Idea for Openmoko application: Tide updates

Stroller stroller at
Fri Sep 19 17:48:28 CEST 2008

On 18 Sep 2008, at 13:52, Denis Galvão wrote:
> ...
> Is this possible to use the actual GTA_02 hardware version to do:
> - Compass ?
> - Altimeter ?

This would be really cool for glider (hang-glider, paraglider) pilots.  
They usually carry a combined altimeter / variometer instrument  
(commonly called a "vario", short for vario-altimeter) which, as well  
as absolute height, indicates rate-of-climb with a (LCD) needle and an  
audible beep. It can be impossible at height to distinguish if you're  
going up or down, so pilots rely on this to find thermals in which to  

It's been a few years since I got my feet off the ground, but back  
then combined GPS / altimeter units were not common at all - the first  
one or two models were only just being introduced and were still  
expensive. But such a combination does allow *accurate* calculation of  
the best speed to fly against a headwind (or with a tailwind),  
allowing the pilot to reach the next thermal "trigger  
point" (geographic feature which may be expected to kick off a  
thermal) with the best height and the best chances of catching lift  

Meanwhile all vario units were proprietary software and most premium  
models appeared to be identical hardware to the cheapest ones, so this  
would be an excellent opportunity for the Open-Source community to add  


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