Height and Distance

Joined
Feb 22, 2017
Messages
25
Reaction score
11
Age
68
Can someone tell me how to correct the height & distance numbers.
The numbers are totally off.
 
Tell us more about your problem. Why exactly do you think those values are incorrect?
 
This is why, When I ascend the numbers start minus, I could be at least 100ft but its telling me I'm only at 35ft, and when descending its the same, when I finally land, the numbers are telling me I'm minus 45ft.
 
Are you setting the home point when aircraft is in the air?
 
If that's what's happening, you probably have a bad barometer circuit. When you first power very thing up, altitude should read 0 (as I'm sure you realize). If not, that's one indicator that there is a problem with the circuit. If you just let it sit with the props turning for 5-10 min, does the altitude change or drift? You mentioned distance too. What's happening there?
 
Are you setting the home point when aircraft is in the air?
Setting the home point only marks the longitude and latitude position. It does not affect the altitude.
 
With the distance, the drone could be 3ft away from the rd but those number go up and down, also the altitude changes even when it's still on the ground
 
Setting the home point only marks the longitude and latitude position. It does not affect the altitude.

Setting home point in air is misleading, actual distance looks totally different than the feel. It's a judgement.

OP has wrong values for position and altitudes.
 
Distance telemetry is based on GPS readings, which have typical error +/- 10-20ft. Under poor satellite geometry, resulting in a high DOP, location errors can get as high as 50-100' (rare, but they do happen).

Under normal circumstances, do not expect precision better than a 30' radius around the home point. Most of the time it will be better, many times much better. However, you will eventually fly some time when the sat configuration is not favorable, and be surprised to see an RTH land 25 feet away.

As for the altitude, barometric sensors are subject to error from changing barometric pressure due to weather. Any time there is significant weather activity in the area, pressure changes.

In 20 minutes flying, it isn't abnormal for pressure to change enough in your locale that an error as much as 20-30' can occur. This is the reason for the ultrasonic rangefinders on the bottom of the craft -- when closer than 30', greater accuracy is needed than a barometric altimeter.

As @msinger points out, however, immediately after powering up before flying, it should tare itself to 0ft, at the current (startup) pressure. If not, something's wrong.
 
This is why, When I ascend the numbers start minus, I could be at least 100ft but its telling me I'm only at 35ft, and when descending its the same, when I finally land, the numbers are telling me I'm minus 45ft.
The usual thing to do when your altitude numbers are out is the recalibrate the IMU.
Do it indoors on a perfectly level surface.
 
The usual thing to do when your altitude numbers are out is the recalibrate the IMU.
Do it indoors on a perfectly level surface.
No, don't do it indoors unless you're in an unheated, cold room/building. I made the mistake of doing it at room temp, and now it takes 2-5 minutes for the IMU to "Warm up" when I power it up.

As has been suggested in many threads where this subject comes up, find a cold place to do it. 50's-60's (farenheit). This will keep the startup time reasonable.

I plan to redo mine in colder conditions eventually, but it's a PITA, so I haven't gotten around to it. I can say from direct experience it's very annoying.
 
No, don't do it indoors unless you're in an unheated, cold room/building. I made the mistake of doing it at room temp, and now it takes 2-5 minutes for the IMU to "Warm up" when I power it up.
The important thing is to do it on a level surface and these are easier to find indoors.
 
The important thing is to do it on a level surface and these are easier to find indoors.
Well yeah, but in my opinion that's a very minor advantage. It's trivial to create a level surface with a level. If a drone enthusiast doesn't have one, s/he should simply go out and buy one for this purpose.

It's certainly worth it to avoid the agonizingly long warmup times.
 

Members online

Forum statistics

Threads
143,066
Messages
1,467,358
Members
104,935
Latest member
Pauos31