ECR: Add independent absolute time marker to frame files

Other Versions:

Abstract:: In initial LIGO we had and absolute and independent time marker in the frame files. It was an IRIG-B signal digitized in one of the end stations. We lost this feature as part of the timing upgrades in Advanced LIGO. We propose to add the IRIG-B channel back to the science frame, derived from an independent GPS clock.

Files in Document:

Other Files:

Notes and Changes:: The existing aLIGO Timing GPS modules (D1002546) brings out the serial port of the Trimble GPS receiver through a Lantronix Serial->Ethernet adapter to an Ethernet port on the front-panel. It is now desired to read out the GPS module directly from the serial port to a port on the Beckhoff system Serial Concentrator. To do this cleanly, modify the GPS module to bring the embedded serial port on a DB9 cable to a DB9 feed through, mostly likely on the back panel D1002555. This change needs to be reflected in drawings and likely requires updating the
test procedure (T1000659) to use a direct serial port. In addition, this change requires updates to the Beckhoff EtherCAT software (already completed at LHO). All of this work is (implicitly) part of this ECR.

Issue tracker:
https://services.ligo-wa.caltech.edu/integrationissues/show_bug.cgi?id=1093
for associated changes to get the serial output of the GPS receiver, see also https://services.ligo-wa.caltech.edu/integrationissues/show_bug.cgi?id=1111

approved by Dennis Coyne

LIGO Document E1500355-v1