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

[Esa Heikkinen]

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, 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...

Best regards,

-- 
73s!
Esa
OH4KJU