Moving positional errors
Clearly a far more useful demonstration of positional accuracy is with the system actually moving around the test track, rather than the “artificial” stationary case. Positional errors under high dynamics are a far more complicated subject, and are affected by many different error sources. Further, accurate assessment of positional errors under high dynamic conditions is not trivial, and particular care has to be taken to align the data very accurately in time.
For this test a high accuracy RTK system was used as the positional reference. RTK systems have a typical accuracy of about 2cm; however, they are prone to losing lock under anything but excellent GPS reception conditions. The positional errors were calculated by simply comparing the positional information from the test systems with the output of the reference RTK system. The data was disregarded in places around the circuit where the RTK system lost lock. The graphs below plot the errors in the positional data from the 5Hz DL2, the 20Hz DL2, the 20Hz DL2 with DGPS option and the VBOX3 with option trackside RCTM/DGPS option.