“…On this basis, the built-in barometer is further used to assist indoor positioning [ 24 , 25 , 26 , 27 ], altitude change monitoring [ 17 ] and motion recognition [ 13 ]. The applications are all based on the pressure-altitude correlation model [ 2 , 24 , 28 , 29 ], expressed as Equation (1): where p abs ( h ) is pressure, h is altitude, and p 0 and T 0 are the pressure reference and temperature reference, respectively. The reference conditions are usually set as 288.15 K (15 °C), where p 0 = 1013.25 hPa, T 0 = 288.15 K. However, the pressure is not only influenced by the height, but also by the environmental factors, such as weather, temperature, humidity, and wind speed [ 27 , 30 ].…”