公开(公告)号：US4109281A

公开(公告)日：1978-08-22

申请号：US787592

申请日：1977-04-14

申请人： Tetsuo Kanazashi ,  Tsuyoshi Fujiwara

发明人： Tetsuo Kanazashi ,  Tsuyoshi Fujiwara

IPC分类号： H04N7/10 ,  H04N7/081 ,  H04N7/167 ,  H04N7/173 ,  H04N1/44

CPC分类号： H04N7/167 ,  H04N7/081

摘要： In a CATV system, a received signal band containing video channels and a data signal at a selected frequency is successively converted in frequency so as to provide a chosen video signal at the frequency of a selected channel. After the first conversion a residual fundamental of the data signal carrier is bandpass filtered, amplified and then demodulated to extract the data signal. The needed filtering and signal processing can thereby be more economically accomplished without adverse effects on adjacent video signal channels.