Also, you can do your own calculations with the spreadsheet below. You have two options. Either get the signal strength in dBm from your phone (see how to do it for Android and how to do it for iPhone) and put this value in the appropriate cell of the first sheet, or put in the second sheet your distance to the closest cellular network antenna .
FAQ
Q: The flashing led is always red, what does it mean?
References
For the calibration of the calculation parameters (gain, transmission dBm, etc.) the following measurements were used:
For the safety standards:
This app theoretical background is based on: