Patent ID: 7440035

Claim:
A cable extension unit having a signal transmitter for inputting video signals therein, and a signal receiver being freely connecting with said signal transmitter through signal lines, for outputting said video signals received from said signal transmitter through said signal lines, comprising: said signal transmitter comprising: sound signal receiving means for receiving input of a sound signal; and digital sound signal transmitting means for outputting said sound signal inputted into said sound signal receiving means to said signal receiver through said signal lines as a digital sound signal wherein pulses of digital data are arranged; said signal receiver comprising: attenuation compensation volume computing means for computing attenuation compensation volume of said video signal which receives from said signal transmitter on the basis of attenuation of pulses which are arranged in said digital sound signal received from said signal transmitter; and video signal attenuation compensation means for compensating attenuation of said video signal received from said signal transmitter on the basis of said attenuation compensation volume computed by said attenuation compensation volume computing means.