Multilevel modulator capable of producing a composite modulated signal comprising a quadrature amplitude modulated component and a phase modulated component
AssigneeNEC Corporation
InventorYasuharu Yoshida
Life of this patent
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Abstract
Responsive to a first and a second main data signal and a subdata signal, a multilevel modulator produces a composite modulated signal which comprises a quadrature amplitude modulated component modulated by the first and the second main data signals and represented by a radius on a phase plane and a phase modulated component modulated by the subdata signal are represented by a clockwise and a counterclockwise shift on the phase plane. A multilevel demodulator carries out an inverse operation to reproduce the composite modulated signal into first and second reproduced main data signal and a reproduced subdata signal.
Claims18
A multilevel modulator for modulating a first and a second main data signal and a subdata signal into a composite modulated signal, each of said first and said second main data signals being represented by first through n-th bits where n is a positive integer which is not less than two, said subdata signal being represented by one of a first and a second binary value at a time, wherein the improvement comprises:
- modulating means responsive to said first and said second main data signals and said subdata signal for modulating said first and said second main data signals and said subdata signal into said composite modulated signal comprising a quadrature amplitude modulated component and a phase modulated component, said quadrature amplitude modulated component being modulated by said first and said second main data signals and having 2.sup.2n output signal points on a phase plane, said phase modulated component being modulated by said subdata signal.
A multilevel modulator for modulating a main data signal and a subdata signal into a composite modulated signal, said main data signal being represented by first through N-th bits where N is an odd number, said subdata signal being represented by one of a first and a second binary value at a time, wherein the improvement comprises:
- modulating means responsive to said main data signal and said subdata signal for modulating said main data signal and said subdata signal into said composite modulated signal comprising a quadrature amplitude modulated component and a phase modulated component, said quadrature amplitude modulated component being modulated by said main data signal and having 2.sup.N signal points on a phase plane, said phase modulated component being modulated by said subdata signal.
A multilevel demodulator for demodulating a composite modulated signal comprising a multilevel quadrature amplitude modulated component modulated by a first and a second main data signal and a phase modulated component modulated by a subdata signal, each of said first and said second main data signals being represented by first through n-th bits and having a first bit rate f.sub.1 where n represents a positive integer which is not less than two, said subdata signal being represented by one of a first and a second binary value at a time and having a second bit rate f.sub.2 which is not greater than said first bit rate divided by a predetermined natural number m, said phase modulated component having a first phase difference of plus .alpha. radian when said subdata signal is represented by said first binary value, where .alpha. is not greater than said phase modulated component having a second phase difference of minus .alpha. ( radian when said subdata signal is represented by said second binary value, said demodulator comprising detecting means for phase detecting said composite modulated signal to produce a first and a second phase detection signal, wherein the improvement comprises:
- reproducing means coupled to said detecting means for reproducing a reproduced subdata signal and a first and a second reproduced main data signal in response to said first and said second phase detection signals.
A multilevel demodulator for demodulating a composite modulated signal comprising a multilevel quadrature amplitude modulated component modulated by a main data signal and a phase modulated component modulated by a subdata signal, said main data signal being represented by first through N-th bits and having a first bit rate f.sub.1 where N represents an odd number, said subdata signal being represented by one of a first and a second binary value at a time and having a second bit rate f.sub.2 which is not greater than said first bit rate divided by a predetermined natural number m, said phase modulated component having a first phase difference of plus .alpha. radian when said subdata signal is represented by said first binary value, where .alpha. is not greater than .pi./2.sup.N, said phase modulated component having a second phase difference of minus .alpha. radian when said subdata signal is represented by said second binary value, said demodulator comprising detecting means for phase detecting said composite modulated signal to produce a first and a second phase detection signal, wherein the improvement comprises:
- reproducing means coupled to said detecting means for reproducing a reproduced subdata signal and a first and a second reproduced main data signal in response to said first and said second phase detection signals.
Dependencies are inferred from the claim text.