Hi,

Anyone else experiencing wrong altitude readout with the Air2s. I have seen a few videos online and it seems i am certainly not the only one.
I am allready at my second Air2s because the first one wouldn't fly correctly. Now the replacement has extremely poor range and the altitude readout close to ground is wrong on every flight. Severe negative readout yet staying on perfectly level terrain?? After a short flight when still being at like 5 m height, the readout on the app would for example be -2.5m and more?? Surely at that point the sensors should correct the barrometric readout no?
I also start loosing video connection before even reaching 500m distance? Is this the second 'dud' in a couple weeks?
I am starting to regret my purchase and am loosing confidence in the quality of dji products fast??

After a short flight when still being at like 5 m height, the readout on the app would for example be -2.5m and more??
It's common and normal for the altitude shown by the barometric sensor to diift 10 or more feet over the duration of a flight

Surely at that point the sensors should correct the barrometric readout no?
No .. what sensors would you suggest, and how would that work?
If the error in yours is excessive, it might be improved by recalibrating the IMU, but you'll still see some normal variation.

Labroides Posted at 8-14 18:28
After a short flight when still being at like 5 m height, the readout on the app would for example be -2.5m and more??

It's common and normal for the altitude shown by the barometric sensor to diift 10 or more feet over the duration of a flight

I don't agree that a difference that big should be normal or acceptable in any way. did another flight just now and with the drone about 8m up (24ft) the readout said -2.6m (7,8ft), that is nearly 32ft off, surely a dji drone is expected to do better than that? With those kind of readouts what is the point of even putting the height indication on the app as it is completely off the mark and unreliable.

I did a full re-calibration and it did not fix the issue. The previous Air2s i had did not have the issue at all (however it needed to be returned for a different issue) so i think i can clearly assume that this is not normal. I also see other videos and posts online from people experiencing the same issue with the Air2s. These users have multiple drones and all report not having the issue in any of their other drones. So, maybe its time to just admit that at least some Air2s have a serious issue? A 32ft difference in the negative sense on my RTH height could have serious consequences

As for the sensors, i was under the impression that the bottom optical sensors also did a height measurement? just like the top ones will tell you at what height an obstacle above the drone is located and could therefore double check the barometric readout and adjust if needed. I guess it doesn't because it could mistake an obstacle for ground and adjust unwanted, so, fair enough.

BartClaes Posted at 8-15 01:35
I don't agree that a difference that big should be normal or acceptable in any way. did another flight just now and with the drone about 8m up (24ft) the readout said -2.6m (7,8ft), that is nearly 32ft off, surely a dji drone is expected to do better than that? With those kind of readouts what is the point of even putting the height indication on the app as it is completely off the mark and unreliable.

I did a full re-calibration and it did not fix the issue. The previous Air2s i had did not have the issue at all (however it needed to be returned for a different issue) so i think i can clearly assume that this is not normal. I also see other videos and posts online from people experiencing the same issue with the Air2s. These users have multiple drones and all report not having the issue in any of their other drones. So, maybe its time to just admit that at least some Air2s have a serious issue? A 32ft difference in the negative sense on my RTH height could have serious consequences

What do you mean by "a full recalibration"?
Did you recalibrate the IMU? (because nothing else would have any effect on the altitude measurement).

As for the sensors, i was under the impression that the bottom optical sensors also did a height measurement? just like the top ones will tell you at what height an obstacle above the drone is located and could therefore double check the barometric readout and adjust if needed.

The downward facing sensors do measure the height of the drone above whatever is below it (within the limited range of the sensors).
But the screen height is showing height above launch point.
Unless the drone is directly above the launch point or the local terrain is perfectly flat and level, there's no way to correlate the VPS height and the barometric height.
The VPS sensors show differing heights if the drone is above an obstacle or terrain of a different height from the launch point.

Labroides Posted at 8-15 03:49
What do you mean by "a full recalibration"?
Did you recalibrate the IMU? (because nothing else would have any effect on the altitude measurement).

Recalibrated IMU, compass and sensors, so everything. I might be wrong but it also seems like the discrepancy is fairly consistent which could simply point at a bad barometric sensor.

500m height? Where in Belgium is that legal? DJI makes a drone that works great, but not in ranges that are illegal.

AlexanderK Posted at 8-16 03:46
500m height? Where in Belgium is that legal? DJI makes a drone that works great, but not in ranges that are illegal.

DJI make drones for other countries as well as Belgium.
And Belgium isn't flat.
You have a number of mountains that are almost 700 metres there.

AlexanderK Posted at 8-16 03:46
500m height? Where in Belgium is that legal? DJI makes a drone that works great, but not in ranges that are illegal.

The 500m reference was in regards to distance, not height. The drone has altitude issues as well as very poor reception/signal distance wise

Labroides Posted at 8-16 03:59
DJI make drones for other countries as well as Belgium.
And Belgium isn't flat.
You have a number of mountains that are almost 700 metres there.

jip... thats called AGL (Above Ground Level). It's not measured from sea level. I'm sure all basic drone courses cover this.

BartClaes Posted at 8-16 09:31
The 500m reference was in regards to distance, not height. The drone has altitude issues as well as very poor reception/signal distance wise

Ah my bad, I misread and assumed you talked about height.

AlexanderK Posted at 8-16 10:52
jip... thats called AGL (Above Ground Level). It's not measured from sea level. I'm sure all basic drone courses cover this.

Sorry .. the point you are trying to make isn't coming through.
What were you trying to say?

