SX BLUE GPS iSXblue II+ GNSSTM, User Manual

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SXblue Series User Manual 41
1.4.5.1 Generic Field Data Collection Software Configuration
The software that will be used for collecting GPS data should accept standard
NMEA messages . As mentioned in section 1.3.1, the SXblue receiver output by
default eight (8) NMEA sentences: GGA, GSA, GST, GSV, VTG, RMC, RRE and
ZDA all at 1Hz (once every second) on the Bluetooth and USB ports. Minimum
sentences are activated by default on the Serial port, as it is often used with radios
for Base/Rover RTK operations, this port can be set for specific use. Refer to
Technical Reference Manual for more details on NMEA messages.
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To communicate with the SXblue receiver via its Serial or USB port, a baud
rate of 19200 must be set in the communicating software. To set the baud
rate to higher values on these two ports, refer to Technical Reference
Manual for sending commands to the SXblue receiver.
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The coordinates output by the SXblue receiver follow the differential
correction source datum. You should make sure that your data collection
software is up-to-date, supports and applies the proper transforms to GPS
data it receives to match your existing map data.
- When not using differential correction, the output coordinates from the
SXblue receiver are in the current GPS WGS84 (G1674) datum (note
that there have been many evolutions of the WGS84 datum over the
years and the current revision differs greatly from the original one).
- When using SBAS, the coordinates will be in ITRF 2008 current epoch.
- When using the SXblue Platinum with an Atlas subscription, the datum
will be in ITRF 2008 (epoch 2010) worldwide.
- When using RTK corrections, the datum will depend on the reference
frame of the local RTK network, or if using a base/rover configuration,
the output coordinates will follow the same datum of the base station
coordinates.
Masks and filters are very useful features of field data collection software and
prevent recording of poor GPS data. HDOP or PDOP limits should be set to proper
values to suit the application (accuracy vs. productivity). A “3D only” mode is useful
for optimal accuracy but an “Allow 2D Mode” can be very convenient in some
forestry applications. If a “DGPS Only” or an “RTK Only” mode is available, we
strongly suggest that it be used. Also for RTK operations a mask on the RMS value
(found in the standard GST NMEA sentence) offers great benefits. For optimal
performance and results of field data collection, proper configuration of the field
software and some common GPS guidelines are essential when using the SXblue
series.