Just saw a post on a car forum saying this.
Some GPS receivers record horizontal and vertical accuracy values in the logged data which I think are probably good enough to use in court as reasonable proof if accompanied by an appropriate statement from an "expert". However I've never seen a dashcam record these in the gps data and I have seen obvious substantial errors in the readings, so dashcam gps is useless as proof, it is only useful as a guide during the investigation and then you get the proof by analysing the video.How would you prove the GPS was accurate, anyway?
...
Having it digitally signed is not going to make any difference since there is no way to know that someone hasn't found a way around the digital signing!Unless GPS data is embedded in some digitally signed way that is impossible to forge...
Having it digitally signed is not going to make any difference since there is no way to know that someone hasn't found a way around the digital signing!
Maybe that is why the police don't use gps - there is no way to calibrate it, much better to use an analogue speedometer that is affected by tire pressure and temperature but which can be calibrated!Even the equipment used by police needs regular scheduled recalibration and documented evidence of that having happened to be admissible as evidence, no consumer device is going to stand up to scrutiny if accuracy is being questioned
Maybe that is why the police don't use gps - there is no way to calibrate it.
OK, I've thought of a way around it!By digital signing I mean a calculated value using encryption techniques that is based on both the visible data and a private key. The whole point of it is that it is trustworthy - for now. Once it is cracked it becomes useless.
So when you're sitting at a stop light it would show you traveling in reverse at 10MPH?... or would it show a speed of -10MPH?OK, I've thought of a way around it!
When you calibrate a GPS receiver, you do it using a GPS simulator which transmits a signal to simulate the satellites. You can put whatever information you want in that signal so I could produce a GPS signal that always gives a speed 10mph less than my actual speed and transmit that to the dashcam for it to be recorded and correctly digitally signed....
It would be show +10 mph at a 180 degree angle to original trajectory, unless I made it just a little more complexSo when you're sitting at a stop light it would show you traveling in reverse at 10MPH?... or would it show a speed of -10MPH?
unless I made it just a little more complex