TRANSMISSION SYSTEM FOR TELEVISION SIGNAL

PURPOSE:To reduce interference disturbance by selecting the vicinity of a video carrier of a current broadcast NTSC to be a blank region, allocating the frequency region higher and lower than the blank region to the transmission of a high frequency and a low frequency component of a television signal respectively and controlling a spectrum of a modulation signal. CONSTITUTION:A low frequency component is extracted by an LPF and modulated by a carrier of a frequency fo and only a lower side band is extracted by a BPF 1. A high frequency component is obtained by an input output difference of the LPF and modulated by the same carrier as the low frequency component and an upper side band is extracted by a BPF 2. Then both the components are subject to frequency multiplex. The operation of a demodulator is in reverse operation to the modulator. A carrier used for synchronization demodulation is reproduced by a PLL circuit 69. In this case, since the low frequency component of an HDTV broadcast wave being a major cause to disturbance from the HDTV broadcast wave onto the NTSC broadcast wave is attenuated by nearly 10dB by the Nyquist filter included in an NTSC receiver, the disturbance is reduced.