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Incorrect Starting Point When Viewing Logs

Matt M PA

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I'm still trying to get the logs to be correct. When I view a flight on the Fly app...it appear accurate.

When I download the flight from the app, and view it on, for example DroneLogBook...it shows an incorrect starting location. Often, it's way off.

I'd love to figure this out...glad for you thoughts...
 

slup

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Matt M PA

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I can try another....but AirData matches what DroneLogBook shows.

I was wondering it taking off...even if only a short distance from the ground...before I have satellite lock could cause errors on starting point?
 

Meta4

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I was wondering it taking off...even if only a short distance from the ground...before I have satellite lock could cause errors on starting point?
Your drone will record its home point as soon as it gets good GPS location data.
If you are impatient and launch before you have GPS, the drone won't be able to record a home point or any locations until it gets GPS.
If you fly some distance before getting GPS, your home point won't be where you launched.

If you look at the actual flight data, it should be obvious if you launched and flew off without waiting for GPS.
 
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Matt M PA

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Ok guys, here's one from the other day. The Fly app shows it accurately, only around the house.

Yet, in this screenshot from DroneLogBook it shows starting the flight to the West a good distance..which I didn't. AirData and the Phantom Help tool also show this spike to the West. As I see it, this far West point is at the very beginning of the flight and only for a very short time.

I've attached theTXT file that was uploaded.

Screen Shot 2020-08-01 at 8.26.08 AM.png
 

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Meta4

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Yet, in this screenshot from DroneLogBook it shows starting the flight to the West a good distance..which I didn't. AirData and the Phantom Help tool also show this spike to the West. As I see it, this far West point is at the very beginning of the flight and only for a very short time.
The explanation is quite simple.
You were impatient and launched without any satellites.
You climbed to 13 feet, rotated the drone and at 11.6 seconds started flying sideways.
At 13.6 secs you also gave it some elevator until 17.3 secs and took it higher, with the drone starting to receive satellites but still not having recorded a home point since the GPS Health was only 1/5.
At 22 seconds the GPS Health was 4 and the drone recorded a home point.

But at 18.4 seconds, with 10 satellites acquired (but GPS Health still at zero, there the drone was recording its position (even though the accuracy was poor).
There are some numbers in the GPS speed column of spreadsheet data.
We can tell that the location data was wrong because it's briefly giving a speed of 800 miles/hour.

If you wait for GPS before flying off, you won't record any ghost flying and your recorded home point will be at the lainch point.
 
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boblui

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The Fly app shows it accurately, only around the house.....
..... Yet, in this screenshot from DroneLogBook it shows starting the flight to the West a good distance..which I didn't. ....
Only 3 GPS coordinates are recorded along that spike towards the west over a timer period of just 0.4 second. All these GPS data were seen by the flight controller as inaccurate ( navHealth = 2 on a 0 to 5 scale ) and were ignored for navigation purpose. Otherwise you would have seen some very irratic movement of the drone.

On-line log players show the coordinates regardless of the accuracy but the FLY app apparently filters them away.
 
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Matt M PA

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Meta4, thanks.

So, the A/C should stay on the ground until GPS? Simple error, but glad as it makes sense now.
 
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