Carrier injecting waveform-based modulation scheme for reducing satellite transponder power requirements and earth terminal antenna size
AssigneeHarris Corporation
InventorsRaymond F. Cobb, Michael B. Luntz
Life of this patent
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Abstract
A QPSK modulation scheme uses a data spreading mechanism to rob a relatively limited portion of available transmitter power, and inject into the QPSK waveform a prescribed amount of carrier signal power, through which detection and non-regenerative extraction of the carrier at the receiver may be achieved without incurring a signal-to-noise degradation penalty. In addition, the injected carrier-based modulation scheme of the invention may employ high performance forward error correction coding, to significantly reduce the signal power required for achieving a very low energy per bit-to-noise density ratio (Eb/N0)—on the order of one to zero dB.
Claims31
A method of transmitting information comprising the steps of:
- providing a data signal representative of the information and comprising in-phase (I) and quadrature (Q) components;
- biasing at least one of the I and Q components with an offset comprising a direct current (DC) offset;
- generating a quadrature phase shift keyed (QPSK) waveform based upon a carrier signal:
- and the at least one biased component;
- and
- transmitting the QPSK waveform.
A communication system comprising:
- a quadrature phase shift keyed (QPSK) waveform generator for generating a QPSK waveform based upon a carrier signal and a data signal, the data signal being representative of information to be transmitted and comprising I and Q components, and said QPSK waveform generator biasing at least one of the I and Q components with an offset prior to generating the QPSK waveform, the offset comprising a direct current (DC) offset voltage;
- and
- a transmitter for transmitting the QPSK waveform produced by said QPSK waveform generator.
A method comprising the steps of:
- (a) providing a carrier signal comprising in-phase (I) and quadrature (Q) components;
- (b) providing a data signal comprising I and Q components and biasing the I and Q components of the data signal with at least one offset comprising a spreading waveform;
- and
- (c) combining the I and Q components of the carrier signal with the biased I and Q components of the data signal, respectively, to produce a quadrature phase shift keyed (QPSK) waveform.
A method comprising the steps of:
- (a) receiving a quadrature phase shift keyed (QPSK) waveform having in-phase (I) and quadrature (Q) components of a carrier modulated with I and Q components of a data signal, at least one of the I and Q components of the data signal being biased by an offset comprising a direct current (DC) offset voltage;
- and
- (b) conducting non-regenerative recovery of the QPSK waveform received in step (a) to extract said carrier signal based upon the offset.
A method of transmitting information comprising the steps of:
- providing a data signal representative of the information and comprising in-phase (I) and quadrature (Q) components;
- biasing at least one of the I and Q components with an offset comprising a spreading waveform;
- generating a quadrature phase shift keyed (QPSK) waveform based upon a carrier signal and the at least one biased component;
- and
- transmitting the QPSK waveform.
A communication system comprising:
- a quadrature phase shift keyed (QPSK) waveform generator for generating a QPSK waveform based upon a carrier signal and a data signal, the data signal being representative of information to be transmitted and comprising I and Q components, and said QPSK waveform generator biasing at least one of the I and Q components with an offset prior to generating the QPSK waveform, the offset comprising a spreading waveform;
- and
- a transmitter for transmitting the QPSK waveform produced by said QPSK waveform generator.
Dependencies are inferred from the claim text.