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Phantom 4 Altitude showing incorrect on screen
6040 29 2016-7-1
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Ken Freeman
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United States
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When I fly my Phantom 4, the altitude starts off as correctly at 0.  Lift off to 20', all good.  As I fly forward over a grassy field, the on screen display starts to drift.  By the end of the flight, I was hovering at 5 feet and the OSD read 20 feet.  This has happened 3 days in a row.  Yesterday was much worse, 50 feet off. I reached out to DJI and uploaded my flight data.  They were very polite and I am waiting for their response.  I hate to loose my drone for several weeks to send it for repair.

I have also noticed altitude drops on ocassion.  Maybe they are related. I've recaled the compass and IMU.
Anyone else having problems?
Any solutions?




2016-7-1
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Heebus
Second Officer

Canada
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I have had this problem as well, I think its the firmware, but I am NO expert by far, I have had a -15.7 feet after landing in same spot from where I have taken off, I haven't worried to much as I always use line of sight as judgement, but I have wondered if this will effect my auto land ( I land softer by manual anyways so haven't done the auto land too much)
2016-7-1
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Jan Jensen
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Denmark
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I flew the up along a chimney measuring 8 meters.
but on the screen showed the 13 meters and I took off right next to the chimney.
I can not remember if it was before the last update, but have not tried to measure after since then
2016-7-1
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DJI-Ken
DJI team
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Jan Jensen Posted at 2016-7-2 03:59
I flew the up along a chimney measuring 8 meters.
but on the screen showed the 13 meters and I took  ...

You can perform and I am you calibration and that may help out.
2016-7-1
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rliamharpurb
lvl.1

United Kingdom
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I have the same problem reported it on here weeks ago

Imu Cali makes no difference
2016-7-1
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DJI-Paladin
Administrator
Flight distance : 2408 ft
Hong Kong
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rliamharpurb Posted at 2016-7-2 05:35
I have the same problem reported it on here weeks ago

Imu Cali makes no difference

Have you also tried to calibrate the the sensing system? Which firmware version and app version do you use? Does the same issue happen no matter where your drone fly?
2016-7-1
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rliamharpurb
lvl.1

United Kingdom
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I have calibrated everything availible on the craft and no it doesn't make any difference, upon landing or after reaching say 20m altitude I can drop down to say 5m and the reading can show -15m to 0.2m for example,

I have made a thread about this and the suggestion of recalibration make no difference,

Will this be firmware related?
2016-7-2
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Ken Freeman
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United States
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DJI-Paladin Posted at 2016-7-1 23:57
Have you also tried to calibrate the the sensing system? Which firmware version and app version do ...

Latest firmware and software.  All up to date. Different locations, same problem.  Tried IMU cal and compass cal. I wonder if this will cause problems with waypoint flights?  Haven't tried them since I fly manually line of sight.
2016-7-2
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Same boat here.  All locations
2016-7-2
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Thomas.
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Germany
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lpcmedic@yahoo. Posted at 2016-7-2 22:26
Same boat here.  All locations

I do have the same problem. Additionally, when hovering it slowly descends until it touches the ground.  I sent my first unit need back to DJI and they exchanged it with a new one. The new device shows exactly the same problem.

I spoke with some guys at the European service center  in Germany and they told me that this is a mathematic problem with the barometric altitude meter which they are not able to correct.  He explained that the longer you fly, the bigger the altitude difference becomes. I wonder why their exchange the first one.  I'm an engineer and have a private pilot license and for me it's very hard to believe that this is true.
2016-7-2
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Mabou2
First Officer
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My altitude indicators are spot on, whether just a quick lift off or through draining three batteries.  Just stating this so you know it probably isn't a firmware issue.  I have all the latest updates, and IOS iPhone 6.
Best of luck.
2016-7-2
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jwt873
First Officer
Flight distance : 6754350 ft
Canada
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Mabou2 Posted at 2016-7-2 14:24
My altitude indicators are spot on, whether just a quick lift off or through draining three batterie ...

Mine is the same...  I have no issues at all with the altitude.  

