The logarithmic detector circuit outputs a dB-proportional voltage to the A/D converter. Hence the measured ADC samples reflect directly the receiver's input power in dBm. The readings however are subject to vary by temperature. There is an absolute offset which changes with the temperature, but also the dB to voltage relation slightly may change.
The beacon receiver software compensates this effect by varying the scale and offset values used to compute the dBm value from the ADC reading. During the factory tests each beacon receiver gets calibrated at several temperatures. The data processing of the receiver software then works as described below: