Total posts : 45366
It is very simple. Read the FCC rules on part 15.
For FM the maximum field strength is specified in the rules.
For AM, the alternative to the field strength rules is specified.
These rules are written in clearly understandable engineering terms based on the laws of physics. I am an engineer and I have no problem understanding the rules. The rules are not based on what you think should be so. You don’t want me on the jury when you interpret the rules based on what you think they say and get busted.
I, and others on this board, especially Rich, have interpreted the rules based on engineering knowledge and physics with the intent of keeping you out of trouble. I receive replies to my posts about he said this, they said that, the FCC is laid back about enforcement and that somehow changes the law? You are free to do what you want but I believe that I and others have tried to educate you about the truth of the law and the engineering priniciples which apply. I am not the definitive authority on this, but I do know a few things about radio technology.
I do not accept that the FCC field engineers are being “hard noses” when they enforce the rules.