[time-nuts] Trimble Resolution [T, SMT, SMT GG] - spontaneous GPS loss of signal events, multiple locations

Wojciech Owczarek wojciech at owczarek.co.uk
Mon Sep 14 11:28:59 UTC 2015


Hello Time Nuts,

I was wondering if other people have seen this. 20+ receivers and they all
use different variants of the Resolution boards - majority are the old
Resolution T.We have observed sudden GPS loss of signal occurring.
Seemingly nothing unusual, these things happen, that's what holdover is
for, etc... however:

- All devices are connected via decent distribution amps,
- All installations use roof-mounted antennas with unobstructed 180 degree
sky view
- All devices see about 11 birds most of the time
- None of these events coincided with known GPS SV outages

And here's the fun part:

- This is happening in multiple locations in the US, AND in the UK
- The log timestamps (UTC) for the alarms, are *exactly the same* across
all sites, down to the second. This happens twenty to ten seconds before
midnight, and usually recovers within two or three minutes.

The last event was on 5th September, at 23:59:37 UTC. We have seen this
happening anywhere between once every month to once every two months. Time
may differ by a few seconds, but it's the same across all devices.

I'm trying to establish whether the issue is with Trimble or with the
vendor who embedded Trimble. Because of what I refer to as "vendor
anal-digital decoupling delay", I have to investigate in parallel.

Has anyone seen this with Resolution? Unfortunately I have no visibility
into firmware versions in the Resolution boards.

Any pointers welcome.

Many thanks,
Wojciech



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