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XLi Time & Frequency System
XLi-man, Issue 8, 6/17/2008, Rev. H
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1
GPS Antenna (Ok, Open, or Short)
The GPS antenna is powered by 12 volts from the ANTENNA connector on the rear of the XLi. If this
circuit is complete (e.g., connected to an antenna) GPS Antenna status is “OK”. If the circuit is
incomplete (e.g., no antenna, a cable break, or a splitter) the GPS Antenna status is “Open”. If circuit
detects a short, the GPS Antenna status is “Short”.
GPS Time Reference (Primary, Secondary, or Standby)
Configure the GPS receiver as a Primary or Secondary time reference. This setting is used by F74 –
Clock Source Control to control switching between reference sources. Selecting Standby makes the
receiver unavailable as a reference source.
If one time reference is configured as Primary or Secondary, and another time reference is assigned the
same priority, the first time reference is reset to Standby. For example, with GPS receiver 1 configured
as Secondary, when an operator configures GPS receiver 2 (or an IRIG input on J2) as Secondary and
saves changes, GPS receiver 1 is reset to Standby.
The XLi front panel status display identifies the reference source and its priority (e.g. “
GPS PRI
”).
GPS Acquisition State
Please note that after starting the GPS receiver, F119 may report several acquisition states before
settling on the one that was selected using F53.
With the GPS C/A Receiver (87-8028-2), F119 reports the following GPS acquisition states after a reboot
when F53 is in
Time Mode
:
•
Start Site Survey
: The receiver is checking for changes in its saved static position (occurs after
boot).
•
Survey Position
: The receiver is establishing an initial position following a reset. If the receiver
had “current” satellites prior to being reset, it can establish the position in a matter of seconds;
otherwise establishing the position takes a few minutes.
•
Stop Site Survey
: The receiver is ending site survey.
•
Position Hold
: The receiver has determined its most accurate position, and is using this static
position to calculate its most accurate time solution.
•
Start TRAIM
: (for Time Receiver Autonomous Integrity Monitoring) The receiver is in Position
Hold and is monitoring the integrity of the time solution using redundant satellite measurements
in order to eliminate unreliable signal information.
•
Stop TRAIM
: The receiver is ending TRAIM monitoring.
•
Dynamic Mode
: The user has determined that the position of the system could change and has
set F53 GPS operation mode to Dynamic Mode (see
“F53 – GPS Operation Mode”, page 80
).
The system is resolving its position so that it can compensate for position changes.
With the GPS C/A Receiver (87-8028-2), F119 does not report GPS acquisition states.
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