VSB HDTV transmission system with reduced NTSC co-channel interference
First Claim
1. A method of transmitting a television signal comprising:
- providing an N-level digitally encoded signal at a sample rate fs substantially equal to three times the NTSC color subcarrier frequency;
generating a carrier signal;
modulating said carrier signal with said N-level digitally encoded signal; and
forming a transmission signal in response to said modulated carrier signal.
9 Assignments
0 Petitions
Accused Products
Abstract
A television signal transmission signal comprises a suppressed carrier, VSB signal having respective Nyquist slopes at the lower and upper edges of a 6 MHz television channel, the center frequency of the Nyquist slope at the lower edge of the channel being substantially coincident with the frequency of the suppressed carrier, and a pilot signal in quadrature relation with the suppressed carrier. The suppressed carrier is modulated by an N-level digitally encoded signal having a sample rate fs substantially equal to three times the NTSC color subcarrier frequency, with the frequency of the color subcarrier being less than the co-channel NTSC picture carrier by an amount equal to about fs/12. The received signal is demodulated by a synchronous detector in response to the received pilot signal and interfering NTSC beat components are attenuated by a linear filter having notches at fs/12, 5fs/12 and fs/2. The output of the filter comprises an M-level signal, where M is greater than N, which is converted to a N-level output signal representing the televised image.
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Citations
38 Claims
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1. A method of transmitting a television signal comprising:
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providing an N-level digitally encoded signal at a sample rate fs substantially equal to three times the NTSC color subcarrier frequency; generating a carrier signal; modulating said carrier signal with said N-level digitally encoded signal; and forming a transmission signal in response to said modulated carrier signal. - View Dependent Claims (2, 3, 4, 5)
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6. A method of transmitting a television signal over a television channel comprising:
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providing an N-level digitally encoded signal at a sample rate fs substantially equal to three times the NTSC color subcarrier frequency; generating a carrier signal having a frequency less than the frequency of the picture carrier of an NTSC co-channel signal by an amount of about fs/12; and modulating said carrier signal with said N-level digitally encoded signal for forming a transmission signal comprising a suppressed carrier, VSB signal having respective Nyquist slopes at the lower and upper edges of said channel, the center frequency of the Nyquist slope at the lower edge of said channel being substantially coincident with the frequency of said carrier signal. - View Dependent Claims (7, 8, 38)
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9. A television signal receiver comprising:
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means for receiving an N-level digitally encoded signal modulating a suppressed carrier signal, said N-level signal having a sample rate fs substantially equal to three times the NTSC color subcarrier frequency and said suppressed carrier signal having a frequency less than the frequency of the picture carrier of an NTSC co-channel signal by an amount of about fs/12; means for demodulating said received N-level signal; filter means processing said demodulated signal for providing an M-level output signal, where M is greater than N, said filter means having a frequency response including a notch at a frequency substantially equal to fs/12; and means for converting said M-level signal to an N-level signal representing a televised image. - View Dependent Claims (10, 11, 12, 13, 14)
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15. A television signal receiver comprising:
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means for receiving an N-level digitally encoded signal modulating a suppressed carrier signal, said N-level signal having a sample rate fs substantially equal to three time the NTSC color subcarrier frequency and said suppressed carrier signal having a frequency less than the frequency of the picture carrier of an NTSC co-channel signal by an amount of about fs/12; means for demodulating said received N-level signal; filter means comprising means for delaying said demodulated signal by an interval substantially equal to 12/fs and means for subtracting the delayed signal from said demodulated signal for providing an M-level output signal, where M is greater than N; and means for converting said M-level signal to an N-level signal representing a televised image.
