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Spark - wrong altitude
1288 21 2019-3-3
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petic537
lvl.2

Czechia
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Hello DJI,

my grandpa bought a Spark. Most of the time it works fine. But during two flights Spark shown wrong altitude. I will describe what happend:

1) Spark was flying in altitude of 30 meters with correct altitude reading
2) RTH button was pressed
3) altitude in app started to show numbers like 0 m, -5 m, 2 m even though Spark was at 30 meters
4) Spark started to climb abowe RTH altitude
5) I have stopped RTH and landed manually.

Spark was still showing wrong altitude till I was close to ground.

Can you please help me how to fix this problem?

Thank you,
Petr

2019-3-3
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petic537
lvl.2

Czechia
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EDIT:  I made another test flight today. Spark was showing wrong altitude all the time when it was higher then cca 6 meters above ground.
2019-3-3
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S-e-ven
Captain
Flight distance : 5759259 ft
Thailand
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New Spark?
Still plastic on the ground sensors?
Or some dirt?
2019-3-3
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petic537
lvl.2

Czechia
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S-e-ven Posted at 3-3 01:37
New Spark?
Still plastic on the ground sensors?
Or some dirt?

2 months old. No dirt or cover on sensors.
2019-3-3
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petic537
lvl.2

Czechia
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S-e-ven Posted at 3-3 01:37
New Spark?
Still plastic on the ground sensors?
Or some dirt?

Ground sensors works ok. Problem occurs when Spark is in cca 6 meters and higher - out of reach of ground sensors. ... Maybe barometric sensor is not working correctly.
2019-3-3
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Nidge
First Officer

United Kingdom
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I’m thinking it might be an issue in the way the telemetry is being handled. As you quite rightly say the VPS is only effective at about 6m and below. If the barometric sensor was sending erroneous data The flight controller would be trying to correct the height and you’d see the Spark continuously making vertical adjustments.  I’m not sure if the Go4App reports Barometer altitude or GPS Altitude (GAlt) or a mathematical function of the two. If it is the latter then the Spark might benefit from a full factory reset and recalibration. If that doesn’t fix the issue then it will most likely need sending to the DJI Elves for further analysis.

Regards

Nidge.
2019-3-3
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S-e-ven
Captain
Flight distance : 5759259 ft
Thailand
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petic537 Posted at 3-3 01:59
Ground sensors works ok. Problem occurs when Spark is in cca 6 meters and higher - out of reach of ground sensors. ... Maybe barometric sensor is not working correctly.

That can be.
But how about you look it up, first?
https://www.phantomhelp.com/logviewer/upload/
follow the instructions, upload the flightrecord and check, what the bird has recorded for both systems

And, perhaps, post the link to the flight record here, so that some of the flightlog-gurus can have a look, too

2019-3-3
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snowbird pilot
Second Officer
United States
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were you flying from a hill? calibrate compass/imu?
2019-3-3
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petic537
lvl.2

Czechia
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snowbird pilot Posted at 3-3 10:39
were you flying from a hill? calibrate compass/imu?

No, I was flying only from flat surface everytime. I have already calibrated IMU and compass. It did not fix the issue.
2019-3-3
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Hobbyshop
lvl.4
Flight distance : 32769 ft
United States
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Are you flying around any large steel structure?
2019-3-3
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petic537
lvl.2

Czechia
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Hobbyshop Posted at 3-3 15:26
Are you flying around any large steel structure?

No, I did not.
2019-3-4
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S-e-ven
Captain
Flight distance : 5759259 ft
Thailand
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Did you check the flightlog?
2019-3-4
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snowbird pilot
Second Officer
United States
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petic537 Posted at 3-3 11:39
No, I was flying only from flat surface everytime. I have already calibrated IMU and compass. It did not fix the issue.

have you figured it out?
2019-3-8
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djiuser_4aCBK4a3NhhO
lvl.1
Flight distance : 110571 ft

Greece
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Did you fix it somehow? I have the same exact problem. Thanks
4-11 04:17
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Flyingstoo
lvl.2
Flight distance : 42556 ft

United Kingdom
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I am having exactly the same issues and it has been doing it for sometime now. I have analyzed the flight logs and the spark onboard altitude is changing to a negative value.

