Abstract: An improved system is disclosed for generating a signal encoded with stereophonic information and adapted to be used with a monophonic signal to synthesize stereophonic reproduction. The system includes means for generating the encoded signal as a function of at least a portion of the program information of a monophonic input signal so as to control the amount of stereophonic spread provided during stereophonic reproduction provided by the encoded signal and a monophonic signal derived from the monophonic input signal. The system is particularly adapted for use in the transmission and/or reception of stereophonic television signals.

Abstract: A signal encoding system for generating at least two encoded signals in response to a plurality of information signals containing audio data representative of virtual images of sources of the data so that the encoded signals can be subsequently decoded by a decoding system including a decoding matrix means for decoding the encoded signals so as to regenerate the information signals. The signal encoding system comprises signal encoding means for generating the encoded signals in response to the information signals; and a duplicate of the decoding matrix means coupled to the encoding means for generating a feedback signal corresponding to each of the information signals; wherein the encoding signals are modified in response to the feedback signals so as to reduce the noise artifacts generated by the decoding matrix when the encoded signals are decoded by the decoding system.

Abstract: A signal decoding system for use in a quadraphonic type sound reproducing system is disclosed. In accordance with one aspect of the invention, a multiband expander is used to control the steering of the four information signals decoded from the two input signals. In accordance with another aspect of the invention, the difference between the rear and front signals is used to enhance virtual sound images to one side of a listener.