I've been spending a lot of time looking at 47 CRF 15, and specifically .231, and I don't understand how these limits are possible for many products. I'm designing a remote control for a product that needs to work from 150-200 feet away. It has 6 buttons and is addressable with DIP switches, so the amount of data being sent is tiny. It's basically a glorified garage door opener.
I have a product that is similar to the one I'm designing, and it has the range I need, but the specs say it outputs 10mW or 10dBm, and if I'm reading the FCC guidelines right, that's 1000 times the limit.
A couple more specs in case it matters: the transmitter is based on the PT2262 chip, and is operating at 315mHz using a 12V battery with an antenna on the circuit board traces.
My question is 1) How can I build something that has 150-200 ft. range and still be within FCC specs? 2) Am I reading something wrong or is there some exception that will let me pass FCC or avoid it? 3) How do other devices, like garage door openers, get away with it?