Abstract: A bidirectional cable television system provides for transmission of signals from cable subscribers downlink in the same direction as the ensemble of television channels which the cable television system is already constructed to deliver. The subscriber signals may be transmitted over the cable in the blanking intervals of a cable television channel, using the T-NET technique described in U.S. Pat. No. 4,750,036. Alternatively, the signals may be carried over a dedicated channel, or transmitted cochannel along a cable television channel carrying ordinary programming by adding the subscriber information to alternating video frames in alternating polarity to achieve visual cancellation. The subscriber signals are collected after the last distribution line amplifier in the cable downlink. The collected signals are transmitted to a central receiver via wireless or other customary means such as a modem.

Abstract: A bidirectional cable television system provides for transmission of signals from cable subscribers downlink in the same direction as the ensemble of television channels which the cable television system is already constructed to deliver. The subscriber signals may be transmitted over the cable in the blanking intervals of a cable television channel, using the T-NET technique described in U.S. Pat. No. 4,750,036. Alternatively, the signals may be carried over a dedicated channel, or transmitted cochannel along a cable television channel carrying ordinary programming by adding the subscriber information to alternating video frames in alternating polarity to achieve visual cancellation. The subscriber signals are collected after the last distribution line amplifier in the cable downlink. The collected signals are transmitted to a central receiver via wireless or other customary means such as a modem.

Abstract: A bidirectional cable television system provides for transmission of signals from cable subscribers downlink in the same direction as the ensemble of television channels which the cable television system is already constructed to deliver. The subscriber signals may be transmitted over the cable in the blanking intervals of a cable television channel, using the T-NET technique described in U.S. Pat. No. 4,750,036. Alternatively, the signals may be carried over a dedicated channel, or transmitted cochannel along a cable television channel carrying ordinary programming by adding the subscriber information to alternating video frames in alternating polarity to achieve visual cancellation. The subscriber signals are collected after the last distribution line amplifier in the cable downlink. The collected signals are transmitted to a central receiver via wireless or other customary means such as a modem.

Abstract: A bidirectional cable television system provides for transmission of signals from cable subscribers downlink in the same direction as the ensemble of television channels which the cable television system is already constructed to deliver. The subscriber signals may be transmitted over the cable in the blanking intervals of a cable television channel, using the T-NET technique described in U.S. Pat. No. 4,750,036. Alternatively, the signals may be carried over a dedicated channel, or transmitted cochannel along a cable television channel carrying ordinary programming by adding the subscriber information to alternating video frames in alternating polarity to achieve visual cancellation. The subscriber signals are collected after the last distribution line amplifier in the cable downlink. The collected signals are transmitted to a central receiver via wireless or other customary means such as a modem.

Abstract: A spread spectrum system provides bidirectional digital communication on a vacant television (TV) channel for simultaneous use by more than 75,000 subscribers using time and frequency division multiplex signals locked to horizontal and vertical sync pulses of an adjacent channel Host TV station. The system, whose operation is analogous to a radar system, comprises: (1) the Host TV station to send down-link sync and data pulses to subscribers during the horizontal blanking interval (HBI), (2) subscriber "transponders" which detect those signals and transmits up-link "echo" data pulses only during the HBI to eliminate interference to TV viewers, and (3) a central receiver which also uses the host TV sync pulses to trigger range gates to detect the up-link data pulses.