Constrained-envelope digital-communications transmission system and method therefor
First Claim
1. A constrained-envelope digital communication 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
39 Claims
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1. A constrained-envelope digital communication 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, 30, 31, 32)
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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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33. 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;
a substantially linear amplifier having an input coupled to said combining circuit and having an output; and
a delay element coupled between said pulse-spreading filter and said combining circuit;
wherein;
said constrained-envelope generator is an off-time constrained-envelope generator;
said constrained-bandwidth error signal stream is an off-time constrained bandwidth error signal stream;
said transmitter circuit additionally comprises an on-time constrained-envelope generator coupled to said pulse-spreading filter and configured to produce an on-time constrained-bandwidth error signal stream; and
said combining circuit is coupled to said pulse-spreading filter, to said off-time constrained-envelope generator, and to said on-time constrained-envelope generator, and said combining circuit is configured to combined said filtered signal stream, said off-time constrained-bandwidth error signal stream, and said on-time constrained bandwidth error signal stream to produce said constrained-envelope signal stream.
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34. 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;
delaying said filtered signal streams;
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;
wherein;
said filtering step comprises the step of receiving one quadrature phase point per unit baud interval;
said filtering step additionally comprises the step of producing two complex samples of said filtered signal stream per unit baud interval;
said generating step comprises the step of evaluating one of said two complex samples of said filtered signal stream per unit baud interval to produce an error signal stream having one error pulse per unit baud interval; and
said generating step additionally comprises the step of filtering said error signal stream to produce said constrained-bandwidth error signal stream having two complex samples of said constrained-bandwidth error signal stream per unit baud interval. - View Dependent Claims (35, 36, 37, 38, 39)
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Specification