Lost GPS signal

[MAvic_South_Oz]

This is interesting. Off topic question here. On my daily commute to work I normally listen to AM radio in the car. There is one particular intersection I need to go through that if the lights are red I need to stop under high transmission power lines that go straight over the top of my car. During this time I lose all AM radio reception until the lights are green and I can move away from under the power lines. What would this mean?

Strong radio signal interference.
It doesn't interfere with GPS though (AFAIK).

I'm no expert on the science, but I know if we take a plain fluorescent tube up the hill and approach the HT powerlines up there, it will start to glow, and get very bright underneath them.
The strong magnetic field from the power flow lines up the argon, xenon, neon, or krypton, and mercury vapor in them.

It's why we shouldn't fly our drones too close to powerlines.

 

[GadgetGuy]

Yes im up in Saskatchewan Canada the satellites screw up 2 times a day at certain times of the year. I've been seeing this since the 1980s with satellite TV .

I didn't realize that satellite TV depended upon GPS!

 

[BerndM]

ok.
i think this is correct.
please forgive me if its not as im only new at this.
once again , i greatly appreciate your time and expertise.
this should be the link to the flight data:

DJI Flight Log Viewer | Phantom Help

Upload and view flight logs from your DJI drones

www.phantomhelp.com

Just a quick suggestion for you that has nothing to do with the issue you had, but I noticed on one of the alarms you received on your log, it indicated that your RTH altitude was set to 120M...... WOW!!!!! that is way way higher than you needed for where you were flying based on the map. Using street view, I saw nothing in that general area that even came close to being that high. IMHO, you should always set your RTH altitude for the actual location you are currently flying at to prevent to quad from using up what battery power you may have left in a low battery situation. Climbing to 120M is a huge drain on your battery especially if your RTH kicks in because of a low battery condition. You'd never get the quad back to your takeoff point in that case. Just sayin'

 

[romko1]

Hello,
I live in Slovakia and I had exactly the same problem with the loss of GPS signal when Mavic was at a height of approx. 80 m. It is not caused by electrical wiring. I also don't think it's caused by solar activity. For a logical reason, I get a problem with the IMU and then switch to ATTI mode.
It is recommended to calibrate the IMU and compass before each start.

 

[Meta4]

It is recommended to calibrate the IMU and compass before each start.

It isn't recommended to recalibrate either the compass or the IMU before each flight.

 

[Jonathonmp]

This is interesting. Off topic question here. On my daily commute to work I normally listen to AM radio in the car. There is one particular intersection I need to go through that if the lights are red I need to stop under high transmission power lines that go straight over the top of my car. During this time I lose all AM radio reception until the lights are green and I can move away from under the power lines. What would this mean?

it could be a number of things but yes it is related to the power lines. Either a leaking or arching insulator and it's either arching in that area or could travel up the line as well. Also depending on the KV voltage of the transmission lines in that area there could be lighting arrestors that take the hit from lighting to protect the power lines and or traffic lights need replace after taking to many hits.

 

[lencomm]

Is there a way to access messages/errors on-the-fly? Sometimes things are missed while flying and there have been plenty of incidents where warnings were given but were missed by the operator only to show in the flight log. For example, I've reviewed flight logs from my P4A that showed brief disconnects that I was not aware were happening during that flight.

 

[romko1]

It isn't recommended to recalibrate either the compass or the IMU before each flight.

Um, and then what needs to be done to avoid losing the GPS signal during the flight? It's annoying. Thanks

 

[MAvic_South_Oz]

Um, and then what needs to be done to avoid losing the GPS signal during the flight? It's annoying. Thanks

Stay out of deep valleys, keep away from enclosed areas like between tall buildings, don't go under really wide or heavily dense items, like road bridges, long culverts, caves etc.
If you are in clear sky, and had a good lock before taking off (home point recorded etc), then it is really very rare you would lose satellites while flying.

 

[Meta4]

Um, and then what needs to be done to avoid losing the GPS signal during the flight? It's annoying. Thanks

You shouldn't need to do anything to prevent losing GPS because losing GPS is not normal (if you are flying out in the open).
And recalibrating your compass or IMU won't have any effect on GPS reception.

 

[VFR-Pilot42]

I had the same exact problem happen yesterday with my Mavic Air. Drone was 1000 ft away at 395ft. Message popped up several times that GPS signal lost. Also got a message once during the flight about magnetic interference. And one message about losing connection with controller. Everything was fully charged including the controller.

 

[sar104]

Um, and then what needs to be done to avoid losing the GPS signal during the flight? It's annoying. Thanks

Except when flying with a limited sky view, such as between tall buildings or narrow gorges, the GPS error messages are generally misleading, because they don't actually result from any problem with the GPS reception. Mostly they result from a disagreement between the IMU inertial solution and the GPS data, at which point the FC stops attempting to navigate and ignores the GPS data. It's still there, and still good, as can be seen by inspection of the DAT file.

 

[Drones.n.Pixels]

There are millions of GPS users around the world so what you are suggesting would certainly be noticed ... if it happened.
But it just doesn't happen.

Of course it hapens. This is why KP index gets measured and published in navigation forecasts. The fact that many people ignore it - and often do not link their problems with it - is another story.
Strong interference was recorded in the very begining of the flight and it appears to have created problems. It may have of course been caused by different type of interference, but stating that solar interference does not happen is a bit off a missed statement.

