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110 XLi IEEE 1588 Clock
997-01510-03, Rev. C, 12/12/2006
SSSSSSSSSSSS SSSSSSSSSS SSSSSSS S SSS S SSSSS S
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F119 – GPS Receiver Configuration
Note: The standard XLi IEEE 1588 clock features the GPS C/A Receiver (87-8028-2). Other receiver types
are currently unavailable as options for the standard XLi IEEE 1588 clock.
Summary
Use function F119 to select a specific GPS receiver, display its status information, and configure it as a
reference source.
F119’s functions apply to all models of GPS receiver option cards available for the XLi. Where
differences exist, this manual refers to the card by its name and part number.
In F119, a GPS receivers are identified by number of the option bay where they are located. See
Figure 1 on page 7 for a diagram of the option bay numbers.
F119 provides the following GPS receiver information and status:
• Availability (indicates the option bay location)
•Part Number
• Software Version
• FPGA Number
• GPS Status (Locked or Unlocked)
• GPS Antenna (Ok or Open)
• GPS Acquisition State (Dynamic Mode, Stop Site Survey, Stop TRAIM, Start Site Survey, Start
TRAIM, Survey Position, Position Hold)
GPS Time Reference (Primary, Secondary, or Standby) Each of F119’s information, status, and
configuration items are explained below. Because F119 is an important function, this section explains the
behavior of F119 and related functions in some detail.
Part Number, Software Version, and FPGA Number
This information is useful for identifying the option card.
GPS Status (Locked or Unlocked)
During normal operation, “Locked” means the receiver has a Time Figure of Merit (TFOM) less than or
equal to 3, or less than 100 ns Estimated Time Error (ETE). Unlocked means the TFOM is greater than
3. For additional information on “good current” GPS satellites, see “
F60 – GPS Receiver Satellite List” on
page 60.
The GPS receiver serves as a time reference for the XLi system clock. To be a valid time reference, the
receiver requires the following information:
• Current UTC time
• The current position of the receiver