I’m having a problem with my altitude on my new P2v+V3 not reading correctly on the app. It will start out reading 10ft on the ground and will climb without ever leaving the ground. It has read as high as 70ft sitting on the ground.

I have done a basic imu calibration but no luck. My mod value is hovering around 1500/1700 which is way off if I’m understanding what I’ve been able to find on my own. It should be between 500 and 600, correct? Any ideas??

sounds like a defective barometric sensor, send it back for replacement or repair if it's a new unit

Well, here’s the thing. I had 2 P2V+ and had the exact same problem with them. I returned both of them. I figured that I’d give the new v3 version a try hoping that I’d have better luck. I think that since this is the third unit that is doing the exact same thing it HAS to be something I’m doing wrong! I just can’t see getting three defective Phantoms with the same problem.

With the other 2 I even took them 15 miles from where I live to see if it was something in my area causing the problem. I’ve tried 2 different phones, same thing. I tried to reset the compass by rubbing it with a strong magnet then doing the imu calibration. It will get close in the high 600’s but then just climbs to 1500/1700?!

I just can’t believe I have that horrible of luck with these birds!! It has to be something I’m doing I just don’t know what. LOL!!

I don't believe the repeatability of the barometric sensor is good.  I believe that may be normal?  Don't know why they can't be more exact?

the barometric sensors are not high precision but they shouldn't vary that much.  As for your compass yes 1500 is a little on the high side but still within range so wouldn't worry about it ( might be influenced by your local inclination), raw value of over 2200 for the compass would be out of range.

Just curious what your surroundings are where you are trying to calibrate.
Some of my initial checks on IMU calibration etc. on our desktop computer in our home are near a large wall speaker and few other pieces of large electronics. I did not clue in at first.

I later loaded all the software onto a laptop and was sitting at my kitchen table with no electronics or interference of any kind within several feet and found that all of my settings were well within the specified limits. I realized at that point that the other location of my home had been creating havoc. I repeated this several times for both locations and found this to be accurate.

Is it possible that you are trying to make adjustments that could simply be futile due to your surroundings?

in addition, I once tried to launch my phantom from a trampoline in our yard which is also where I tried to calibrate my Compass/set my home point. After several attempts at not being able to get the LEDs on the Phantom showing properly I went several feet away from the trampoline and had no problem at all after that. I determined that the trampoline must have been causing a great amount of interference as it is big, round and made of mostly metal which is probably not good when trying to calibrate the Compass.

Northofthe49th Posted at 2015-2-7 12:17
Just curious what your surroundings are where you are trying to calibrate.
Some of my initial checks ...

dont you mean calibrate the compass not the gps, north49?

Great suggestions! Thanks for the replies.

I
calibrate the compass outside in the empty lot next to my house. As far as where I run the software, it's on my dining room table with my laptop and  there isn't any electronics that would interfere that I can figure.

I just received this unit today so I haven't taken it anywhere else to try it but the other 2 that I had I did take to my parents house. They live way out in the country only to have the same results.

I'll be taking it to another spot tomorrow and bring the laptop and see what I come up with. I'll try to make some video of what I'm doing and post it here. Hopefully that'll help and maybe someone will see something I'm missing or doing wrong!

I'm not claiming to be an expert but I do feel I have a pretty good understanding of what I'm doing but ya never know.

gnixon2015 Posted at 2015-2-7 12:43
dont you mean calibrate the compass not the gps, north49?

Yes, oops!..it was late, will fix

flyingduck88.gm Posted at 2015-2-7 12:54
Great suggestions! Thanks for the replies.

I

Any ferromagnetic or magnetic material in the vicinity of you phantom cause interference to your magnetic compass sensor thus make sure there are no such interferences when you do any of the calibration procedures including the ones done with the computer connected.

so i get the concept of not calibrating around metal or emfs but why would it be bad to take off from a metal object (like a truck bed or car hood or boat) if not near those things when calibrating?

gnixon2015 Posted at 2015-2-8 00:54
so i get the concept of not calibrating around metal or emfs but why would it be bad to take off fro ...

The problem you might get taking off from ferromagnetic surfaces is that it could have some problems holding horizontal position until far enough away from the interference since compass and GPS data might fight each other.

ok that makes sense but im usually at a height of 2-3 meters in just a second or even less (i take off pretty full throttle, get up a few meters and let it hover there to evaluate performance before heading off... that is part of my checklist).  so in that type of situation, isnt the compass interference possibility rather low for me (not negligible but low none the less)?

gnixon2015 Posted at 2015-2-8 02:27
ok that makes sense but im usually at a height of 2-3 meters in just a second or even less (i take o ...

Yeah I'd say that compass interference is pretty minimal at such a distance.

Hi,

Has anyone been able to resolve this issue. I am constantly getting an altitude of  minus 30 meters ( On the ground)  on my Phantom  P2v+V3 . Tried calibrating the IMU etc but nothing seems to work.

