[time-nuts] IRIG B
dmw at weiten.com
Tue May 25 13:05:19 UTC 2010
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>
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Can anyone help with a modern IRIG B chipset manufacturer
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.
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