Satellite connections decrease as altitude rises

[e-XPLoDeR]

Hi,
I'm new to MavicPilots, first of all, sorry for my first thread to be an issue.

I made my first outdoor flight with my new Mini 2, but I got GPS Position Mismatch errors, dropped GPS satellites gradually and it automatically set to ATTI mode on about 350 feets high and from 40 feets distance.

Here is my flight log: DJI Flight Log Viewer - PhantomHelp.com

And here is the replay:

Today, I've made a new flight on the same area and just returned back to my PC. I would like to give a brief what I've done:

First of all, today's flight log: DJI Flight Log Viewer - PhantomHelp.com

1. I switched my phone to airplane mode but switched GPS on.
2. I started DJI Fly app and turned on the drone, then calibrated both IMU and Compass (unfortunately there are cars every where, but I kept 2 meters distance between a car and a drone, and I am so sorry, I know I shouldnt fly in such areas, in urban, with a crowded pigeon colony, in a stony road etc. but I couldnt wait, since I feel blue).
3. I started asceding to 100 meters slowly, as yesterday, but as you can see from the screen record, as soon as I ascend , the amount of satellites started dropping (from 16-17 max. to 8, please refer to the video, 1:25 and the log, 3m 0.1s and below)
4. As I saw 8 satellites, I didnt want to risk anymore and started descending and finally landed. As you will see, satellite connections are instable. It There are drops to 8 gradually but fast from 14-16 sattellites.

My question is: Is it normal to drop satellites from 16-17 to 8-9 while in the air, especially as altitude rises? And I know it would be zero if I ascended to 100 meters (like yesterday). There exactly is instable GPS connection as you can see both from the log and the video.

 

[Deleted member 103366]

Welcome.
I saw your other thread, both here and over on the DJI forum.
I think you did well to get the drone back on the first flight especially with the flawed flight path that was shown in the App of that flight. As this is the second flight in which this occurred I think you should begin to think about returning the drone as faulty.

DJI will almost certainly ask for the txt and DAT logs, I would suggest that BEFORE send DJI any records you copy the entire FlightRecord folder (that is the folder containing these txt flight logs and the folder that starts MCDat......) from you phone to a computer or some form of back up.
I say this simply because it ensures you have copies of the logs just in case the ones sent to DJI get lost.

I would also suggest you make a 3rd flight but not in that area and try to get out of the city into open country side with no trees and certainly away from that one location ( those pigeons are a nightmare).
But I would suggest that you DO NOT go so high, I think you did well to get the drone back on the first flight especially with the flawed flight path that was shown in the App of that flight but going high increase the chances of you losing the drone.

What you are seeing is not normal and I would be surprised if it was location related but trying a flight somewhere else would, I think. be a good idea.



Long term and assuming you end up with a correctly behaving drone, that car park, with those pigeons, is not a safe place to fly.

 

[e-XPLoDeR]

Welcome.
I saw your other thread, both here and over on the DJI forum.
I think you did well to get the drone back on the first flight especially with the flawed flight path that was shown in the App of that flight. As this is the second flight in which this occurred I think you should begin to think about returning the drone as faulty.

DJI will almost certainly ask for the txt and DAT logs, I would suggest that BEFORE send DJI any records you copy the entire FlightRecord folder (that is the folder containing these txt flight logs and the folder that starts MCDat......) from you phone to a computer or some form of back up.
I say this simply because it ensures you have copies of the logs just in case the ones sent to DJI get lost.

I would also suggest you make a 3rd flight but not in that area and try to get out of the city into open country side with no trees and certainly away from that one location ( those pigeons are a nightmare).
But I would suggest that you DO NOT go so high, I think you did well to get the drone back on the first flight especially with the flawed flight path that was shown in the App of that flight but going high increase the chances of you losing the drone.

What you are seeing is not normal and I would be surprised if it was location related but trying a flight somewhere else would, I think. be a good idea.



Long term and assuming you end up with a correctly behaving drone, that car park, with those pigeons, is not a safe place to fly.

Thank you many much, PhiliusFoggg. I used my Mini 2 somewhere else, nearly outside of the city and there were no problems. I was at the altitude of 170 meters and there were even more satellite links than normal. I'm so happy now. Anyways, thank you many much for your detailed reply.

 

[Deleted member 103366]

OK, now I think that is wierd.
I would make several more test flights in differing places BEFORE considering the matter 'solved'.

In addition
1) I think you will find that the legal ceiling for drones in Turkey is 120m above the ground directly beneath the drone (AGL) i.e. a weighted string attached to the drone that is 120m long MUST ALWAYS be in contact with the ground. If so, your 170m may have been too high unless the drone was flying up a hill etc. etc.
2) Wind strength generally increases with height so when going high the drone might climb into strong winds, if that happens descend to get into slower winds lower down otherwise your drone may literally be "blown away".

 

[e-XPLoDeR]

I will exactly try on different areas and keep in my mind the articles you wrote. Many thanks.

 

[EpicFlight]

Little data to go on, but behavior is consistent with a strong very close transmitter in GPS frequency range, shielded by buildings around the takeoff location. As the drone clears the buildings, the GPS receiver starts getting interference, overwhelming weaker signals from sats lower on the horizon.

I have no way of knowing this is what's occurring, however it wouldn't be the first time I've heard of this (if indeed that's the explanation).

Private, directional microwave links are all over the place in large cities.