Thanks in advance

aidy.outlook Posted at 2015-2-12 20:02
Hi,

Has anyone been able to resolve this issue. I am constantly getting an altitude of  minus 30 me ...

There is no fix other than sending it in for repair or replacing the Naza-M V2 Phantom controller. However I wouldn't worry if it is a constant offset of around -30 feet since GS WP heights and RTH height will include that offset. More problematic would be an offset value that varies greatly over time.

Thanks for your reply, Its actually minus 30 meters / 90 feet. Anyhow I will contact my dealer for advice.

what a load of tosh, to fix this simply restart the phantom after a few minutes and it will stabilize the height reading, its because the IMU is warming up and it reads a different barometric pressure, restarting it resets the settings in the IMU and it will be fine,

I start with about 15ft AGL and after a restart its down to 1 feet.

The Naza in the Phantom is a cheap version in order to get the price down so in essence its a trade off with price versus cost of units.

crash1sttime Posted at 2015-2-13 17:43
what a load of tosh, to fix this simply restart the phantom after a few minutes and it will stabiliz ...

hey crash, when you say restart are you totally powering down the phantom (power off state) or do you mean just powering down the motors and back on again.  assumed the whole bird but wanted to clarify.  i have this problem but usually let mine go if the delta is only a few feet (and is positive) becasue it will not affect where it wants to stop landing only the rth altitude but would like to try your suggestion i think.

I mean fully power it off, hit the big button till its lights go out then wait a few seconds and power on.

crash1sttime Posted at 2015-2-13 20:59
I mean fully power it off, hit the big button till its lights go out then wait a few seconds and pow ...

My experience is the same...usually start out showing -345 ft. on the ground, but after flying for 3-5 minutes, bringing my P2V+ V2 down, power-cycling it, awaiting GPS again, then altitude is closer to being accurate.

crash1sttime Posted at 2015-2-13 17:43
what a load of tosh, to fix this simply restart the phantom after a few minutes and it will stabiliz ...

Not a load of tosh,  why would some units be within 5-6 feet no matter if you just start it up or 10 minutes later and others show a big difference that varies over time.  Btw where does it say in the manual to power up for 5-10 minutes and then power cycle to get an accurate altitude reading?
Sorry but DJI has to get their ducks in a row.

I tried letting mine hover about 15ft off the ground through a full battery.  As it hovered it slowly got closer to the ground.   I throttled back to about 15ft and it slowly dropped again.  Looking at the reported altitude, it was showing about 30ft after I landed.  I'm thinking it is drifting slightly while powered on, but I'm wondering if it is so sensitive that the actual weather changing could be effecting it?  If it can determine pressure difference of only a few feet of elevation, I would think atmospheric pressure might be able to change that quickly too, but I'm no meteorologist.

Generally within the  20 minutes or so you're flying their won't be overly high change in Barometric pressure unless you have a sudden storm front moving in but I'd think you'd already running for cover by then
There is also some change in the alt reading from the props or Wind pressure but that's also not so significant.

Yep, I'm with ya.  Either way, I'm good with it being within 15-20ft or so, it just makes some of the auto landings a little faster than I would like, but 90% of the time I'm landing it myself anyway.  Now if it was incorrect by >50ft, I think I would want it fixed.

There will always be a margin of error but differences of 30 meters/ 100 feet is just too much even worse if it changes by many meters while warming up

kleake.rapfire Posted at 2015-2-13 23:27
I tried letting mine hover about 15ft off the ground through a full battery.  As it hovered it slowl ...

This is the same thing I’m seeing as far as it slowly descending in a hover but mine is off by 40/50 ft+. I’ve done the power cycles and it will start off within 5’ or so but jumps pretty quickly.so I’d have to say it’s not a “load of tosh” too. In a 20’ hover I’m getting readings as high as 70’/80’+

My biggest concern is if I do ground station missions with any real distance, if I don’t set the altitude ridiculously high I’ll be flying into the ground! LOL!
I asked the initial question in hopes that the problem was user error since as I said up top, this is the 3rd bird doing the same thing. I guess it’s just the way it is.

Got it all figured out
The numbers are right, it's the Earth in the wrong place.  {:3_64:}

crash1sttime Posted at 2015-2-13 17:43
what a load of tosh, to fix this simply restart the phantom after a few minutes and it will stabiliz ...

Okay, the weather has gone to pot here so I haven’t been able to mess around with this thing much. I took some time today and played around and would have to agree with crash1.
When I first power on the phantom the altitude will jump to 14’ and rapidly climb from there to well over 50’. If I let it sit there idle for say 30seconds to a minute then power cycle JUST the phantom the altitude will hover around 10’ to 15’ and on the second or third power cycle it’s pretty much spot on with maybe a 2’ to 5’ variance!
It’s defiantly a pain in the butt starting procedure but it works at least in my case. So a big thank you to crash1sttime!!!

I am having same issue. So not users fault.

Just to corroborate,I also see this first time I fly.  After a power cycle the altitude sets itself correctly.