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

Chris Albertson albertson.chris at gmail.com
Tue May 14 11:21:15 EDT 2013

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.

Now you have a standard IRIG signal that can be fed to the PC's sound
card and NTP will sync the clock to it.

TTL level IRIG is a funny thing, the entire point of IRIG was that it
could be set over a radio or recored to tape.  a modulated 1KHz
carrier is perfect for that.

On Tue, May 14, 2013 at 4:36 AM, Esa Heikkinen <tn1ajb at nic.fi> wrote:
> Hello!
> What is needed now is to decode IRIG-B timecode and syncronize the system
> time (or hardware timer) to it with about 1 ms precision. Operating system
> is Linux based and runs on embedded environment. It should support both, AM
> modulated and digital pulse versions of IRIG-B (for now it's unsure which
> will be used).
> Is there any IRIG-B decoder chips or reference schematics available with
> full support for the standard?  Google didn't find any ready solution for
> this need. It looks like only way to get this is to design it from
> scratch...
> --
> 73s!
> Esa
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Chris Albertson
Redondo Beach, California

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