A television multiplexing and transmission system and method, which is using certain portions of the standard television channel-bandwidth to superimpose additional information by phase-modulating said information using precisely-derived frequency carriers combined with reference frequencies and injecting said phase modulated electronic signals at amplitudes below the standard minimum detectable signal without affecting the simultaneous orderly operation of the same standard television channels into which the additional information is multiplexed, which system may be used to simultaneously transmit to a plurality of users various data in response to their corresponding queries, with particular applications to CATV systems, comprising a user data unit, a multiplexing and transmission unit and a alternate frequency unit.