Labroides Posted at 8-16 16:10
Sorry .. the point you are trying to make isn't coming through.
What were you trying to say?

Did you take a drone course? If a mountain is 700 meters high (measured from sea level) of course you can fly there. Basic knowledge you should have flying a drone.

Or what point did you want to make with your "mountains that are almost 700 meters there"?

AlexanderK Posted at 8-16 21:33
Did you take a drone course? If a mountain is 700 meters high (measured from sea level) of course you can fly there. Basic knowledge you should have flying a drone.

Or what point did you want to make with your "mountains that are almost 700 meters there"?

Did you take a drone course?
I understand drone flying iof that's what you are asking.
I've been flying professionally for 6 years.

Or what point did you want to make with your "mountains that are almost 700 meters there"?
I tried to point out that your earlier post made no sense.

You said:  500m height? Where in Belgium is that legal? DJI makes a drone that works great, but not in ranges that are illegal.
First, DJI drones are made for use in all countries, not just Belgium.
There are many situations, even in Belgium where it could be completely legal to fly 500 metres higher than your launch point.
Drone altitude regulations all over the world are based on the height of teh drone above the ground (below it) and not height above launch point (which is what's shown on your screen).

BartClaes Posted at 8-15 10:41
Recalibrated IMU, compass and sensors, so everything. I might be wrong but it also seems like the discrepancy is fairly consistent which could simply point at a bad barometric sensor.

No. Baro, GPS are both not very accurate at height. All GNSS systems available to normal people has a variance more than 8-15 meters vertically.  Barometers are also easily affected by weather and hot/cool air flows... so your drone basically has no way to figure out its height with pinpoint accuracy once if it's out of VPS range.

FriedChicken_II Posted at 8-16 21:56
No. Baro, GPS are both not very accurate at height. All GNSS systems available to normal people has a variance more than 8-15 meters vertically.  Barometers are also easily affected by weather and hot/cool air flows... so your drone basically has no way to figure out its height with pinpoint accuracy once if it's out of VPS range.

And DJI drones don't use GPS for altitude information anyway.

Labroides Posted at 8-16 21:57
And DJI drones don't use GPS for altitude information anyway.

On the official spec list:

Vertical:
± 0.1 m (with vision positioning)
± 0.5 m (with GNSS positioning)

FriedChicken_II Posted at 8-16 22:19
On the official spec list:

Vertical:

Yes ... it says that, but DJI drones get their altitude input from a barometric sensor, not from GPS
If they used GPS, they wouldn't be able hold altitude that well.

FriedChicken_II Posted at 8-16 22:19
On the official spec list:

Vertical:

That figure for GNSS  accuracy will not be real, GPS systems do not measure altitude to that degree of accuracy, no matter whose GPS system is in use. And yes, I realise that it is a published DJI specification, but it is not achievable, much like their flying endurance times.

FriedChicken_II Posted at 8-16 22:19
On the official spec list:

Vertical:

When the specs show: with GNSS positioning, thats as opposed to when using VPS for positioning.
It's poorly worded, like a lot of DJI documentation.
If they spelled it out properly, it would say:  When using GNSS for horizontal positioning and barometric sensor for vertical positioning.

Talking about the transmitting power, in CE mode signal strength is really poor in Europe, flying in airplane mode and pointing the controller towards the drone is a must all the time. If there's heavy interference in the 2.4Ghz band range can become quite poor because the 5.8Ghz has so low power that is not usable at all.

You can easily solve that with the DH desktop app, which enables FCC mode in Europe (doubles the power in 2.4Ghz and quadruples in 5.8Ghz). I've been using it for a while in dual band transmission mode and the signal strength is just awesome, by far the best thing you can buy for your drone together with the oficial sunhood for the RC-N1.

Labroides Posted at 8-16 22:50
When the specs show: with GNSS positioning, thats as opposed to when using VPS for positioning.
It's poorly worded, like a lot of DJI documentation.
If they spelled it out properly, it would say:  When using GNSS for horizontal positioning and barometric sensor for vertical positioning.

It's a fushion system, not just barometer or GNSS. In fact, both barometer, GNSS and acceleration meters are used and multiple streams of data would go through a couple algorithms to mix together. Baros are good at stationary, relative altitude measuring, GNSS are good at large range / change and calibration, acceleration meters can be used by going through the reversed attitude matrix and use integrals to calculate instant changes. The 3 sensors are combined to get a height, each has different weight in different situation.

So i did another simple test flight in the garden today. Standing on the take-off point with the drone hovering right in front of me at head height (I am about 1.85m), the read out on the app is -12.6m
Are you all saying that i should accept this as being perfectly normal? And if so... what is the purpose of the height indication on the app???
In addition, and while we are on the subject. Are you all saying that you are all happily flying your drones and getting these kinds of results in the app, being perfectly fine with it? ie. you don't really care when flying your drone and looking at your controller/app at what height your drone actually is?

Yo tengo el mismo problema. No registra en el matadato la altura sobre el nivel del mar sino registra la altura en referencia al punto de origen. Esto NO me pasó nunca con drones anteriores como phantom 4, phantom 4v2, inspire 2, es mi primera vez... Y en el metadato de la foto no está registrado la altura absoluta más bien se repite la altura de vuelo....
COMO REPARAR ESTE ERROR DE DJI?

AlexanderK Posted at 2021-8-16 03:46
500m height? Where in Belgium is that legal? DJI makes a drone that works great, but not in ranges that are illegal.

I believe he said 500 distance, not 50 height