file, then you
can apply all kinds of post processing later.

The waveform peaks are probably not meaningful due to all the various
harmonics.  Try taking the raw WAV file and making a square wave from it
by looking at the zero crossings only.  You could even apply a little
hysterisis in the process if you want to.

> Then I thought of the attached schematic : grab an AF sig gen & feed
> its o/p thru a CD4016 analogue gate and use the IR Rx chip to gate it
> on/off. That way u should get a train of pulses made up of pure sine
> waves going into the PC? 5KHz in this case.

Again, this sounds like a kludge to work around some other problem that
should be understood in its own right.


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