LC29D

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GNSS Board v1.0 Copyright © 5GHUB.US
5 Augmentation System
5.1 SBAS
The GNSS module supports SBAS (Satellite-Based Augmentation System) broadcast signal reception, and
GPS data are complemented by additional regional or wide area GPS enhancement data. The system
enhances the data through satellite broadcasting, and this information can be used in GNSS receivers to
improve the accuracy of the results. SBAS satellites can also be used as additional signals for ranging or
distance measurement, further improving availability. Supported SBAS systems: WAAS, EGNOS, MSAS
and GAGAN.
5.2 AGNSS
The module supports AGNSS feature that significantly reduces the module’s TTFF, especially under lower
signal conditions. To implement AGNSS feature, the module should get the assistance data including the
current time, rough position, and LTO data.
5.3 Real-Time Kinematic (RTK)
The GNSS module modules support RTK functionality as rovers. Before supporting the RTK navigation
technique, the module needs to receive the RTK correction messages via its UART port. RTK correction
messages can be delivered either using a cellular module or other terrestrial network technology. In
default configuration, the module will attempt to achieve the best positioning accuracy based on the
correction data that it receives. When the module receives an input stream of RTCM messages, it enters
RTK float mode. Once it fixes carrier phase ambiguities, the module enters the RTK fixed mode.
The module may be expected to achieve sub-meter level accuracy only when it is in RTK fixed mode. If
the module loses the carrier phase lock, at the minimum semaphore required to maintain the RTK fixed
mode, it returns to the RTK float mode. The module will also continue to try to resolve carrier phase
ambiguity and return to RTK fixed mode after restoring the minimum semaphore.
The current mode of operation is set by the associated NMEA messages.
5.4 Odometer (ODO)
The FWD hardware input is used to input vehicle forward/backward status signals. When it is at low
voltage level, the vehicle is moving forward, and when it is at high level, it is moving backward.
The WHEELTICK hardware input is used to input odometer signals from a vehicle. It can be sampled from
the wheel revolution sensors or the transmission of the vehicle.
Only cars need to be connected to the FWD signal, electric bicycles do not.
5.5 Geofencing
The GNSS module supports geofence areas, defined on the Earth's surface using a 2D model.
Geofencing is active when at least one geofence area is defined. The current status can be found by
polling the receiver. The receiver evaluates whether the current location of each region is within that
region or not and signals its status via GEOFENCE pin. Geofencing feature can be configured using
geofence messages. The evaluation is activated whenever one or more geofences are configured.