Pressure Sensor to Measure Height

Projects General Guidance
1

Hi,
I was going to use the pressure sensor here http://ie.farnell.com/jsp/search/productdetail.jsp?sku=1457151
to measure altitude.
What i am doing is putting this sensor on the arduino and logging maximum altitude of my remote control helicopter.
Question is - will a sensor like this be sensitive enough for centimetres accuracy. e.g if i take off at height 0 and climb to 1 ft - will the sensor be able to see a pressure change at this small change in altitude or is this just not possible with this sort of sensor?
thanks
Damo

2

Sensitivity, V/P:45.9mV/kPa

What is the pressure difference between, say, sea-level and sea-level plus 30cm?

3

good question -
according to this Atmospheric Pressure vs. Elevation above Sea Level
the KPA difference from 0 to 500m height change is 1.5 KPA
so the sensor mv would change by (45.9mv X 1.5)

if the sensor states Sensitivity, V/P:45.9mV/kPa then will the voltage only jump in increments of that or will it jump by e.g .001 mv so i can be really accurate?

thanks
Damo

4

Do you want to look again at that pressure change?
I make it 1.5 kPa over 152m.
Not sure where (45.9mv X 2) comes from either.

So, what does that give you as a pressure difference over 30cm?

5

(152 x100)/1.5)x.3

6

..somebody offers a miniature pressure senzor to be used in mobile phones (google it) with digital output, they claim 80cm resolution from -700m to +8km. p.

well, "..extremely high-resolution measurements..": STMicroelectronics MEMS pressure sensor – Dangerous Prototypes

7

Pressure alone is not enough to determine altitude, especially not that accurate. Temperature, density, humidity, and local deviations from the globally-averaged gravitational potential all play a role in atmospheric pressure. You can get a SHT1x, SHT7x, or SHT2x and incorporate that into your project (they're so small they're practically weightless, though you will need to find a library to work them properly) and then do tons of math, or you can buck all that and get a gps module that returns altitude. The one I'm using currently is GPS Shield Retail Kit - RTL-10709 - SparkFun Electronics.

8

.it seems to detect 1ft is not feasible today... 3ft would be feasible, for flight in a range of +/- 30m the other influences could be neglected..

9

.somebody offers a miniature pressure senzor to be used in mobile phones (google it) with digital output, they claim 80cm resolution from -700m to +8km.

Which might work, if you have a 14 bit (or better) ADC.