 

[Drones.n.Pixels]

That satellite TV transmissions may be affected is interesting but the topic of this thread is GPS.
Can you show where GPS has been affected the way you describe ?

GPS strength may not have been affected, but quality of the GPS signal possibly.
Saying this, I also think that you are right in your earlier statement, that the casue of interference was close to the take off point, as the interference was recorded at that point already.
As @sar104 pointed out, a lot of the errors identified as GPS errors are casued by compass or IMU, but what it often comes down to, is that the drone doesn't "know" how to define it's current position, therefore until it finds the point of reference, it will rely on manual controls (atti).

 

[Meta4]

Of course it hapens. This is why KP index gets measured and published in navigation forecasts. The fact that many people ignore it - and often do not link their problems with it - is another story.

It doesn't happen ... if your drone is out in the open with a clear sky view, you should never have any problem with lost GPS.
A high KP index won't cause dropped GPS (or any other issue you'll ever notice flying your drone).
In six years of flying and involvement with drone forums, I still haven't seen any reports of any incident that could be attributed to it.

Strong interference was recorded in the very begining of the flight and it appears to have created problems. It may have of course been caused by different type of interference, but stating that solar interference does not happen is a bit off a missed statement.

The interference you saw, was interference of the radio control signal and almost certainly caused by terrestrial wifi and electrical activity.
The app won't record GPS interference, only the quality of GPS reception.

 

[Drones.n.Pixels]

It doesn't happen ... if your drone is out in the open with a clear sky view, you should never have any problem with lost GPS.
A high KP index won't cause dropped GPS (or any other issue you'll ever notice flying your drone).
In six years of flying and involvement with drone forums, I still haven't seen any reports of any incident that could be attributed to it.

The interference you saw, was interference of the radio control signal and almost certainly caused by terrestrial wifi and electrical activity.
The app won't record GPS interference, only the quality of GPS reception.

Interesting topic... I'm actually doing my flight course and have been discussing this as well. I don't know about losing drones, but our instructor was actually saying that he did get more unexplained interference when he flew with high KP index.
As for the actual GPS - I edited my post later to point out that the interference could have caused issues with compas and IMU, which I kind of losely interpreted as GPS quality (perhaps this is not correct).

 

[Meta4]

I don't know about losing drones, but our instructor was actually saying that he did get more unexplained interference when he flew with high KP index.

It's almost certainly terrestrial influences rather than solar activity.

As for the actual GPS - I edited my post later to point out that the interference could have caused issues with compas and IMU, which I kind of losely interpreted as GPS quality (perhaps this is not correct).

The IMU won't be affected by any kind of interference and the compass would only be affected by magnetic interference from steel objects that are quite close to the drone or nearby live electric cables.

 

[Drones.n.Pixels]

It's almost certainly terrestrial influences rather than solar activity.

The IMU won't be affected by any kind of interference and the compass would only be affected by magnetic interference from steel objects that are quite close to the drone or nearby live electric cables.

Good to know - so the impact of KP index on flying ir rather small then (at least for drones, that don't fly as high as planes)?
So scientificaly speaking, if it did have impact - what would be impacted? The actual GPS only? Or anything else as well?

 

[sar104]

Good to know - so the impact of KP index on flying ir rather small then (at least for drones, that don't fly as high as planes)?
So scientificaly speaking, if it did have impact - what would be impacted? The actual GPS only? Or anything else as well?

Geomagnetic storms primarily cause disruption to radio signals passing through the ionosphere (satellite signals including GNSS) or reflecting off the ionosphere (HF comms, over-the-horizon radars etc.). It won't affect local radio control signals. The effect on GNSS signal time-of-arrival is measurable, but almost never (except at very high latitudes) enough to degrade consumer SF GNSS sufficiently to prevent its use by sUAS control systems.

 

[Michael Ainsworth]

Hi Michael, I see that is the Shellharbour / Illawarra Regional Airport you refer to ?
On the DJI Flysafe map as I linked to in post #63, as follows . . .

The Aussie Open Sky used by CASA shows that, out at Shellharbour beach area is outside the regional airport flight path restriction. People get confused with the multiple areas named Shellharbour I.e Shellharbour airport is based at Albion Park Rail on the Highway, Shellharbour Hospital with the heliport is actually at Mt Warrigal, also Shellharbour Village I believe is the original Shellharbour with its small harbour but now is being swallowed up with big developments and a Marina. The only restriction the OP is under where he was flying was to be aware of the Heliport at the Hospital, if a Copter around just bring Drone down safely.
It’s all a bit confusing sometimes which app to follow. I yet been restricted by DJIs app yet.
Maybe I will take a drive down to test this out with my Mavic Pro. With the current Covid lockdowns it would come under essential “educational” purposes ?

Where to OP was flying is apparently under the flight path according to DJI, and limits alt to 60m.
That's where the OP height was restricted as well.

It most likely has nothing to do with this error, but found it interesting that our fly safe apps recommended by CASA, one doesn't list it at all (!), the other calls it uncontrolled airport, so it shouldn't be restricted at all, just 'land if you become aware of manned aircraft in the area'.