Mini-JLT GNSS™
User Manual
28
© 2017 Jackson Labs Technologies, Inc.
accuracy. All other frequency-disciplining functions of the unit will behave as if the GNSS antenna
was disconnected from the unit while in this forced-holdover state.
3.6.3 SYNChronization:HOLDover:RECovery:INITiate
This command will disable the forced holdover state (see the SYNC:HOLD:INIT command). The
unit will resume normal GPS locking operation after this command has been sent.
3.6.4 SYNChronization:SOURce:MODE
This command is not supported in the Mini-JLT™ board.
3.6.5 SYNChronization:SOURce:STATE?
This command is not supported in the Mini-JLT™ board.
3.6.6 SYNChronization:TINTerval?
This query returns the difference or timing shift between the Mini-JLT™ 1 PPS and the GPS 1 PPS
signals. The resolution is 1E-10 seconds.
3.6.7 SYNChronization:TINTerval:THReshold [50,2000]
This command selects the oscillator 1PPS phase-offset threshold as compared to the reference 1PPS
at which point the unit will initiate a counter-reset (jam-sync) aligning the oscillator generated 1PPS
with the reference 1PPS phase. The oscillator phase is slowly and continuously adjusted toward 0ns
offset to the reference 1PPS while the phase difference is less than the THReshold phase limit. The
oscillator generated 1PPS phase is allowed to drift up to this threshold before a jam-sync is initiated.
The default setting is 220ns, allowing a drift of up to +/-220ns. Reaching this selected threshold will
cause a jam-sync phase-normalization to be initiated, which will also cause the SYNC:HEALTH?
Status to indicate 0x200, and the lock status to be unlocked as indicated by the Green LED turning
off for several minutes.
3.6.8 SYNChronization:IMMEdiate
This command initiates a near-instantaneous alignment of the GPS 1 PPS and Receiver output 1 PPS.
To be effective, this command has to be issued while not in holdover.
3.6.9 SYNChronization:FEEstimate?
This query returns the Frequency Error Estimate, similar to the Allan Variance using a 1000s
measurement interval and comparing the internal 1PPS to GPS 1PPS offset.
Values less than 1E-012 are below the noise floor, and are not significant.
Содержание Mini-JLT GNSS
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