If I had, or borrowed, a GPS, global postioning system, would it also show my altitude?
Or, is there some moderately priced device that would show altitude to say the nearest 10 feet? Do they rent them?
Thanks.
Most GPSes do show altitude (on my Garmin Nuvi 350, the satellite reception screen shows coordinates and elevation), but beware -- because of the location of the satellites in the sky, altitude is much less accurate than longitude and latitude. I'd say it's +/- 100 feet typically, based on comparisons with roadside elevation signs and a barometric altimeter.
I don't know if more expensive commercial devices have better accuracy, perhaps by incorporating a barometric sensor into the device.
Josh
My Garmin shows altitude, but I don't know that all of them do. You can get elevations from Google Earth if you are looking for just a spot or two. The GPS and Google Earth are within a couple of feet of each other so if not accurate, they are consistent.
Depends on the brand/model.
Garmin ETrex hand held I own shows altitude if you desire. Some models for street navigation may or may not.
Do who rent them?
Josh's 100 feet is not precise enough,
so I guess it will be google earth. I dl'd it months ago but haven't installed it. I'll do that.
Good enough, and I wanted to compare elevations anyhow. Hmmm. I should have said that. So maybe Joshe's 100 feet is good enough. Even if a gps is off by 100 feet, if it is off by the same amount a couple blocks away, that would be fine. Now I have to find someone I know who has a gps. Believe it or not, none of the six people I see most often do.
Thanks all.
Ask the janitor?
Jeff
Possibly, maybe probably it would "indicate" altitude, with varying degrees of accuracy.
A USGS 7.5 minute map is, or used to be $4.
There are a lot of variables.
- gpsman
Hi, I don't know about renting but I have a Casio G-shock watch which gives altitude display. Before initial use, you need to calibrate it. When I go alpine trekking I use it.
GPS is accurate in altitude to the same degree it is in location - so it COULD be accurate to within 3 feet - or 30. Depending on how good a satelite fix you get.
Aneroid (barometric) altimiter - it looses accuracy very quickly when a storm front comes in. Lots of Ultralite and hang-glider pilots use them though.
That would only be in low end units. Kollsman was the one who first devised a method to compensate for changes in barometric pressure from standard pressure.
Google earth pretty much agrees with old US contour maps I have of my house. My old ETrex will not give that kind of accuracy but when I use it out in the field, altitude and location will vary much more than the specs you want.
: Most GPSes do show altitude (on my Garmin Nuvi 350, the satellite : reception screen shows coordinates and elevation), but beware -- : because of the location of the satellites in the sky, altitude is much : less accurate than longitude and latitude. I'd say it's +/- 100 feet : typically, based on comparisons with roadside elevation signs and a : barometric altimeter.
The difference between 'altitude and 'elevation' - is it just semantics or is there a difference? I've always taken 'elevation' to mean distance above the ground, and 'altitude' to be distance above sea level. I believe pilots assume the same as I - if you were flying at 1000' 'altitude' near 1500' hills, you'd be in trouble.
Hi, Consumer GPS readings are diluted from accurate military readings coming from the satellite. That is why ~ +/ 100 ft. tolerance.
Would that be the "selective availability" that was turned off in
2000?
Consumer GPS readings aren't "diluted" in the true sense. That would be the "selective availability" you mentioned which is no longer used.
The GPS system also transmits "P(Y) code" which is encrypted. That code enables higher precision but consumer receivers can't decrypt it.
recently mine dont appear as accurate, wonder if the satellites are failing? or more likely spread futher apart and fewer equal less accurate?
Yes, but you can bet the wrist-watch style is NOT a Kollsman, and to compensate even a Kollsman you need to know ground level, or better yet, sea level adjusted barometric pressure.
I don't think there is any difference. Mainly it's that if you are in the air it's thought of as altitude and if you are standing on the ground it's thought of as elevation but they are the same, both are above sea level.
I don't think that's correct, due to the geometry, GPS is much more accurate with lat/long info then it is with elevation info.
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