Let's say, hypothetically, that I design some product that uses radio communication. Maybe something like a wireless lock. Or a scanner that tells you if a tag is near (in range of a few feet). Or a homemade radio.
If I didn't tell anyone, I assume I could (perhaps illegally) use whichever frequencies I fancied. However, imagine I wanted to sell one of these products. Which frequencies would I be allowed to use? Does it depend on how far the radiation is designed to travel for the given application?
I am aware that the information regarding FCC frequency allocation and regulations is out there. However, I came here because I was a bit overwhelmed by the information I got from other sources. What frequencies can safely be used?