Become a MacRumors Supporter for $50/year with no ads, ability to filter front page stories, and private forums.

dagomike

macrumors 65816
Original poster
Jun 22, 2007
1,451
1
Is there a list of things that mess with the compass? If I point my iPhone at the Apple logo in my iMac, it flips out. Something in my car dashboard makes it nuts too.
 
Well, if it operates using magnets, then it stands to reason that anything that produces a magnetic field would affect it...
 
I'll tell you, I wasn't impressed driving today while tracking on the map. That thing must be picking up a ton of interference in the car or something. The map was just randomly spinning all over the place while never locking into my direction. I was on I-290/I-355 headed south. Maybe from other cars and trucks? Nice to see where all the traffic hot spots were at least, but man, the compass part really made the map unusable!

Tests in my office here or taking a long walk yielded perfect compass results though.
 
Take a REAL compass and check around. See if it's actually your iPhone or if it is just a magnetic field.
 
Take a REAL compass and check around. See if it's actually your iPhone or if it is just a magnetic field.

I'll try to test it again tomorrow and see. I'm just concerned how a TomTom app in the future would work (or maybe it doesn't care about the compass).
 
I'll tell you, I wasn't impressed driving today while tracking on the map. That thing must be picking up a ton of interference in the car or something. The map was just randomly spinning all over the place while never locking into my direction. I was on I-290/I-355 headed south. Maybe from other cars and trucks? Nice to see where all the traffic hot spots were at least, but man, the compass part really made the map unusable!

Tests in my office here or taking a long walk yielded perfect compass results though.

Magnetic interference decreases with the square of the distance. Unless the sensor is lab grade equipment, the interference is coming from something close by.
 
Magnetic interference decreases with the square of the distance. Unless the sensor is lab grade equipment, the interference is coming from something close by.

Like car stereo speakers perhaps?
 
Like car stereo speakers perhaps?

That's a really good guess. I can't think of any other car parts that contain powerful magnets.

But, the speakers are usually hidden, on the bottom of doors and such. I find it unlikely that there would be a speaker located at the same place as someone would put their phone. And, if they're using the phone, they're probably holding it, so it would be far enough from the magnets not to affect it.:confused:
 
That's a really good guess. I can't think of any other car parts that contain powerful magnets.

But, the speakers are usually hidden, on the bottom of doors and such. I find it unlikely that there would be a speaker located at the same place as someone would put their phone. And, if they're using the phone, they're probably holding it, so it would be far enough from the magnets not to affect it.:confused:

The phone was probably a good 2 feet from the closest speaker, maybe 5 feet from the furthest?
 
Welcome to the ancient world of compasses :) Compasses need regular calibration to take interference in to account, and exhibit indication errors and lag due to turning and acceleration, etc. Even Apple's own knowledge base says

The digital compass should only be used for basic navigation assistance and should not be solely relied on to determine precise locations, proximity, distance, or direction.

I think it's more suitable for handheld use on the street. When in the car your GPS app will provide a more useful and consistent reading.
 
That was kind of the point, no?

Ah, the way I read it was "verify the iPhone's compass using a real one" ... but yeah if the real compass is also off then you know its magnetic interference and not a software problem.
 
Welcome to the ancient world of compasses :) Compasses need regular calibration to take interference in to account, and exhibit indication errors and lag due to turning and acceleration, etc. Even Apple's own knowledge base says

The digital compass should only be used for basic navigation assistance and should not be solely relied on to determine precise locations, proximity, distance, or direction.

I think it's more suitable for handheld use on the street. When in the car your GPS app will provide a more useful and consistent reading.

Exactly, the compass is barely useful at all and I'm really surprised they bothered adding it. In ideal conditions it can be a cool toy. Ultimately however, the GPS alone is far better for navigation purposes.

The trick with orienting the map, when it actually works, is pretty cool though.

In my experience, I have interference almost everywhere I go. Everywhere there is any notable amount of metal, magnetized or otherwise. I'm at a metal desk, I'm near a metal filing cabinet, I'm in the car, I'm by my wifi base station, etc. etc.

Outside though? Works fine. And that's what counts.
 
You would have to think someone is pretty stupid to point out a compass will be drawn to a magnetic source. A little more helpful I would think would be a discussion of where the compass isn't useful and perhaps what could be done with that.

Holding it near anything electronic seems to mess with it. Particularly while driving it doesn't seem to work well. It doesn't seem to be the radio that's causing the problem, more the instrument cluster. Not sure how far away it needs to be, maybe a foot or two.
 
You would have to think someone is pretty stupid to point out a compass will be drawn to a magnetic source. A little more helpful I would think would be a discussion of where the compass isn't useful and perhaps what could be done with that...

Sorry :eek:. I don't have an iPhone 3GS so I can't do any field testing, but if the 3GS's compass actually has a small spinning metal piece, then it might be affected by the acceleration/deceleration of the car.

...Outside though? Works fine. And that's what counts.

So that's what it must be for. :D
 
Welcome to the ancient world of compasses :) Compasses need regular calibration to take interference in to account, and exhibit indication errors and lag due to turning and acceleration, etc. Even Apple's own knowledge base says

The digital compass should only be used for basic navigation assistance and should not be solely relied on to determine precise locations, proximity, distance, or direction.

I think it's more suitable for handheld use on the street. When in the car your GPS app will provide a more useful and consistent reading.

I can't agree more. Today for the first time I used it with GoogleMap and I kept getting errors with some dialog box. As I was driving I really couldn't read the dialog box, but the dialog box was blocking my view of the map. Very annoying. I won't make the mistake again of using GoogleMap with the Compass feature while driving. Probably really isn't needed when your moving as you can generally see where your "dot' is headed.

Oddly, I also kept getting the legal disclaimer coming up while this compass interference was happening. Geez! "While your reading this your likely to crash, but that is your fault not ours in any way shape or form. Just keep reading while your driving and die a horrible death" ;)

This will certainly make me use my TomTom One Third Edition and probably drive me to the TomTom iPhone software and hardware. I guess I really didn't expect it to work that well out of the box.
 
Register on MacRumors! This sidebar will go away, and you'll see fewer ads.