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 includes security means. A security sensor is provided a subscriber's house and when it generates an emergency signal a transmission path is formed by non-active elements from the security sensor to a trunk cable. An external control unit has a checking function of a power supplying state to the security sensor. The external control unit can communicate with a central station with respect to power source conditions of subscribers.

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: An external control unit for a CATV system has a CPU and a RAM with many kinds of memory maps. Reference data to be stored in the memory maps is transmitted from a central station. When a subscriber requests the tuning of a TV channel for a pay program to a converter tuner, the CPU in the external control unit can work, using the reference data.

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: A phase locked loop tuning system for a television receiver includes a reference oscillator, a reference divider for dividing the frequency of the output signal of the reference oscillator, a voltage controlled local oscillator, a prescaler for dividing the frequency of the output signal of the local oscillator by a predetermined factor, a programmable divider for dividing the frequency of the output signal of the prescaler by a factor determined by the presently selected channel, a phase comparator for generating a series of pulses representing the phase and frequency relationships between the output signal of the reference divider and the output signal of the programmable divider and a low pass filter for deriving a control voltage for the local oscillator in response to the pulses generated by the phase comparator.