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GPX Kompasswerte?

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Mitglied
Registriert seit: Jun 2011
Beiträge: 334
Ort: zwischen Donau, Isar und Vils
Hallo Forum,

im GPX File sind 4 Kompasswerte gespeichert. Im Wiki finde ich dazu:

<Compass>349,344,356,357</Compass> --> >Yaw Gyro stabilized Compass signal ; compass signal (raw) ; Compass setpoint (corrected with declination) ; Gyro Compass corrected (declination)


Kann mir das Jemand mal erläutern? Welcher Wert wird nun für die Richtung, in die der Kopter schaut, angenommen?
Kann das angegebene Beispiel überhaupt stimmen? immerhin sind compass(raw) und compass(corr with declination) um 12 Grad auseinander. Kann ja bei uns in D eigentlich nicht sein.

Gruß, Armin
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Registriert seit: Jun 2013
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Ort: Luxembourg
ArminW meinte
Kann mir das Jemand mal erläutern? Welcher Wert wird nun für die Richtung, in die der Kopter schaut, angenommen?

Nr. 4, the last one.

I thought you were the expert on this topic. ;)

ArminW meinte
Kann das angegebene Beispiel überhaupt stimmen? immerhin sind compass(raw) und compass(corr with declination) um 12 Grad auseinander. Kann ja bei uns in D eigentlich nicht sein.

I do not know which location the 12 degree example comes from. I have looked on some GPX logs (from Luxembourg) and the 1., 3. and 4. values are much closer together. 2. (raw compass) jumps more around:

<Compass>346,342,349.1,347.8</Compass>
<MagnetField>098</MagnetField>
<MagnetInclination>65,-1</MagnetInclination>

For Luxembourg magnetic DEClination should be ~1.7 degree, magnetic INClication is ~65 degree.

magnetic-declination.com/

Feel free to answer auf Deutsch.
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Registriert seit: Jun 2011
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Ort: zwischen Donau, Isar und Vils
Hi Foersom,

thank you for remembering me on my older post ;-)

Yes, the compass[4] value is the important one. I was a little confused about the 3rd compass value in my GPX files and about the strange example in the wiki. I understand now, that the 3rd value seems to be interesting only in case of waypoint flights. In this case, this value is the setpoint for the heading. However, here is my personal summary about magnetic data:

Example in *.GPX:

Header:
...
<CompassOffset>0</CompassOffset>
<FCOrientation>0</FCOrientation>
<GeoMag>2.8</GeoMag>
...

Data:
...
<Compass>295,284,302.2,298.0</Compass>
<MagnetField>095</MagnetField>
<MagnetInclination>69,04</MagnetInclination>
...

Compass values
<Compass>295,284,302.2,298.0</Compass>
Compass[1] = compass value averaged (yaw gyro stabilized)
Compass[2] = compass value original
Compass[3] = setpoint of geographic orientation = heading (used for waypoint flights)
Compass[4] = geographic orientation = heading = averaged compass value [1] + declination (= 2.8°)

Magnetic Field strength
<MagnetField>095</MagnetField>
MagnetField = measured mag field / ideal mag field on the location * 100 %

Magnetic declination
<GeoMag>2.8</GeoMag>
GeoMag = difference of magnetic north from geographic north in degrees. Depends on the location.
Example:
GeoMag = 2.8 -> magnetic north = 2.8° easterly than geographic north
That means: magnetic 0° = geographic 2.8°

Magnetic inclination
<MagnetInclination>69,04</MagnetInclination>
MagnetInclination[1] = inclination of magnetic field vector measured from horizontal (= 0°)
MagnetInclination[2] = measured magnetic inclination - ideal magnetic inclination on the location
Example:
MagnetInclination[1] = 69 -> magnetic field vector points 69° = 69° from horizontal
MagnetInclination[2] = 4 -> ideal magnetic inclination on the location = 65°

Calculations:
compass[4] = compass[1] + GeoMag (+ CompassOffset)
heading = compass[4] + FCOrientation


Regards, Armin

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