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