| 摘要 |
The subject matter of the invention is a ghost signal detector for television purposes which, in the case of the presence of a ghost signal, detects a component of this signal and then tracks this component in order to continuously indicate the presence of the ghost signal and its delay with respect to the main television signal. In detail, a component of the received television signal is taken as reference signal in the television receiver and supplied to a variable delay line (12). If the television signal is contaminated by a ghost signal, the reference signal is followed by a duplicate or "ghost version" of this signal at a certain distance. If the variable delay line has the correct delay time, the delayed reference signal at the output of this line coincides in time with the ghost version of the reference signal at the input of the delay line. A coincidence detector (14) senses this coincidence and the delay of the delay line is subsequently controlled in order to maintain the coincidence condition during the subsequent receptions of the reference signal. The delay time of the delay line is a measure of the delay of the ghost signal compared with the main television signal. If the delay of the delay line is not correct and the coincidence condition does not occur, the delay of the delay line is changed until the desired coincidence is achieved. <IMAGE>
|
