Abstract: A reception controlling apparatus for a CATV system in which jamming signals are added to the signals sent to each subscriber's terminal unit in such a manner as to accurately jam the designated nonpermitted channels without interfering with the permitted channels. A microcomputer receives data from a broadcast center indicating which subscribers are permitted to view which channels. A jamming signal is generated in a time-division manner and gated onto the lines to the individual subscribers under the control of the microcomputer. The jamming signal is produced by a VCO controlled by the microcomputer. The jamming signal is produced by a VCO controlled by the microcomputer while providing correction to its output frequency.

Abstract: A data communication system for use in a CATV system or the like employing only simple data communications operations between a central control device and terminal units for effecting a descrambling function. The central control device is connected to the plural terminal units via respective transmission paths. When the central control device is unable to communicate with the terminal units, a transmission carrier is applied to the terminal units via the transmission paths. When a polling operation is to be carried out by the central control device, application of the carrier to the transmission paths is suspended to allow the central control device to communicate with the terminal units. In each of the terminal units, a transmission request thereto is detected from the fact that the carrier has been suspended. Upon the detection of a transmission request, an up-data transmission to the central control device is performed.

Abstract: A CATV system in which first and second terminal units are provided, connected in series via a transmission line, whereby the first transmission unit effects communiction with a control center while the second terminal unit controls channel selection for associated terminal units. In order to perform data communication, priority is determined between the first and second terminal units such that the second terminal unit is set in a stand-by state when the first terminal unit is in a busy state in which the first terminal unit communicates with the center, while the second terminal unit sends upward data to the first terminal unit in a state in which the first terminal unit requests upward data communication to the second terminal unit.

Abstract: A CATV communication system in which a distribution unit performs the functions of channel tuning and response to polling for plural associated terminal units. The distribution unit includes a main central processing unit for performing data communication between the center and the distribution unit, at least one subsidiary central processing unit and a plurality of terminals associated therewith, and a switching unit for selectively connecting the buses of the respective processing units to buses of a ROM and RAM having sharable addresses with the condition that the main central processing unit has priority.