There is also a fun regulatory hack in bluetooth. As it is frequency hopping, FCC considers it spread spectrum, but only if it hops across a large enough set

There is also a fun regulatory hack in bluetooth. As it is frequency hopping, FCC considers it spread spectrum, but only if it hops across a large enough set of channels. This matters because spread spectrum radios can run significantly more power. Bluetooths frequency hopping system avoids interference to it and from it by dropping channels with interfernce or other users from the hop set. So with enough interference, even monentary interference and the hop set reduces and regulatory limits require dropping power from 100-200mW to 25mW. This usually cuts the connection.