> (b) indicate, when the vehicle is travelling at a speed in excess
> of 50 kilometres per hour, a speed that is not more than 10- less
> than the actual speed, and

JT> Thanks for that. At last, fact that isn't based on "so and so
JT> told whoever that joe blow said...."

 Did you actually read what it said? Firstly, Brenton misquoted, and
second, it says that the speedo is not allowed to be correct. I tried
to explain how it *actually* works in the real world in a message to
Brenton...

 Can you measure *road* speed using GPS? On a straight road, does the
software do a speed calculation?

 If it does, you have discovered the *only* way I know to do a simple
speedo calibration. Brenton's assertion that his speedo is "very
accurate" is crap. I checked mine with a calibrated rev counter using
gear ratios, but that doesn't allow for tyres and road surface. You
either have to use a cop's laser or some way to actually measure road
speed... not tailshaft speed. Timing a measured mile is usless.. I've
tried it.

JT> Yeah, they all use the standard frequency meter technique to
JT> measure speed. 

 Frequency meters measure *both* period and frequency. It's insane to
measure frequency rather than time at that speed, especially when you
only need three digits. I despair of enginerring in Australia
today...

 When we developed our own computer-controlled train, I was really
impressed. I wondered where they got the engineers. Ten years ago, we
were doing consumer-controls on washing machines and shit like that,
and we could never get engineers or programmers who knew their arse
from their elbow in the real world. How did they get engineers for a
*really* complex problem like a train? 

 Now I know. The fuckers don't work...

 Things have not got better in the last ten years...

Regards,
Bob

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