Pages: [1]   Go Down
Author Topic: altitude detector  (Read 878 times)
0 Members and 1 Guest are viewing this topic.
Offline Offline
Jr. Member
**
Karma: 0
Posts: 53
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

 smiley-zipper i everyone...(nice day in paris !! )

i 'looking for an intgrated circuit who provide me the altitude of my position , i'dlike to feet it in my arduino uno , so if it is in i2c mode, it will be great.. smiley-lol

do you know circuits like this ?

best.....
Logged

Belgium
Offline Offline
Full Member
***
Karma: 6
Posts: 135
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Since your not very clear on the range of altitude  cm's  or  100's meters  i'm just going to assume the latter.
I can thing of two methods:
  • a GPS module
  • an absolute barometric pressure sensor
Salut...
Logged

Gear: Arduino- Uno,Due,Ethernet,  OLS, Buspirate, J-Link, TDS1002, Rigol DG1022

0
Offline Offline
Shannon Member
****
Karma: 207
Posts: 12190
Arduino rocks
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

And further its worth knowing that GPS altitude information is complicated by the geoid.

The geoid is the shape of the gravitational equipotential corresponding to what is colloqually called sea-level.
It is not regular - it has lumps and bumps of several 100m all over the earth due to the varying density of
rocks in the earths crust.  GPS determines geometrical position and has to then correct for the local geoid
variation, which is done to much less accuracy than horizontal position (and different GPS units may do
different corrections and not agree with each other.)  Also since GPS satellites are typically over-head the
vertical positional accuracy with GPS is usually a lot less than horizontal accuracy anyway.

However GPS does measure absolute altitude.  Barometric sensing is affected by the weather so without
access to the local pressure at a reference altitude it isn't very useful - in aircraft the altimeter has to be
regularly reset according to the local weather information.  Barometric sensors are now very precise, being
able to measure pressure changes corresponding to less than 1m change in height (in the short term).
Logged

[ I won't respond to messages, use the forum please ]

Offline Offline
Jr. Member
**
Karma: 0
Posts: 53
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

 smiley-zipper thank you every one for the answers , i gona look for a simply solution;

i saw the MPL115A2 i2c cicruit,  smiley-eek i'm going to see if it's good for my apply...

Logged

Offline Offline
Newbie
*
Karma: 0
Posts: 12
View Profile
WWW
 Bigger Bigger  Smaller Smaller  Reset Reset

You might also want to look at the BMP085.  I've been using one very successfully to read altitude.  There's a tutorial located here: http://learn.adafruit.com/bmp085.

Mitch
Logged

Croatia
Offline Offline
God Member
*****
Karma: 13
Posts: 508
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

I'd like to ask you to make sure really you need altitude and not height or elevation.
It could be an important factor in determining the best approach.
Logged

Offline Offline
God Member
*****
Karma: 13
Posts: 587
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Barometric sensors work well for rocketry, However they get zeroed at the location.
Driving around with one however can give very erroneous results, as others have pointed out local pressure variations affect them.
Logged

0
Offline Offline
Full Member
***
Karma: 5
Posts: 238
Arduino rocks
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

If all you want is relative difference in altitude between your location and some other location, say a low-altitude weather balloon, you can use a MPL115A2 on the balloon and one at your location and the difference in atmospheric pressures will tell you the difference in height.  Using the differential pressure method reduces the effects changes in the weather, note I said reduces the effects not eliminates.  After working on systems like this I can tell you the baro method of height estimation will be more accurate then the GPS method in the majority of cases.
Logged

Offline Offline
Jr. Member
**
Karma: 0
Posts: 53
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

right ! 5u very much for all the aswers; here is my appli :

i want to detect in real time the altitude of my position during a travel in my car from point "a" to point"b" and i want to extract the values to get the final curve.

i only want to know what kind of detector is the best for this.....

many thanks... smiley-mr-green
Logged

Pages: [1]   Go Up
Jump to: