Carrier injecting waveform-based modulation scheme for reducing satellite transponder power requirements and earth terminal antenna size
First Claim
Patent Images
1. 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 and encoded with a forward error correction code, the forward error correction code being capable of extending error rate performance to a value of energy per bit to noise density ratio (Eb/No) less than 4 dB;
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;
receiving the transmitted QPSK waveform;
processing the received QPSK waveform to extract said carrier signal therefrom;
processing the received QPSK waveform using the carrier signal extracted therefrom to derive said data signal; and
decoding the encoded data signal to recover said information from said data signal.
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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.
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Citations
44 Claims
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1. A method of transmitting information comprising the steps of:
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providing a data signal representative of the information and comprising in-phase (I) and quadrature (Q) components and encoded with a forward error correction code, the forward error correction code being capable of extending error rate performance to a value of energy per bit to noise density ratio (Eb/No) less than 4 dB;
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;
andtransmitting the QPSK waveform;
receiving the transmitted QPSK waveform;
processing the received QPSK waveform to extract said carrier signal therefrom;
processing the received QPSK waveform using the carrier signal extracted therefrom to derive said data signal; and
decoding the encoded data signal to recover said information from said data signal. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A communication system comprising:
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an encoder operative to encode a data signal with a forward error correction code capable of extending error rate performance to a value of energy per bit to noise density ratio (Eb/No) less than 4 dB; 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;
anda transmitter for transmitting the QPSK waveform produced by said QPSK waveform generator; and
a receiver operative to receive said QPSK waveform and to extract said carrier signal therefrom, process said QPSK waveform using said extracted carrier signal to derive said encoded data signal, and decode the encoded data signal to recover said information from said data signal. - View Dependent Claims (8, 9, 10, 11)
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12. A method comprising the steps of:
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(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 to provide a carrier extraction reference; 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. - View Dependent Claims (13, 14, 15, 16)
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17. A method comprising the steps of:
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(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, the data signal containing information encoded with a forward error correction code capable of extending error rate performance to a value of energy per bit to noise density ratio (Eb/No) less than 4 dB, and 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;
(c) processing the QPSK waveform received in step (a) using the carrier signal extracted therefrom in step (b) to recover said data signal; and
(d) decoding the encoded data signal to recover said information. - View Dependent Claims (18, 19, 20)
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21. A method of transmitting information comprising the steps of:
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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 to provide a carrier extraction reference;
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. - View Dependent Claims (22, 23, 24, 25, 26)
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27. A communication system comprising:
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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 to provide a carrier extraction reference, the offset comprising a spreading waveform; and
a transmitter for transmitting the QPSK waveform produced by said QPSK waveform generator. - View Dependent Claims (28, 29, 30, 31)
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32. A method of transmitting information comprising the steps of:
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providing a data signal representative of the information and comprising in-phase (I) and quadrature (Q) components and encoded with a forward error correction code, the forward error correction code being capable of extending error rate performance to a value of energy per bit to noise density ratio (Eb/No) less than 4 dB;
biasing at least one of the I and Q components with an offset comprising a direct current (DC) offset;
generating a waveform based upon a carrier signal and the at least one biased component;
transmitting the waveform;
receiving the transmitted waveform;
processing the received waveform to extract said carrier signal therefrom;
processing the received waveform using the carrier signal extracted therefrom to derive said data signal; and
decoding the encoded data signal to recover said information from said data signal. - View Dependent Claims (33)
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34. A method of transmitting information comprising the steps of:
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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 to provide a carrier extraction reference;
generating a waveform based upon a carrier signal and the at least one biased component; and
transmitting the waveform. - View Dependent Claims (35, 36, 37, 38, 39)
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40. A communication system comprising:
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a waveform generator for generating a 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 waveform generator biasing at least one of the I and Q components with an offset prior to generating the waveform to provide a carrier extraction reference, the offset comprising a spreading waveform; and
a transmitter for transmitting the waveform produced by said waveform generator. - View Dependent Claims (41, 42, 43, 44)
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Specification