GHOST MEASUREMENT BY WAVE-FORM SYNTHESIS

A television ghost is measured by synthesizing the ghost waveform demo dulated by an In-phase synchronous demodulator. For this purpose, the calculated in-phase and quadrature demodulated waveforms of known tran smitted waveforms are prepared at the receiving site. A ghost path is constructed by a software simulator where a ghost waveform Is synthesi zed by changes in ghost parameters consisting of amplitude, phase and time delay. The ghost parameter in which a synthesized ghost waveform In the simulator equals the demodulated ghost waveform is the ghost pa rameter itself of a real ghost path. The steepest descent method is us ed to optimize the ghost parameter In the simulator. The proposed ghos t measurement method uses only a synchronous demodulated waveform. The refore, as compared with the conventional method using quadrature demo dulated waveforms, the circuit scale is small, and it is possible to a void measurement errors caused by phase fluctuations in the quadrature demodulator