Lost GPS signal

[Martyray]

That looks like the one. I'll take a look.

What program do you use to make the DAT file legible..
Sorry For all the questions but, the flight data is as exciting as the flight...lol

 

[Dakarenduro]

I am curious on preflight checks as well. Mine are-
before powering on
1. check props and arms for anomolies

power on
1. check all imu/compass for any errors
2. check compass / map orientation on go4 against drone
3. wait for Home Point Recorded message
4. acknowledge any warnings or NFZ or nag messages

take-off
1. do small forward/backward/left/right movements
2. do small yaw left/right movements
3. make sure it holds steady for a few seconds and seems stable

off to fly!

 

[MAvic_South_Oz]

I'll be very keen to u understand what went wrong.
My fault or tech, either way I really want to know so I can avoid it in the future

Just had a quick look at your Phantom Help link to the flight.
You got a warning about altitude zone 60m at takeoff for Illawarra Regional Airport/ Shellharbour airport.

Through the flight there were multiple warnings "Current RTH route will pass a no-fly zone. Pay attention to the aircraft's position to avoid RTH failure."
Even though you were near ground level (for most of it, sometimes went higher though).

Yet OpenSky app (one CASA recommends) shows that is is merely a "Heliport - Operating near a known heliport. Safely land if aircraft are operating in the area."
The local hospital for heli landings.

I'll check some of the other apps and se what they show for the airport etc.

Not sure if the NFZ might have had anything to do with the flight problem.

The DJI flysafe map is here DJI - The World Leader in Camera Drones/Quadcopters for Aerial Photography
Paste in Barrack Heights, New South Wales, Australia to the search window.

 

[MAvic_South_Oz]

Pre flight checks ?
I'll send you mine in a PM / Conversation later, they are in my head, but I'll jot them down.
Pretty much the bare necessities for the M1P, I would have different rules for flying a mini, even my Spark are slightly different.

 

[MAvic_South_Oz]

I'll check some of the other apps and see what they show for the airport etc.

Not sure if the NFZ might have had anything to do with the flight problem.

The DJI flysafe map is here DJI - The World Leader in Camera Drones/Quadcopters for Aerial Photography
Paste in Barrack Heights, New South Wales, Australia to the search window.

Checked https://ok2fly.com.au/ same Barrack Heights, New South Wales, Australia to get into view, it at least mentions this as an uncontrolled airport, no altitude limit mentioned, and this should have same rules as a heli zone . . . OK to fly but safely land if aircraft are operating in the area.

Will be interesting to see follow up analysis.

 

[Martyray]

Just had a quick look at your Phantom Help link to the flight.
You got a warning about altitude zone 60m at takeoff for Illawarra Regional Airport/ Shellharbour airport.

Through the flight there were multiple warnings "Current RTH route will pass a no-fly zone. Pay attention to the aircraft's position to avoid RTH failure."
Even though you were near ground level (for most of it, sometimes went higher though).

Yet OpenSky app (one CASA recommends) shows that is is merely a "Heliport - Operating near a known heliport. Safely land if aircraft are operating in the area."
The local hospital for heli landings.

I'll check some of the other apps and se what they show for the airport etc.

Not sure if the NFZ might have had anything to do with the flight problem.

The DJI flysafe map is here DJI - The World Leader in Camera Drones/Quadcopters for Aerial Photography
Paste in Barrack Heights, New South Wales, Australia to the search window.

The NFZ did limit my altitudes.
But I thought that was the only restriction it imparted....
But I may be wrong
Cheers

 

[Martyray]

Checked https://ok2fly.com.au/ same Barrack Heights, New South Wales, Australia to get into view, it at least mentions this as an uncontrolled airport, no altitude limit mentioned, and this should have same rules as a heli zone . . . OK to fly but safely land if aircraft are operating in the area.

Will be interesting to see follow up analysis.

Yes....
Me too...
I'll be very happy to hear what the experts say

 

[Dave Maine]

I would like to emphasize the value of a scientific approach to problem solving as exemplified by the efforts to work with hypotheses and conclusions driven by data. The scientific method that proven by it’s successes over the centuries to work. Importantly, it has always thrived on competition between various scientific teams, whose views start off different. These however, are not at all debates between the personal qualifications of the researcher, but honest attempts to use all available data to get an explanation of what is going on. This testing of explanations is resolved by other teams repeating the experiment to see if they can get the same results, and in the medical field, performing double blind experiments.

All of this is time consuming and frustrating to those wanting clear resolution. These times with the shadow of the corona virus hanging over us reinforce this point.

A drone problem is a science problem asking to be solved by scientific methods. Solutions by opinions and anecdotes are of limited to no value.

 

[JimCanada]

Oh and one other item. You may not notice it in your area because it may not be the time of year or season when solar winds are as strong but also these sun outages and interruptions happen fairly quickly. We had a local channel to Directv and to dish network uplink facility this past Monday lose all locals for those customers for about 1 minute and 12 seconds. Sometimes they are longer around 5 minutes.
The only type of satellite systems or the only type of satellites affected by this at least for a few moments are geostationary satellites.

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 .

