compass calibration on iPhone

[Andrew Johnson]

Hey folks,

In the upcoming release (planned for tomorrow or Wednesday), we turned on a feature to sometimes show a compass calibration dialog. You might have also seen this dialog in other apps, such as the native Maps app.

• Here is the Apple support page about the subject: http://support.apple.com/kb/TS2767

• You can also read all about this on the net: http://www.google.com/search?q=calibrate+iPhone+compass

We would appreciate any feedback you have on: 

1) how the compass works for you, if you can compare it to other compasses

2) any discrepancy between our compass and the native compass app on the iPhone

3) if you see this calibration alert in the future

We think we have implemented the compass properly, and we may not be able to improve poor behavior further. However, we would like to know your experiences so we can give good support to people when they ask questions.

Regards,

Andrew

[Steve Kromer]

What Apple is doing seems strange.  If the have a GPS built in why do they also provide a flux gate compass?  I Don't expect anyone on this group to know the answer.  We did do enough 90 and 180 degree turns on Saturday for the compass to have calibrated. 

 

Steve

[Andrew Johnson]

The compass wasn't added to the spec until the 3GS came out. Neither the original iPhone or 3G had it, but the 3GS, iPhone 4, and iPads all do.

It's true that you can get direction from the GPS, but I think the benefit of having an actual compass is hat you can get a directional reading while stationary. This is useful for a person who wants to get out the iPhone and site a landmark, and for things like adding compass heading data to the EXIF tags of photos you take with the iPhone.

I had to look up flux gate compass... love Wikipedia: http://en.wikipedia.org/wiki/Fluxgate_compass

Andrew

[Rob gmail]

A GPS knows a course. A compass knows a heading. 

In other words a GPS knows which way you are moving - if you are moving.  A compass knows which way it is pointed relative to the earphs magnetic field - moving or not. The biggest error I see in inexperienced helms people is that they pay a lot more attention to heading than course.  This often happens in even a modest cross current or head wind. 

I see people steering for a marker without paying any attention to where they are actually being pushed.

[Rob gmail]

Whoops. head wind = cross wind - most typically.