ALTITUDE

[NAVYSCHIEF]

HOW CAN I FIND THE ALTITUDE OF CITY I LIVE IN. I'M TRYING TO SET GPS

(Edited by NAVYSCHIEF at 5:25 pm on June 17, 2002)

[Tinhorn]

I guess the best way is using a Topographic Map for where you are. ###You can get them Free from topozone.com, just input your location, either UTM or Long/Lat from the GPS. ### ###You need to look at the Contour Lines to figure out your elevation or some rather large lakes might have the elevation.

BTW, ###most GPS units don't do very well when it comes to elevation, the manuals seldom publish the accuracy but it's terrible. ###I understand when the WASS system is fully functional, it'll be pretty accurate tho, like 3 meters.

Tinhorn

[wmidbrook]

None of the publicly available GPS's will do altitude worth a hoot--this is by design for defense purposes. ###The military uses a different frequency for altitude. ###It's possible that that your altitude reading will be even more off when the military is on alert.

I heard the reason for this is so that enemy misssles/pilots can't effectively use our GPS signals against us.

(Edited by wmidbrook at 8:30 am on June 30, 2002)

[Oregon Archer]

Everytime i turn my GPS on at home and look at the elevation i get a different reading than the time before. Itll usually range +/- 25ft or so. So its not real accurate but just a round about figure.

[karstic]

The altimeters on GPS receiver use barometric pressure to determine altitude. Thats way the reading can change over time while staying in the same location.

[Washington Hunter]

Most GPS units that I know of don't have an altimeter. They calculate altitude the same way they calculate your horizontal position. But mathematically, the altitude calculation is not as good as the horizontal.

[karstic]

The Garmin eTrex series (Vista and Summit) use a barometric altimeter. Not sure about Magellan GPSRs