[evlatests] news

[Rob Long]

I've thought for some time that this would be a good idea.  Using 
outside time as a 'sanity check' for our GPS server is also a good idea 
for keeping tabs on the GPS receiver's health.

Rob

Ken Sowinski wrote:
> On Tue, 5 Jun 2007, Ken Sowinski wrote:
> 
> 
>>During one of Rick's observations early this afternoon and for
>>a while afterward it appears that the EVLA antennas' idea of
>>time seemed to differ from the rest of the VLA for while.  I
>>planned to disable phase switching to pin down the source of
>>the problem, but while discussing it with Jim Jackson it
>>magically cured itself.  This raises the obvious question of
>>whether the changed time multicasting contributed to this.
>>Without further evidence I doubt it.  The same thing occurred
>>for a while last week, albeit after many serious disturbances
>>to the system.  Should the antennas continue to lose sync with
>>the VLA over the next few days I think we should consider turning
>>off the multicast of time from andy.
> 
> 
> James explained to me that coincidentally there was a machine in
> Socorro multicasting at the time Monday afternoon when the L302
> mibs appeared to be confused about time.  There is no doubt that
> these packets would have made it to the EVLA antennas.
> 
> While not a clear explanation it this seems a likely cause.  There
> is still no reason to discontinue having both amos and andy multicast
> time, but we should remain alert to possible timing errors.
> 
> James and I discussed the merits of letting the VLA network use the
> GPS at the VLA as its primary NTP server.  This would insulate us
> from drifting time if the network to the outside world is lost.
> I believe it is possible to configure NTP so that it still looks at 
> the outside time servers so that a failure of the GPS will be detected
> and reported.  Is this a good idea?
> 
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