Re: inaccurate speed cameras


"Brimstone" <brimstone520-ng01@xxxxxxxxxxx> wrote in message
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"OG" <owen@xxxxxxxxxxxxxxxxxxx> wrote in message
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"Brimstone" <brimstone520-ng01@xxxxxxxxxxx> wrote in message
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PC Paul wrote:
Brimstone wrote:
Rob wrote:
Eeyore wrote:
Brimstone wrote:

Dr Tann said: "The mobile cameras used are not 100% accurate.

"My system can track a GPS phone within half-a-meter of where it
is, whereas devices currently on the market can, at best, only
track a phone within five metres."

A spokesman for the Crown Prosecution Service (CPS) said: "The
officer who operated the camera has since retired.

"Without his verbal evidence, we could not prove the case to the
required standard."

So the copper had retired, convenient or merely convenient?
So they'd have believed a cop's word over GPS data ?
They would have believed the data from the police mobile camera if
the operator had given verbal evidence. The scientist's invention,
and the claimed accuracy of its data, is a red herring. The CPS
simply offered no evidence and dropped the case.

And if he hadn't had that data?



When you get the NIP, you know where and when the camera 'got' you.

Given an hour, I could produce GPS data (NMEA) to prove I was doing
whatever speed I liked along that road...

I've no doubt you could, but go back and re-read the article.

It's interesting that the article seems to suggest 4 significant figures
precision (quoted speed of 29.18 mph), Given that the accuracy of
location is claimed to be about 0.5 metres, it suggests that the time
over which the speed is measured needs to be somwhere around 40 seconds
(to give a distance baseline of about 500 metres). It would be easy for
the average speed to be in the 29 mph mark, whilst having peaked at
42mph.

There is an 'on the other hand' which I'll come back to tomorrow if
anyone is interested.
Please do.

It's just that 29.18 mph is very close to 13 metres/second which suggests
that the actual calculation was done using those units; hence the claimed
precision drops from very very high to something a couple of orders of
magnitude lower.

Doesn't prove anything either way (tho' if the precision is lower it
suggests that speeds could be measured over much shorter time intervals).

That's all


.

Relevant Pages

  • Re: inaccurate speed cameras
    ... "My system can track a GPS phone within half-a-meter of where it ... "Without his verbal evidence, we could not prove the case to the ... So they'd have believed a cop's word over GPS data? ...
    (uk.rec.driving)
  • Re: inaccurate speed cameras
    ... "My system can track a GPS phone within half-a-meter of where it ... "Without his verbal evidence, we could not prove the case to the ... So they'd have believed a cop's word over GPS data? ...
    (uk.rec.driving)
  • Re: inaccurate speed cameras
    ... "My system can track a GPS phone within half-a-meter of where it ... "Without his verbal evidence, we could not prove the case to the ... So they'd have believed a cop's word over GPS data? ...
    (uk.rec.driving)
  • Re: inaccurate speed cameras
    ... "My system can track a GPS phone within half-a-meter of where it ... "Without his verbal evidence, we could not prove the case to the ... So they'd have believed a cop's word over GPS data? ...
    (uk.rec.driving)
  • Re: inaccurate speed cameras
    ... "My system can track a GPS phone within half-a-meter of where it ... "Without his verbal evidence, we could not prove the case to the ... So they'd have believed a cop's word over GPS data? ...
    (uk.rec.driving)