dweebe Posted March 6, 2003 Posted March 6, 2003 I was in New Orleans this last weekend for Mardi Gras and took my SporTrak Pro with me. When in the Garden District and French Quarter I got altitude readings of 0 feet but nothing below that. I thought these parts of New Orleans were a few feet below sea-level. Is that correct and has anyone gotten a below 0 altitude reading with a GPSr? Quote
+Jamie Z Posted March 6, 2003 Posted March 6, 2003 I believe that the lowest reading that the SporTrak (and the Meridian) will give is zero. No negative altitudes for some reason. Plus... you didn't hold the GPS on the ground did you? It was probably up around chest level, just about zero feet above sea level. Jamie Quote
+BusBoy Posted March 6, 2003 Posted March 6, 2003 I was in Naw'leans last year and I brought my Legend with me for the trip. There were quite a few locations along Canal Street that registered as being below sea level. We stayed in the French Quarter and ventured over to the Garden District, but I didn't have my GPS with me at the time. Man, now I am craving a Po' Boy from Mothers and a beignet from Cafe Du Monde Quote
+Prime Suspect Posted March 6, 2003 Posted March 6, 2003 quote:Originally posted by BusBoy:I was in Naw'leans last year and I brought my Legend with me for the trip. There were quite a few locations along Canal Street that registered as being below sea level. We stayed in the French Quarter and ventured over to the Garden District, but I didn't have my GPS with me at the time. Early version of eTrex OS wouldn't display sub-sea level readings. If your unit doesn't, you may need to upgrade. Quote
+Bloencustoms Posted March 6, 2003 Posted March 6, 2003 Great avatar dweebe! That's one of my favorite lines in a movie ever. Don't even think about putting those muddy boots in my car. Quote
+Katetrex Posted March 7, 2003 Posted March 7, 2003 You must have missed the Founders Geocache in the French Quarter http://www.geocaching.com/seek/cache_details.aspx?ID=42467&log=y&decrypt= The cache hiders gps read -12 below sea level at the cache site, as did my little yellow etrex and many others. My lowest reading to date has been -40 ft in downtwon St. Mary's, GA. Quote
+apersson850 Posted March 7, 2003 Posted March 7, 2003 I've seen -35 meters in the tunnel between Sweden and Denmark. That requires barometric altimeter, of course, since no GPS signals can be received down there. Anders Quote
+Alan2 Posted March 7, 2003 Posted March 7, 2003 quote:Originally posted by Anders:I've seen -35 meters in the tunnel between Sweden and Denmark. Anders Adds a different meaning to the term 'Down Under" alan Quote
+Alan2 Posted March 7, 2003 Posted March 7, 2003 The first time I checked tracking on my computer after downloading when I had travelled through the tunnel from Manhattan to Queens in NYC, I read -35 feet or so where the toll both was. Funny I didn't see the toll collectors wearing scuba gear. Then I realized the Vista had gotten the baromettric reading while under the river, but because satellite lock was lost, carried that reading to points outside the tunnel. It didn't correct itself until it locked on the satellites again further down the road. Alan Quote
Ed2002 Posted March 8, 2003 Posted March 8, 2003 There are lots of posts about this in the Yahoo meridian group; many users complain about magellan units not capable of showing below zero values; up to now even in the newest firmware versions no correction; somebody cited "they did it for marine use, sailors fearing if the GPS shows under zero"? Ed Quote
+apersson850 Posted March 9, 2003 Posted March 9, 2003 In Sweden, we have some of the largest iron ore mines in the world. They are down some 1000 meters below the earth level. Maybe I should go visit that place (it's 1300 km from here...) and see what the Vista says?? Anders Quote
rag-a-muffin Posted March 9, 2003 Posted March 9, 2003 quote:Originally posted by Jamie Z:Plus... you didn't hold the GPS on the ground did you? It was probably up around chest level, just about zero feet above sea level. I have no clue whether or not the Magellans show readings below zero or not, but even if they did... The SporTrack Pro has a vertical accuracy of 10 meters (32.81 feet). Placing your GPSr on the ground would not give you any better accuracy reading. You could be three stories up in your hotel room and get roughly the same altitude reading as if your GPSr were laying flat on the surface of the road. If New Orleans is only "a couple of feet" below sea level in parts, it may show up as zero, and your actual altitude may still be as much as 33 feet below sea level. I would imagine that the barometric altimeters are the way to go if you're looking for true altitude readings. Quote
Kerry. Posted March 9, 2003 Posted March 9, 2003 Standard Positioning Service global average vertical accuracy is <=22m [~72 feet) @ 95% SIS and <=77m [~252 feet) worst case scenario so GPS altitude is not all that relevent. Vertical accuracy is also more affected (for the worse) by latitude than horizontal error especially once one is above about 55 degrees N/S latitude where as the higher latitudes generally improve horizontal accuracy. Cheers, Kerry. I never get lost everybody keeps telling me where to go Quote
+Alan2 Posted March 9, 2003 Posted March 9, 2003 quote:Originally posted by Anders:In Sweden, we have some of the largest iron ore mines in the world. They are down some 1000 meters below the earth level. Maybe I should go visit that place (it's 1300 km from here...) and see what the Vista says?? Anders Don't forget to take a canary! alan Quote
+nincehelser Posted March 9, 2003 Posted March 9, 2003 Barometric Altimeter Range: -2,000 to 30,000 feet So it obviously goes negative. George Quote
+apersson850 Posted March 10, 2003 Posted March 10, 2003 I've seen it (falsely) report parts of cities like Helsingborg and Malmö to be several meters below sea level. Although they are at the coastline, they certainly aren't that wet. It (the Vista) gets a little confused now and then, obviously due to weather differences at different places. Anders Quote
+nincehelser Posted March 10, 2003 Posted March 10, 2003 It only says it's accurate in feet, not meters! Check the specs George Quote
+Jamie Z Posted March 10, 2003 Posted March 10, 2003 quote:Originally posted by Jamie Z:Plus... you didn't hold the GPS on the ground did you? It was probably up around chest level, just about zero feet above sea level. quote:Originally posted by rag-a-muffin:I have no clue whether or not the Magellans show readings below zero or not, but even if they did... Yeah, yeah I know. I was a thinly disguised joke. Jamie Quote
CacheSceneInvestigator Posted April 29, 2003 Posted April 29, 2003 I have an eTrex Venture. The first couple of times I used it, I had gross misreadings of 30+ feet, and have since completely diregarded the "altimeter" on my GPSr. "One man's cache is another man's treasure!" Quote
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