david.barker@LIGO.ORG - posted 11:13, Wednesday 22 February 2017 - last comment - 12:03, Wednesday 22 February 2017(34322)
CNS-II GPS receiver at EY modified to output PWM IRIG-B signal
I made the jumper modification inside of the CNS-II GPS receiver at EY. The jumper block J39 jumper was moved from spanning pins 3-5 (amplitude modulation) to pins 1-3 (pulse width modulation). The procedure was:
- power unit off
- unscrew unit from the rack
- remove front panel and rack mount bracket from unit
- slide unit top cover off
- make the jumper mod
- put back together in reverse order, then power up.
The EY unit label (located on unit bottom)
Model CNSC02-C
Serial Number: 404357
Options: 2
Using dataviewer I verified that the EY IRIG-B DQ channel is now PWM.
I'll modify EX unit at the next opportunity.
Operator notification of loss of end station GPS receiver: I verified that when the EY GPS receiver was powered down: SDF did not report any diffs (and therefore H1 was not knocked out of observation mode), the timing summary status on the CDS overview screen went RED (see attachment, a time-machine plot from 10:30:00 PST), there was no verbal alarm.
The first two of these are the expected behaviour, the lack of a verbal alarm is a fault, we will add this channel to this system.