High speed bidirectional digital cable transmission system

Claim 1

A high speed bidirectional cable television transmission system for providing voice interface between a public switched telephone network and system subscribers comprising a television transmission cable, a head end unit for continuous transmission of voice and video data on said cable to a plurality of cable television subscriber receivers attached to said cable, said continuous transmission including time division multiplexing of data in a plurality of frequency bands, said head end unit including a telephone interface for transmitting and receiving voice data, a quadrature phase shift keyed (QPSK) modulator for receiving and modulating digitized voice data form a public switched telephone network, a mixer for increasing frequency of said QPSK modulated data, a digital to analog conversion means for converting said QPSK modulated data to analog form for transmission on said cable, a burst demodulator including sine and cosine mixers to extract in-phase and quadrature phase encoded data, a transversal matched filter to identify a Barker code at the beginning of a burst of data, and a differential detector operating in synchronization with a detected Barker code for detecting in-phase and quadrature phase encoded data, a plurality of transceivers, each attached to said cable for receiving said continuous transmission of voice and video data, each of said transceivers being assigned an identification number and at least one voice channel for selectively accessing data, each transceiver including transmitting means for transmitting voice data through said cable and said head end unit to the public switched telephone network using time division multiple access transmission of bursts of data in said plurality of frequency bands, a quadrature phase shift keyed (QPSK) modulator for receiving and modulating digitized voice data from a telephone, a mixer for increasing frequency of said QPSK modulated data, and a digital to analog conversion means for converting said QPSK modulated to analog form for transmission on said cable to said head end unit.