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 μs 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