Center for Mapping

Kinematic Test

 

In order to test the GPS hardware in the production environment, kinematic data, collected on July 13, 2000 on the stretch of the state highway 315 were processed, and the results are presented here for the comparison with the static case.  During this test only Trimble 4000SSI and 4000SSE and Topcon Legacy were used, all connected to a single compact L1/L2 Trimble antenna with ground plane, using a 4-way splitter.

 

Table 1 presents the survey statistics in terms of number of kinematic segments processed, gaps duration, total number of fixes along the trajectories, and type of solution selected automatically by the GPSurvey processing engine, based on data quality and distance to the base station (ionosphere free combination is used for base-rover separation of 5 km and more). Figures 1 and 2 illustrate the satellite observability and continuous kinematic RMS for 4000SSI and Topcon/JPS Legacy receivers during the common/overlapping time window. Both receivers were in motion at that time, recovering from the loss of lock caused most probably by severe multipath and interference. The Trimble receiver picked up the signal at 16:53 after a 7-minute gap, and continued tracking the satellites until 17:36, while Legacy picked up a signal at 16:51:59 (after about 5-second gap) and continued tracking until 17:41.

 

Receiver type	Solution segments	Gaps between segments [min]	Total number of points	Solution type
Trimble 4000SSE	16:10 – 16:41 16:41 – 16:46 16:53 – 17:36 17:44 – 18:04	0 7 8	1812 322 2493 1195	Iono free fixed DD Iono free fixed DD Iono free fixed DD Iono free float DD
Total	99 min	15	5822
Trimble 4000SSI	16:10 – 16:37 16:37 – 16:41 16:41 – 16:46 16:53 – 17:36 17:44 – 18:04	0 0 7 8	1600 217 316 2533 1186	Iono free fixed DD Iono free float DD Iono free fixed DD Iono free fixed DD Iono free float DD
Total	99 min	15	5952
Topcon/JPS Legacy	16:10 – 16:41 16:41 – 16:46 16:47 – 16:52 16:52 – 17:41 17:44 – 18:04	0 1 0 3	1806 327 217 2834 1150	Iono free float DD Iono free float DD Iono free float DD Iono free float DD Iono free float DD
Total	110 min	4	6334

 

Table 1. Statistics of the kinematic test of July 13, 2000: antenna splitter and a single Trimble L1/L2 antenna with ground plane were used.

 

 

 

 

 

 

 

 

Figure 1. Satellite visibility for 4000SSI (left) and Legacy (right) during the time window 16:53 – 17:36 (4000SSI) and 16:52 – 17:41 (Legacy).

 

 

 

 

 

 

 

 

Figure 2. Continuous kinematic RMS for 4000SSI (left) and Legacy (right) during the time window 16:53 – 17:36 (4000SSI) and 16:52 – 17:41 (Legacy).

 

Even though Legacy seems to be able to restart and continue tracking somehow better as compared to 4000SSI/SEE, the level of measurement residuals provided by Legacy is higher, as can be observed in Figure 2. Also, due to the higher noise level, only a float solution is available from the Legacy data (Table 1). Moreover, residual plots based on Legacy data experience sometime distinct peaks, which might indicate data outliers. It should also be mentioned that the solution provided by Legacy during the time window of 16:47 – 16:52, when other receivers lost lock, displays position RMS reaching 22 – centimeter level, and some parts of the solution are obviously based on the Kalman filter prediction only, as observability chart shows some gaps in the signal, illustrated in Figure 3.

 

                                   

                                            Figure 3. Satellite visibility for Legacy during the time window 16:47 – 16:52.