LoRa or wifi ..... max received signal strength -20bBm?

ADR function.

Hi thanks for your replies.

Yes but WHY -20dBm ?
What scientific principle limits receivers to only report -20dBm no matter how strong the field strength?
I just tested my mobile phone running 'wifi analyser' app. near my wifi hub and from about 40cm to right against the hub the signal never wavered from -25dBm. A normal CW signal would have varied logarithmically as expected according to the laws of physics (ignoring multipath!)
What anomaly of physics are these devices employing to "defy the laws of physics Jim"?
Joking aside, I know -20dBm is recognised as a strong signal, but why -20dBm and not 0dBm or +20dBm.
I have mostly measured RF power referenced to zero dBm so what's going on?
Dave

Just guessing here, but -20dB in radio is 100uV.  Maybe there's a clamping circuit in the chip to keep the front end from being overloaded.  With it being consistent, it's got to be a feature - not a coincidence.

Also some of the radio chips are so complicated, that it's easy to wrongly compute the measurement, or display a measurement that has not been adjusted to compensate for all the settings.

I don't know what LoRa chip is being used, but the (extremely popular) SX1276 has (seemingly unresolved) comments on the Internet concerning how to translate register values into a dB value. Some people reporting discrepancies in the multiple tens of dB. For that chip at least, the formula depends on if it's LoRa or FSK (the chip can perform both options), and on the SNR value reported in a different register, and whether per-packet measurements are being used (which for some reason are inaccurate) or a non-packet measurement (yet again, a different register for that), plus it's dependent on an amplifier gain setting. Plus there's an error in linearity noticeably at large signal levels for that chip apparently. But I don't know what chip is being used, nor what software, so someone might need to also do that investigation, and perhaps change register values to see the effect, if it was really important to get to the bottom of it. And doing all that, the value is still meaningless if the two antennas are right next to each other.

Also some of the radio chips are so complicated, that it's easy to wrongly compute the measurement, or display a measurement that has not been adjusted to compensate for all the settings.

I don't know what LoRa chip is being used, but the (extremely popular) SX1276 has (seemingly unresolved) comments on the Internet concerning how to translate register values into a dB value. Some people reporting discrepancies in the multiple tens of dB. For that chip at least, the formula depends on if it's LoRa or FSK (the chip can perform both options), and on the SNR value reported in a different register, and whether per-packet measurements are being used (which for some reason are inaccurate) or a non-packet measurement (yet again, a different register for that), plus it's dependent on an amplifier gain setting. Plus there's an error in linearity noticeably at large signal levels for that chip apparently. But I don't know what chip is being used, nor what software, so someone might need to also do that investigation, and perhaps change register values to see the effect, if it was really important to get to the bottom of it. And doing all that, the value is still meaningless if the two antennas are right next to each other.