I guess it all depends on what day the drone was built
2016-7-2
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Heebus
Second Officer

Canada
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I read somewhere that indoors a barometer( not sure on spelling) is used to determine height indoors, is it possible its used outdoors as well, and that it too needs to be calibrated?
2016-7-2
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rliamharpurb
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United Kingdom
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Guys I think it was another dji rep Kevin may have been padalin they checked their flight records and the landing altitude at the end of the flight either shower a negative reading or that it was still above 0m

Can you check your flight logs as sometimes this can be unoticable unless you really pay attention to it

I also posted a video of my phantom idling on the floor, after 5 minutes it showed an altitude of -1.2m and carried on down to -2.4m after a longer duration,

I also posted another video of it hovering 2m high and after 8 minutes or so it showed an altitude of 10. Something m even though it hadn't really moved,

If this is 100% not firmware related I may swap my phantom again. It's not a big issue and doesn't worry me other then 10m could be the difference between missing something during rth and the fact it cost £1300 lol so would prefer as close to perfection as possible

Liam
2016-7-2
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dprovince
lvl.1
Flight distance : 18307 ft
United States
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I am having the same issue.  Has anyone found a fix?
2016-10-28
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Ralphhu
lvl.1

United States
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I have the same problem with a Mavic Pro, all the latest updates on firmware 01.03 on the craft and controller using the GO 4 app.
2016-12-12
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fans8cf0d029
lvl.4
Flight distance : 124672 ft
United States
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Yep, me too.  My altitude and distance are both way off and never consistent.  Has anyone found a cure for this problem?
Thanks,
WA5TEF
2016-12-12
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image23
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Italy
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fans8cf0d029 Posted at 2016-12-12 08:43
Yep, me too.  My altitude and distance are both way off and never consistent.  Has anyone found a cure for this problem?
Thanks,
WA5TEF

Same here. I recently bought a new Phantom 4 and I'm having exactly the same problem of the altitude not being correct.
2017-1-2
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fansa84fe8a4
First Officer
Flight distance : 3 ft
United States
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Very old zombie thread, but yeah, my P4 landing altitude is never zero compared to take-off.  Sometimes 50 deeper (Negative altitude.).  Even flying level over a soccer field it drops in GO.  Playback confirms it too.  Wacky aircraft, or maybe GO.
2017-1-2
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image23
lvl.1
Flight distance : 256686 ft
Italy
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So is it fixable when sending the drone for repair  to DJI?
2017-1-2
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fansa84fe8a4
First Officer
Flight distance : 3 ft
United States
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image23 Posted at 2017-1-2 09:31
So is it fixable when sending the drone for repair  to DJI?

Somehow I doubt it unless it is totally broken.  The new Inspire 2 has redundancy in some sort of dual barometer, IMU, battery, etc. so it may be more accurate than the Phantoms which seem more lax. I've had three of these things and they all have their individual quirks: funky radio, bad camera, feed issues, bad altitudes or speeds, etc.  No doubt a good DJI bench tech could find something wrong with any drone made that the consumer may never know about.  My idea of "Tolerance" may not agree with "Factory tolerance" in anything made too having been a bench tech for a major camera maker.

On point, I've noticed if I fly it in zero wind it seems better than in gusty wind as far as altitude reporting.  Gusty wind also throws off my level horizon too when yawing 90 degrees quickly.  Could be the Phantom just doesn't have a good static port for its barometer and the internal pressure influences it wrongly.  That or the GO is faulty in sampling, but they allegedly did do something in some firmware or GO update months ago to help with the altitude so the matter may still lie there too.

Dunno, guess I'll call it tolerable for me for now until I see some plu-perfect fix for it someplace.  Until then, I won't plan to do some 2,000 foot strafing run 5 feet off the deck in Litchi or Autopilot.


2017-1-2
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Aardvark
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Barometric Altimeters are inherently inaccurate, just google and you'll come up with many examples like This explaining the potential error.
2017-1-2
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Normn8or
Second Officer
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United States
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Are you using the gimbal cover and lock that attaches to the landing gear. If so that is your problem,. There are videos on youtube complaining about the Altitude unsteady problem and they didn't know what was causing it and then there are the videos where users found out that the crossbar that goes in between the landing gears is causing obstruction or partial obstruction of the visual positioning system. They filmed the DJI Phantom 4 and the Autel Xstar pro both with it on first and how they wouldn't hold altitude and also gave incorrect altitude height, then they took the Gimbal protector off of the landing gear and the problem vanished. they did no calibration before test and after test. Here is the video of the test i'm talking about.....
2017-1-3
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Normn8or
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And this guy did a video for DJI Ken, This is the Phantom 4 test..... kinda long and he's over water but still shows that the Gimbal gaurd will mess up the operation of the vision positioning sytem.... He shouldn't have done the test over water when it's known the VPS has a problem with water in the first place but my verdict is if your using such a gimbal gaurd take it off..
2017-1-3
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Normn8or
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I forgot to use your reply button, Check the two posts above this one if your using the Gimbal guard that connects between the Phantoms Landing Gear that is your problem....... {Edit} I didn't realize this is a very old thread. Well still good information. Bad tester on the second video for doing it over water......
2017-1-3
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dwallersv
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Aardvark Posted at 2017-1-2 11:31
Barometric Altimeters are inherently inaccurate, just google and you'll come up with many examples like This explaining the potential error.

