I don't think the idea is to trust the GPS 100% of the time.
Let's take Swiss (ultra long) tunnels as a counter example where you wouldn't
have any reading anyway, and yet lots of VERY expensive speed-cameras ...
what I mean by expensive is that the price to pay for a print is outstanding.
The idea is to 'calibrate' your car-speedo using the GPs once and for all,
at the standard speeds while driving at constant speed for a while on open
roads.
Let's say 30, 50, 90, 110 and 130 km/h which are the standard speed limits in
my own country.
In Switzerland I calibrate at 80 - 100 - 120.
And so on and so forth.
Once you know what the variations are at these points-or-bucks-hungry
thresholds,
the rest is just a question of memory and visualisation of the needle ;-)
And then, if your car has one, I recommend using the electronics to prevent
speeding,
most cars have one such system nowadays, even if it is just a bell ringing at
the set speed,
Or even better setting the speed regulator on.
I find the latter much safer than anything else I know by the way as you can
really concentrate on the road,
and land not as tense as without.
Fern, nicht so schnell, gut!
Philippe whose last speeding ticket dates back 500,000 km ago or so.
========================================
Message du : 19/01/2013 14:26
De : "Chris Barker " <ftog@xxxxxxxxxxxxxx>
A : "Olympus Camera Discussion" <olympus@xxxxxxxxxxxxxxxxx>
Copie à :
Sujet : Re: [OM] [OT] Speeding tolerances
I suspect, Wayne, that the GPS units would be accurate for most of the time,
but would have excursions to ridiculous readings, presumably if the unit lost
lock on sufficient satellites and the position was wrong for a period of time
before being updated. The sudden change of position would be interpreted as
movement for a short time before the unit's logic worked it through the system.
That's how most of the navigations systems have worked in the aircraft that
I've flown. They were all great, as long as you knew where you were and where
you were going :-) -- so that you could monitor them. I never trust systems
completely. It's for similar reasons that I refuse to trust man-made
organisms, such as GMO . . .
Chris
On 19 Jan 2013, at 12:36, Wayne Harridge wrote:
> My previous employer had GPS units in trucks reporting back to a central
> server. In some instances the GPS units reported obviously inaccurate
> speeds (fairly often in excess of 150kph, one I noted @275kph !). The GPS
> units generally appeared to behave ok and these spurious speeds would only
> be registered for a few samples over a day. The problem was that you could
> never be really certain of the speed, if the unit registered 100kph over the
> legal limit you could say it was spurious, but what if it was 10kph over the
> limit, spurious or actually speeding ? I presume too that if the GPS units
> were registering spurious high speeds they probably were registering
> spurious low speeds also.
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