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Questions & Answers
1

How accurate should I expect my RTH? I have a Parrot Anafi and when I press the RTH button on the controller it is often a few metres from where it took off.
I have calibrated it and made sure both GPS are green as well as precise landing.

2

Unless it has a Vision Positioning System as well a few metres is the best you can hope for. The civilian GPS / GLONASS is only accyrate to within a few metres and will tend to wander within its area of accuracy.

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3

Something that’s exacerbated by the most accurate positioning being achieved with plentiful satellites nearer the horizon … and those are the first to be obscured by buildings, trees (wet trees are far worse still), etc.

4

Two things to do to increase the accuracy of the RTH.

  1. Take off from a spot that stands out or has high contrast with the surrounding area.

  2. When you take off hover at around 10ft to 15ft above the take off point for about 10seconds.

Doing these two things will allow the Anafi to recognise its take off point when it starts to decend at the end of the RTH function.

I have one of those popular landing mats, about £10 off Amazon, and following the above steps both my Anafi’s always land back on the mat when I feel lazy and use RTH.

Nidge.

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5

Thanks for the info guys. I’m planning on flying later today (if this wind ever finally stops) so will see how I get on.

6

Say a bit more about wet trees in relation to obscuring signal, please?

7

They can reduce the signals of those that are lower in the sky, the signals from which having to pass through the wet trees.
As a result you become more dependant on satellites that are higher in the sky.

The best lateral location is obtained from GPS satellites lower in the sky, so as these become more obscured the circle of location probability increases. (The position error can be higher.)

The more densely the trees are spaced the greater the chance of losing the signal from those lower GPS satellites.
Coniferous trees are the worst because of the height range of their rain holding greenery.

Walking along tracks through a wet forest, with an accurate handheld GPS, I’ve sometimes gone several minutes without any location being fixed.

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