Microchip Technology GPS-2700, Руководство пользователя

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GPS-2700 User’s Guide
DS50003016A-page 38
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2020 Microchip Technology Inc.
3.3.17 GPS:DYNAM:MODE <int> [0,7]
This command allows the user to select the dynamic motion model being applied to the
Kalman filters in the GNSS receiver. This allows for larger amounts of filtering for lower
velocity applications, effectively reducing noise and multipath interference. Applica-
tions with high acceleration can now be used with fast filter settings to allow for the most
accurate GPS coordinates to be provided in high-dynamic applications such as Jet air-
craft. Doppler tracking is enabled in all airborne modes, as Carrier Phase tracking is
very difficult to achieve in high velocity applications. The GNSS receiver will perform
Carrier Phase tracking for non-airborne modes.
The command has the following syntax:
GPS:DYNAM:MODE <int> [0,8]
Sending the following command to the GPS-2700 will select a stationary GNSS
dynamic model for example:
GPS:DYNAM:MODE 1
The following table lists all available modes:
TABLE 3-2: SUPPORTED DYNAMIC GNSS OPERATING MODES
Value Model Application
0 Portable Recommended as a default setting.
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.
The GPS-2700 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 sta-
bility 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 3.3.23 for a description of the GPS:TMODE command):
1. Manually setting Timing Mode to ON with a hard-coded position in NV memory.
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:DYNAM: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 indepen-
dent of the user selection for GPS:DYNAM:MODE.
The current dynamic state being applied to the GNSS receiver can be queried with the
command
GPS:DYNAM:STATE?
Please note that this command syntax has changed from previous products such as
the FireFly-IIA GNSSDO units that did not support Position Hold Auto Survey modes.