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DGS (General)
keiko.kokeyama - 19:21 Thursday 07 January 2016 (583) Print this report
Timing Sync Problem

We have the sync problem between ADC0 and a corresponding real time computer. It disables dolphine network, therefore IMC lock is not possible at this moment.


As are GS_TP screens attached, for k1imc0 (top right) and k1lsc0 (not shown in the figure) have good sync between the ADC0 and computer. On the other hand, k1pr0, k1pr2 and k1ioo (left column) have a bad number in each IRIG B box.  For pr0, pr2, GPS time is 113607660 and IRIG B is 999997 [usec], whereas imc0 shows 113607661 and 12usec. This means that they all indicate the same absolute time within -3usec to +12usec, but the reference (GPS time) is taken 1 second off between good ones and bad ones. Cause is unknown even for a LIGO CDS specialist.

We tried following but didn't help

1. Rebooting everything related to the timing, i.e. the master board (GPS antenna), FANOUT, IRIGB board, IO chassis and FE computers.

2. Changing the fiber cable between the ADC to FE computer

3. Changing the IOP master model, which is related to the timing on each RT model

Also, with some tests, each ADC0 has unique IRIGB box number. So for me, ADC0 seems to have a cause, but we cannot idenfity what.


Miyakawa-san is digging the RCG code to see where this issue is raised. I might try to use a different ADC card.

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