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Old 11-25-2005, 18:01   #1 (permalink)
Nomen Nescio
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Speedometer Accuracy to 1/2% Accuracy - Here's How

Low reading speedometers are costly in terms of police citations and create
safety problems as well.

Speedometers are inaccurate inherently and made worse as new tires are
installed and worn down due to the rolling radius variation.

A speedometer can be designed using the same principle as the optical
mouse. It reads the road and calculates V = D/T. Such a speedometer need
not be digital. A calibrated analog readout is feasible for 0.5% accuracy
at all speeds. It does not have to calibrate continuously if light or road
conditions are not within its capability. It simply uses memory and
reverts to the most recent self-calibration.

Some speedos are 5 or 6 mph off at road speeds. This should not be
tolerated in this day and age of high tech.

Such a speedo is quite elementary and involves absolutely no technology; I
have actually constructed a working model, breadboarded testbed. Although
it is the size of a shoebox and far from practical, it is entirely possible
to miniaturize it via a single dedicated I.C. I suggest this type
speedometer be standard equipment in the 2007 models and be made mandatory
by law.

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Old 11-25-2005, 18:01   #2 (permalink)
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Re: Speedometer Accuracy to 1/2% Accuracy - Here's How

Most speedometers, from the factory, read high. If it says you are doing
75, you are probably
doing less. Hence there is a bit of builtin safety. Cops in our state
normally wont ticket
you anyway until you exceed the limit by 5 mph.

Speedometers can often be calibrated by appropriate professionals. There
may be some
that cant be calibrated, but normally they can.

If you are worried about getting a ticket, run a calibration. Then dont
speed.

I sincerely doubt your optical mouse speedometer would maintain a high
accuracy over
varied types of road surfaces. There is no reason why it should.


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Old 11-25-2005, 20:01   #3 (permalink)
Whoever
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Re: Speedometer Accuracy to 1/2% Accuracy - Here's How



On Sat, 26 Nov 2005, HLS@nospam.nix wrote:

> Most speedometers, from the factory, read high. If it says you are doing
> 75, you are probably
> doing less.


I don't think this is true on modern vehicles. It ceratinly used to be
true in the past.

I have checked my speedo in couple of ways:
1. Reading the speed indicated by a GPS unit and comparing it to the
speedo.
2. Reading the speed on roadside radar speed signs.

It's quite possible that the latter (roadside speed indicators put in
place by local police) may read high, to encourage people to slow down,
but I rather doubt that the GPS unit would be inaccurate. However, both
tests show my speedo to be as accurate as I can read it (ie. within 1
mph).

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Old 11-25-2005, 21:01   #4 (permalink)
Spike
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Re: Speedometer Accuracy to 1/2% Accuracy - Here's How

On Sat, 26 Nov 2005 01:10:03 +0100 (CET), Nomen Nescio
<nobody@dizum.com> wrote:

>Low reading speedometers are costly in terms of police citations and create
>safety problems as well.
>
>Speedometers are inaccurate inherently and made worse as new tires are
>installed and worn down due to the rolling radius variation.
>
>A speedometer can be designed using the same principle as the optical
>mouse. It reads the road and calculates V = D/T. Such a speedometer need
>not be digital. A calibrated analog readout is feasible for 0.5% accuracy
>at all speeds. It does not have to calibrate continuously if light or road
>conditions are not within its capability. It simply uses memory and
>reverts to the most recent self-calibration.
>
>Some speedos are 5 or 6 mph off at road speeds. This should not be
>tolerated in this day and age of high tech.
>
>Such a speedo is quite elementary and involves absolutely no technology; I
>have actually constructed a working model, breadboarded testbed. Although
>it is the size of a shoebox and far from practical, it is entirely possible
>to miniaturize it via a single dedicated I.C. I suggest this type
>speedometer be standard equipment in the 2007 models and be made mandatory
>by law.

Speedometers might be off slightly on a stock vehicle. If you change
things like wheel size, then you have cause to be concerned.
Generally, police, depending on jurisdiction, concentrate more on how
people drive.

I think it's a waste of time and money to seek the kind of exactness
you want. There is too much to throw it off. Like tire pressure. And
wouldn't it require ever tire manufacturer to produce exactly the same
size tire so that the owner could not change the aspect ratio by
changing tires from what was OEM?

Many places I have been, you can be well above the limit, but as long
as you are flowing with the pack, it is ignored. The one who weaves in
and out trying to get ahead of the pack is the one asking for trouble.
Naturally, there are exceptions. And the 5mph rule can go either way;
either be a fudge factor, or be a citation.
--

Spike
1965 Ford Mustang Fastback 2+2, Vintage Burgundy
w/Black Std Interior, A Code 289 C4 Trac-Lok;
Vintage 40 16" rims w/225/50ZR16 KDWS BF Goodrich
gForce Radial T/As, Cobra drop; surround sound
audio-video...
See my ride at....
Feb 2004- http://207.36.208.198/albums/86810/003_May_21_3004.jpg
Feb 2004- http://207.36.208.198/albums/86810/005_May_21_2004.jpg
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Old 11-25-2005, 21:01   #5 (permalink)
Steve Mackie
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Re: Speedometer Accuracy to 1/2% Accuracy - Here's How

> I have checked my speedo in couple of ways:
> 1. Reading the speed indicated by a GPS unit and comparing it to the
> speedo.
> 2. Reading the speed on roadside radar speed signs.
>
> It's quite possible that the latter (roadside speed indicators put in
> place by local police) may read high, to encourage people to slow down,
> but I rather doubt that the GPS unit would be inaccurate. However, both
> tests show my speedo to be as accurate as I can read it (ie. within 1
> mph).


