Question Re: How to calculate the altitude from the pressure senso... in Question and answers
https://community.bosch-sensortec.com/t5/Question-and-answers/Re-How-to-calculate-the-altitude-from-the-pressure-senso/qaq-p/10452/comment-id/106#M106
<P>The formula that you provided will give the different results to the one in the cited eurocontrol document.</P><P>The result form the sensor (on of the popular Bosh sensors) is a pressure - we convert it to altitude using International Standard Atmosphere model (formula is different than the one presented here). And that result is a proof of beating some World record.</P><P>There is no other technical way to use different sensor (GPS altitude indication is not correct on these altitudes and also not correct by the definition).</P><P>radar could not be used same as Lidar or laser measurement.</P><P> </P><P>How the formula should be used?</P><P>1. conditions at the object take off</P><P>altitude above mean sea level = 78 m - from digital terrain model</P><P>temperature measured by termometer in the car 8deg C</P><P>temperature indicated by the ventusky (weather forecast) 11degC</P><P>pressure indicated by the ventusky (weather forecast) 1016hPa</P><P>pressure indicated by one of the altimeters (not conatining pressure sensor that we are talking about) = 1005hPa</P><P> </P><P>Which pressure should be used and feed to the formula as p0 (p0 is present in formula presented here as well as in eurocontrol document as pb)?</P><P>Shall i take pressure at altitude 76m and find pressure at the Mean Sea Level = 0m and use that pressure from mean sea level in the formula or something else.</P><P>From that what I see the idea is to adjust pressure at the sea level and than calculate altitude.</P><P>Regarding airplanes yes they switch altimeters around some altitude (i belive 12 000 feet) and switch their mean se level pressure to 1013 hPa in their altimeters.</P><P>That pressure is different in comparison to the altimeter that has been zeroed at QFE = 1025 hPa theses 12hPa is around 12*9m for low altitudes but for high altitudes it will even more like 12*30m).<BR /><BR />So from perspective of people thatare setting the "word record " it is very important what to put in the fomula and correct it by ground level.<BR />Also theere is one more what if altitude is 11km (tropopause) and accoridng to ISA model the p0 is around 226mbar.</P><P> </P><P> </P><P> </P>Wed, 13 Nov 2019 20:06:12 GMTStan2019-11-13T20:06:12ZHow to calculate the altitude from the pressure sensor data?
https://community.bosch-sensortec.com/t5/Question-and-answers/How-to-calculate-the-altitude-from-the-pressure-sensor-data/qaq-p/5702
<P>can you please explain how to get altitude measurement from pressure data from the sensor</P>Wed, 19 Dec 2018 12:23:49 GMThttps://community.bosch-sensortec.com/t5/Question-and-answers/How-to-calculate-the-altitude-from-the-pressure-sensor-data/qaq-p/5702elrhoul2018-12-19T12:23:49ZRe: How to calculate the altitude from the pressure senso...
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<P>The <STRONG>altitude</STRONG> in meters can be calculated with the international barometric formula:</P><P><STRONG>H = 44330 * [1 - (P/p0)^(1/5.255) ]</STRONG></P><P><BR />H = altitude (m)<BR />P = measured pressure (Pa) from the sensor<BR />p0 = reference pressure at sea level (e.g. 1013.25hPa)</P><P> </P><P> </P>Wed, 19 Dec 2018 12:33:37 GMThttps://community.bosch-sensortec.com/t5/Question-and-answers/Re-How-to-calculate-the-altitude-from-the-pressure-senso/qaq-p/5703/comment-id/56#M56elrhoul2018-12-19T12:33:37ZRe: How to calculate the altitude from the pressure senso...
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Well This formula is not givving accurate results.Mon, 04 Nov 2019 22:47:09 GMThttps://community.bosch-sensortec.com/t5/Question-and-answers/Re-How-to-calculate-the-altitude-from-the-pressure-senso/qaq-p/10328/comment-id/98#M98Stan2019-11-04T22:47:09ZRe: How to calculate the altitude from the pressure senso...
