Abstract: A system for controlling a cable television network includes a head end, a plurality of addressable external control units having subscriber converters located off the subscriber's premises, and one or more subscriber devices located on the subscriber premises for communicating with associated external control units. The head end can selectively and rapidly poll the external control units for information on a general or on a priority basis. Information is transmitted to the head end from the external control units on any of a plurality of reverse communication channels under control of the head end. External control units use a two-part polling scheme to poll a plurality of associated drop cables, and individual subscriber devices attached to the drop cables. The polling rapidly identifies subscriber devices desiring to communicate with the external control unit.

Abstract: A cable television system and method in which each subscriber's converter is located outside the subscriber's premises in an external control unit ("ECU") which also includes several other subscribers' converters. The ECU includes common signal processing circuitry for controlling all the converters in the ECU. In addition to television signals, the cable network transmits control and data signals in both directions between the ECU and the head end of the system and between the ECU and each subscriber. Each subscriber supplies a portion of the power required by the associated ECU. Multiple television channels can be supplied to each subscriber via a single drop cable connecting the subscriber to the ECU.

Abstract: A system for controlling a cable television network includes a headend, a plurality of addressable external control units having subscriber converters located off the subscribers' premises, and one or more subscriber devices located on the subscriber premises for communicating with associated external control units. The headend can selectively and rapidly poll the external control units for information on a general or on a priority basis. Information is transmitted to the headend from the external control units on any of a plurality of reverse communication channels under control of the head end. External control units use a two-part polling scheme to poll a plurality of associated drop cables, and individual subscriber devices attached to the drop cables. The polling rapidly identifies subscriber devices desiring to communicate with the external control unit.

Abstract: In a cable television system in which the individual subscriber's converter/tuner is located outside the subscriber's premises in an external control unit ("ECU") and controlled remotely via a subscriber processing unit ("SPU") connected to the ECU by a drop cable, data transmitted from the SPU to the ECU (e.g., channel selection data) is verified by transmitting similar echo back data from the ECU to the SPU. The SPU compares the original and echo back data to assure that the ECU correctly received the original data.

Abstract: A tap-off unit or signal transmission device for use in a cable TV system having a plurality of such tap-off units, each tap-off unit receiving cable TV signals from a feeder cable and distributing the signals to a plurality of homes. The tap-off unit has a signal coupler which facilitates removal from the tap-off unit of a circuitry unit and which minimizes the interruption of cable TV signals further down the feeder cable in the event of repair or maintenance of the circuitry unit.

Abstract: In a cable television system in which one or more tap-off devices deliver television signals to an associated subscriber via drop cables connecting the tap-off devices at the subscribers' premises, and in which the tap-off devices receive electrical power from the subscribers via the drop cables, a power safety apparatus and method interrupts the application of power to the drop cable when the drop cable becomes cut, broken or disconnected to prevent individuals from receiving hazardous electrical shocks.

Abstract: Subscription apparatus and methods wherein an encoder begins inversion of a video signal during the last horizontal trace line of a randomly selected vertical interval and continues to invert trace lines in the following field of the video signal. The encoder also suppresses the amplitude of randomly selected horizontal blanking pulses only during fields of the video signal while maintaining unaltered the absolute amplitude differential between the horizontal blanking pulses and associated horizontal synchronization pulses. A decoder reinverts trace lines of the field following detection of an inverted last horizontal trace line of a vertical interval. The decoder also selectively rebiases the video signal to restore the horizontal blanking pulses upon detection of a suppressed amplitude during the front porch of a horizontal blanking pulse. Reinversion of the trace lines and rebiasing of the blanking pulses is achieved by selective reference biasing of a video modulator circuit in the decoder.