Quote: Originally Posted by
v8 scimitar 
The stuff you are on about has a lot more than GPS in them, in fact they probably use GPS very little and use it more as a sales pitch than anything else. The main part is the accelerometer. If you know the weight, G pulled and the length of time along with engine RPM and a few other things you can work out just about anything. So far as I know GPS is GPS whether its domestic or military that's why smart weapons have a + or - 5 meter accuracy.
The unit I'm tailing about is not a accelerometer, it has just a GPS unit that size of a tool box. A accelerometer would need to be set up a level surface and would have sensors, this thing was just a box with an antenna.
I read about it when car and driver did a test on a bunch of accelerometer performance meters against their GPS based unit.
Quote:
Our sophisticated VBOX system doesn’t use accelerometers, precisely to avoid this problem. Instead, the VBOX relies on the global-positioning system (GPS) to measure a vehicle’s motion. To work, the VBOX must be in communication with at least four of 24 GPS satellites orbiting the earth. As a vehicle travels down the test venue, there’s a minuscule shift in the arrival time of the radio signals that travel between the satellites and the VBOX’s antenna. By measuring this shift, the VBOX calculates speed, acceleration, and distance. Racelogic, the company that makes the VBOX, asserts that its devices are accurate to within 0.06 mph.
They said it cost 30 grand..
http://www.caranddriver.com/features...ters-work.html
So it seems it compensates for the delay by using a mathematical algorithm of some sort. So, who do you need a 30 thousand dollar unit to do this? I would think software could do it just as well.