Transmission manner null of the vestigial sideband digital television signal which possesses NTSC identical channel audio carrier frequency adjacent carrier

摘要

PROBLEM TO BE SOLVED: To substantially reduce NTSC same channel interference by modulating the amplitude of a carrier signal with an N level digital encoding signal for generating two amplitude modulating sidebands and forming a transmitting signal. ;SOLUTION: The transmitter 10 of digital television(DTV) is provided with a video source 11 receiving a clock signal (f_s) from a clock generator 12. A carrier and pilot signal generating circuit 17 supplies a carrier signal with the horizontal frequency (f_h) of an official frequency off-set to be lower than a corresponding NTSC voice carrier frequency (f_s) for a residual sideband (VSB) amplitude modulator 16. The circuit 17 supplies the pilot signal of a frequency (f_p) with a frequency and a phase equal to the carrier signal. The pilot signal is combined with a residual sideband amplitude modulating output signal from the modulator 16 by a combining circuit 18 to form a signal to be impressed to a final amplifying circuit 19 to be used for driving a transmission antenna 20.;COPYRIGHT: (C)1999,JPO