Constrained-envelope digital-communications transmission system and method therefor
First Claim
1. A constrained-envelope digital communications transmitter circuit comprising:
- a pulse-spreading filter configured to receive a quadrature phase-point signal stream of digitized quadrature phase points and produce a filtered signal stream, said filtered signal stream exhibiting energy corresponding to each phase point spread throughout a plurality of unit baud intervals;
a constrained-envelope generator coupled to said pulse-spreading filter and configured to produce a constrained-bandwidth error signal stream;
a combining circuit coupled to said pulse-spreading filter and to said constrained-envelope generator, said combining circuit configured to combine said filtered signal stream and said constrained-bandwidth error signal stream to produce a constrained-envelope signal stream; and
a substantially linear amplifier having an input coupled to said combining circuit.
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Accused Products
Abstract
A constrained-envelope digital-communications transmitter circuit (22) in which a binary data source (32) provides an input signal stream (34), a phase mapper (44) maps the input signal stream (34) into a quadrature phase-point signal stream (50) having a predetermined number of symbols per unit baud interval (64) and defining a phase point (54) in a phase-point constellation (46), a pulse-spreading filter (76) filters the phase-point signal stream (50) into a filtered signal stream (74), a constrained-envelope generator (106) generates a constrained-bandwidth error signal stream (108) from the filtered signal stream (74), a delay element (138) delays the filtered signal stream (74) into a delayed signal stream (140) synchronized with the constrained-bandwidth error signal stream (108), a complex summing circuit (110) sums the delayed signal stream (140) and the constrained-bandwidth error signal stream (108) into a constrained-envelope signal stream (112), and a substantially linear amplifier (146) amplifies the constrained-envelope signal stream (112) and transmits it as a radio-frequency broadcast signal (26).
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Citations
38 Claims
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1. A constrained-envelope digital communications transmitter circuit comprising:
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a pulse-spreading filter configured to receive a quadrature phase-point signal stream of digitized quadrature phase points and produce a filtered signal stream, said filtered signal stream exhibiting energy corresponding to each phase point spread throughout a plurality of unit baud intervals; a constrained-envelope generator coupled to said pulse-spreading filter and configured to produce a constrained-bandwidth error signal stream; a combining circuit coupled to said pulse-spreading filter and to said constrained-envelope generator, said combining circuit configured to combine said filtered signal stream and said constrained-bandwidth error signal stream to produce a constrained-envelope signal stream; and a substantially linear amplifier having an input coupled to said combining circuit. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. In a digital communications system, a method for the transmission of a constrained-envelope communications signal, said transmission method comprising the steps of:
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filtering a quadrature phase-point signal stream to produce a filtered signal stream, said filtering step spreading energy from each phase point in said filtered signal stream over a plurality of unit baud intervals; generating a constrained-bandwidth error signal stream from said filtered signal stream and a threshold signal; combining said filtered signal stream and said constrained-bandwidth error signal stream to produce a constrained-envelope signal stream; linearly amplifying said constrained-envelope signal stream to produce said constrained-envelope communications signal; and transmitting said constrained-envelope communications signal. - View Dependent Claims (17, 18, 19, 20, 21, 22)
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23. A constrained-envelope digital-communications transmitter circuit comprising:
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a binary data source configured to provide a binary input signal stream; a phase mapper coupled to said binary data source and configured to produce a quadrature phase-point signal stream, wherein said phase-point signal stream has a predetermined number of symbols per unit baud interval, said predetermined number of symbols defining a phase point in a phase-point constellation; a Nyquist-type filter coupled to said phase mapper and configured to produce a filtered signal stream; a constrained-envelope generator coupled to said Nyquist-type filter and configured to produce a constrained-bandwidth error signal stream; a delay element coupled to said Nyquist-type filter and configured to produce a delayed signal stream synchronized with said constrained-bandwidth error signal stream; a complex summing circuit coupled to said delay element and said constrained-envelope generator and configured to produce a constrained-envelope signal stream; and a substantially linear amplifier coupled to said complex summing circuit and configured to produce a radio-frequency broadcast signal. - View Dependent Claims (24, 25, 26, 27, 28, 29)
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30. A constrained-envelope digital communications transmitter circuit comprising:
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a first pulse spreading filter configured to receive a quadrature phase-point signal stream of digitized quadrature phase points and produce a filtered signal stream, said filtered signal stream exhibiting energy corresponding to each phase point spread over a plurality of unit baud intervals; a constrained-envelope generator coupled to said first pulse spreading filter and configured to produce a constrained-bandwidth error signal in response to said filtered signal stream and a threshold generator, wherein the constrained-envelope generator comprises a circuit to produce the constrained-bandwidth error signal comprising; a difference circuit that produces a difference signal stream that is the difference between said filtered signal stream and a threshold from the threshold generator; a discriminator coupled to the difference circuit to produce an error signal stream, where said error signal stream is produced from the difference signal stream by passing unchanged pulses having positive values while all other pulses are eliminated; and a second pulse spreading filter to constrain the bandwidth of the error signal stream to produce the constrained-bandwidth error signal stream; a delay element, coupled to said first pulse spreading filter, for use in delaying the output of said first pulse spreading filter; a combining circuit coupled to said delay element and to said second pulse spreading filter, said combining circuit configured to combine said filtered signal stream and said constrained-bandwidth error signal stream to produce a constrained-envelope signal stream; and a substantially linear amplifier having an input coupled to said combining circuit. - View Dependent Claims (31, 32, 33, 34)
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35. A method for transmitting a constrained-envelope communications signal, said method comprising:
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a) filtering a quadrature phase-point signal stream to produce a filtered signal stream, said filtering step spreading energy from each phase point over a plurality of unit baud intervals; b) generating a constrained-bandwidth error signal stream from said filtered signal stream and a threshold signal, wherein generating a constrained-bandwidth error signal stream comprises producing a difference signal stream that is the difference between the filtered signal stream and the threshold, producing an error signal stream from the difference signal stream in a discriminator by passing unchanged pulses having positive values while all other pulses are eliminated, and pulse-spread filtering the error signal stream; c) delaying the filtered signal stream; d) combining the delayed filtered signal stream and said constrained-bandwidth error signal stream to produce a constrained-envelope signal stream; e) linearly amplifying said constrained-envelope signal stream to produce said constrained-envelope communications signal; and f) transmitting said constrained-envelope communications signal. - View Dependent Claims (36, 37, 38)
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Specification