# Calculate the resolution of pressure sensor ( altimeter ) ?

1. Jul 27, 2015

### ThienPhuNg

1. The problem statement, all variables and given/known data

How can I calculate the resolution of a pressure sensor used to measure hight ( altimeter ) ? We have barometirc equation ( refer to http://hyperphysics.phy-astr.gsu.edu/hbase/kinetic/barfor.html#c3 ) , and I can't find out the solution.

Can the resolution be the same as the sensitivity which infered by diriving the barometric equation ?

2. Relevant equations
Barometric equation

3. The attempt at a solution
I can't attempt an solution because of being stuck in many problems =.=

2. Jul 27, 2015

### DEvens

You can't get the sensitivity of a pressure sensor from the equation you will use the pressure in. You need to know something about the device you will use.

Just to emphasize, here is an extreme example. Some pressure sensors consist of a diaphragm that pushes a "dimple" in or out. If the pressure rises above some set point, the dimple pops in. It stays there until reset. The sensitivity of such a device is "the pressure went above X" and that's it.

Other pressure sensors are much more sensitive and have much better resolution. This will be a characteristic of the device.

That sensitivity will then allow you to infer a sensitivity to altitude using the equation you refer to. Plus you need to know some estimate of the barometric pressure at some reference altitude. That gives you the $P_0$ in your equation. For example, planes frequently get barometric pressure readings for local airports. They then use this to update the reading on their on-board equipment.