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[NOT A BUG] Wrong course/speed data from SPA/SKU type II fix


Flappie
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I've been testing the SPA/SKU type II fix procedure with the Caucasus map. I'm getting odd results:

 

  • Calculated angle is systematically wrong by ~15°.
  • Calculated speed is often incorrect as well.

 

I waited up to 5 minutes between two fixes to be sure the measurement would be effective, but it's not.

 

Angle is 270°, speed is 9.71922 knots.

image.png

 

Calculated angle is 254, calculated speed is 14 knots.

sku254.jpg

 


Edited by Flappie
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A track or it didn't happen.

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Another try with a track attached. This time I got 265° (instead of 270) and 11 knots (good speed estimation). This is much more precise but I don't know what I did differently.

How long do you guys wait between two fixes to get a correct course/speed calculation?

AJS37_SKU.trk

A track or it didn't happen.

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Radar fix precision depend of your scale, try with different scales.

A pixel doesn't have the same wide in 15km scale and in 120km scale.

On the second screen the ship is not in the center of the circle, maybe a bad fix.

And try with the vertical fix.


Edited by JG300_Papaye
  • Thanks 1

[sIGPIC][/sIGPIC]

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I agree, but I didn't think I would get such a huge error margin (15° difference). I'll do the maths with coordinates to better understand what happens.

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A track or it didn't happen.

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Merci @JG300_Papaye!

 

I did a radar fix with range 120 and saw my target fix coordinates were quite a bit up north the real position, meaning the measured course would obvisously be incorrect.

Then I did the same SKU measurement only with visual fixes this time: this allowed me to see target measurement works just fine (271°-10 knots, whch grossly corresponds to 270-20km/h). False alarm.

A track or it didn't happen.

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  • Flappie changed the title to [NOT A BUG] Wrong course/speed data from SPA/SKU type II fix
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