[time-nuts] IRIG-B audio decoder circuits and ICs sought

Graham / KE9H ke9h.graham at gmail.com
Wed May 20 14:19:47 UTC 2015


Be aware that there are about 100 variations on "IRIG B", that is, B000
through B257.
You should obtain a copy of "IRIG STANDARD 200-04", the 2004 version,
which I believe is the most current.  It is available on line, if you
Google for it.

--- Graham / KE9H

==

On Tue, May 19, 2015 at 8:11 PM, Neil Schroeder <gigneil at gmail.com> wrote:

> A bc635 can be had on eBay for almost nothing. It's not a pleasant piece of
> gear, but this is one task it can help you with greatly.
>
> Tools exist to let you analyse the stream extensively, and the Api is
> trivial to learn -but not super featured at the high level.
>
> On Tuesday, May 19, 2015, Tim Shoppa <tshoppa at gmail.com> wrote:
>
> > See for example the Truetime 820 decoder. Discriminators, One-shots, and
> > Flip-Flops with pots to tweak the levels.
> >
> > Tim N3QE
> >
> > On Tuesday, May 19, 2015, Joseph Gwinn <joegwinn at comcast.net
> > <javascript:;>> wrote:
> >
> > > I'm studying up on how IRIG-B decoder circuits work.  What are the good
> > > approaches, the bad approaches, especially in the presence of noise?
> > > (I asked on the NTP group, with little result beyond the C/C++ decoder
> > > software written for the audio channel of a 1990s Sun workstation,
> > > which it ate alive: 50% cpu load.)
> > >
> > > Are there decoder ICs available?
> > >
> > > The closest to a decoder IC I've found is some FPGA code from a partner
> > > of Microsemi (nee Symmetricom):
> > >
> > > ..<
> > >
> >
> http://www.microsemi.com/products/fpga-soc/design-resources/partners/semquest
> > > >
> > >
> > > All marketing and little technical information.  I'll have to find out
> > > the details.
> > >
> > >
> > > I find very little, though I did find one intriguing idea using a
> > > Costas Loop to lock to the 1 KHz carrier, and a posting suggesting
> > > squaring the input signal and phase-locking to the 2 KHz result.  Most
> > > recent articles on IRIG decoders come from Chinese sources, mostly in
> > > the AC power industry.
> > >
> > > Joe Gwinn
> > > _______________________________________________
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