On 14/07/2014 02:53, Tudor Hughes wrote:
On Sunday, 13 July 2014 18:22:10 UTC+1, Tim wrote:
I came across an app (CPUZ for Android in the Google store) which I wanted for another reason. I was rather surprised that there's a barometer in my Samsung S3 giving hPa to one decimal place. I have no idea how many phones have this sensor, but the app is free.

Us it as an altimeter. 37 mb per thousand feet.

Tudor Hughes, Warlingham, surrey.


It would be interesting to know just how this android unit works for
barometric pressure. A quick Google and I'm none the wiser. If it is a
barometric pressure sensor, which I doubt, then all well and good.
Nevertheless that will still require regular resetting to QFE or QNH,
for example, in order to provide accurate altitude. However if the
'phone is calculating pressure from the GPS sensor then the
altitude/pressure will be less accurate-see below. On the other hand for
*changes* in these parameters then it would be fine.

Civilian GPS are fine for navigation being accurate to within 5-10m
(horizontally) 95% of the time but only 15-20m (vertically) 95% of the
time. (Military GPS are better than this).

A neighbour was recently singing the praises of his Garmin GPS. He
quoted an altitude for our location which as I pointed out would put us
some distance away at the foot of the hill close to a busy road. The
definitive source for altitude is the OS map with the 175m contour
passing through our gardens.

I must get out more

--
George in Swanston, Edinburgh, 575'asl
www.eppingweather.co.uk
www.winter1947.co.uk