Measuring Altitude using BMP280 sensor

[Ravi]

Hi,

    My application requires measuring the altitude with 0.5m to 1m accuracy. So, I am using the BMP280 sensor to calculate the altitude. The sensor is connected to the NODEMCU(ESP8266) and data read using the I2C interface in Arduino IDE. But while testing the altitude varies to 20m even though the sensor is kept at someplace over a period of time(around 6hrs). PFA for the code and image which shows the variation in altitude (MIN and MAX). Please suggest some solution in order to get the required functionality.

[Jachoo]

https://en.wikipedia.org/wiki/Barometric_formula

[mahivarma]

calculating altitude compensating for atmospheric lapse rate shall be done using the formulae given below

one issue with using two sensors to measure the relative height is the effect of absolute error in the pressure sensor. the absolute error for BMB390 is +/-50 pascals which approximately is equivalent to +/-4m in altitude. considering the absolute accuracy error in both sensors the tolerance for th measured height can be up to +/-8m. this probably can be improved, improved a lot by marrying the two sensors. record the difference in absolute pressure reading between the two sensors while at same altitude and then compensate for this difference with the future measurements. I haven't tried this yet. but I am going to. if anyone else in the group has tried this pls let me know.

regards

Mahi

[zliu]

I am trying to reference my altitude measurement to nearest weather station's air pressure report.

however, I believe I still need to calibrate BMP barometer first to an absolute reference.  any one has experience on how often this calibration needs to be done? can I do a factory calibration and use the result for the life of the product which might be 5-10 years?

I intend to use BMP581 in my design.

much thanks

Leo