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Example 1: path surveyed using two TOPCON dual frequency LEGACY-E+ receivers (PG-A1 antennas) and one u-blox AEK-4T receiver (ANN-MS antenna) mounted on the rooftop of a car (picture) moving at a constant velocity of ~20 km/h. The two TOPCON dual frequency solutions were used as references for computing the accuracy of the goGPS solutions. goGPS was used to process both TOPCON receivers (L1 only) and the u-blox receiver in RTK mode. The AEK-4T internally computed solution was saved in order to compare it with the goGPS solution using the same hardware and the same GPS observations. The VRS used as a master was provided by JENOBA.

This is one of nine tests carried out with the same hardware configuration. Results were consistent and showed an accuracy ranging between 20 and 40 cm for goGPS+TOPCON and between 40 and 80 cm for goGPS+ublox.

Legend:
green – TOPCON dual frequency solutions
blue – goGPS single frequency solutions using TOPCON hardware
cyan – goGPS single frequency solution using u-blox hardware
red – u-blox internally computed solution

Each solution is on a different layer; layers can be enabled/disabled using the layer switcher (“+” symbol on the right). Please zoom-in to see the positioning in details. KML files can be downloaded (links below the map) and loaded in Google Earth in order to allow more zoom capability.

goGPS_ublox.kml
goGPS_TOPCON_L1_front.kml
goGPS_TOPCON_L1_back.kml
TOPCON_L1L2_front.kml
TOPCON_L1L2_back.kml
ublox_NMEA.kml
Master_station_VRS.kml

Example 2: in order to improve the positioning with goGPS it is possible to adapt the dynamic model of the Kalman filter to the state of the receiver (e.g. setting a static model when it is kept still and a constant velocity model when it is moving). One of the TOPCON datasets described in Example 1 has been processed again by manually setting the dynamic model consistently with the receiver motion. The resulting positioning was improved, obtaining an accuracy ranging between 10 and 20 cm (excluding the few epochs corresponding to when the car stopped – see figure below).

goGPS TOPCON L1 with adaptive dynamic modelgoGPS accuracy TOPCON L1 with adaptive dynamic model
goGPS_TOPCON_L1_back_dyn.kml
TOPCON_L1L2_back_dyn.kml

Example 3: half the perimeter of a tennis court was surveyed multiple times by using the u-blox AEK-4T receiver (ANN-MS antenna) with goGPS. Both goGPS solution and the AEK-4T internally computed solution were saved.

Blue: goGPS positioning (RTK using a Virtual Reference Station provided by JENOBA)

Pink: u-blox AEK-4T positioning (stand-alone)

goGPS_yamatogawa_01.kml

Example 4: a smaller perimeter was surveyed multiple times by using the u-blox AEK-4T receiver (ANN-MS antenna) with goGPS. Both goGPS solution and the AEK-4T internally computed solution were saved.

Blue: goGPS positioning (RTK using a Virtual Reference Station provided by JENOBA)

Pink: u-blox AEK-4T positioning (stand-alone)

goGPS_yamatogawa_02.kml