^This.

Everyone here is expecting more from the sensors than they are capable of.

The accurate elevation (NOT altitude, BTW) sensor on the P4 is the ultrasonic rangefinder on the bottom, which is good to +/- centimeter, thereabouts. However, its range is limited to something like 33 feet, so it isn't used by the bird for elevation measurement, only positioning and avoidance.

The other ways to sense altitude -- which tared to starting altitude becomes elevation, the datum displayed in the DJI GO app -- is with a barometer. However, since barometric pressure is always changing, it is only really "accurate" for changes in altitude, not absolutely altitude measurement. The latter requires periodic calibration to update for constant barometric changes caused by atmospheric dynamics.

This means that, the longer you fly after takeoff, the greater the potential error in elevation. With volatile weather conditions, ambient BP can easily change enough in 10 minutes to register the equivalent of 10-30 feet of error.

"Volatile" can simply mean windy, BTW. Instability indicates pressure gradients in the atmosphere, which means pressure's going to change as that airmass moves over you.

The other way to sense altitude is via GPS, but this too lacks the +/-1ft accuracy that everyone here (understandably) expects.

So, bottom line, don't look at the "altitude" (actually elevation) telemetry with any more accuracy than +/- 10ft or so.

Now, all that said, consistent errors to one side or the other, again and again, are suspicious. Justifies a deeper look. However, to be "consistent" a group of errors like this must be taken days apart, under different weather conditions ideally. If you simply do several flights in a row on the same afternoon and get the same trend in elevation error, its more likely because the pressure is changing consistently rather than you have a consistent error.

Finally, if you have consistent climbing/descending behavior relatively quickly (like, 3-5'+/min), this is definitely something "broken".
2017-1-3
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Roadstar1700
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United States
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image23 Posted at 2017-1-2 09:12
Same here. I recently bought a new Phantom 4 and I'm having exactly the same problem of the altitude not being correct.

Calibrate your VPS using Assistant 2 software.
2017-1-3
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fansa84fe8a4
First Officer
Flight distance : 3 ft
United States
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dwallersv Posted at 2017-1-3 17:35
^This.

Everyone here is expecting more from the sensors than they are capable of.

Until a DJI engineer comes along to tell us how the drone figures altitude/elevation numbers we won't know.  Could be they do not even use VPS or the sonar in the calculation, but some combo of the GPS and its barometer, or all four, or some three.  Dunno.

However, if my iPad, phone, and handheld Garmin GPS report better numbers and consistent compared to the drone while nearby, then something is off someplace with the DJI.  No way should take-off be zero and a later landing show -50 feet or +50 feet.  A couple of feet okay, but their reported GO numbers are not near accurate enough when other elevation devices nearby are steady and not deviating as wild as the drone.  Change in air pressure while flying, okay some change, but landing it is back to a level comparison field and it isn't there.

Trimble's Surveyor drone for mapping claims an accuracy of 7 inches, but the DJI P4 drone of ours is too far off and I doubt if take-off and landing is zero with most of them after 25 minutes flying time.  If the VPS/sonar was truly accurate and actually used for elevation numbers over aerial braking - or engineered correctly - it should report zero feet on landing as with a sonar tape measure, but mine doesn't nor have the other two I've had and sent back.  I'm skeptical that they use the collision portions for flight elevation to the GO and just for braking, and maybe use just the barometer and GPS combo, but the GPS on many P4's deviate a lot in flight (15 Sats. to 7 and back up again.) so it may be getting spurious GPS signals and tying them together with the barometer and why it fluctuates so fast.  They did one attempt in some firmware/update for altitude fixes months ago, but still haven't nailed it, imho.

As far as I can tell, the things drift over a time period.  Even sitting on the ground it may creep in the numbers in GO so something electronic is drifting someplace or a bum program is running and tabulating bad data.  Take off should equal landing elevation, or very close, if the electronics and compensation circuitry (If it has any, which I doubt as it needs a cold IMU cal. ?? which could point to thermal drift issues.) are working right.

Have to wait and see if they improve it, or perhaps learn if the Inspire 2 with redundancy has better numbers against the P4 series.
2017-1-3
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P4 Pro Birdy
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Australia
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I am having the same problem with my Phantom 4 Pro and hence why I am on this thread. And air pressure does not change that much to effect the errors in altitude we are getting.
2017-4-19
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Phantom of The
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I reported the same altitude reading problem last summer with my Phantom 4.  First outing this year and same problem using new DJI Go 4.0.  Readings all over the place...... -50 to + 50 or more.  Can't rely on readings at all....  Frustrating.Just purchased Mavic Pro today....hope it has better luck with altitude or elevation readings.

2017-5-8
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