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« on: December 14, 2016, 05:34:33 pm »
I'm just getting back into PAW after a rather lengthy hiatus. I have the new bridge and it's working as far as I can tell (after six days not a single P3i transmission received, despite an external antenna out in the clear, but then I am in the far north!).
I am lucky to know my exact altitude (705ft) and I also have a calibrated barometer that is corrected to QNH on site. The GPS reported GNSS altitude does, of course, vary but it is typically within 20ft of actual (less than 1mb error). Correcting for that as necessary, PAW is consistently reporting my calculated QNH as around 2.5mb higher than actual, i.e. around 70ft out. This seems to be a barometer reporting error.
I realise that 70ft is nothing to worry about in practice but I just wonder what sort of nominal accuracy I should be expecting from the bridge barometer? The barometers on the old Harkwood ARF boards, which I still have, were both accurate to significantly better than 1mb.