[time-nuts] IRIG B

[Bob Camp]

Hi

Audio codecs (especially monophonic ones) are pretty cheap these days.
Depending on volume they can get to the sub $1 range. Even in small quantity
they are below $4. That makes them a pretty tempting "front end" for a send
/ receive box.

Bob

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Dean Weiten
Sent: Tuesday, May 25, 2010 9:05 AM
To: cgreen at quartzlock.com
Cc: time-nuts at febo.com
Subject: Re: [time-nuts] IRIG B

Date: Tue, 25 May 2010 09:08:18 +0100
From: "Clive Green" <cgreen at quartzlock.com>
Subject: [time-nuts] IRIG B
To: <time-nuts at febo.com>
Message-ID: <000d01cafbe1$6f6788b0$4e369a10$@com>
Content-Type: text/plain;	charset="iso-8859-2"

Can anyone help with a modern IRIG B chipset manufacturer

Many thanks

Clive Green

----------------------

Hi Clive and the group.

I can't give you a lead on an ready-made chipset, but I've implemented an
IRIG-B decoder in a 68HC11 and in an 68HCS12.  I found the difficult part to
be the analog section, as it can introduce significant uncertainties in the
timing stream, especially in a modulated signal.  We got ours down to around
10 uSec which we considered quite good.  Of course the 5 volt logic levels
of the unmodulated signal makes it easier to get better accuracy.

The IRIG-B decoder work I did was implemented on power systems relays &
disturbance recorders several years ago, then I left the company and in the
meantime, they changed over to an FPGA implementation and skipped the
processor altogether.  Now I'm back with that same company (although
ownership has changed), but I haven't yet had a chat with the new FPGA
designer to find out how he did it :-)

I've also tweaked and "upgraded" (well in my opinion) the TG program of the
NTP package, which generates WWV(H) and IRIG-B audio signals in *NIX
operating systems.  It was targeted for the Sun Sparc and I moved it to OSS
audio which was what I was using on X86 GNU/LINUX at the time.  I think I
submitted it for inclusion in the NTP package but I don't think it ever got
in there; I used to claim that it was rejected, but then again it's also
possible that I didn't submit it correctly.  I can give this to you if you
would like.

If you would advise on your application and parametric requirements, perhaps
I (or someone else on the mailing list) could make further suggestion or
help directly.

-- 

Dean Weiten


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