How can i use this formula to obtain distance from home from the data flash log?

Hi all,
I would like to graph my RSSI and distance from home from the data flash log.

How can i use this formula :
sqrt(XKF1.PE^2 + XKF1.PN^2)

to get distance from home?

It would be nice to have this value pre-calculated and ready for selection from the mission planner.Thanks.

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i can look at adding this, but just note its distance from EKF origin… not home.


That would be great Michael.Even EKF origin is fine.Many thanks!!

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Or this formula for distance from home?I took this example from Henry’s GitHub for dashware OSD implementation.Not sure this will help to implement as I have no expertise to read and understand it.It just looks like a trigonometric formula to me but don’t know how it’s derived :slight_smile:

Distance from Home

Since ArduPilot does not provide this as a logged value, once you have created the .CSV file, you will need to add a column next to the GPS Lat/Lon column labeled “Home_Dist” and at the first row with a value, add something like this for the Home_Dist calculation for row 18, with GPS Lat and Lon in columns H and I,and home value in row 8,for example:

=IF (I18 = "", "",ACOS( SIN($H$8*PI()/180)*SIN(H18*PI()/180) + COS($H$8*PI()/180)*COS(H18*PI()/180)*COS(I18*PI()/180-$I$8*PI()/180) ) * 6371000)

where the home lat long is in H8/I8 (or change to whatever row has the home gps value after lock) and then fill the column downward with this formula in order to compute each GPS entry into a distance (in meters) from home. Note: you wont see this formula in the example file, since its already been converted back to CSV."

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Thanks a lot Michael for adding this feature!! Its going to be quite useful in plotting distance vs RSSI.

I found there are 2 options for the same graphs.

“RADIO/RSSI_Distance mavgraphs2” and
“Radio/RSSI_Distance mavgraphs2”

But only “RADIO/RSSI_Distance mavgraphs2” works.

ive removed one of these from the latest beta

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I have a question about the distance from the ekf origin.

Lets say airplane is flying 5kms away and 2kms high above the ground. If we draw a triangle, then the distance from Ekf origin is base of the triangle or hypotenuse of the triangle? In other words straight 3d distance or 2d distance on the map? Thanks.

does not include alt, so its 2d distance

Got it.Thanks Michael.