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airplane orientation in magnetic compass heading mode

PostPosted: 12 Jan 2019, 12:59
by marpdiaz
Hi Petr,

I think I may have found a problem in the plane setting at moving map screen.

While in compass heading mode:

The airplane orientation over map fails for a (true) heading range between magnetic north and true north.

Plane orientations within this range are never shown. The plane (true heading) shown in the map just jumps to (true north - |var|) or (true north) for heading values in between.

The heading displayed in compass rose is always correct.

- moto-g 6 android 8.0.0.
- magnetometer values ok. compass calibrated and working fine in other apps.
- compass heading and accelerometer are enabled in FiF.
- occurs for map orientations (north up), (track up) and (course up).
- all screen magnifications are affected.
- occurs with or without background map selection.
- min GS for GPS track is set to 10kt.
- tested staticaly by turning the device.
- mag compass readings averaged by 100. (problem occurs independently of sensor average settings)
- current var here is -21 deg

let me know if you need any additional info.

cheers and happy flights in 2019!


Re: airplane orientation in magnetic compass heading mode

PostPosted: 23 Jan 2019, 20:13
by kitercuda
Hi Marcos,
Map North is always true. I do not know why at this moment. You need map in mag unit?

Re: airplane orientation in magnetic compass heading mode

PostPosted: 24 Jan 2019, 22:13
by marpdiaz
Hi Petr,

The map orientation options are fine (true north, track and course). I dont need another option.

The failure is in the rotation angle of the aircraft as displayed when the device is still or slow moving during taxi (no GPS track).

The following procedure would show the bug more evidently:

i. force VAR to -21.5 (this is the value here - other large value may show the bug as well). This is possibly hardwired in the code, so you may have to assign a fixed test value to VAR by hand.

ii. with the compass and accelerometers enabled, turn the device slowly (in a flat position, simulating turns of our airplanes in taxiways) and watch the plane turning (and compass rose) as you turn the device.

iii. near north headings you will see a sudden jump of the plane orientation regarding the map - there are "forbidden" headings that are never displayed. The moving and values of the compass rose are OK. The angular jump seems equal to VAR.
It is a minor glitch. Only realize that when using georef ADCs for taxi.


Re: airplane orientation in magnetic compass heading mode

PostPosted: 10 Feb 2019, 18:53
by kitercuda
Thanks, I will have a look.

Re: airplane orientation in magnetic compass heading mode

PostPosted: 17 Feb 2019, 18:07
by kitercuda
I had a look and it should be OK. I tried to display log - we have mag var around 5. Mag var is calculated...

2019-02-17 18:57:54.557 8104-19668/gps.ils.vor.glasscockpit D/AAA: Mag heading = 265.89578
2019-02-17 18:57:54.557 8104-19668/gps.ils.vor.glasscockpit D/AAA: Map heading = 270.64215

A made 2 screenshots. One with FIF set to display true directions and second one to disply magnetic directions. Map is always true. It seams to be OK. Can you send me your screenshot?
At the map you can see WPT called West. it is exactly on radial 270 (true) from my place.

Re: airplane orientation in magnetic compass heading mode

PostPosted: 21 Feb 2019, 16:58
by marpdiaz
Hi Petr,

The problem may be difficult to see with a small VAR of 5 degrees. In addition, it is only visible for headings close to north.

I tried the last FiF version and the glitch is still there.

I just sent you an e-mail with a link to a video of the test above. The video shows the jumps in heading as I slowly turn the device.

The problem only appears when the depicted plane heading (when provided by the device compass) is near north.
You will notice that headings between north and (north + VAR) are never displayed and the plane orientation jumps to either edge of this range. The displayed compass rose values are always correct.

It is a minor issue. You can leave as it is, in case you are already busy with more important fixes and db updates.

many thanks,