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The reference pressure at sea level needs to be adjusted according to the current weather. This varies between 870 to 1084 (based on current maximums ever recorded)Tue, 05 Nov 2019 12:36:25 GMThttps://community.bosch-sensortec.com/t5/Question-and-answers/Re-How-to-calculate-the-altitude-from-the-pressure-senso/qaq-p/10334/comment-id/99#M99o_o2019-11-05T12:36:25ZRe: How to calculate the altitude from the pressure senso...
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So it means that for a day when pressuere at the ground level (lets say 78m above mean sea level) is lets say 1016 hPa it should be pyt as p0 in the formula?Wed, 06 Nov 2019 23:49:29 GMThttps://community.bosch-sensortec.com/t5/Question-and-answers/Re-How-to-calculate-the-altitude-from-the-pressure-senso/qaq-p/10372/comment-id/100#M100Stan2019-11-06T23:49:29ZRe: How to calculate the altitude from the pressure senso...
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The p0 is the equivalent pressure at sea level. If the current pressure is 1018mbar and altitude of the weather station is 78m, then the p0 is ~1027,5mbarThu, 07 Nov 2019 10:40:04 GMThttps://community.bosch-sensortec.com/t5/Question-and-answers/Re-How-to-calculate-the-altitude-from-the-pressure-senso/qaq-p/10378/comment-id/101#M101o_o2019-11-07T10:40:04ZRe: How to calculate the altitude from the pressure senso...
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How you do the math from my 1016hPA at 78m above Mean Sea Level to Your 1018hPa at weather station level (78m above ground ) and than to 1027.5hPa at the mean sea level = p0Tue, 12 Nov 2019 01:06:12 GMThttps://community.bosch-sensortec.com/t5/Question-and-answers/Re-How-to-calculate-the-altitude-from-the-pressure-senso/qaq-p/10427/comment-id/102#M102Stan2019-11-12T01:06:12ZRe: How to calculate the altitude from the pressure senso...
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<P>Also there is a bit different formula in ISA model in this publication: <A href="https://www.eurocontrol.int/publication/revision-atmosphere-model-bada-aircraft-performance-model" target="_blank" rel="noopener">https://www.eurocontrol.int/publication/revision-atmosphere-model-bada-aircraft-performance-model</A><BR />see page 22.</P><P>these formuals gives different reasult in comparision to one provided in this answer on the top of discussion</P><P> </P><P> </P>Tue, 12 Nov 2019 01:10:47 GMThttps://community.bosch-sensortec.com/t5/Question-and-answers/Re-How-to-calculate-the-altitude-from-the-pressure-senso/qaq-p/10428/comment-id/103#M103Stan2019-11-12T01:10:47ZRe: How to calculate the altitude from the pressure senso...
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If you isolate p0, the equation becomes : p0 = (2.62057x10^24 * p) / ( (44330 - H)^5.255 ). With p= 101800 and H=78, then the p0 is 102746. With p=101600, the p0 would be 102545. This simplified formula assumes a sea level temperature of 15 celsius and a standard temperature gradient. It is important to note 2 things: 1) All altitude calculation from pressure formulas are estimations, and 2) Aircrafts use a standardized formula to calculate pressure altitude, which is not necessarily the true altitude of the aircraft, so that they do not collide regardless of where their altimeter was calibrated.Tue, 12 Nov 2019 09:07:02 GMThttps://community.bosch-sensortec.com/t5/Question-and-answers/Re-How-to-calculate-the-altitude-from-the-pressure-senso/qaq-p/10432/comment-id/104#M104o_o2019-11-12T09:07:02ZRe: How to calculate the altitude from the pressure sensor data?
https://community.bosch-sensortec.com/t5/Question-and-answers/Re-How-to-calculate-the-altitude-from-the-pressure-sensor-data/qaq-p/10451/comment-id/105#M105
The formula that you provided will give the different results to the one in the cited eurocontrol document.Wed, 13 Nov 2019 12:43:30 GMThttps://community.bosch-sensortec.com/t5/Question-and-answers/Re-How-to-calculate-the-altitude-from-the-pressure-sensor-data/qaq-p/10451/comment-id/105#M105Stan2019-11-13T12:43:30ZRe: How to calculate the altitude from the pressure senso...
