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?
Best Answer
1)place to look eqn 9 is what you'll need.
2) no exceptions, unless you get a registered device and go through that hassle -> or move to ISM band
3) they get away with it but not being able to connect at those distances. The power limits are there to limit the locality.