Abstract: A cable TV system, which is arranged to permit a transmission of signals in the return direction from local networks (10), included in the system, to a head end (11) of the system within a predetermined carrier frequency band, serving for the transmission of signals in said direction, comprises means (11?, 23) for monitoring the system in respect of disturbances occurring within said carrier frequency band. Said monitoring means (11?, 23) comprise detector means (32, 33, 34, 35) within each local network (10) which are arranged to compare the energy level of signals occurring within said carrier frequency band with at least one predetermined reference level and to generate logic signals, depending upon the result of said comparison, and memory means (36) within each local network (10) which are arranged to store information about time intervals during which said energy level exceeds said reference level, derived from the values of said logic signals at different times.

Abstract: An arrangement for the reduction of noise transmitted in the return direction fron a local cable TV network (10) comprises an input (14), an output (16), means (21) for evaluating signals incoming at the input (14), and blocking means (17) controllable by said evaluation means (21). Said blocking means are formed by a reprogrammable digital signal processing unit (17), which is connected to the input (14) via an analog-to-digital converter (19) and which is arranged to generate digital output signals corresponding to portions of the incoming signals, depending upon the existing programming of the signal processing unit (17) and the result of the evaluation of the incoming signals effected by the evaluation means (21), and to deliver said digital output signals to a digital-to-analog converter (24) connected to the output (16).

Abstract: A local network (10), forming part of a cable TV system, includes subscriber outlets (21), from which signals can be transmitted in the return direction to a head end (11) of the system within a predetermined carrier frequency band.

Abstract: A cable TV system, which is arranged to permit a transmission of signals in the return direction from local networks (10), included in the system, to a head end (11) of the system within a predetermined carrier frequency band, serving for the transmission of signals in said direction, comprises means (11′, 23) for monitoring the system in respect of disturbances occurring within said carrier frequency band. Said monitoring means (11′, 23) comprise detector means (32, 33, 34, 35) within each local network (10) which are arranged to compare the energy level of signals occurring within said carrier frequency band with at least one predetermined reference level and to generate logic signals, depending upon the result of said comparison, and memory means (36) within each local network (10) which are arranged to store information about time intervals during which said energy level exceeds said reference level, derived from the values of said logic signals at different times.