Not sure if this will show picture correctly but hopefully you can sees an image of my flight log . The blue line is relative altitude which starts  at zero obn the left but look what happens it goes negative even though the spark has been flown level. When RTH was initiated the spark went vertically up over 30m as the RTH min altitude was set at 30m so the error was amplified. I had to override it to get it down
5-6 13:39
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Flyingstoo
lvl.2
Flight distance : 42556 ft

United Kingdom
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Has anyone got an answer for this problem as I know it is becoming a major fault on several Spark drones
Thanks
5-6 13:41
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petic537
lvl.2

Czechia
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Flyingstoo Posted at 5-6 13:41
Has anyone got an answer for this problem as I know it is becoming a major fault on several Spark drones
Thanks

I have sent Spark back to my dealer for warranty repair. Dealer said that baro sensor is broken and send me new Spark for replacement for free.
5-6 22:35
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Flyingstoo
lvl.2
Flight distance : 42556 ft

United Kingdom
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Thanks for that

Unfortunately mine is out of guarantee so I am looking closely at what the problem could be.

I have analyzed the flight data using csview (see previous post) and it is obvious that the spark starts to compute an incorrect relative altitude affter about 4mins of flight. The relative altitude ramps down from 17m to a negative value -9.2m over a period of 40 seconds . The aircraft thouigh remains at the 17 m point. I also get big lags when climbing and descending and sometimes have to reverse the input control to stop a climb or descent.

One oddity is that there is no data in the absolute altitude location , is this normal?

I have tried using DJI assistant to uplaod the data to DJI but the upload form requires a mobile number and for some reason whatever data I put in that box is invalid and I cant get any further with the data submition  , is it only available to USA or chinese people.... I am UK based

Just to be clear this problem has been occurring for some time on different flights. The clue that something is wrong is that the height data transmitted to the phone whilst in flight is corrupted.  All other systems IMU,Compass etc are calibrated and the WIFI signals are good and I am using latest software with OTG cable.
5-7 00:13
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petic537
lvl.2

Czechia
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Flyingstoo Posted at 5-7 00:13
Thanks for that

Unfortunately mine is out of guarantee so I am looking closely at what the problem could be.

You can try website airdata.com to investigate the issue (maybe you already know this site).

Upload your flight log and start "HD Flight Player". You will see different parameters of the flight like baro alt., sonar alt., flight mode and error messages.

This could be useful for issue investigation.
5-7 02:22
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petic537
lvl.2

Czechia
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petic537 Posted at 5-7 02:22
You can try website airdata.com to investigate the issue (maybe you already know this site).

Upload your flight log and start "HD Flight Player". You will see different parameters of the flight like baro alt., sonar alt., flight mode and error messages.

Grandpa's Spark was ok when he flew in small alt like 5 meters where altitude is meausred by downward looking sensors. When he climbed above 10 meters alt data are feed from baro sensor which was faulty.

Be carefull about autoflight modes now. Once we used RTH function (RTH alt was set to 50 m) and Spark was climbing to 200 meters and went back down only because battery was at 10%. In the log we have seen that Spark was reading alt of 0 meters and kept climbing bacause of faulty baro altimeter reading.

I would guess that it will be faulty baro altimeter in your case too.
5-7 02:33
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Flyingstoo
lvl.2
Flight distance : 42556 ft

United Kingdom
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Thanks Petic537

I have uploaded the data of the flight to airdata.com and it does reveal that the Baro altitude suddenly descends over about 40 seconds after 4mins and 20 secs, I know the aircraft was level at 56ft as this occurred.
After 5 mins and 13secs into flight the baro altitude had sbilised at -27ft an error now of 81ft !!
At 7 mins 18 secs into flight the altitude has dropped to -33ft and a notification error is now present on the plot 'Not Enough Force/ESC Error'  ( not sure if that is a motor speed controller fault?)
At 8 mins 30 secs an RTH signal is given and the altitude is now given as  7.2ft when in reality it is more like 60ft so of course the aircraft deciddes to climb up to its RTH altitude (30m) and it starts aiming for space!!
The Spark reaches what it thinks is 86ft when in reality it is probably more like 150ft at this point I intervene and issue a full desend command.

Eventually I get visual contact again and continue a manual descent with a now critical battery situation

The sonar altimeter reading becomes active from an actual altitude of 14ft for the last part of the descent the Baro altitude at this point is below -100ft !

This does suggest a Baro altimeter failure but is that replaceable or is it a new spark complete main board replacement?

Thanks to all
5-7 04:04
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Flyingstoo
lvl.2
Flight distance : 42556 ft

United Kingdom
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Have discovered that the Baro Altimeter is part of the GPS module that is available as a seperate part. I have located a second hand unit on ebay that is returnable if it doesnt fix the fault
I will keep you updated
Cheers
5-7 09:32
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