[pitou2k]

All the firmwares I tested, even the 167, using GPS applications, it reports a negative altitude.

i.e. Paris -162 m, below the see?

[beartenor1]

I have an 8830 on Sprint and Spot always reports a negative altitude for me as well ( -550 ft in Huntsville, Alabama ).

[PittsDriver]

What program are you using to see altitude?

[Branta]

All the firmwares I tested, even the 167, using GPS applications, it reports a negative altitude.

i.e. Paris -162 m, below the see?

Altitude is the least accurate parameter determined by GPS. If your position is correct (Latitude, Longitude or as shown on a map) don't worry too much about it.

FWIW I have seen a 20,000 tonne ship go from near sea level (alt = 0) to +300 metres if the GPS was to be believed (This was a good quality approved marine GPS). We suspected local interference to the radio signals, probably a microwave radio link but it was never proved.

[ohbarnes]

I have the same problem on 8310 with most GPS software (GPSed, TrekBuddy, GPSTracker, bbTracker) except InstaMapper (http://www.instamapper.com/download/GPSTrackerBB.jad) which shows the same altitude without the -XXXft

[jonasbeaver]

get WAAS for the phone
Wide Area Augmentation System - Wikipedia, the free encyclopedia
its only a $5k upgrade for the plane i fly...

that said, my GPS seems to be within about 30 feet horizontal and 300 feet vertical, that is about what you can expect with a normal GPS

[ydaraishy]

WAAS won't work on a phone. You need separate dedicated equipment for that.

[AP1618]

some applications give an option to remove the minus sign. i think blackstar and GPSlogger have that option.