Safran SecureSync 2400 User Manual page 347

4.5 Quality Management
Displays log entries related to oscillator disciplining. Provides the calculated fre-
quency error periodically while synchronizing to a reference.
GPS Qualification Log
If SecureSync is connected to a GNSS antenna and is tracking satellites, this log
contains a running hourly count of the number of GNSS satellites tracked each
hour. This history data can be used to determine if a GNSS reception problem
exists and whether this is a continuous or intermittent reception issue.
GNSS reception may be displayed as cyclic in nature. A cyclic 12 hour pattern of
decreased GNSS reception typically indicates that the GNSS antenna has an
obstructed view of the horizon. The GNSS satellites are in a 12-hour orbit, so if
part of the sky is blocked by large obstructions, at the same time every day (at
approximately 12 hour intervals), the GNSS reception may be reduced or may van-
ish altogether. If this occurs, the antenna should be relocated to afford it an unob-
structed view of the sky.
Every hour (displayed in the log as UTC time), SecureSync counts the total num-
ber of satellites that were tracked during that hour. The GNSS qualification log
shows the number of satellites that were tracked followed by the number of
seconds that the particular number of satellites were tracked during the hour
(3600 seconds indicates a full hour). The number to the left of the "=" sign indic-
ates the number of satellites tracked and the number to the right of the "=" sign
indicates the number of seconds (out of a total of 3600 seconds in an hour) that
the unit was tracking that number of satellites. For example, "0=3600" indicates
the unit was tracking 0 satellites for the entire hour, while "0=2700 1=900" indic-
ates the unit was tracking one satellite for 900 seconds, but for the remaining por-
tion of the hour it was tracking zero satellites.
Every hourly entry in the log also contains a quality value, represented by "Q=
xxxx" (where x can be any number from 0000 through 3600). The Qualification
log records how many satellites were tracked over a given hour. If for every
second of the hour a tracked satellite was in view, the Quality value will equal
3600. For every second SecureSync tracked less than the minimum number of
satellites, the value will be less than 3600. The minimum requirement is one satel-
lite at all times after the unit has completed the GNSS survey and indicates "Sta-
tionary". A minimum of four satellites are required in order for the GNSS survey
to be initially completed.
If all entries in the qualification log are displayed as "0=3600", a constant GNSS
reception problem exists, so the cause of the reception issue is continuous. If the
unit occasionally shows 0=3600 but at other times shows that 1 through 12 have
numbers of other than "0000", the reception is intermittent, so the cause of the
reception issue is intermittent. If the Quality value normally equals 3600 but
drops to lower than 3600 about every 12 hours, the issue is likely caused by the
GNSS antenna having an obstructed view of the sky.
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