[time-nuts] IRIG B

Morris Odell vilgotch at bigpond.net.au
Wed May 26 11:26:01 UTC 2010

I have done this with an AVR microcontroller and it turned out to be very
easy. Just program one output to generate a 1 KHz carrier and another to
modulate the amplitude using a resistive divider. A simple LPF will knock
the edges off the carrier and not affect the timing accuracy too much.

Receive is easy too if you have a micro with a comparator which can tell the
difference between the two amplitude levels. I would extract the carrier
first and feed it to another input of the micro to provide a phase reference
and then do the decoding all in firmware.


> i would think, given that the audio carrier is 1kHz-ish, that almost
> any
> of the small microcontrollers would work, using a single bit in/out
> with
> some RC signal conditioning.  Maybe a bit of a challenge for the
> receive.. you'd need two inputs with different resistors.

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