A multiple converter system is provided for a remote user in a cable communications system. The converters at the user location are linked together via a splitter. One converter operates as a master converter transmitting a master control signal to the other converters, designated as slave converters. The slave converters are actuated only upon reception of the master control signal. The master control signal is interrupted by the master converter only when it transmits data upstream to the central office or when one of the slave converters is required to transmit data. A slave converter notifies the master converter of the need to transmit data by a slave signal. A transmitter unit is automatically activated for transmitting data upstream upon the absence of the master signal on the bus.

A data communications terminal is provided for interfacing with a central data processing system to handle a variety of data acquisition and control functions including the minitoring and control of security devices and pay television receivers. The terminal includes a microcomputer unit for receiving and processing data from the central processing system and from remote units which generate data signals in response to abnormal conditions. A data reception and transmission unit include a radio frequency modem for converting data to and from a frequency modulated format and a data converter for changing the serial bit data to parallel word data. An identification unit provides data to the microcomputer regarding the identification of the terminal which can be compared to the address portion of the incoming data from the central processing system. Data generating means are provided for generating and transmitting response data to the microcomputer for transmission to the central processing system. An address decode unit identifies and actuates the various element in this system. The remote data terminal functions in an "interrupt" mode with relation to the central data system so that it communicates with the central data system only when abnormal conditions are detected. Otherwise, the terminal handles its own internal monitoring and control functions. Transmission of data to and from the terminal is preferably along coaxial cable. When used in conjunction with a television receiver, the same coaxial cable may be used for the transmission of television signals to the receiver. In this mode, the terminal includes a television port unit which is activated by the microcomputer to enable access by the receiver to the cable television network in response to appropriate authorization data from the microcomputer.

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.

In two-way cable television systems, return channel noise inherently limits the number of permissible subscribers. The apparatus of this invention reduces the return noise from subscribers not using the service by means of an adaptive return path amplifier, through carrier operated squelch control or through digital interrogation control.

A cable television signal distribution system provides a plurality of television programs and radio programs which are transmitted in frequency multiplex to a plurality of subscriber drop lines. A data receiver and logic control unit, after decoding suitable supplied codes, control the operation of a plurality of high frequency switches by which the received programs can be switched and/or jammed from a remote locate to selectively provide subscribers the desired program.