iPhone 3GS Compass Flakiness: Blame The Hardware, Or The OS?

iPhone 3GS Compass Flakiness: Blame The Hardware, Or The OS? 1

Whenever Apple launches a new product, reports of problems with new and old features alike begin to stream in, and the two questions that we always ask are whether they’re widespread, and whether they’re due to user error, software issues, or hardware issues. For instance, iPhone OS 3.0 Wi-Fi problems were so widely reported by iPod touch-using readers that they didn’t seem isolated, and we’ve had the same issues ourselves—clearly not hardware problems because Wi-Fi worked perfectly on the same devices with the prior 1.0 and 2.0 versions of the OS.

iPhone 3GS Compass Flakiness: Blame The Hardware, Or The OS? 2

We’ve noticed that the iPhone 3GS compass is having some issues, too, though the scope and cause of those issues is difficult to quantify. The 3GS units we’ve tested have showed a fairly obvious unreliability in getting Maps or even their own Compass apps to agree on what the “right direction” is, and appear to have a very high degree of susceptibility to in-car magnetic fields. A week or two ago, we stopped by an Apple Store and put three 3GS units on a counter in the same direction, finding that their compasses all seemed to be pointing in somewhat different orientations that were off by single- or double-digit degrees. Repeated re-tests of something we noted in the iPhone 3GS review—Maps’ tendency to show north-south movement down a street as diagonal motion rather than northerly when the compass is activated—have continued to yield the same results in our test cars.


iPhone 3GS Compass Flakiness: Blame The Hardware, Or The OS? 3

Now there’s a game out, SurrounDEAD, that optionally uses the Compass for its movement control scheme. It places you in the center of a city filled with zombies and challenges you to turn around and shoot them before they grab you, which they can do from your front, left, right, or back; constant turning is necessary to stop them. With the default control scheme, you turn by tilting the iPhone, which works, but the compass requires you to actually spin around, and all too often doesn’t appear to be properly registering movements. It’s like what we saw when driving around in cars with Maps, only zombies are eating us alive because the compass is wonky.


iPhone 3GS Compass Flakiness: Blame The Hardware, Or The OS? 4

Our hope is that Apple will correct these issues with an OS 3.1 update, but the question of whether they’re truly software or hardware specific is going to remain a mystery until then. In the interim, such issues do raise a concern that prior “it just works” Apple products haven’t faced for any significant length of time: how many months should users expect to have to wait until a promised feature of the device or software they just purchased works properly? When an iPod touch’s Wi-Fi goes out in 3.0, but works in 2.2.1, should users be expected to downgrade? Has Apple tested the 3GS compass enough in its labs to know that it can correct whatever the issues currently are? We don’t have the answers, but as users, we’re as anxious as you are to find out.

  1. No offense but what is Apple going to do about the level of interference in real-world settings? A *real* compass has issues in a car. You don’t need a compass for GPS to know what direction you’re going…you just need to be moving. The 3GS compass doesn’t seem to work well where you’d expect…inside a car….train…right next to your computer….speakers….etc. When I use it outside of those environments it works great.

    While we all know Apple is good its going to be a long time before they can master magnetic field interference in a compass 😉

  2. The 3GS compass appears to have bigger issues in a car than any GPS compass we’ve tried. If you don’t think people would expect to use the compass in a car… you must really enjoy walking. And even then, or in a house nowhere near speakers, the compass is flaky.

  3. Jeremy, Ron, in my experience, the “compass” in most car GPS satnav units doesn’t use magnetic fields at all; it’s a calculation of which direction you’re moving based on your most recent position updates (I think Jason tried to point this out). That’s why the compass doesn’t point the right way if you turn on the satnav before you start moving the car (unless it cached which direction your car was facing when you parked it last, and even then, it sometimes points the wrong way when you first pull out of your parking space, before it’s had time to acquire enough satellites to get good position info on you).

