P155ed Off in a big way

[Spike56]

CFE canbus function extender?

[XC90Mk1]

You sped and they caught you. It’s pretty simple really.

[garethXC]

GPS speed is easy, use a garmin sat nav

I would (personally) not rely on the GPS speed - GPS speed calculations can be inaccurate as they have an element of result buffering or smoothing built into the data sent & returned from the sat connection and resulting calculation which can cause the speed displayed to be inaccurate or misleading....

Generally the speedo reading is more reliable - its obtained from the cars ABS/wheel sensors/throttle position sensor etc & not reliant on a satellite connection..

[green van man]

Originally Posted by garethXC

I would (personally) not rely on the GPS speed - GPS speed calculations can be inaccurate as they have an element of result buffering or smoothing built into the data sent & returned from the sat connection and resulting calculation which can cause the speed displayed to be inaccurate or misleading....

Generally the speedo reading is more reliable - its obtained from the cars ABS/wheel sensors/throttle position sensor etc & not reliant on a satellite connection..

May be more reliable but still inaccurate. The van has a calibrated tachograph, that agrees with the garmin that the speedo reads 4 mph fast.

Paul.

[DaveNP]

As I understand it-
GPS speeds have a theoretical inaccuracy as they only measure position on the horizontal plane, if one is going up or downhill it does not allow for the extra distance over the road that is covered (for instance this line /\/\/\/\/\/\/\ is longer than this one __________ ), smilarly it measures at distance intervals so does not allow for bends. I say these are theoretical inaccuracies as they are less than 0.5% even in extreme cases, in real life you can't read a speedo to that level of accuracy.
Tachographs as fitted to commercial vehicles whilst they are calibrated are still subject to error and may be subject to +/- 6km/h error (+/-3.75mph). Typically on the fleet where I work they are going between 1 and 3% slower than indicated, this is often attriibutable to the tyres being worn down, as the tacho works by counting how many times the wheels go round then multiplying by the circumference to establish the distance covered, if they've worn down that circumference has got smaller so it doesn't go as far for each turn so you actually go a bit slower, on a truck tyre which has 25mm of usable tread that's worth about 1.5% on the speedo.
Car speedometers are not calibrated but their design is required to show the speed or up to 10% higher so you don't actually go faster than the indicated speed.

Any way round if you get doe for speeding your speedo will have shown a higher speed than the one you get done for.

Back to Macxc60t5's original point, why is there a tolerance on speed but not drink?, apart from the info that drink limits are effectively given a tolerance as they won't proceed if there isn't a clear excess, firstly they would also need some clear excess of speed to keep out of arguments about accuracy of measurement, and secondly (in my opinion) if they prosecuted everyone who did just a little bit over the speed limit the police would spend all their time (plus some overtime) just doing speeding paperwork and the courts would collapse under the increased workload too.

Years ago it was socially acceptable to drink and drive, that has changed over the years, but a little bit of speeding is still seen as acceptable, it would seem to me that a change on that is a long way off.

[Bendolfc]

Did you actually get pulled and done, if so you were unlucky as most forces in England and Wales follow the NPCC guidelines and ordinarilly you wouldn't be done until 57.