Method for transmitting VSB digital TV with carrier frequency near co-channel NTSC audio carrier frequency

A method of transmitting a digital television signal through a channel subject at times to the presence of a co-channel NTSC analog television signal having a modulated video carrier, a modulated color subcarrier, and a modulated audio carrier, said method comprising steps of:

• providing an N-level digitally encoded signal at a symbol rate fs substantially equal to three times the NTSC color subcarrier frequency, N being a plural integer;
• generating a suppressed carrier signal having a frequency offset below the co-channel NTSC audio carrier frequency by a frequency corresponding to a NTSC horizontal scanning frequency;
• generating a pilot signal having a frequency and phase equal to the frequency and phase of said carrier signal;
• modulating the amplitude of said carrier signal with said N-level digitally encoded signal to generate a vestigial-sideband amplitude-modulation output signal;
• and
• forming a transmission signal by combining said pilot signal and said vestigial-sideband amplitude-modulation output signal.

A method of transmitting a digital television signal over a 6 MHz television channel comprising steps of:

• providing an N-level digitally encoded signal at a sample rate fs substantially equal to three times a co-channel NTSC color subcarrier frequency;
• generating a carrier signal having a frequency greater than a frequency of a co-channel NTSC picture carrier and less than a frequency of a co-channel NTSC audio carrier;
• modulating said carrier signal with said N-level digitally encoded signal for forming a vestigial-sideband amplitude-modulation output signal;
• generating a pilot signal having a frequency and phase equal to the frequency and phase of said carrier signal;
• and
• combining said pilot signal and said vestigial-sideband amplitude-modulation output signal.