    It would be interesting to compare the iPhone 3GS’s digital magnetic compass to other digital magnetic compasses, and other analog magnetic compasses, in the same position (both in your lap, or both on the same spot on the dash) in the same car.

  4. One more thing: Even before the 3GS, there were apps for the 3G with GPS reckoning-based “compass” features. The official Geocaching app had that feature, and last I checked, still hadn’t been updated to support the 3GS’s digital magnetic compass. It might be interesting to run one of those GPS-reckoning-based pseudo-compass apps on a 3G or 3GS and see if you find its results to be more like your car’s satnav results.

  5. I am on beta 3.1 right now, and no (in my car), the compass issues have not been addressed, and I don’t see this getting better until they mix using it with the GPS directional help, as far as complaining about in the house usage (GPS barely works in a building), I’ve had not many issues except when sitting it on a table with iron legs! which is most likely the cause…

    To me the compass only comes in handy when driving/walking, and as soon as tomtom comes out with their offering, that has a better GPS radio built in the h/w accessory, then the compass issues will matter only when walking… which i believe works good.

  6. @Jeremy – think about how many things are generating magentic fields in your house. Seriously. Why is it surprising that the compass is wonky in your house?

    Oh, and actually I do enjoy walking outdoors….and that is the environment a compass works best. Not surprisingly the 3GS compass works fine in that environment.

    When you have a GPS unit it doesn’t need a compass as already pointed out by spiff and myself. It can determine your direction based on the deltas in the coordinates. As spiff pointed out there are already iPhone apps that do this…such as Motion-X GPS which does it well.

    @Gex – used in the right environment – ie: outside like a normal compass, the iPhone compass does exactly that.

  7. I have the same issues with the compass. I think it’s just too sensitive to interference. I’ll recalibrate and find North. Then turn the iphone 180 degrees and north is suddenly a different. Isn’t a compass supposed to point north regardless of it’s orientation?

  8. Jason: It feels wonky and unreliable everywhere we’ve tested it. In the current implementation it’s ill-equipped to be used for map directions, game controls, and other sorts of features depending upon consistent performance – the sorts of things Apple suggested it could be used for. If Apple only enabled the compass when the Maps feature was offering Walking directions, maybe what you’re suggesting would make sense, but to have the magnetometer running and producing poor results in other patently obvious, real-world use scenarios is unacceptable for many other applications that people would expect to use it in.

  9. I tested my iPhone compass and find it pretty much matches up with an ordinary hand-held compass. Remember, all normal compasses only measure the magnetic north as a projection on the horizontal plane of the actual earth’s magnetic field vector, which in the US and EU dips about 60 – 75 degrees down from the horizontal; Japan about 30. The 3GS has a 3-axis Hall-effect (made by Asahi Kasei ) magnetometer that might use (?) the accelerometer to select the horizontal component, and thus might also cause problems when in a dynamic mode. As for these posted complaints, a car has all kinds of ferromagnetic things as do many tables, if you look carefully underneath. Non-local electric currents are not usually large enough to effect a compass. Also, the sensitivity seems to be +/- 1 or 2 degrees. A car compass is often near the windshield or, if a quality car, in a place in the roof without much steel (??).For obvious reasons, do not check compasses by placing them next to each other as suggested. It is fun to map the location of the mag sensor by placing the iPhone on a mag clean surface, pointing it mag north and holding a pin north and approximately down along the dip angle. Move it around to look for max rate of deviation per unit moved (horiz. gradient). The spot is in the upper right corner of the screen. If I sound like a magnetic geek, Google or Bing me using last name, ‘breiner’

  10. I think the compass and the gps suck.. In google maps and a gps app I have both showed I was pointing in the totaly opesite direction then I was and when I started walking it was showing me walking towds my house when I was walking away from it. If you use this to find your way you will get lost because it’s junk thanks apple for putting crap in a phone that don’t work. Are your computers like this too?

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