 

[sar104]

This is one of the more puzzling events that I've seen - I really can't find a definitive smoking gun. The IMU velocity solution diverges from the GPS velocity, as I mentioned above. The question is why. I resorted to solving the inertial problem via the orientation quaternions, which adds a bit more clarity:



Unfortunately that doesn't do much more than confirm the problem by visualizing it differently. It could still be the IMU or GNSS. Looking harder at the magnetic data does reveal the ATTI switch trigger:



The yaw discrepancy spikes to over 60° at 910 seconds (DAT offset time). In this case I think that the magnetometers are the issue, since the rate gyros are not seeing the excursions:



Looking at the magnetic modulus shows a significant variation of modulus with tilt, which is consistent with the earlier observation of a 2π periodicity in magmod - i.e. the compass is not well calibrated:



So perhaps it is just a badly calibrated compass - I would start by seeing if that can be improved and then post another DAT file. Not a very satisfying explanation, but more data may help narrow it down further.

 

[Gindra]

Oh and one other item. You may not notice it in your area because it may not be the time of year or season when solar winds are as strong but also these sun outages and interruptions happen fairly quickly. We had a local channel to Directv and to dish network uplink facility this past Monday lose all locals for those customers for about 1 minute and 12 seconds. Sometimes they are longer around 5 minutes.
The only type of satellite systems or the only type of satellites affected by this at least for a few moments are geostationary satellites.

As you may know, we have been in a period of Solar Minimum for about 5 years now. The sun cycles between solar minimum and solar maximum approximately every 12-13 years.

We are now starting to see, for the first time in a few years, sunspot activity. However, it really isn't the sunspots themselves that affect earth's geomagnetic field, it is solar flares and coronal mass ejections (CMEs).

Just a few days ago, there was a small CME that sent a slow moving solar wind our direction. It grazed earth rather than hitting us head-on and only caused a minor increase in Kp value.

So, even if GPS satellites were affected by solar activity, there hasn't been enough of that of late to make a difference anyways.

 

[Rcarman]

At takeoff, I received a verbal " home point set" from contract...
When I lost GPS signal I received " GPS signal lost. Return home will not function while no GPS signal" or words to that effect

That’s def not suppose to happen...

 

[sar104]

That’s def not suppose to happen...

It was an FC switch to ATTI mode due to IMU errors, which disables GPS navigation. There was no actual loss of GPS positioning data.

 

[MAvic_South_Oz]

This is one of the more puzzling events that I've seen - I really can't find a definitive smoking gun.

Looking at the magnetic modulus shows a significant variation of modulus with tilt, which is consistent with the earlier observation of a 2π periodicity in magmod - i.e. the compass is not well calibrated:

So perhaps it is just a badly calibrated compass - I would start by seeing if that can be improved and then post another DAT file. Not a very satisfying explanation, but more data may help narrow it down further.

So, maybe the OP should leave as is, fly a very low, safe flight to get TXT / DAT, land, very short safe flight, 30 seconds ?

Shut down, restart, calibrate compass, fly again and get a new TXT / DAT with calibrated compass.

Is that the best course from here, then post up the 2 flight logs, and attach both DAT ?

Or, just calibrate compass and do another test flight ?

Suggest doing this is another location, similar park / oval, try and get away from any anomalies where the original problem occurred ?

 

[Martyray]

Thank you so much for the info.
I will recalibrate and do a text flight.
Where can I find information on these graphs as I would like to understand what I'm looking at?

 

[sar104]

Thank you so much for the info.
I will recalibrate and do a text flight.
Where can I find information on these graphs as I would like to understand what I'm looking at?

Mavic Flight Log Retrieval and Analysis Guide

With the introduction of the Mavic Mini there has been a noticeable uptick in the number of posts requesting help with lost or crashed aircraft. While there is plenty of help and advice available on this forum, and detailed guidance and options on several other websites, I thought that perhaps a...

mavicpilots.com

 

[7bonedrone7]

At takeoff, I received a verbal " home point set" from contract...
When I lost GPS signal I received " GPS signal lost. Return home will not function while no GPS signal" or words to that effect

I had the exact same thing happen to me yesterday, even showing that I had 17 satellites connected and then the same message. I was probably only about 2000 ft. away and I really got worried for a minute and finally after pushing rth a couple times it started the beeping and came back.

 

[Michael Ainsworth]

The NFZ did limit my altitudes.
But I thought that was the only restriction it imparted....
But I may be wrong
Cheers

Hi, I also live in Illawarra area NSW Australia. There is a regional airport in Albion Park but the OP was outside that area. The other warning is for the Hospital Heliport at Shellharbour Hospital, this is unmanned. OpenSky is correct for these warnings.

 

[MAvic_South_Oz]

Hi, I also live in Illawarra area NSW Australia. There is a regional airport in Albion Park but the OP was outside that area. The other warning is for the Hospital Heliport at Shellharbour Hospital, this is unmanned. OpenSky is correct for these warnings.

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 DJI flysafe map is here DJI - The World Leader in Camera Drones/Quadcopters for Aerial Photography
Paste in Barrack Heights, New South Wales, Australia to the search window.

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'.

 

[Aaron24]

Perhaps if that tower has microwave capabilities or not?

Here is a quick test as well to see if you have a leaking insulator from overhead power lines or something else. Get an am portable radio and aim at that tower. If there is no degradation or increase in noise walk along the power lines of they are over head.

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?