Cable TV with subscriber fault interrogation - has microprocessor controlled fault monitor to digitally interrogate all line equipment over two-way transmission system

摘要

The cable TV system has two way transmission between the central programme source (1) and the individual subscriber terminals (5) via the various intermediate branching and amplifying points (3). The design enables a fault and information monitor control (2) associated with the central programme source (1) regularly to interrogate all the terminals (5) by using address and command digitally encoded signals. The intermediate points (3) have storage facilities and are equipped with reception and transmission circuitry. The transmit signals are in the band 40 to 300 MHz with 43.9 and 44.1 MHz being used for transmission of the interrogation signals at a bit rate of 19.2 kbit/s. The return direction from the subscriber points (5) through the various intermediate and branching points (3) is in the frequency band 5 to 25 MHz with 6.5 MHZ being used for the data transmission. The monitor (2) is microprocessor controlled and the central signal source (1) distributes off-air transmissions received on its own aerial (6).