US4601044A — Carrier-phase adjustment using absolute phase det…

Claim 1

Independent Claim 251 words

A modulation-demodulation system for transmitting a plurality of information bit sequences, said system including a transmitter having state machine means for transforming by a coding process each said information bit sequence into an expanded bit sequence having at least a coded bit group portion, and said transmitter further having modulated carrier generating means for modulating a carrier signal to assume one of a plurality of multilevel symbols from a signal constellation in response to each sequentially applied said expanded bit sequence with said coded bit group portion associated with one of a plurality of subsets of said multilevel symbols, said multilevel symbols being capable of representation in a two-dimensional complex plane, and said system further including a receiver having demodulation and slicer means for demodulating and detecting said modulated carrier signal to obtain a received expanded bit sequence, wherein the improvement comprises: said subsets arranged and identified so that, when rotated in said complex plane by one of a plurality of adverse angular rotations, each said subset substantially maps upon a unique, predetermined said subset other than itself for each of said adverse angular rotations; phase rotation detection means, coupled to said demodulation and slicer means, for uniquely identifying each said adverse angular rotation and 0° angular rotation, in response to a plurality of sequentially received coded bit group portions of said received expanded bit sequence, and phase correction means, coupled to said phase rotation detection means, for compensating for said adverse angular rotations in an output signal of said receiver.

Claim 2

Dependent Claim 251 words

A modulation-demodulation system for transmitting a plurality of information bit sequences, said system including a transmitter having state machine means for transforming by a coding process each said information bit sequence into an expanded bit sequence having at least a coded bit group portion, and said transmitter further having modulated carrier generating means for modulating a carrier signal to assume one of a plurality of multilevel symbols from a signal constellation in response to each sequentially applied said expanded bit sequence with said coded bit group portion associated with one of a plurality of subsets of said multilevel symbols, said multilevel symbols being capable of representation in a two-dimensional complex plane, and said system further including a receiver having demodulation and slicer means for demodulating and detecting said modulated carrier signal to obtain a received expanded bit sequence, wherein the improvement comprises: said subsets arranged and identified so that, when rotated in said complex plane by one of a plurality of adverse angular rotations, each said subset substantially maps upon a unique, predetermined said subset other than itself for each of said adverse angular rotations; phase rotation detection means, coupled to said demodulation and slicer means, for uniquely identifying each said adverse angular rotation and 0° angular rotation, in response to a plurality of sequentially received coded bit group portions of said received expanded bit sequence, and phase correction means, coupled to said phase rotation detection means, for compensating for said adverse angular rotations in an output signal of said receiver.

Claim 3

Dependent Claim 16 words

The modulation-demodulation system of claim 1, wherein said adverse angular rotations are substantially ±90° and 180°.

Claim 4

Dependent Claim 71 words

The modulation-demodulation system of claim 2, wherein said phase rotation detection means includes means for computing a parity check equation P n (j) to determine j, where: ##EQU27## and where y(D) represents each bit of said received coded bit group portion, H(D) represents each term of a parity check matrix, n is the symbol period, j=0 for 0°, j=1 for 90° rotation, j=2 for 180° rotation, and j=3 for 270° rotation.

Claim 5

Dependent Claim 96 words

The modulation-demodulation system of claim 3, wherein said phase rotation detection means further includes means for computing an equation Q n (j) for at least each said P n (j) that does not provide a unique identifying value for a given said adverse angular rotation, where: Q.sub.n (j)=P.sub.n (j)⊕P.sub.n (i) and where i=1 or 3, i=1 for 90° rotation and i=3 for 270° rotation, whereby said P n (j) provides said unique identifying values for 0° rotation and 180° rotation and said Q n (j) provides said unique identifying values for 90° rotation and 270° rotation.

Claim 6

Dependent Claim 78 words

The modulation-demodulation system of claim 4, wherein both said equations P n (j) and Q n (j) provide a discrete binary value for each of a plurality of symbol periods, each said symbol period corresponding to a time interval during which one of said multilevel symbols is transmitted, and wherein said phase rotation means further includes means for determining at the end of said plurality of symbol periods one of said angular rotations from said discrete binary values.

Claim 7

Dependent Claim 76 words

The modulation-demodulation system of claim 5, wherein said means for determining further includes computing an average value of said discrete binary values over said plurality of symbol periods for both said equations P n (j) and Q n (j), said average value which has a magnitude at the end of said plurality of symbol periods which approaches or is equal to a discrete binary value comprises said unique identifying value for one of said angular rotations.

