This is the one in the S6. Quite accurate but takes a long time to stabilise
Where does it get the info from? As long as one is moving (even at taxi speed), nothing beats the accuracy of gps-derived heading and ground speed info.
It gets its information form Earth’s magnetic field :-)
The iPhone’s compass is great, very precise … but I don’treally have a mission for it
It gets its information form Earth’s magnetic field
That’s not a really reliable source of info, is it? Does it offer any ISO certification, 9000 or 9001 or 9002 or what not?
The phones have the same fluxgate magnetometers as the glass cockpits have. The biggest challenge is ambient magnetic noise.
GPS derived direction is track but we’re interested in heading.
They are actually pretty precise. I have used it once in the plane, for fun, and it worked just as good as the airplane’s whiskey compass
GPS derived direction is track but we’re interested in heading.
Agree to that. But the difference is either in WCA*, which can be calculated if once there is a reliable source of wind data (and that will be needed anyway), or magvar, which can be determined even more easily from a table of magvar for given coordinates.
Come to think of it: are we really interested in heading? My own very primitive gps/moving map shows track as planned vs. track as flown – if they diverge too much I steer the other way – what need to make things more complicated?
*WCA = wind correction angle
WCA = wind correction angle
ah! And I always tried to figure out what WCA means!! ;-))
Jan_Olieslagers wrote:
Agree to that. But the difference is either in WCA*, which can be calculated if once there is a reliable source of wind data (and that will be needed anyway), or magvar, which can be determined even more easily from a table of magvar for given coordinates.
It’s the other way around actually, the wind is calculated based on the difference between heading and track and pitot speed versus ground speed. The mag var plays no role, everything we do is based on magnetic north (unless navigating near the poles where a different system is used for IFR).
A correct heading indication is a requirement for all IFR approved airplanes. All electronic systems use fluxgates, just like the mobile phones.
Does the phone use a fluxgate? A fluxgate is a saturable magnetic core, which uses the principle of the relative permeability of the material collapsing when the flux density is too high for it, and that needs a fair bit of power (at 400Hz in the aircraft version) to drive it. I would think they use Hall effect sensors.