https://community.bosch-sensortec.com/t5/Question-and-answers/Re-How-to-calculate-the-altitude-from-the-pressure-senso/qaq-p/10452/comment-id/106#M106
<P>The formula that you provided will give the different results to the one in the cited eurocontrol document.</P><P>The result form the sensor (on of the popular Bosh sensors) is a pressure - we convert it to altitude using International Standard Atmosphere model (formula is different than the one presented here). And that result is a proof of beating some World record.</P><P>There is no other technical way to use different sensor (GPS altitude indication is not correct on these altitudes and also not correct by the definition).</P><P>radar could not be used same as Lidar or laser measurement.</P><P> </P><P>How the formula should be used?</P><P>1. conditions at the object take off</P><P>altitude above mean sea level = 78 m - from digital terrain model</P><P>temperature measured by termometer in the car 8deg C</P><P>temperature indicated by the ventusky (weather forecast) 11degC</P><P>pressure indicated by the ventusky (weather forecast) 1016hPa</P><P>pressure indicated by one of the altimeters (not conatining pressure sensor that we are talking about) = 1005hPa</P><P> </P><P>Which pressure should be used and feed to the formula as p0 (p0 is present in formula presented here as well as in eurocontrol document as pb)?</P><P>Shall i take pressure at altitude 76m and find pressure at the Mean Sea Level = 0m and use that pressure from mean sea level in the formula or something else.</P><P>From that what I see the idea is to adjust pressure at the sea level and than calculate altitude.</P><P>Regarding airplanes yes they switch altimeters around some altitude (i belive 12 000 feet) and switch their mean se level pressure to 1013 hPa in their altimeters.</P><P>That pressure is different in comparison to the altimeter that has been zeroed at QFE = 1025 hPa theses 12hPa is around 12*9m for low altitudes but for high altitudes it will even more like 12*30m).<BR /><BR />So from perspective of people thatare setting the "word record " it is very important what to put in the fomula and correct it by ground level.<BR />Also theere is one more what if altitude is 11km (tropopause) and accoridng to ISA model the p0 is around 226mbar.</P><P> </P><P> </P><P> </P>Wed, 13 Nov 2019 20:06:12 GMThttps://community.bosch-sensortec.com/t5/Question-and-answers/Re-How-to-calculate-the-altitude-from-the-pressure-senso/qaq-p/10452/comment-id/106#M106Stan2019-11-13T20:06:12ZRe: How to calculate the altitude from the pressure sensor data?
https://community.bosch-sensortec.com/t5/Question-and-answers/Re-How-to-calculate-the-altitude-from-the-pressure-sensor-data/qaq-p/10453/comment-id/107#M107
Also the another question arises. The sensor is used for Altitude estimation and that estimation is as a result is used as a proof of beating the record (WORLD RECORD)Wed, 13 Nov 2019 12:45:48 GMThttps://community.bosch-sensortec.com/t5/Question-and-answers/Re-How-to-calculate-the-altitude-from-the-pressure-sensor-data/qaq-p/10453/comment-id/107#M107Stan2019-11-13T12:45:48ZRe: How to calculate the altitude from the pressure senso...
https://community.bosch-sensortec.com/t5/Question-and-answers/Re-How-to-calculate-the-altitude-from-the-pressure-senso/qaq-p/47339/comment-id/117#M117
<P>The equation to convert barometric pressure to altitude, derived from the first principles, is as shown below.</P><P>this should work well for relative altitude measurements. you need to know the current environmental lapse rate. the equation assumes the atmosphere to have a constant lapse rate.</P><P><span class="lia-inline-image-display-wrapper lia-image-align-inline" image-alt="mahivarma_0-1634518091695.png" style="width: 400px;"><img src="https://community.bosch-sensortec.com/t5/image/serverpage/image-id/11439i69B5F86B1DCF9625/image-size/medium?v=v2&px=400" role="button" title="mahivarma_0-1634518091695.png" alt="mahivarma_0-1634518091695.png" /></span></P><P> </P>Mon, 18 Oct 2021 00:48:39 GMThttps://community.bosch-sensortec.com/t5/Question-and-answers/Re-How-to-calculate-the-altitude-from-the-pressure-senso/qaq-p/47339/comment-id/117#M117mahivarma2021-10-18T00:48:39Z