If you're "below the noise floor" you may well be under Part 15, which is the "who the hell cares" part of the rules, and you're fine. If your signal is strong

If you're "below the noise floor" you may well be under Part 15, which is the "who the hell cares" part of the rules, and you're fine. If your signal is strong enough to interfere with common uses of the band, well, then that's why people care.