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Losing GPS hold

Valdez

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Oct 10, 2018
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Two days ago, after taking off, I lost GPS at around 300ft, the drone went into ATTI mode, and started drifting with the wind.

I tried replicating that today. At an indicated 317ft, I have 14/15 satellites, ascend another 20ft, and that number falls to 6/7.

Has anyone else experienced this?
 

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Flying in what surroundings?
Middle of no where?
In between buildings?
 
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Flying in what surroundings?
Middle of no where?
In between buildings?
It's nothing obvious like surrounding buildings..

I took off from the top of a fifty metre building, with ten satellites, and no higher buildings in the vicinity. I hovered a while at 50ft, and the satellite count increased to fifteen, then with a stable number of satellites, ascended another 300ft.

The issue occurs at 320ft. Climb any higher, and I seem to lose satellites, half of them in 20ft, and ATTI mode any higher. Descend 20ft, and I regain them fairly instantly. It's almost as if the authorities are disabling GPS above a certain altitude....
 
I assume your checklist includes "confirm GPS, RC and Telemetry signals" before you takeoff. I check this again at 10', only take 2 secs.
 
Considering gps comes from space, I'd have to say there is a magnetic field or transmission causing this.
 
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I've lost a GPS fix, it went into ATTI and hasn't re-acuire the fix up until i've landed the bird and rebooted it. It has successfully regained the fix after reboot, at the same location. It wasn't in Russia, it was in Atlantic City, NJ, US. It was over a year ago and only happened once. I no longer have the flight logs, but as far as i recall, there was a GPS related error in there, but a very undescriptive one.
 
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I found an area where literally satellites drop from approx 22-24 to about 4-5 and it goes into atti. It’s either very magnetic out there or literally dead area? I’m able to replicate it by going to that particular location. However, I can easily recover by flying away from that area.

Mine has nothing to do with altitude though.
 
I found an area where literally satellites drop from approx 22-24 to about 4-5 and it goes into atti.
It’s either very magnetic out there or literally dead area?
Magnetism won't cause what you describe and there are no dead areas.
It's got to be some sort of interference, but why it doesn't affect all sats sounds unusual.

I’m able to replicate it by going to that particular location. However, I can easily recover by flying away from that area.
It sounds a little like a report from an urban area in Switzerland where GPS was dropping out when approaching one particular area.
Can you describe the area where this is happening?
What's nearby?
 
Magnetism won't cause what you describe and there are no dead areas.
It's got to be some sort of interference, but why it doesn't affect all sats sounds unusual.


It sounds a little like a report from an urban area in Switzerland where GPS was dropping out when approaching one particular area.
Can you describe the area where this is happening?
What's nearby?

Thanks for your insight.

It’s a creek, and when I get near a bridge (I’m at least 50m in altitude) is when the signal just drops. There is a high school nearby and residential homes. No military, police, ambulance, fire station, or anything that I could think of that’s could interfere with it. Baffled on my end really what sort of interference would make such a significant satellite drop.

I’ll record it next time if it’s of interest along with the area....
 
Dropping to a low number of satellites in a specific place is probably just some buildings or other big things "shading" the other satellites.
 

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