Re: Speed accuracy at high update rates


Now there are available cheap 4 Hz update GPS models based on u-blox
Antaris4 chip and a 5 Hz model by Garmin (18 5Hz). On top of that VBOX
has rather expensive GPS models with 5, 10, 20 and 100 Hz update rate:http://www.racelogic.co.uk/_downloads/vbox/Datasheets/Overview/VBOX_P...

What is the real different between all these? Do they all use same
method (doppler) for speed calculation? Do they all have the same
accuracy for each update? Or does the higher update rate result in a
worse speed accuracy? What kind of speed noise of individual update to
expect with all these?


Speed is derived from integrated carrier phase. At 5 Hz update rate,
the GPS receiver will only have 200ms to do the integration, which
will be more noisy than doing 1Hz having 1000ms for integration. At
higher update rate, accuracy of the position is less affected, but the
speed is. Of course there is also the possibility of integrating
carrier phase for 1000ms for each 200ms update, overlapping previous
measurement 800ms, but this would defeat the original idea of more
accurate instantaneous speed when doing 5Hz update...

Chipset manufacturers do not reveal details of how results are
generate at higher update rates, thus it should not be taken for
granted that that higher update rate always mean more accuracy for all
data...

Mike

.

Quantcast