Jackson Labs Micro-JLT GNSS, Руководство пользователя

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Micro-JLT GNSS™ User Manual
40 © 2019 Jackson Labs Technologies, Inc.
SYNChronization:HEAlth?
SYNChronization?
3.6.1 SYNChronization:HOLDover:DURation?
The SYNChronization:HOLDover:DURation? 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 duration of the present or most recent period of operation in the holdover and
holdover processes. This is the length of time the reference oscillator was not locked to GNSS
receiver 1PPS, and thus “coasting”. The time units are seconds.
The first number in the response is the holdover duration. The duration units are seconds, and the
resolution is 1 second. If the Receiver is in holdover, the response quantifies the current holdover
duration. If the Receiver is not in holdover, the response quantifies the previous holdover.
The second number in the response identifies the holdover state. A value of 0 indicates the Receiver
is not in holdover; a value of 1 indicates the Receiver is in holdover.
3.6.2 SYNChronization:HOLDover:INITiate
The SYNChronization:HOLDover:INITiate command is unrelated to the Micro-JLT GNSS™
time-stamping subsystem. For more information on time-stamping, please refer to Section
3.5.11 .
The SYNC:HOLD:INIT and SYNC:HOLD:REC:INIT commands allow the user to manually enter
and exit the holdover state, even while GNSS signals are still being properly received. This
forced-holdover allows the unit to effectively disable GNSS locking, while still keeping track of the
state of the 1PPS output in relation to the UTC 1PPS signal as generated by the GNSS receiver.
When the unit is placed into forced-holdover with this command, the unit will indicate the time
interval difference between the 1PPS output and the GNSS receiver 1PPS by using the SYNC:TINT?
command. This allows the user to see the OCXO drift when not locked to GNSS signals for testing
purposes, or to prevent the GNSS receiver from being spoofed and affecting the OCXO frequency
accuracy. The measurement range is limited to +/-2,000ns phase offset. All other
frequency-disciplining functions of the unit will behave as if the GNSS antenna is disconnected from
the unit while in this forced-holdover state.
3.6.3 SYNChronization:HOLDover:RECovery:INITiate
The SYNChronization:HOLDover:RECovery:INITiate 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 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 <GPS|EXTernal|AUTO>
The SYNChronization:SOURce:MODE command is unrelated to the Micro-JLT GNSS™
time-stamping subsystem. To select a source for time-stamping, please refer to the
PTIMe:STAMp:SOURce command in Section
3.5.13 .