According to my GPS, my speedo is bang on. Also, as HLS mentioned, police in
Ontario usually don't touch you unless you are going 15km/h over except on
the 401 where you have to be going at least 40km/h faster than everyone else
before getting pulled over.

Here in NS, 10+km/h over will usually get you at least a warning, but I have
gotten away with more.

Steve


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Old 11-25-2005, 21:02   #6 (permalink)
Bob
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Re: Speedometer Accuracy to 1/2% Accuracy - Here's How


"Nomen Nescio" <nobody@dizum.com> wrote in message
news:9c05645453af8ca4bc26b6ac030d93c7@dizum.com...
> Low reading speedometers are costly in terms of police citations and
> create
> safety problems as well.
>
> Speedometers are inaccurate inherently and made worse as new tires are
> installed and worn down due to the rolling radius variation.
>
> A speedometer can be designed using the same principle as the optical
> mouse. It reads the road and calculates V = D/T. Such a speedometer need
> not be digital. A calibrated analog readout is feasible for 0.5% accuracy
> at all speeds. It does not have to calibrate continuously if light or
> road
> conditions are not within its capability. It simply uses memory and
> reverts to the most recent self-calibration.
>
> Some speedos are 5 or 6 mph off at road speeds. This should not be
> tolerated in this day and age of high tech.
>
> Such a speedo is quite elementary and involves absolutely no technology;
> I
> have actually constructed a working model, breadboarded testbed. Although
> it is the size of a shoebox and far from practical, it is entirely
> possible
> to miniaturize it via a single dedicated I.C. I suggest this type
> speedometer be standard equipment in the 2007 models and be made mandatory
> by law.
>


Yea, let's pass another useless law that costs us all money with no real
benefit. I've checked several vehicles against a GPS and found them all to
be pretty damn close. Close enough at least that if the owner gets a
speeding ticket it isn't the speedo's fault.
Bob


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Old 11-25-2005, 22:02   #7 (permalink)
nospam.clare.nce@sny.der.on.ca
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Re: Speedometer Accuracy to 1/2% Accuracy - Here's How

On Sat, 26 Nov 2005 01:10:03 +0100 (CET), Nomen Nescio
<nobody@dizum.com> wrote:

>Low reading speedometers are costly in terms of police citations and create
>safety problems as well.
>
>Speedometers are inaccurate inherently and made worse as new tires are
>installed and worn down due to the rolling radius variation.
>
>A speedometer can be designed using the same principle as the optical
>mouse. It reads the road and calculates V = D/T. Such a speedometer need
>not be digital. A calibrated analog readout is feasible for 0.5% accuracy
>at all speeds. It does not have to calibrate continuously if light or road
>conditions are not within its capability. It simply uses memory and
>reverts to the most recent self-calibration.
>
>Some speedos are 5 or 6 mph off at road speeds. This should not be
>tolerated in this day and age of high tech.
>
>Such a speedo is quite elementary and involves absolutely no technology; I
>have actually constructed a working model, breadboarded testbed. Although
>it is the size of a shoebox and far from practical, it is entirely possible
>to miniaturize it via a single dedicated I.C. I suggest this type
>speedometer be standard equipment in the 2007 models and be made mandatory
>by law.



Does Nomen Nescio by chance meen "Not a Clue"?????

Haven't seen ANYTHING of any substance from this poster in over a year
- just a lot of psuedo science babble nonsense.
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Old 11-26-2005, 03:01   #8 (permalink)
Ted Mittelstaedt
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Re: Speedometer Accuracy to 1/2% Accuracy - Here's How


"Nomen Nescio" <nobody@dizum.com> wrote in message
news:9c05645453af8ca4bc26b6ac030d93c7@dizum.com...
> Low reading speedometers are costly in terms of police citations and

create
> safety problems as well.
>


We heard this from you about a month ago. Here we go again. Yawn.

Ted


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Old 11-26-2005, 03:01   #9 (permalink)
joe schmoe
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Re: Speedometer Accuracy to 1/2% Accuracy - Here's How

On Sat, 26 Nov 2005 01:10:03 +0100 (CET), Nomen Nescio
<nobody@dizum.com> wrote:

><snip>
> I suggest this type
>speedometer be standard equipment in the 2007 models and be made mandatory
>by law.


Seeing as inexperience and inattentiveness are the source of virtually
all accidents I don't see how this would be of any value.

Interstate speed limits are in place to placate fanatical do-gooding
busy bodies.

If legislation is the solution to the worlds problems then:

Want to reduce accidents? Legislate in Electronic Stability control &
forward looking adaptive radar (like the newer MB's), built in GPS
networked into road sensors warning of standing traffic, poor road
conditions etc.

Want to save fuel? Mandate regenerative braking, aerodynamic bodies
and minimally rolling resistant tires in addition to battery packs
that are charged when a vehicle is parked.

There are two other ways of saving even more fuel. Solar Cars (a few
Universities have demonstrated these can be quite fast in the noon day
sunshine) and of course Walking / bicycling



One thing to keep in mind is that life is a sexually transmitted
disease that is fatal in 100% of all cases. In the grand scheme of
things 1 persons life is pretty insignificant to the global population
of 6 billion people. An accurate speedometer's significance in the
life of one person is as significant.

That's my way of saying..............
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Old 11-26-2005, 08:01   #10 (permalink)
Dori A Schmetterling
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Re: Speedometer Accuracy to 1/2% Accuracy - Here's How

Exactly. (Or they are correct.)

The OP is just polemical, based on an incorrect premise.

DAS
--
For direct contact replace nospam with schmetterling
---

<HLS@nospam.nix> wrote in message
news:fpOhf.18407$BZ5.637@newssvr13.news.prodigy.com...
> Most speedometers, from the factory, read high. If it says you are doing

[...]


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