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.
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.