[time-nuts] Symmetricom TimeSource 2700

Charles P. Steinmetz charles_steinmetz at lavabit.com
Mon Nov 21 23:13:39 UTC 2011


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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