Method and apparatus for transmission and reception of a digital television signal using multicarrier modulation
First Claim
1. A system for encoding a television signal comprising:
- a) means for coding a first television signal into a plurality of digital symbols;
b) means coupled to said coding means, for mapping each of said digital symbols into respective complex symbols;
c) means coupled to said mapping means, for deriving a plurality of coefficients based upon a signal reference;
d) means coupled to said deriving means, for multiplying each of said complex symbols with a respective coefficient so as to form a plurality of weighted complex symbols; and
e) means coupled to said multiplying means, for modulating each of said weighted complex symbols on a respective carrier.
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Abstract
A method and apparatus for modulating and demodulating an MCM television signal is described which is particularly useful in proposed "simulcast" HDTV terrestrial broadcasting. The MCM spectrum of the television signal is shaped using weighting coefficients which are derived from either an idealized NTSC signal or an actual NTSC co-channel signal. These coefficients are used to shape the respective MCM carriers to provide an energy distribution in the MCM signal which provides greater degree of robustness with a minimum degree of co-channel interference to and from an NTSC co-channel signal. The instant invention further takes advantage of the interference characteristics of composite television signals described above, to position the placement of the MCM carriers in frequency, to minimize interference with an NTSC co-channel signal. Several methods of deriving the weighting coefficients are described including an adaptive approach whereby the characteristics of the interfering NTSC transmission are received and the instantaneous NTSC spectrum calculated therefrom and weighting coefficients assigned accordingly. These coefficients can be transmitted to a receiver to update its coefficient table.
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Citations
15 Claims
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1. A system for encoding a television signal comprising:
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a) means for coding a first television signal into a plurality of digital symbols; b) means coupled to said coding means, for mapping each of said digital symbols into respective complex symbols; c) means coupled to said mapping means, for deriving a plurality of coefficients based upon a signal reference; d) means coupled to said deriving means, for multiplying each of said complex symbols with a respective coefficient so as to form a plurality of weighted complex symbols; and e) means coupled to said multiplying means, for modulating each of said weighted complex symbols on a respective carrier. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A method for encoding a television signal comprising the steps of:
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a) coding a first television into a plurality of digital symbols; b) mapping each of said digital symbols into respective complex symbols; c) deriving a plurality of coefficients based upon a signal reference; d) multiplying each of said complex symbols with a respective coefficient so as to form a plurality of weighted complex symbols; and e) modulating each of said weighted complex symbols on a respective carrier.
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Specification