Looks like we might have a problem with the IRIG-B output of the GPS receiver.
Rolf came over this morning to help debug the strange symmetricom driver behavior on fb1 with the new Spectracom card. We restarted the machine againt and this time when we loaded the drive rit was clocking at a normal rate (second/second). However, the overall GPS time was still wrong, showing a time in October from this year.
The IRIG-B122 output is supposed to encode the time of year via amplitude modulation of a 1kHz carrier. The current time of year is:
controls@fb1:~ 0$ TZ=utc date +'%j day, %T'
162 day, 18:57:35
The absolute year is not encoded, though, so the symmetricon driver has the year offset hard coded into the driver (yuck), to which it adds the time of year from the IRIG-B signal to get the correct GPS time.
However, loading the symmetricom module shows the following:
[ 1601.607403] Spectracom GPS card on bus 1; device 0
[ 1601.607408] TSYNC PIC BASE 0 address = fb500000
[ 1601.607429] Remapped 0xffffc90017012000
[ 1606.606164] TSYNC NOT receiving YEAR info, defaulting to by year patch
[ 1606.606168] date = 299 days 18:28:1161455320
[ 1606.606169] bcd time = 1161455320 sec 959 milliseconds 398 microseconds 959398630 nanosec
[ 1606.606171] Board sync = 1
[ 1606.616076] TSYNC NOT receiving YEAR info, defaulting to by year patch
[ 1606.616079] date = 299 days 18:28:1161455320
[ 1606.616080] bcd time = 1161455320 sec 969 milliseconds 331 microseconds 969331350 nanosec
[ 1606.616081] Board sync = 1
Apparently the symmetricom driver thinks it's the 299nth day of the year, which of course corresponds to some time in october, which jives with the GPS time the driver is spitting out.
Rolf then noticed that the timing module in the VME crate in the adjacent rack, which also receives an IRIG-B signal from the distribution box, was also showing day 299 on it's front panel display. We checked and confirmed that the symmetricom card and the VME timing module both agree on the wrong time of year, strongly suggesting that the GPS receiver is outputing bogus data on it's IRIG-B output, even though it's showing the correct time on it's front panel. We played around with setting in the GPS receiver to no avail. Finally we rebooted the GPS receiver, but it seemed to come up with the same bogus IRIG-B output (again both symmetricom driver and VME timing module agree on the wrong day).
So maybe our GPS receiver is busted? Not sure what to try now.