[evlatests] Rubidium drift and the WIDAR timecode PPS faults

[Keith Morris]

On the upcoming Wednesday maintenance day we propose to do two things:

1. Calibrate the 5MHz crystal in the Rubidium standard in order to 
minimize its drift.  If we are unable to tune it to an acceptable drift 
rate (and by acceptable, I mean on the order of what the Maser drift 
rate was, ~10ns/day), then we will bypass the L356 entirely and 
discipline the Rubidium with the GPS tick directly.

2. Try to revert the MIB software in the L350s to version 1.00 -- if you 
recall, among the other changes I made to the MLO last week was the 
application of the newest MIB framework to the L350s.  The 60-second 
flag from the MIB to the FPGA timecode generator is implicated in the 
timecode PPS faults, so it makes sense to scrutinize the MIB software 
that changed.


-- 
Keith Morris
National Radio Astronomy Observatory
1003 Lopezville Rd.
Socorro, NM 87801
575-835-7060 (phone)
575-835-7027 (fax)