NavList:

I wonder if the problem is not simply that the technology that lies behind the electronic-magnetic compass is too new and immature.  It seems that the signals in a cellphone, at least, that relate to pitch, roll, and compass bearing are all electrically "noisy".

You may recall that computers first started appearing with USB ports back in 1997 or 98, but nothing worked quite right (and often not at all) when plugged into one of them at that time.  After a few years, USB finally lived up to its billing, and became reliable and ubiquitous.

We are in a similar place (at least as far a the shops of car dealerships are concerned) with wireless networking.  No dealership in Edmonton has yet been able to make wireless work reliably back in the mechanical area.  Too many big blocks of metal, moving here and there (and up and down), reflecting and blocking signals.

I expect that eventually WiFi devices will mature enough to reliably sort out usable signals in due time, even in challenging environments like a mechanical shop.  And I expect electronic compasses to undergo a maturational process of their own.

I have played with two bespoke handheld electronic compasses as well as with compass apps in three different cellphones...and the accuracy is off enough, frequently enough, that I am back to the old fashioned magnetic hand compass.  It is not sexy, but it works. 

I will probably revisit this area of technology in year 2020.

Bob