I'm trying to program a BMP180 pressure/temperature sensor to calculate altitude. The method I've seen used is to input your current base station altitude to calculate the sea-level pressure. It seems a little tedious to input the base station altitude everytime, so I was wondering if it is possible to calculate sea-level pressure without a known base station pressure.
I've been trying to calculate sea-level pressure through iteration. I would set the default sea-level pressure at 1013.25 mb, use this number to calculate an estimated altitude, use the estimated altitude as my current base-station altitude to calculate a new sea-level pressure, use this new number to calculate an estimated altitude, etc... However, I noticed that my results are diverging. Is there a better way to calculate the sea-level pressure?