Abstract: In a pay television device, a horizontal sync signal, a vertical sync signal, and the like are removed from a composite video signal, and first-frequency and second-frequency signals for descrambling processing are attached in the intervals corresponding to the removed signals, thus eliminating the need for multiplexing signals which are necessary for descrambling processing on an audio signal.

Abstract: A key signal conversion device for use in a CATV television system in which more than one different scrambling process is performed, the conversion device receiving one of a scrambled high-frequency signal in a television system and a sound intermediate frequency signal in the television system, extracting a key signal for unscrambling the scrambling in the television system and adding the key signal to a nonscrambled television signal which is to be subsequently scrambled by a process other than a process used to scramble the received signal, the key signal conversion device including: a first detecting circuit, for receiving the one of a scrambled television signal and a sound intermediate frequency signal, and for detecting one of a synchronizing signal of the television signal and a synchronizing signal superimposed on the sound intermediate frequency signal; a gate circuit, for receiving the one of a scrambled television signal and a sound intermediate-frequency signal, and for extracting the key signal

Abstract: A cable television system includes a transmitter and at least one receiver. In the transmitter, sync information is suppressed in amplitude to execute scrambling, and a sync width information signal and key data are superimposed on a television signal during a vertical blanking period. The sync width information signal has a burst form and a predetermined width, and represents whether sync information is present or absent. The key data represents contents of the scrambling. In the receiver, the sync width information signal is recovered, and a sync width information pulse corresponding to the sync width information signal is generated. A reference signal is generated on the basis of an edge of the sync width information pulse. The key data is extracted from the scrambled video information in response to the reference signal. Pseudo sync signals are generated in response to an edge of the sync width information pulse.

Abstract: A control system for a cable television transmission line which has functions of collecting and controlling data. Information is collected by generating an instruction and transmitting same to a microcomputer by space communication. Furthermore, the operating conditions of a remote cable television line amplifier can be changed by generating an instruction from the microcomputer.

Abstract: This invention provides a surge absorber for absorbing surges of electric current. The absorber has a metal oxide varistor hermetically sealed in a hollow insulator by a top and a lower electrical terminal and also has a conductive rod extending substantially downwardly and electrically connected to ground and to the lower electrical terminal by solder and also thermally connected to the metal oxide varistor whereby when the varistor is heated by a surge of an electric current therethrough to a temperature to heat the solder above the melting point of the solder, said conductive rod gets separated from the lower electrical terminal to fall downwardly, thereby stopping the electric current through the metal oxide varistor to ground.