Claim 8

Dependent Claim 79 words

The modulation-demodulation system of any one of claims 1 through 6, wherein said expanded bit sequence includes an uncoded bit group portion having at least one bit and each said subset includes a plurality of said multilevel symbols, said modulated carrier generating means further including means for using said uncoded bit group portion for selecting said one multilevel symbol for modulating said carrier signal from said one of a plurality of subsets selected by said coded bit group portion.

Claim 9

Dependent Claim 33 words

The modulation-demodulation system of any one of claims 1 through 6, wherein said expanded bit sequence includes only said coded bit group portion and each said subset includes a single said multilevel symbol.

Claim 10

Dependent Claim 242 words

In a data modem including a transmitter having a convolutional encoder for transforming each of a plurality of information bit sequences into an expanded bit sequence having at least a coded bit group portion; said modem further including a modulated signal generating means for generating a plurality of complex-valued symbols, for selecting from said plurality of complex-valued symbols at least one said symbol to define a subset in response to said expanded bit sequence, and for modulating a carrier signal to assume one of said symbols from said subset so as to generate a modulated carrier signal for transmission; and said modem further including a receiver having demodulation and slicer means for demodulating and detecting a received modulated carrier signal to obtain a received expanded bit sequence having at least a received coded bit group portion, the improvement comprising: said modulated carrier generating means having said subsets arranged and identified so that, when rotated in a complex plane by one of a plurality of adverse angular rotations, each said subset is substantially coincident with a unique, predetermined said subset other than itself for each of said adverse angular rotations; phase rotation detection means, coupled to said demodulation and slicer means, for uniquely identifying each possible adverse angular rotation, in response to a plurality of said received coded bit group portions; and phase correction means, coupled to said phase rotation detection means, for correcting for said detected adverse angular rotation in said receiver.

Claim 11

Dependent Claim 242 words

In a data modem including a transmitter having a convolutional encoder for transforming each of a plurality of information bit sequences into an expanded bit sequence having at least a coded bit group portion; said modem further including a modulated signal generating means for generating a plurality of complex-valued symbols, for selecting from said plurality of complex-valued symbols at least one said symbol to define a subset in response to said expanded bit sequence, and for modulating a carrier signal to assume one of said symbols from said subset so as to generate a modulated carrier signal for transmission; and said modem further including a receiver having demodulation and slicer means for demodulating and detecting a received modulated carrier signal to obtain a received expanded bit sequence having at least a received coded bit group portion, the improvement comprising: said modulated carrier generating means having said subsets arranged and identified so that, when rotated in a complex plane by one of a plurality of adverse angular rotations, each said subset is substantially coincident with a unique, predetermined said subset other than itself for each of said adverse angular rotations; phase rotation detection means, coupled to said demodulation and slicer means, for uniquely identifying each possible adverse angular rotation, in response to a plurality of said received coded bit group portions; and phase correction means, coupled to said phase rotation detection means, for correcting for said detected adverse angular rotation in said receiver.

Claim 12

Dependent Claim 16 words

The data modem of claim 9, wherein said adverse angular rotations are substantially ±90° and 180°.

Claim 13

Dependent Claim 71 words

The data modem of claim 10, wherein said phase rotation detection means includes means for computing a parity check equation P n (j) to determine j, where: ##EQU28## and where y(D) represents each bit of said received coded bit group portion, H(D) represents each term of a parity check matrix, n is the symbol period, j=0 for 0°, j=1 for 90° rotation, j=2 for 180° rotation, and j=3 for 270° rotation.

Claim 14

Dependent Claim 96 words

The data modem of claim 11, wherein said phase rotation detection means further includes means for computing an equation Q n (j) for at least each said P n (j) that does not provide a unique identifying value for a given said adverse angular rotation, where: Q.sub.n (j)=P.sub.n (j)⊕P.sub.n (i) and where i=1 or 3, i=1 for 90° rotation and i=3 for 270° rotation, whereby said P n (j) provides said unique identifying values for 0° rotation and 180° rotation and said Q n (j) provides said unique identifying values for 90° rotation and 270° rotation.

Claim 15

Dependent Claim 78 words

The data modem of claim 12, wherein both said equations P n (j) and Q n (j) provide a discrete binary value for each of a plurality of symbol periods, each said symbol period corresponding to a time interval during which one of said multilevel symbols is transmitted, and wherein said phase rotation means further includes means for determining at the end of said plurality of symbol periods one of said angular rotations from said discrete binary values.

Claim 16

Dependent Claim 76 words

The data modem of claim 13, wherein said means for determining further includes computing an average value of said discrete binary values over said plurality of symbol periods for both said equations P n (j) and Q n (j), said average value which has a magnitude at the end of said plurality of symbol periods which approaches or is equal to a discrete binary value comprises said unique identifying value for one of said angular rotations.

