System and method for recognizing zero-amplitude symbols in a QAM signal and digital receiver incorporating the same
First Claim
1. A system for recognizing zero-amplitude symbols in a quadrature amplitude modulated (QAM) signal, comprising:
- an amplitude detector that extracts a candidate symbol from said signal and locates said candidate symbol relative to a constellation of symbols; and
a zero-amplitude symbol interpreter, associated with said amplitude detector, that recognizes said candidate symbol as being a zero-amplitude symbol when said candidate symbol is closer to an origin of said constellation than to symbols proximate thereto.
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Abstract
A system for, and method of, recognizing zero-amplitude symbols in a quadrature amplitude modulated (QAM) signal and a digital receiver incorporating the system or the method. In one embodiment, the system includes: (1) an amplitude detector that extracts a candidate symbol from the signal and locates the candidate symbol relative to a constellation of symbols and (2) a zero-amplitude symbol interpreter, associated with the amplitude detector, that recognizes the candidate symbol as being a zero-amplitude symbol when the candidate symbol is closer to an origin of the constellation than to symbols proximate thereto.
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Citations
21 Claims
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1. A system for recognizing zero-amplitude symbols in a quadrature amplitude modulated (QAM) signal, comprising:
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an amplitude detector that extracts a candidate symbol from said signal and locates said candidate symbol relative to a constellation of symbols; and
a zero-amplitude symbol interpreter, associated with said amplitude detector, that recognizes said candidate symbol as being a zero-amplitude symbol when said candidate symbol is closer to an origin of said constellation than to symbols proximate thereto. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method of recognizing zero-amplitude symbols in a quadrature amplitude modulated (QAM) signal, comprising:
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extracting a candidate symbol from said signal;
locating said candidate symbol relative to a constellation of symbols; and
recognizing said candidate symbol as being a zero-amplitude symbol when said candidate symbol is closer to an origin of said constellation than to symbols proximate thereto. - View Dependent Claims (9, 10, 11, 12, 13, 14, 16, 17, 18, 19, 20, 21)
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15. A digital receiver, comprising:
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a digital-to-analog (D/A) converter that converts a received quadrature amplitude modulated (QAM) signal in digital form to analog form;
a demodulator, coupled to said D/A converter, that demodulates said QAM signal;
an equalizer, coupled to said demodulator, that equalizes said QAM signal;
a slicer, coupled to said equalizer, that recognizes nonzero-and zero-amplitude symbols in said QAM signal, said slicer having a system for recognizing said zero-amplitude symbols, including;
an amplitude detector that extracts a candidate symbol from said signal and locates said candidate symbol relative to a constellation of symbols, and a zero-amplitude symbol interpreter, associated with said amplitude detector, that recognizes said candidate symbol as being a zero-amplitude symbol when said candidate symbol is closer to an origin of said constellation than to symbols proximate thereto; and
a decoder, coupled to said slicer, that decodes said nonzero- and zero-amplitude symbols to yield data.
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Specification