Abstract: Apparatus and method for reducing the cost and complexity of equipment placed on subscribers' premises in a subscription communications system, such as a cable television system, while at the same time providing security against unauthorized system access includes a microprocessor controlled frequency converter in proximity to the subscriber's premises to convert information transmission signals to subscriber-receivable frequencies; a channel selection unit at the subscriber's premises for producing a command signal to initiate the transmission of information to the subscriber; and a verification circuit coupled to receive the command signals, to verify the same and electronically to instruct the microprocessor. The microprocessor may be provided with plural, plug-in converter modules for feeding signals to several subscribers and may be made responsive to subscriber generated auxiliary function signals from alarm detector units, utility meter reading devices, and the like.

Abstract: Apparatus and method for monitoring the quality and integrity of a communications system, such as a cable television system, which includes several monitoring circuits placed throughout the system to detect and amplify RF or audio frequency signals received at any number of selected points. The detected signals are used to amplitude modulate a continuous wave oscillator at a selected one of several discrete frequencies identifiable with the position of the monitoring circuits. The modulated CW signals are then fed upstream for processing at a central location. Each monitoring network includes a broadband detector so as to enable the detection of one or more discrete frequency signals or a band of signals. The use of several discrete frequency signals for normal monitoring purposes allows reliable monitoring to be carried out on a continuous basis without casing interference to the information signals being transmitted through the system.

Abstract: The embodiment of the invention disclosed herein is directed to a code operated switching device having a receiver for handling RF frequencies in a superheterodyne fashion without the need of local oscillators, or the like at the receiver. Input means is provided for receiving first and second RF frequencies having a predetermined frequency difference. The RF frequencies are FSK modulated simultaneously, one frequency increasing and the other decreasing, so that the frequency difference will produce a control signal at the output of an FM audio discriminator circuit. The control signal can be code modulated with series digital pulse information and applied to a code logic circuit that will detect if the proper code for the receiver has been received. If the proper code is received the logic circuit will energize an active control element such as a relay or the like to allow data to be transmitted back through the switching device.