[time-nuts] Symmetricom TimeSource 2700

Mark Spencer mspencer12345 at yahoo.ca
Wed Nov 23 20:01:31 EST 2011

I'm curious if any one has any specific information about how TOD data could be sent via the native T1 data frames (as opposed to a signal which another piece of equipment could use as a clock source.)

I've never seen any specs for sending TOD information via the ESF Data Link or any other means, but that doesn't mean a spec doesn't exist somewhere.

--- On Mon, 11/21/11, Charles P. Steinmetz <charles_steinmetz at lavabit.com> wrote:

> From: Charles P. Steinmetz <charles_steinmetz at lavabit.com>
> Subject: Re: [time-nuts] Symmetricom TimeSource 2700
> To: "Discussion of precise time and frequency measurement" <time-nuts at febo.com>
> Received: Monday, November 21, 2011, 6:13 PM
> Kevin wrote:
> > The PPS in/out of the PRS10 do not appear to connected
> to the TS2700
> > logic board.
> I believe the TS2700 does not take PPS timing from the
> PRS10, nor does it discipline the PRS10.  It does,
> however, keep tabs on the frequency of the PRS10, and I
> believe it uses this information to generate corrections to
> the TS2700 frequency and timing outputs during holdover --
> that is, I believe it does not just pass through the PRS10
> 10 MHz signal and derive other timing signals from it during
> holdover, but applies corrections that it has learned from
> its monitoring.  See the block diagram at p. 19 of the
> TS2700 manual and text at p. 14.
> > I'm not looking for a
> > PPS that's just a frequency/period reference, but
> instead places the PPS
> > at the GPS PPS position. Perhaps the TS2700 is already
> do it, but so far,
> > I've only seed evidence that it's a frequency
> reference.
> The whole point of the TS2700 is to be a Stratum 1 time
> source.  See the TS2700 manual at pp. 14 and 113. 
> The TS2700 clearly sends TOD information -- pretty much
> every BTMon window contains a TOD display.
> Because the TS2700 was designed for telecommunications
> central office applications, the main outputs are two T1s,
> "Span A" and "Span B," rather than computing protocols that
> would be more familiar to most techies.  To access the
> TOD and timing information, I think you would need to decode
> the T1 data stream.  It may be available at the "Craft"
> output, as well -- the TOD data definitely is, but I do not
> know about the precision timing data.  (For those who
> are curious, "Craft" is an ancient telecommunications
> term.)
> Best regards,
> Charles
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