Modulating array QAM transmitter
First Claim
1. A method for producing one of a plurality of symbols, wherein the produced symbol represents j bits, comprising the steps of:
- applying j input bits to a data storage device to output N bits to N/2 QPSK modulators, each of the N/2 QPSK modulators receiving a pair of the N bits, each of bit pairs specifying one of four phase shifts;
within each of the N/2 QPSK modulators, QPSK modulating a reference signal in accordance with a phase shift specified by the received bit pair;
amplifying the outputs of each of the N/2 QPSK modulators to produce respective amplified signals; and
combining the amplified signals to produce one of a plurality of QAM symbols, wherein each produced QAM symbol represents a particular value of the j bits.
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Abstract
This invention pertains to a method for producing high power microwave transmission signals conveying one of a plurality of symbols, wherein a symbol represents a plurality of bits, and also to a modulating array transmitter that operates in accordance with the method. The method includes a first step of applying j bits to a data storage device to address the data storage device to output N bits to N/2 QPSK modulators. Each of the N/2 QPSK modulators receives a subset (a pair) of the N bits. Each of the bit pairs specifies one of up to four phase shifts. Within each of the N/20 PSK modulators, a next step phase modulates a reference (e.g., local oscillator) signal in accordance with a phase shift specified by the received pair of bits. A next step amplifies the outputs of each of the N/2 QPSK modulators to produce respective amplified QPSK modulated signals. A further step combines the amplified OPSK modulated signals by vector addition to produce one of a plurality of symbols, wherein the produced symbol represents a value of the j (even number) input bits. Also disclosed is a BPSK embodiment of the invention, wherein there are N BPSK modulators, each receiving one of the N bits.
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Citations
15 Claims
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1. A method for producing one of a plurality of symbols, wherein the produced symbol represents j bits, comprising the steps of:
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applying j input bits to a data storage device to output N bits to N/2 QPSK modulators, each of the N/2 QPSK modulators receiving a pair of the N bits, each of bit pairs specifying one of four phase shifts; within each of the N/2 QPSK modulators, QPSK modulating a reference signal in accordance with a phase shift specified by the received bit pair; amplifying the outputs of each of the N/2 QPSK modulators to produce respective amplified signals; and combining the amplified signals to produce one of a plurality of QAM symbols, wherein each produced QAM symbol represents a particular value of the j bits. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A modulating array transmitter comprising:
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data storage means storing M words each comprised of N bits, said data storage means having a plurality of inputs for selecting one of said M words to output said N bits of said selected word; a plurality of modulating means, each of, said modulating means having a first input coupled to a reference signal and at least one second input coupled to an output of said data storage means, each of said modulating means comprising means for phase modulating said reference signal for generating one state of a signal constellation in response to receiving a subset of said N bits from said data storage means; a plurality of amplifying means, individual ones of said plurality of amplifying means being coupled to an output of an individual one of said plurality of modulating means; and means for combining outputs of said plurality of amplifying means to generate a symbol representing a value of data bits that are applied to said plurality of inputs of said data storage means. - View Dependent Claims (8, 9, 10)
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11. A transmitter comprising:
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a plurality of PSK modulators each comprising means for PSK modulating a local oscillator signal in accordance with a digital input signal comprised of a predetermined number of bits; a plurality of amplifiers individual ones of which have an input coupled to an output of one of said PSK modulators; and means for combining together amplified PSK modulated signals emanating from said plurality of amplifiers and outputting a composite signal representing a symbol within a QAM symbol constellation. - View Dependent Claims (12, 13, 14, 15)
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Specification