Hello,

What I'm looking to do is decode (or detect the present of) a sub audible
audio tone using a PIC.  The tones are received on a radio receiver and
range from 67.0Hz to 254.1Hz.  Accuracy needs to be around -+1%.  Faster
the better!  False triggers are acceptable but need to be minimal.  Anyone
ever done this or have tips on how to accomplish this?  I'm using CCS C but
can always snip in ASM code.  Code samples would be great!

GE did this with an Intel 8049 at 6MHz, surely it can be done with a PIC
16F877 at 20MHz!  GE used a low pass filter to filter out all audio above
300Hz, then sent the low frequency audio into the CPU and decoded the
tones.  GE did this very fast and accurate.

Thanks,
-Dale

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