Jackson Labs Mini-JLT GNSS, Руководство пользователя

Страница: 27 / 62

© 2017 Jackson Labs Technologies, Inc. 21
Mini-JLT GNSS™
User Manual
3.3.16 GPS:DYNAMic:STATe?
This query returns the actual state of the dynamic model, chosen by the firmware to be applied to the
GNSS receiver depending on vehicle velocity. It returns a value between 0 and 7, which correspond
to one of the dynamic models defined in the Table in section
3.3.15 .
This state can be different from the user-selected Dynamic model mode for two reasons:
•
if the dynamic mode is set to 8 (Automatic mode), the state will reflect the dynamic model being
applied to the GNSS receiver depending on actual vehicle dynamics
•
if the GPS Timing Mode is set to ON or to RSTSURV, the dynamic state will always be set to 1
(Stationary)
3.3.17 GPS:REFerence:ADELay <float> <s | ns >
[-32767ns,32767ns]
The ADELay command allows bi-directional shifting of the 1PPS output in relation to the UTC 1PPS
reference in one nanosecond steps. This allows antenna cable delay compensation, as well as
retarding or advancing the 1PPS pulse arbitrarily. Typical antenna delays for a 30 foot antenna cable
with 1.5ns per foot propagation delay would be compensated with the following command:
GPS:REF:ADEL 45ns
This command can be used to fine-tune different units to have co-incident 1PPS pulse outputs. Please
note that during normal operation the 1PPS pulse may wander around the UTC 1PPS pulse while the
unit is tracking the GNSS signals. The present offset between the 1PPS output and the UTC 1PPS
signal can be queried with the command SYNC:TINT? and this offset should be taken into account
when calibrating two unit’s 1PPS outputs to each other, since the lock algorithms will try to steer the
OCXO for a 0.0ns offset to the UTC 1PPS time-pulse.
3.3.18 GPS:REFerence:PULse:SAWtooth?
This command returns the momentary sawtooth correction factor that the GNSS receiver indicated.
3.3.19 GPS:RESET ONCE
Issues a reset to the internal GNSS receiver. This can be helpful when changing the antenna for
example, since the GNSS receiver measures the antenna system’s C/No right after reset, and adjusts
its internal antenna amplifier gains accordingly. It takes approximately 1 minute for locking to
commence after a GNSS receiver reset, as indicated by the red blinking LED.
3.3.20 GPS:TMODe <ON|OFF|RSTSURV>
This command selects the Timing Mode of the GNSS receiver.