Jackson Labs Micro-JLT GNSS, Руководство пользователя

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Micro-JLT GNSS™ User Manual
42 © 2019 Jackson Labs Technologies, Inc.
3.6.7 SYNChronization:HOLDover:STATE?
The SYNChronization:HOLDover:STATE? command is unrelated to the Micro-JLT GNSS™
time-stamping subsystem. For more information on time-stamping, please refer to Section
3.5.11 .
This query returns the current holdover state with possible responses being NONE, MANUAL, or
ON. NONE indicates the holdover state is off. MANUAL indicates the holdover is manually enabled
with the SYNChronization:HOLDover:INITiate command. ON indicates that holdover is enabled
due to lack of external PPS signal or valid GNSS fix from internal receiver.
3.6.8 SYNChronization:TINTerval?
The SYNChronization:TINTerval? command is unrelated to the Micro-JLT GNSS™ time-stamping
subsystem. For more information on time-stamping, please refer to Section
3.5.11 .
This query returns the difference or timing shift between the Micro-JLT GNSS™ 1PPS output and
the GNSS 1PPS signals. The resolution is 1E-10 seconds.
3.6.9 SYNChronization:TINTerval:THReshold <int> [50,2000]
The SYNChronization:TINTerval:THReshold command is unrelated to the Micro-JLT GNSS™
time-stamping subsystem. For more information on time-stamping, please refer to Section
3.5.11 .
This command selects the oscillator driven 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 driven
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 driven 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. Setting the threshold to larger values (i.e. 1000ns or higher) will prevent
nuisance jam-sync events to happen to the 1PPS output phase, at the expense of potentially larger
phase errors to accumulate on the 1PPS output before the loop algorithms can pull the phase error
toward 0ns.
The following command queries the state of SYNChronization:TINTerval:THReshold:
SYNChronization:TINTerval:THReshold?
3.6.10 SYNChronization:IMMEdiate
The SYNChronization:IMMEdiate command is unrelated to the Micro-JLT GNSS™ time-stamping
subsystem. For more information on time-stamping, please refer to Section
3.5.11 .
This command initiates a near-instantaneous alignment of the GNSS 1PPS and Receiver output 1
PPS. To be effective, this command has to be issued while not in holdover.