differential altitude measurement

Phaedra DG

Hello everyone,

I am searching for a solution to measure the altitude difference between 2 locations, to a mm accurate (!).

One possible solution to this would be to measure the barometric altitude at both locations, and have the microcontrollers communicate their altitude to each other.· The problem is that I can not find any sensor that measures with this precision (or it would be terribly expensive).
Another solution would be to work with accelerometers (3 axis), and calculate the displacement when I move the sensor from one location to the other.· But this would pose other problems, like measuring the rotation of the accelerator platform, and the performance of the whole (will shocks be measured correctly ?)

Any other ideas ?


Thanks,

Phaedra

Phil Pilgrim (PhiPi)

Can you describe the two locations? Indoors or outdoors? Mountaintops? Buildings? Boxes? How far apart are they? Are they visible from each other?

If they're far apart, you also have to specify which geoid you want ot use as a baseline for the altitude measurement, since the earth is not a perfect sphere.

Millimeter accuracy is a bit ahead of the envelope, I fear; but maybe, if we knew more, somebody could come up with some suggestions.

-Phil

Phaedra DG

Hello Phil,

thanks for the reply.

The idea I'm trying to implement is to communicate a "level" from one room to another, or even between two buildings, not necessarily in "line of sight".· If I want - for instance - to communicate the height of a window in one room, to another room (to put the windows at the same height).

If it were in line of sight, I could use a laser.· But in this example, that would not be possible.

Phil Pilgrim (PhiPi)

A hose with clear sight tubes at each end and filled with water would be a good low-tech approach. The water level will be at the same "altitude" at both ends and can be used a reference. No fancy electronic gizmos needed!

-Phil