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16. A receiver for receiving a television signal transmitted over a selected channel comprising:
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means for receiving a transmission signal comprising a suppressed carrier, VSB signal having respective Nyquist slopes at the lower and upper edges of said selected channel, the center frequency of the Nyquist slope at the lower edge of said selected channel being substantially coincident with the frequency of said suppressed carrier, said suppressed carrier being modulated by an N-level digitally encoded signal having a sample rate fs substantially equal to three times the NTSC color subcarrier frequency and said suppressed carrier having a frequency less than the frequency of the picture carrier of an NTSC co-channel signal by an amount of about fs/12; means coupled to said receiving means for demodulating said N-level signal; and filter means processing said demodulated signal for providing an N-level output signal, said filter means having a frequency response including notches at frequencies substantially equal to fs/12 and 5fs/12. - View Dependent Claims (17, 18)
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19. A receiver for receiving a television signal transmitted over a selected channel comprising:
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means for receiving a transmission signal comprising a suppressed carrier, VSB signal having respective Nyquist slopes at the lower and upper edges of said selected channel, the center frequency of the Nyquist slope at the lower edge of said selected channel being substantially coincident with the frequency of said suppressed carrier, and a pilot signal, said suppressed carrier being modulated by an N-level digitally encoded signal having a sample rate fs substantially equal to three times the NTSC color subcarrier frequency and said suppressed carrier having a frequency less than the frequency of the picture carrier of an NTSC co-channel signal by an amount equal to about fs/12; means responsive to said pilot signal for developing a regenerated carrier signal having frequency and phase characteristics corresponding to said suppressed carrier signal; means coupled to said receiving means and responsive to said regenerated carrier signal for demodulating said N-level signal; and filter means processing said demodulated signal for providing an N-level output signal, said filter means having a frequency response including notches at frequencies substantially equal to fs/12 and 5fs/12. - View Dependent Claims (20, 21, 22)
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23. A method of transmitting and receiving a television signal over a selected channel comprising:
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providing a transmission signal comprising a suppressed carrier, VSB signal having respective Nyquist slopes at the upper and lower edges of said selected channel, the center frequency of the Nyquist slope at the lower edge of said selected channel being substantially coincident with the frequency of said suppressed carrier, said suppressed carrier being modulated by an N-level digitally encoded signal having a sample rate fs substantially equal to three times the NTSC color subcarrier frequency and said suppressed carrier having a frequency less than the frequency of the picture carrier of an NTSC co-channel signal by an amount equal to about fs/12; transmitting said transmission signal over said selected channel; receiving said transmitted signal; demodulating said received signal for recovering said N-level signal; subjecting said recovered N-level signal to a filter response having notches at frequencies substantially equal to fs/12 and 5fs/12 for providing a filtered M-level signal, where M is greater than N; and converting said M-level signal to an N-level output signal representing said television signal. - View Dependent Claims (24, 25, 26, 27)
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28. A method of transmitting and receiving a television signal over a selected channel comprising:
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providing a transmission signal comprising a suppressed carrier, VSB signal having respective Nyquist slopes at the upper and lower edges of said selected channel, the center frequency of the Nyquist slope at the lower edge of said selected channel being substantially coincident with the frequency of said suppressed carrier, and a pilot signal, said suppressed carrier being modulated by an N-level digitally encoded signal having a sample rate fs substantially equal to three times the NTSC color subcarrier frequency and said suppressed carrier having a frequency less than the frequency of the picture carrier of an NTSC co-channel signal by an amount equal to about fs/12; transmitting said transmission signal over said selected channel; receiving said transmitted signal; regenerating a carrier signal in response to said received pilot signal, said regenerated carrier signal having frequency and phase characteristics corresponding to said suppressed carrier; demodulating said received signal in response to said regenerated carrier signal for recovering said N-level signal; subjecting said recovered N-level signal to a filter response having notches at frequencies substantially equal to fs/12 and 5fs/12 for providing a filtered M-level signal, where M is greater than N; and converting said M-level signal to an N-level output signal representing said television signal. - View Dependent Claims (29, 30, 31)
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32. A method of providing a television transmission signal for transmission over a selected television channel comprising:
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providing an N-level digitally encoded signal at a sample rate fs; and modulating a carrier signal with said N-level digitally encoded signal for forming a transmission signal comprising a suppressed carrier, VSB signal having respective Nyquist slopes at the lower and upper edges of said selected television channel, the frequency of said carrier signal being substantially coincident with the center frequency of the Nyquist slope at the lower edge of said selected television channel and the frequency fs/2 being substantially coincident with the center frequency of the Nyquist slope at the upper edge of said selected television channel. - View Dependent Claims (33)
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34. A receiver for receiving a television signal transmitted over a selected channel comprising:
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means for receiving a television signal comprising a suppressed carrier, VSB signal having respective Nyquist slopes at the lower and upper edges of said selected channel, said suppressed carrier being modulated by an N-level digitally encoded signal having a sample rate fs, the frequency of said suppressed carrier being substantially coincident with the center frequency of the Nyquist slope at the lower edge of said selected channel and the frequency fs/2 being substantially coincident with the center frequency of the Nyquist slope at the upper edge of said selected channel; and demodulation means coupled to said receiving means and responsive to said received television signal for recovering said N-level digitally encoded signal. - View Dependent Claims (35, 36, 37)
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Specification