Development of a ghost cancel reference signal for TV broadcasting

A method for reducing ghost interference of TV signals is described. As part of a ghost canceler that is designed to eliminate ghost signals inside a signal receiver, the authors developed a ghost cancel reference (GCR) signal as part of the EDTV (extended definition television) system. In this system, a bar signal with a rise waveform of sin x/x is inserted as a reference signal into the vertical blanking period using a special send sequence on the transmitter's side. With this GCR, the ghost canceler built into a TV receiver is able to detect ghost signals with a delay time of about 45 mu s or less (i.e. from the limit of subjective observation to that of objective observation). This GCR method has been adopted as Japan's standard for broadcasting and was introduced in the fall of 1989.<>