Upstream signal control apparatus for cable television system

DETAILED DESCRIPTION It is, therefore, an object of the present invention to provide an upstream signal control apparatus for a cable television system in which the transmission level of an upstream signal is automatically managed by a terminal itself so as to be always kept stable.
It is another object of the present invention to provide an apparatus which can decrease the number of times that a broadcasting center controls a terminal when the transmission level of an upstream signal from the terminal is to be set.
In order to achieve the above object, according to the present invention, there is provided an upstream signal control apparatus for a cable television system having a two-way communication function in which downstream signals are transmitted from a broadcasting center to a plurality of terminals, upstream signals are transmitted from the plurality of terminals to the broadcasting center, and the broadcasting center and the plurality of terminals receive and demodulate the transmitted signals, comprising: level detecting means, arranged in each of the terminals, for obtaining a level detection signal by detecting a level of a downstream signal from the broadcasting center; storage means for storing a level setting signal exhibiting a level change of negative linear characteristics with respect to the level of the downstream signal; and level setting means for setting a transmission level of the upstream signal on the basis of the level setting signal.