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

[Joseph Gwinn]

Responses interspersed below.  Joe

On Sun, 24 May 2015 12:00:01 -0400, time-nuts-request at febo.com wrote:
> 
> Today's Topics:
> 
>    9. Re: IRIG-B audio decoder circuits and ICs sought (Esa Heikkinen)
>   13. IRIG-B decoder schematic (Tim Shoppa)
> 
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> Message: 9
> Date: Sun, 24 May 2015 10:33:47 +0300
> From: Esa Heikkinen <tn1ajb at nic.fi>
> To: Discussion of precise time and frequency measurement
> 	<time-nuts at febo.com>
> Subject: Re: [time-nuts] IRIG-B audio decoder circuits and ICs sought
> Message-ID: <55617EDB.5070706 at nic.fi>
> Content-Type: text/plain; charset=UTF-8; format=flowed
> 
> Joseph Gwinn kirjoitti:
> 
>> When I last used IRIG-B005, the vendor (Symmetricom?) said it was good 
>> for a few meters only on shielded twisted pair. I recall that the 
>> handling of shield grounds was strange.   This was OK, because the 
>> signal was confined to one cabinet, and it worked just fine.
>> But there was no mention that the B005 followed RS422 or RS485 or 
>> anything else.  Nor does IRIG 200-04 say this, so I suspect that each 
>> company solves it differently.
> 
> Yes, there seems to be many implementations.
> Quote from Technical Note TN-102 from Cyber Sciences:
> <http://www.cyber-sciences.com/documents/TN-102_IRIG-B.pdf>
> 
> The IRIG 200-04 standard does not define specific signal levels for IRIG-B.
> Typical techniques for transmission of unmodulated IRIG-B include:
> - TTL-level signal over coaxial cable or shielded twisted-pair cable
> - Multi-point distribution using 24 Vdc for signal and control power
> - RS-485 differential signal over shielded twisted-pair cable
> - RS-232 signal over shielded cable (short distances only)
> - Optical fiber
> Typical techniques for transmission of modulated IRIG-B include:
> - Coaxial cable, terminated in 50 ohms or higher.
> - Shielded twisted-pair cable
> 
> So your main concern with unmodulated version is compatibility between 
> different vendors.

Yes, now and in the future as things fail and are replaced.


>>> Yes, planning to buy at least one spare unit when their prices will drop 
>>> on Ebay... :)
>> The problem is that they don't handle GPS week field overflow gracefuly.
> 
> Yes. Internal GPS of TS2100 cannot be used anymore, it failed alrady in 
> February. Used external PPS since then. Since having external PPS is 
> major problem for most of the TS2100 users I hope that the price of 
> these units will drop soon on Ebay.
> 
> I'm interested to buy especially rubidium version of the TS2100, if 
> someone has working one having only the GPS problem...

Are you trying to synchronize a Rb unit via IRIG-B12x?  Tried that 
once.  It doesn't work - the IRIG-B12x signal can wiggle faster that 
the Rb can follow, so the Rb never syncs, or the sync is ratty and 
fragile.  IRIG-B005 can work though.  That was the solution.



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> Message: 13
> Date: Sun, 24 May 2015 07:05:14 -0400
> From: Tim Shoppa <tshoppa at gmail.com>
> To: Discussion of precise time and frequency measurement
> 	<time-nuts at febo.com>
> Subject: [time-nuts] IRIG-B decoder schematic
> Message-ID:
> 	<CAJ_qRvZ0E08747RYeKQNuNGgP6X5wTW145n6bCDti6AX6PdPag at mail.gmail.com>
> Content-Type: text/plain; charset=UTF-8
> 
> Truetime 820 was made in the 80's and 90's and we have many at my day job
> fed with 1kHz AM modulated IRIG-B120.
> 
> Schematic at http://www.trailing-edge.com/IRIG-B-DECODER.pdf
> 
> Useful if you also have the theory of operation at
> http://www.arsitec.com.br/arquivos/produtos/man-820-210.pdf
> 
> Tim N3QE

Got them; thanks.  I'll sturdy them.

 

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> End of time-nuts Digest, Vol 130, Issue 35
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