[time-nuts] Is there any IRIG-B hardware decoders available?

Chris Albertson albertson.chris at gmail.com
Tue May 14 13:35:44 EDT 2013

OK the 555 timer is not so good of an idea.  You need a phase locked
1KHz oscillator.

You can also buy IRIG cards for the PCI bus.  We used them where I
used to work.  They are not cheap.  Almost any company that working in
timing or telemetry will have these cards.

But still if the goal is to have the computer's system time track
irig, use NTP.  It should be easy to build a phase locked 1KHz
oscillator.  1K is such a low frequency.  I'd thing a 4046 chip would
do the job.

On Tue, May 14, 2013 at 10:04 AM, Esa Heikkinen <tn1ajb at nic.fi> wrote:
> 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 (?)
> --
> 73s!
> Esa
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Chris Albertson
Redondo Beach, California

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