Cable television spread spectrum data transmission apparatus

A data reception apparatus for use in receiving data spread across at least a portion of a spectrum provided by a cable television channel of a cable television system comprising a cable distribution plant susceptible to interference noise, the data reception apparatus comprising:

• a quadrature demodulation circuit for removing a spread spectrum data signal from a carrier of the cable television channel;
• a Costa loop, responsive to the quadrature demodulation circuit, for synchronization of the quadrature demodulation circuit with a carrier signal modulator of a cable television transmitter;
• a pseudorandom sequence generator for generating a pseudorandom chip sequence identical to a pseudorandom sequence generated at said cable television transmitter, the chip rate of said chip sequence being much greater than the data bit rate;
• a digital correlation loop, responsive to the quadrature demodulation circuit, for correlating and synchronizing the pseudorandom chip sequence generated at the cable television receiver with the sequence generated at the cable television transmitter;
• and
• a quadrature mixer, responsive to the pseudorandom sequence generator and the quadrature demodulation circuit, for recovering the data signal from the spread spectrum data signal.

A cable television data transmission system for transmitting data spread across at least a portion of a spectrum provided by a cable television channel of a cable television system, comprising a cable television signal distribution plant susceptible to interference noise from proximate power lines, telephone lines, defective cable television signal distribution apparatus of the distribution plant, ineffective grounding of cable sheaths, radio frequency interferences and other sources of interference noise, the data transmission system comprising:

• a controller, responsive to an incoming data signal, for providing a stepwise digital control signal for controlling the power level of a signal input to the cable television signal distribution plant, for providing the incoming data signal at a data bit rate to a spread spectrum data signal generator and for controlling the operation of a carrier signal oscillator;
• the carrier signal oscillator, responsive to the controller, for providing a carrier signal at a frequency consistent with the frequency of the cable television channel;
• a frequency divider, responsive to the carrier signal oscillator, for providing a sequencing signal;
• a first pseudorandom sequence generator, responsive to the sequencing signal, for generating a predetermined pseudorandom chip sequence at a chip rate for transmission on the cable television channel within at least a portion of the spectrum corresponding to the cable television channel;
• the spread spectrum data signal generator, responsive to the first pseudorandom sequence generator and the data signal output of the controller, for generating a spread spectrum data signal;
• a carrier signal modulator, responsive to the carrier signal oscillator and the spread spectrum data signal generator, for modulating the spread spectrum data signal for transmission over the cable television channel;
• a programmable power amplifier for amplifying the modulated spread spectrum data signal output of the carrier signal modulator in accordance with said stepwise digital control signal from the controller;
• a quadrature demodulation circuit for removing said spread spectrum data signal from a carrier of the cable television channel;
• a Costa loop, responsive to the quadrature demodulation circuit, for synchronization of the quadrature demodulation circuit with the carrier signal modulator;
• a second pseudorandom sequence generator for generating a pseudorandom sequence identical to the predetermined pseudorandom chip sequence generated by the first pseudorandom sequence generator;
• a digital correlation loop, responsive to the quadrature demodulation circuit, for correlating and synchronizing the pseudorandom chip sequence generated by the second pseudorandom sequence generator with the sequence generated by the first pseudorandom sequence generator;
• and
• a quadrature mixer, responsive to the second pseudorandom sequence generator and the quadrature demodulation circuit, for recovering the data signal from the spread spectrum data signal.