[time-nuts] TSIP, SCIP time sync

[Mark Sims]

I did some digging around and testing on the Thunderbolt 1PPS output.  Their docs say that the timing message is sent within 20 milliseconds after the 1PPS output pulse.

I tweaked Heather to pulse a modem control signal when the program receives the complete timing message (which is around 20 bytes long).  I am seeing a delay of 46 milliseconds from the 1PPS pulse until I sync the system clock.

I have since added a (user settable) time_sync_offset value to back this delay out of the time sync.

The unanswered question is does the receiver time message go with the previous or next 1PPS pulse (i.e. is the pulse pre-dated or post dated)?  I can't receive WWV here to check whether the time display is correct or off 1 second. 		 	   		  
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