[time-nuts] Is there any IRIG-B hardware decoders available?
tn1ajb at nic.fi
Tue May 14 13:04:25 EDT 2013
Chris Albertson kirjoitti:
> NTP will so this. There is an IRIG reference clock. You really do
> want to use NTP to discipline the PC's clock. Almost every other
> method is worse and causes time discontinuities.
> If you happen to have TTL level IRIG it s very easy to convert it to
> amplitude modulated IRIG. The standard is a 1KHz tone.
> Build a cheap 1KHz oscillator. A 555 timer is good enough. Then you
> a single transister if IC time switch to modulate the amplitude of the
> signal. The details are not critical.
That's good idea if the phase of the 1 kHz signal is not critical?
I checked the IRIG-B signal with oscilloscope and looks like the 1 kHz
signal's phase is locked to the time signal. The bits will always start
and stop at exactly same phase. That makes sense because with phase
detector it could be possible to get very accurate timing from the 1 kHz
signal - much better than following the amplitude only. That's one
reason why I was interested about chipsets; if they can follow the phase
also. I think if I design any hardware for that it should follow the
phase also? It may be complex...
Does anyone know if the soundcard based IRIG decoder will follow the
phase also, or only the amplitude (?)
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