Oh indeed. And don't forget tyre wear. Which of course increases the over reading. But the fact is a pulse counting speedo could be 1% accurate for no extra cost - not the 10% as specified from years ago.
Originally it was a device which had to be plugged into a computer to enable software to be used on it. Now used often for anything plugged into a computer/phone socket to do stuff - hence "GPS dongle" for a plug-in GPS receive, "broadband dongle" for a plug-in to use mobile telephone for internet, "Bluetooth dongle".....
How much allowance would you build in for changes in wear and tyre pressure? For example, with a tyre radius of 13 inches wear of 4mm changes the circumference by 1.2 per cent. Pressure variations worth the same again at least?
That might make a difference.
It's not often I lose my temper when driving but when I do lose it I really do lose it.
The other driver really has to push me hard and start being aggressive to make me go for it. I do make a point of never making hand gestures, blowing horns and flashing lights etc just because someone has made a mistake. It could be an new driver or an old granny that has messed up. It could be someone not familiar with a road junction that they have never used before.
The other driver needs to be the first one to be aggressive and then I respond.
Legally a speedo can be inaccurate by up to 10% but are not allowed to under read. Hence they have to err on the side of over reading.
My ancient TomTom will run for about 5 hours on a full charge, so its not a across the board problem.
In terms of why so much power, well its basically running the equal of what would have been a pretty decent multitasking desktop PC not too many years ago. Colour screens also sap a bit of power, and price pressure forces the component cost of the devices down - so hence batteries are a place you can economise.
or Doppler radar based readings from the road etc.
Yes - mine does indeed lag behind the car speedo very noticeably . But it also reads significantly lower. When trying to keep a steady speed as accurately as possible, the difference is towards, but slightly under, 10%.
I think I must have been spoiled in the past because my Saabs always seemed quite accurate.
Not with the potholes we have!
So how does it manage to work out that you are stationary then?
and load in the car will alter the rolling radius even more...
and the GO 700 has a power hungry spinning 2.5GB HDD in it as well rather than just flash. (its also got space for decent sized batteries, and cost enough to make fitting them cost effective).
No, but I would not nudge anybody up the arse for doing that.
the legal requirement is +10%/-0% Its hard to make them 100% as tyre pressures and stuff like that makes them vary. You can't rely on GPS either.
My GPS logger lasts 20+ hrs, it doesn't need to do route calculations and has a 3.7V 1400mAhr battery.
I expect its the route calculation and the bigger display that takes the power.
summat that plugs into a computer.
bumper usually gets them to move"
No aggression there that I can see.
Hell Adam!
No allowances needed. A speedo by law mustn't read slow, but can read fast. Wear on the tyres or underinflation will make it read fast. The only change which would make it read fast would be larger diameter tyres.
They are the same idiots that think they are speeding and jump on their brakes at the cameras and wonder why I sail past them in the other lane.
They don't have to err at all. Or certainly not by as much as many do.
Utter bullshit again "harry". Your disguise keeps slipping, doesn't it, Drivel?
GPS used for vehicle satnav does not, and to the best of my knowledge never has, calculate speed by interpolation between points. Speed is calculated as the Pseudo Range Rate which is done by determining the lag between the local clock and the incoming satellite clock pulses. After correction for relativistic effects it is possible to determine the velocity of the moving receiver usually to within 0.1Kt. There are inaccuracies possible from effects such as moving in a curve and the fact that the GPS WGS84 spheroid is not the same as the terrain surface, but these are relatively small compared to the inaccuracies of a speedometer or a doppler speed measurement system such as a radar gun or speed camera.
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