© 2017 Jackson Labs Technologies, Inc. 19
Mini-JLT GNSS™ User Manual
The Mini-JLT GNSS™ GPSDO uses a GNSS receiver that is capable of running in a stationary mode
with Position Auto Survey called Position Hold Mode. This mode increases timing stability by
storing the position into memory, and solving the GNSS signal only for time as the position is not
expected to change. Two modes can be selected for Auto Survey operation (see section 3.3.20 for a
description of the GPS:TMODE command):
1) Manually setting Timing Mode to ON with a hard-coded position in NVRAM
2) Enabling Auto Survey to start automatically after power-on by setting Timing Mode to
RSTSURV
If either one of the above two GPS:TMODE Auto Survey/Position Hold modes is selected, the
GPS:DYNAMIC:MODE command is disabled internally and its setting is ignored as the unit does
not expect any motion on the antenna. In this case, the dynamic state as programmed into the GNSS
receiver is set to STATIONARY independent of the user selection for GPS:DYNAMIC:MODE.
The current dynamic state being applied to the GNSS receiver can be queried with the command
GPS:DYNAMIC:STATE?
Please note that this command syntax has changed from previous products such as the FireFly-IIA
GPSDO units which did not support Position Hold Auto Survey modes.
3.3.15 GPS:DYNAMic:MODE 8 (Automatic Dynamic Mode)
Automatic Dynamic Mode allows the Mini-JLT GNSS™ GPSDO firmware to automatically
configure the GNSS receiver Kalman filter parameters based on actual mission velocities and motion
profiles. The unit will try to set the GNSS receiver to the optimal setting for any given velocity. The
unit is able to set 7 different modes, as shown in section 3.3.14 .
1 Stationary Used in stationary applications
2 Pedestrian Used in man-pack, pedestrian settings
3 Automotive Vehicular velocity applications
4 Sea Used on Ships, where altitude is expected to be
constant
5 Airborne <1g Airborne applications with less than 1g acceleration
6 Airborne <2g Airborne applications with less than 2g acceleration
7 Airborne <4g Airborne applications with less than 4g acceleration
8 Automatic Mode Select one of the above states (0 – 7) based on the
actual velocity of the vehicle
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