Cable "system operators" now receive programming by satellite, terrestrial optical fiber (a method used primarily to relay local stations based within metropolitan areas to the franchise, and acts as a backup for the system operator if a broadcast station's over-the-air signal is affected by a power outage or other technical malfunction involving the main transmitter), off the air (a method used to relay broadcast stations to cable franchises in outlying areas and satellite providers), and from in-house sources and relay it to subscribers' homes.