Depending on the type of rover unit used, position accuracies of up to 2 cm can be achieved. VBOX accuracy (RMS): Horizontal: 5 mm + 0.5 ppm x baseline; Vertical: 10 mm - 0.8 ppm x baseline
Power can be obtained either from the internal battery or from an external source via a front panel. The battery life is up to 18 hrs, depending on radios in use.
By utilising corrections from a fixed base station, the GPS engine can fix the position of the antenna very accurately. The technique involves the measurement of the carrier phase of the satellite signal, which is then subject to some sophisticated statistical methods to align the phase of these signals to eliminate the majority of normal GPS type errors.
This alignment process goes through three phases: acquisition, ambiguity ‘Float’ mode and ambiguity ‘Fixed’ mode. Accuracies in Float mode are in the region of 0.75-0.2 m and 0.01-0.02 m in fixed mode. The correction signal is normally sent out at intervals of 1 second, but can be increased if needed in order to reduce the required data rate.
The VBOX RTK Base Station can be used to improve the positional accuracy of VBOX GPS systems, by calculating and then transmitting differential correction data via radio to allow the roving GPS system to correct its position. Because a single base station can be used simultaneously by all the receivers in range, fixed based stations are ideal for proving grounds or test tracks, where you are testing in a confined area of up to 10 kilometres radius.