Six iPhones tested, and they can't agree on magnetic north

[bikehikeskifish]

If it is showing you true north, isn't it showing you a correction already? It knows where you are and applies the declination. Unless you are moving fast enough to compute truth north strictly from the gps.

Tim

 

[DougPaul]

My GPSr points to True north while my compass points to magnetic. I don't have an iPhone but could the ~15 degree discrepancy they are seeing be as simple as the iPhone is calibrated to true north?

This is a settable mode--you can have the magnetic compass read out true or magnetic headings.

Since the GPS knows where you are, it can apply the appropriate correction to convert magnetic between and true.

In theory, any GPS can do this--it simply depends on the software.

Doug

 

[Remix]

This is a settable mode--you can have the magnetic compass read out true or magnetic headings.

Since the GPS knows where you are, it can apply the appropriate correction to convert magnetic between and true.

In theory, any GPS can do this--it simply depends on the software.

Doug

Not always..I have not seen it on my Garmin Colorado or my Magellen Meridian. Moreover, there is no indication on the screen as to what reference is being used.

All the adjustments that I have seen refer to the compass heading computed by motion and the GPS, not necessarily the magnetic compass. Again, there is no indication of on the screen of compass computed by the GPS to indicate magentic or true north.

Its much easier to use a compass when use of a compass is needed....no calibration. a clear indication of correction, and the map and sighting aids.

 

[DougPaul]

This is a settable mode--you can have the magnetic compass read out true or magnetic headings.

Since the GPS knows where you are, it can apply the appropriate correction to convert magnetic between and true.

In theory, any GPS can do this--it simply depends on the software.

Doug

Not always..I have not seen it on my Garmin Colorado or my Magellen Meridian. Moreover, there is no indication on the screen as to what reference is being used.

It has certainly been settable on my GPSes (which include Garmin 60CSx and 62s).
On the 60CSx:
main menu > setup > heading > "North Reference"
Can be set to: True, Magnetic, Grid, User (set the magnetic variation manually)
I am not aware of anyplace except the above menu entry which displays the current mode.

I don't have access to the other models that you mention.

All the adjustments that I have seen refer to the compass heading computed by motion and the GPS, not necessarily the magnetic compass.

This is a separate issue.

Its much easier to use a compass when use of a compass is needed....no calibration. a clear indication of correction, and the map and sighting aids.

I generally follow bearings or make sightings using a mechanical compass (a Silva Ranger with built-in variation adjustment and sighting mirror) and do my navigation using true bearings. It doesn't really matter whether one uses true or magnetic as long as one is consistent.

Doug