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From: Wes Groleau on 3 Apr 2010 00:43
On 04-02-2010 23:47, Ian Gregory wrote:
> There is a knowledgebase article about this:
> http://support.apple.com/kb/TS2767

"Some areas have more magnetic interference than others. For example,
your car's dashboard may have a high level of magnetic interference"

There were some other reviews complaining that it doesn't work in a car,
but (1) mine is unreliable with no magnets or magnetic material
near it; (2) I have been in two Doge vans and one Cadillac that had
consistently accurate compasses in spite of the vehicle's composition.

--
Wes Groleau

Race Doesn't Matter
http://Ideas.Lang-Learn.us/WWW?itemid=876
From: Alex Stubbins on 3 Apr 2010 01:25
Wes Groleau wrote:
> On 04-02-2010 21:23, nospam wrote:
>> the compass is separate from the gps
>
> Why does it keep asking permission to use my current location?
>
> > and accelerometer. there are even
>
> What is your hypothesis for the advice to fix the "interference"
> by waving the iPhone in a figure eight pattern?
>
>> apps that use it as a metal detector.
>
> Works by magnetism? Why does it claim interference in a wood
> frame house with the nearest metal horizontally being nails in
> the walls ten feet away and vertically, nails in the sub-floor
> three feet below it?
>
> For the purpose of this post, I placed it on a cloth and wood
> stool in the center of a room five meters by seven meters.
> As I was typing, after almost a minute of not moving, it
> stopped alleging interference and the "north" marker pointed
> northwest--about 45 degrees off.
>
> I walked over and rotated the iPhone about 90 degrees counter-
> clockwise, without lifting it, and with minimal horizontal
> translation. The needle rotated with it, and remained pointing
> southwest. After sometime, however, it "woke up" and is now
> pointing northwest again.
>
> Tune in here later for the results of a different experiment.
>
> :-)
>

I do not understand. Why do people ask these things in the
comp.os.linux.advocacy newsgroup. Will you people please write these
things in the right category.

--
No matter what you believe, no government is what you think it is.
From: ZnU on 3 Apr 2010 16:54
In article <hp6h1l$d8p$1(a)news.eternal-september.org>,
Wes Groleau <Groleau+news(a)FreeShell.org> wrote:

> On 04-02-2010 23:47, Ian Gregory wrote:
> > There is a knowledgebase article about this:
> > http://support.apple.com/kb/TS2767
>
> "Some areas have more magnetic interference than others. For example,
> your car's dashboard may have a high level of magnetic interference"
>
> There were some other reviews complaining that it doesn't work in a
> car, but (1) mine is unreliable with no magnets or magnetic material
> near it;

That you happen to know of, knowing nothing about the local geology and
probably not that much about what's in the walls.

> (2) I have been in two Doge vans and one Cadillac that had
> consistently accurate compasses in spite of the vehicle's
> composition.

Which, being built into those vehicles, are presumably designed to avoid
that interference.

Do you really expect people to buy the notion that Apple is lying about
the compass being magnetic, and you've managed to demonstrate this with
some totally uncontrolled experiments? For what reason would Apple be
doing this?

--
"The game of professional investment is intolerably boring and over-exacting to
anyone who is entirely exempt from the gambling instinct; whilst he who has it
must pay to this propensity the appropriate toll." -- John Maynard Keynes
From: Wes Groleau on 3 Apr 2010 17:50
On 04-03-2010 16:54, ZnU wrote:
> Wes Groleau<Groleau+news(a)FreeShell.org> wrote:
>
>> On 04-02-2010 23:47, Ian Gregory wrote:
>>> There is a knowledgebase article about this:
>>> http://support.apple.com/kb/TS2767
>>
>> "Some areas have more magnetic interference than others. For example,
>> your car's dashboard may have a high level of magnetic interference"
>>
>> There were some other reviews complaining that it doesn't work in a
>> car, but (1) mine is unreliable with no magnets or magnetic material
>> near it;
>
> That you happen to know of, knowing nothing about the local geology and
> probably not that much about what's in the walls.

Having been present a good portion of the time the house was being
built, I am aware that the only magnetic materials in the walls are
nails and screws. Of course, electric wiring could conceivably also
affect it. But it is unreliable ten feet from any wall, unreliable
in my car, unreliable in the street twenty feet from anything metal,
etc. Apple advertised a compass, not a "compass that might work if
you aren't anywhere that most people go."

>> (2) I have been in two Doge vans and one Cadillac that had
>> consistently accurate compasses in spite of the vehicle's
>> composition.
>
> Which, being built into those vehicles, are presumably designed to avoid
> that interference.
>
> Do you really expect people to buy the notion that Apple is lying about
> the compass being magnetic, and you've managed to demonstrate this with
> some totally uncontrolled experiments? For what reason would Apple be
> doing this?

Did Apple actually say the compass is magnetic? I've read that it
uses a magnetometer, which is not quite the same thing. Be that
as it may, the reason it is unreliable is not important. What matters
(though it doesn't matter much) is that it IS unreliable.

I had surmised that it's failure was due to its needing GPS readings
with sufficient distance to compute. But that hypothesis is
inconsistent with the fact that it was unable to correct itself when I
drove two kilometers nor when I walked 30+ meters.

Again, I'm just guessing about _how_ it fails, but the failure itself
is plain to see.

--
Wes Groleau

You be the judge
http://Ideas.Lang-Learn.us/WWW?itemid=463
From: JF Mezei on 3 Apr 2010 19:46
Wes Groleau wrote:

> affect it. But it is unreliable ten feet from any wall, unreliable
> in my car, unreliable in the street twenty feet from anything metal,
> etc. Apple advertised a compass, not a "compass that might work if
> you aren't anywhere that most people go."

Welcome to the world of compass. They are made to point to a magnetic
field. Without nearby magnetic fields, it points to the "default" one at
the magnetic north pole (depending where you are, the difference between
true north and magnetic north can be substantial).

This isn't like a radio station where the radio can tune in to one
station and filter the rest. A compass looks at any/all magnetic fields.


> Did Apple actually say the compass is magnetic?

By definition, a compass is magnetic. It has to be to point to the
magnetic north pole. A GPS can *emulate* a compass when you are moving,
but not when standing still.

My GPS has a separate "compass" (electronic). There is a function/meny
to calibrate it, otherwise it is not accurate. Similarly, compasses in
ships and airplanes would be calibrated to compensate for local
interference.

> as it may, the reason it is unreliable is not important. What matters
> (though it doesn't matter much) is that it IS unreliable.

As are all compasses in urban areas. To judge the Apple compass'
reliability, you would need to have a real compass nextr to it and
compare results.

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