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C Commands Summary
MiLLennium GPSCard SW Version 4.503/4.52 Command Descriptions Manual Rev 2 85
CLOCKADJUST
All oscillators have some inherent drift. On the MiLLennium GPSCard, the clock and the PPS strobe have a 50 ns
jitter due to the receiver’s attempts to keep the clock as close as possible to GPS time. This option is disabled by
entering CLOCKADJUST DISABLE. The jitter will vanish, but the unsteered and free-running clock will drift
relative to GPS time. CLOCKADJUST must also be disabled if the user wishes to measure the drift rate of the
oscillator using the CLKA/B data logs.
NOTE 1: This feature is to be used by advanced users only.
NOTE 2: Please note that, when disabled, the range measurement bias errors will continue to accumulate with
clock drift.
NOTE 3: Pseudorange, carrier phase and Doppler measurements may jump if CLOCKADJUST DISABLE is
issued while the receiver is tracking.
NOTE 4: Do not disable CLOCKADJUST after 30 seconds from turning the power on, as unpredictable clock
drifts may result. When disabled, the range measurement bias errors will continue to accumulate with
clock drift.
NOTE 5: If you have difficulty issuing the CLOCKADJUST DISABLE command within the 30 second time
limit, you can enter it using a terminal emulator program and then issuing the SAVECONFIG command
to save this setting to the NVM of the receiver, where it will be automatically loaded each time the
GPSCard is powered on. Do not issue the SAVECONFIG command when using GPSolution.
Syntax:
Example:
clockadjust disable
CLOCKADJUST switch
Syntax Range Value Description Default
CLOCKADJUST - Command
switch enable or disable Allows or disallows adjustment to the internal clock enable