Altitude / Elevation based on barometer - Use barometric pressure to calculate altitude / elevation Options  Email this topic  Watch this topic  Print this topic » Normal Threaded

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Joe D.		#1 Posted : Sunday, December 27, 2020 10:19:09 PM(UTC)
Rank: Newbie Groups: Registered Joined: 12/26/2020(UTC) Posts: 6		Can barometric pressure ( if available) be used to calculate altitude for devices without gps?
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Mark		#2 Posted : Tuesday, December 29, 2020 2:10:58 PM(UTC)
Rank: Administration Groups: Administrators Joined: 4/12/2014(UTC) Posts: 690 Was thanked: 12 time(s) in 10 post(s)		Looks like you need sea level pressure to start off with - https://keisan.casio.com/exec/system/1224585971
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Joe D.		#3 Posted : Tuesday, December 29, 2020 6:30:18 PM(UTC)
Rank: Newbie Groups: Registered Joined: 12/26/2020(UTC) Posts: 6		Normal sea level barometric pressure is 29.9 inHg. Pressure drops by approximately. .95 inHg per 1000 ft. That is how an altimeter works. The barometer would likely be more accurate than the gps would be. Weather will make it vary slightly but accuracy would still be very close.
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Mark		#4 Posted : Tuesday, December 29, 2020 6:53:25 PM(UTC)
Rank: Administration Groups: Administrators Joined: 4/12/2014(UTC) Posts: 690 Was thanked: 12 time(s) in 10 post(s)		Ok, I'll give it a try. Still need outside temp, which the App gets from the ECM and is not always accurate but if it is, this may work. Edited by user Tuesday, December 29, 2020 6:54:47 PM(UTC)  | Reason: Not specified
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Joe D.		#5 Posted : Thursday, January 7, 2021 7:25:39 PM(UTC)
Rank: Newbie Groups: Registered Joined: 12/26/2020(UTC) Posts: 6		I think you can get by using 59 degrees F. You are not figuring density altitude, you are just wanting barometric pressure converted directly to altitude. Ambient temp shouldn’t make a difference because you are not trying to figure density.
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Joe D.		#6 Posted : Thursday, January 7, 2021 7:36:55 PM(UTC)
Rank: Newbie Groups: Registered Joined: 12/26/2020(UTC) Posts: 6		https://www.engineeringt...tude-pressure-d_462.html
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Mark		#7 Posted : Thursday, January 7, 2021 9:05:14 PM(UTC)
Rank: Administration Groups: Administrators Joined: 4/12/2014(UTC) Posts: 690 Was thanked: 12 time(s) in 10 post(s)		Tried that and using standard sea level pressure of 1013.25 and a temp of 59F I was off on my home altitude (550 calculated vs 660 actual). Not sure if the difference would exaggerate itself the higher you go though so I'm still skeptical at implementing this. If anybody at a higher altitude wants to compare here is the conversion website - https://keisan.casio.com/exec/system/1224585971. Just put in your current pressure.
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Mark		#8 Posted : Thursday, January 7, 2021 9:13:45 PM(UTC)
Rank: Administration Groups: Administrators Joined: 4/12/2014(UTC) Posts: 690 Was thanked: 12 time(s) in 10 post(s)		Well, I just put in the local pressure of Denver (1023.5) and it gave me an altitude of -279 feet. Don't think that's correct...
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Joe D.		#9 Posted : Friday, January 8, 2021 2:26:04 PM(UTC)
Rank: Newbie Groups: Registered Joined: 12/26/2020(UTC) Posts: 6		You can’t use local pressure from a weather station... the weather barometer is corrected for altitude so everyone can compare their barometric pressure to sea level. You need a direct pressure reading.
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Joe D.		#10 Posted : Friday, January 8, 2021 2:31:54 PM(UTC)
Rank: Newbie Groups: Registered Joined: 12/26/2020(UTC) Posts: 6		My barometer reading is 28.0 inches. Altitude is 1850 ft. It’s pretty close.
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Mark		#11 Posted : Friday, January 8, 2021 8:01:11 PM(UTC)
Rank: Administration Groups: Administrators Joined: 4/12/2014(UTC) Posts: 690 Was thanked: 12 time(s) in 10 post(s)		Ok, I'll try again with my daughter in Ogden but it looks it may now work.
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