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DOC 6501_Release V
ATS-6501 Users Guide
194
7.
Once the system time is correct and the fraction second is w/in 100 ns monitor the clock
offset as reported by the measurement device (TIC/6502) and try to get an idea on the rate
on
the
internal
clock.
You
can
use
the
adjust_pps
command
and
steer_frequency/steer_phase commands to remove the offset as well as the rate to provide a
more stable local clock.
Note:
It is possible the ATS-6511s may report the fiber from the ATS-6501 being recovered as
“dark” after the adjust_pps commands are executed. It is recommended you perform a
restart --
cold
on the ATS-6511 driving the ATS-6502 to clear this condition. Once this unit restarts and
turns the outputs on, use the
recal
command on the ATS-6502 to recalibrate the system to ensure
the reported measurements are accurate.
8.
Use the restart --cold on the remaining downstream ATS-6511s to fully recover the time to
all of the outlying reference clocks. It is possible you may need to issue the jam_sync
command as well.
9.
Once the GNSS signal is restored, use the steer_source command to switch back to GPS.
steer_source gps
To recover time quickly use the jam_sync command after the ATS-6501
starts reporting kas2 phase/ptd measurements. You can also jam_sync all of the
downstream ATS-6511s. Keep in mind you may need to
recal
the ATS-6502 depending on
how far the system clocks moved during this step.
10.
Leap Second Information
a.
It is possible to set the system time beyond the current leap second information stored
on the system. To ensure the leap second data is correct users may need to
verify/adjust the data stored on the system to ensure proper operation, especially when
the GNSS reference is restored.
b.
Log into the system (port 23, username/password = tsc) and use the
more
/mod/tsc/leap-seconds.list
command to review the current file.
ATS-6501> more /mod/tsc/leap-seconds.list
# Automatically generated leap second info file. For complete
# comments and information on this file, look at
# ftp://time.nist.gov/pub/leap-seconds.list
#
# Expiration date of this file: Mon Jun 30 23:59:59 2014
#@ 3613161599
#
# Update date of this file: Tue Dec 17 00:00:14 2013
#$ 3596227214
#
2272060800 10 #Sat Jan 1 00:00:00 1972
2287785600 11 #Sat Jul 1 00:00:00 1972
2303683200 12 #Mon Jan 1 00:00:00 1973
2335219200 13 #Tue Jan 1 00:00:00 1974
2366755200 14 #Wed Jan 1 00:00:00 1975
2398291200 15 #Thu Jan 1 00:00:00 1976
2429913600 16 #Sat Jan 1 00:00:00 1977
2461449600 17 #Sun Jan 1 00:00:00 1978
2492985600 18 #Mon Jan 1 00:00:00 1979
2524521600 19 #Tue Jan 1 00:00:00 1980
2571782400 20 #Wed Jul 1 00:00:00 1981
2603318400 21 #Thu Jul 1 00:00:00 1982
2634854400 22 #Fri Jul 1 00:00:00 1983
2698012800 23 #Mon Jul 1 00:00:00 1985
2776982400 24 #Fri Jan 1 00:00:00 1988