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Old 01-07-2009, 02:28 AM   #1
Homeslice
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Default Altimeters on a cellphone? watch?

Anyone know about altimeters? What is the most accurate way to calculate it ---- using GPS, or by measuring the atmospheric pressure?

And I know lots of watches have an altimeter, and of course GPS devices can do it, but are there any cellphones that have it?
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Old 01-07-2009, 04:49 AM   #2
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probably gps or find a survey point. the barometric pressure can work but you need to know the density altitude. if you are near a small airport the local FBO could help you out
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Old 01-07-2009, 09:40 AM   #3
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most altimeters are barometers that measure atmospheric pressure...and changes in weather can make you think you are higher/lower than you really are.

Take a look at this watch...

Casio (PAG50-1V) Pathfinder Triple Sensor Tough Solar Watch

iPhone 3G has GPS hardware built in, so it will support altimeter applications...like this one...

www.apptism.com/apps/altimeter
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Old 01-07-2009, 09:44 AM   #4
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You need to receive 4 satellite to get altitude. GPS is the only accurate way. Barometric pressure varies by the air temperature. It will get you close, but not as close as GPS. I don't know of any phones that give you altitude, but if that's what you want, get a cheap handheld GPS for under a $100.
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Old 01-07-2009, 09:53 AM   #5
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I think I read somewhere that there's an app being developed for the iPhone... not sure how accurate it would be
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Old 01-07-2009, 10:01 AM   #6
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Quote:
Originally Posted by Particle Man View Post
I think I read somewhere that there's an app being developed for the iPhone... not sure how accurate it would be
You cant just have an app. You need the correct hardware built into the IPone to receive the data.. ie GPS receiver.
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Old 01-07-2009, 11:13 AM   #7
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Actually, barometric pressure is more accurate than gps for elevation measurements. You need to know what the local baro pressure is when you're taking a reading, but it is definately more accurate. A typical gps can only get you within a few hundred feet accuracy for elevation. A barometer type device will be dead nuts.

Some gps's (like the Garmin Csx60) have a barometric altimeter included. You still have to manually input your local pressure, but it has one.
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Old 01-07-2009, 11:28 AM   #8
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There's also this option - http://www.thealtimeterstore.com/wat...FSJIagod-Wc-Cg
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Old 01-07-2009, 11:48 AM   #9
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Quote:
Originally Posted by Krabill View Post
Actually, barometric pressure is more accurate than gps for elevation measurements. You need to know what the local baro pressure is when you're taking a reading, but it is definately more accurate. A typical gps can only get you within a few hundred feet accuracy for elevation. A barometer type device will be dead nuts.

Some gps's (like the Garmin Csx60) have a barometric altimeter included. You still have to manually input your local pressure, but it has one.
Bullshit. I work in the aerospace navigation industry and I can tell you GPS is dead nuts accurate. It has to be. I see aircraft do Cat III precison approaches using GPS. That is a full autopilot landing so your altitude must be dead on or you die.
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Old 01-07-2009, 12:44 PM   #10
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Well I don't want to input the local pressure every time I want a reading........Would you have to do that every day? Screw that, I guess GPS is it then.
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