Good Morning, I´m Ph2 V+, Ph3 Pro and Ph4 Pro owner, and I want to know the accuracy of their barometers.
Thank you.
Fabian

I'm sure it has a tolerance, but nothing is exact or perfect.   It is very close tho.   Why did you double post?  

The barometer is used for maintaining height, but a deviation may occur due to the barometer’s accuracy.

The barometer may encounter interference from airflow disturbances caused by the propellers rotating.

Also, barometer performance may be affected by environmental conditions, such as high winds and the abnormal airflows between buildings.

To maintain a constant altitude in a variety of situations, additional sensors need to be used, such as vision sensors and ultrasonic sensors.

ALABAMA Posted at 2018-6-1 04:13
I'm sure it has a tolerance, but nothing is exact or perfect.   It is very close tho.   Why did you double post?

Cause I have 3 models (PH2 V+, Ph3 Pro and Ph4 Pro)  and try to see the differences between them. I need to know the accuracy ameasurement to obtain height data..

Thanks to all.

T&T Ing Posted at 2018-6-1 08:48
Cause I have 3 models (PH2 V+, Ph3 Pro and Ph4 Pro)  and try to see the differences between them. I need to know the accuracy ameasurement to obtain height data..

Thanks to all.

You'll need RTK system to obtain centimetre accuracy, using GPS triangulation. Barometric measurements are way less accurate and prone to be affected by various environmental conditions. I would estimate approx. +/- 3 ft. accuracy of barometric sensors.

Matthew Dobrski Posted at 2018-6-1 09:41
You'll need RTK system to obtain centimetre accuracy, using GPS triangulation. Barometric measurements are way less accurate and prone to be affected by various environmental conditions. I would estimate approx. +/- 3 ft. accuracy of barometric sensors.

Hi, i have and SP60 GNSS RTK, but i only know barometer thecnical data.

In Ph3 pro data, the GPS accuracy is specificated, but no extra data is given to barometer. For example:

Hover Accuracy Range        Vertical:
±0.1 m (with Vision Positioning)
±0.5 m (with GPS Positioning)
Horizontal:
±0.3 m (with Vision Positioning)
±1.5 m (with GPS Positioning)  

(https://www.dji.com/phantom-3-pro/info)

T&T Ing Posted at 2018-6-2 05:43
Hi, i have and SP60 GNSS RTK, but i only know barometer thecnical data.

In Ph3 pro data, the GPS accuracy is specificated, but no extra data is given to barometer. For example:

T&T, hovering accuracy has nothing to do with GPS reading accuracy. This specification for Phantom 3 you're referring to merely tells you how big is the estimated space where the drone will wobble within and about measured position. How accurately this position is measured by internal GPS receiver is what you're after, and Phantom 3 aren't the best at it. Newer generation of DJI drones (P4P, Inspire 2, Matrice 200) have better, more accurate sensors, but still no cigar. Again, only onboard RTK systems which M210 can be equipped with, may give you precise GPS positioning you're looking for. Anything below this class of equipment will provide you with ball park info only, good enough for safe piloting.

Matthew Dobrski Posted at 2018-6-2 11:05
T&T, hovering accuracy has nothing to do with GPS reading accuracy. This specification for Phantom 3 you're referring to merely tells you how big is the estimated space where the drone will wobble within and about measured position. How accurately this position is measured by internal GPS receiver is what you're after, and Phantom 3 aren't the best at it. Newer generation of DJI drones (P4P, Inspire 2, Matrice 200) have better, more accurate sensors, but still no cigar. Again, only onboard RTK systems which M210 can be equipped with, may give you precise GPS positioning you're looking for. Anything below this class of equipment will provide you with ball park info only, good enough for safe piloting.

Matthew, the DJI aircraft do not use GPS data for height measurement, as it is way too inaccurate. The 'barometer' is a simple solid state pressure sensor, and all it measures is air pressure and converts it to a figure that shows the aircraft height relative to where it took off from.

Geebax Posted at 2018-6-2 15:34
Matthew, the DJI aircraft do not use GPS data for height measurement, as it is way too inaccurate. The 'barometer' is a simple solid state pressure sensor, and all it measures is air pressure and converts it to a figure that shows the aircraft height relative to where it took off from.

Sorry, my mistake. I'm under impression that RTK system is somehow involved in determining the accurate drone attitude among X/Y coordinates, since commonly used primitive barometric sensor can't be good enough ...

Matthew Dobrski Posted at 2018-6-3 01:27
Sorry, my mistake. I'm under impression that RTK system is somehow involved in determining the accurate drone attitude among X/Y coordinates, since commonly used primitive barometric sensor can't be good enough ...

I do believe that DJI have an RTK system, at least undergoing trials. Whether it is available, I don't know. That would provide a quantum leap in accuracy for height, but it requires you to use the system in a limited area and you have to have a base station employed on the ground to make it work.

Geebax Posted at 2018-6-3 17:27
I do believe that DJI have an RTK system, at least undergoing trials. Whether it is available, I don't know. That would provide a quantum leap in accuracy for height, but it requires you to use the system in a limited area and you have to have a base station employed on the ground to make it work.

Oh, so we weren't on the same page, I assume . Yes, DJI developed an RTK system of this kind and employed on Matrice 210 drones.

Matthew Dobrski Posted at 2018-6-3 20:38
Oh, so we weren't on the same page, I assume . Yes, DJI developed an RTK system of this kind and employed on Matrice 210 drones.

Sorry, I meant DJI appear to be trialling an RTK system on a P4, not just the Matrice. There have been photos of a P4 equipped with such a system.

But in any event, even the P3 is very accurate. Mine, even in a stiff breeze, sits almost perfectly still in the sky.

Geebax Posted at 2018-6-2 15:34
Matthew, the DJI aircraft do not use GPS data for height measurement, as it is way too inaccurate. The 'barometer' is a simple solid state pressure sensor, and all it measures is air pressure and converts it to a figure that shows the aircraft height relative to where it took off from.

"DJI aircraft do not use GPS data for height measurement, as it is way too inaccurate"
It must be using it to something when it take the effort to read/calculate the values and stamp it to the EXIF information. Apparently not very useful but used by the aircraft anyway.

Geebax Posted at 2018-6-3 20:45
Sorry, I meant DJI appear to be trialling an RTK system on a P4, not just the Matrice. There have been photos of a P4 equipped with such a system.

But in any event, even the P3 is very accurate. Mine, even in a stiff breeze, sits almost perfectly still in the sky.

Brother Geebax, OP is not talking about the ability of the drone to hold attitude steady while hovering. This talent has nothing to do with accuracy of barometric sensor. Sensor sufficiency? Perhaps yes, but not accuracy.

Instead he want to know how accurate is attitude measurement as being displayed on the app screen. To answer this question ... land two or three drones on the roof of an building and compare the readings to find out ...

As for attitude stability ... Phantoms are particularly good holding attitude, wind or not. Unfortunately I can't say the same about my Inspire 1. She may bounce a meter or two while shooting a pano in windy conditions, or just during landing gear rise.

Matthew Dobrski Posted at 2018-6-4 00:31
Brother Geebax, OP is not talking about the ability of the drone to hold attitude steady while hovering. This talent has nothing to do with accuracy of barometric sensor. Sensor sufficiency? Perhaps yes, but not accuracy.

Instead he want to know how accurate is attitude measurement as being displayed on the app screen. To answer this question ... land two or three drones on the roof of an building to find out ...

OK den, I must have missed the meaning in his question. I will now STFU