Claim 17

Dependent Claim 74 words

The data modem of claim 14, wherein said expanded bit sequence includes an uncoded bit group portion having at least one bit and each said subset includes a plurality of said complexed-valued symbols, said modulated carrier generating means further including means for using said uncoded bit group portion for selecting said one complexed-valued symbol for modulating said carrier signal from said one of a plurality of subsets selected by said coded bit group portion.

Claim 18

Dependent Claim 28 words

The data modem of claim 14, wherein said expanded bit sequence includes only said coded bit group portion and each said subset includes a single said complexed-valued symbol.

Claim 19

Dependent Claim 206 words

In a modulation-demodulation method for transmitting a plurality of information bit sequences including the steps of transforming by a coding process each of the information bit sequences into an expanded bit sequence having at least a coded bit group portion, subdividing a signal constellation of multilevel symbols into a plurality of subsets with each subset having at least one multilevel symbol, selecting one of the plurality of subsets in response to each sequentially applied coded bit group portion, modulating a carrier signal by one multilevel symbol from the selected subset to generate a modulated carrier signal for transmission, and demodulating and detecting a received modulated carrier signal to obtain a received expanded bit sequence having at least a received coded bit group portion, wherein the improvement comprises: said step of subdividing including the step of arranging and identifying the subsets so that, when rotated in the complex plane by one of a plurality of adverse angular rotations, each said subset substantially maps upon a unique, predetermined subset other than itself for each of the adverse angular rotations; and after said step of demodulating, uniquely identifying by analyzing a plurality of the received coded bit group portions each of said adverse angular rotation and 0° angular rotation.

Claim 20

Dependent Claim 206 words

In a modulation-demodulation method for transmitting a plurality of information bit sequences including the steps of transforming by a coding process each of the information bit sequences into an expanded bit sequence having at least a coded bit group portion, subdividing a signal constellation of multilevel symbols into a plurality of subsets with each subset having at least one multilevel symbol, selecting one of the plurality of subsets in response to each sequentially applied coded bit group portion, modulating a carrier signal by one multilevel symbol from the selected subset to generate a modulated carrier signal for transmission, and demodulating and detecting a received modulated carrier signal to obtain a received expanded bit sequence having at least a received coded bit group portion, wherein the improvement comprises: said step of subdividing including the step of arranging and identifying the subsets so that, when rotated in the complex plane by one of a plurality of adverse angular rotations, each said subset substantially maps upon a unique, predetermined subset other than itself for each of the adverse angular rotations; and after said step of demodulating, uniquely identifying by analyzing a plurality of the received coded bit group portions each of said adverse angular rotation and 0° angular rotation.

Claim 21

Dependent Claim 25 words

The modulation-demodulation method of claim 17, wherein said step of uniquely identifying includes uniquely identifying each of the adverse angular rotations and 0° angular rotation.

Claim 22

Dependent Claim 79 words

The modulation-demodulation method of claims 17 or 18, wherein said step of uniquely identifying includes applying a parity check equation P n (j) to the sequentially received coded bit group portions to determine j, where: ##EQU29## and where y(D) represents each bit of said received coded bit group portion, H(D) represents each term of a parity check matrix, n is the symbol period, j=0 for 0°, j=1 for 90° rotation, j=2 for 180° rotation, and j=3 for 270° rotation.

Claim 23

Dependent Claim 94 words

The modulation-demodulation method of claim 19, wherein said step of uniquely identifying further includes computing an equation Q n (j) for at least each said P n (j) that does not provide a unique identifying value for a given said adverse angular rotation, where: Q.sub.n (j)=P.sub.n (j)⊕P.sub.n (i) and where i=1 or 3, i=1 for 90° rotation and i=3 for 270° rotation, whereby said P n (j) provides said unique identifying values for 0° rotation and 180° rotation and said Q n (j) provides said unique identifying values for 90° rotation and 270° rotation.

Claim 24

Dependent Claim 77 words

The modulation-demodulation method of claim 20, wherein both said equations P n (j) and Q n (j) provide a discrete binary value for each of a plurality of symbol periods, each said symbol period corresponding to a time interval during which one of said multilevel symbols is transmitted, and wherein said step of uniquely identifying further includes determining at the end of said plurality of symbol periods one of said angular rotations from said discrete binary values.

Claim 25

Dependent Claim 77 words

The modulation-demodulation method of claim 21, wherein said step of uniquely identifying further includes computing an average value of said discrete binary values over said plurality of symbol periods for both said equations P n (j) and Q n (j), said average value which has a magnitude at the end of said plurality of symbol periods which approaches or is equal to a discrete binary value comprises said unique identifying value for one of said angular rotations.

Claim 26

Dependent Claim 73 words

The modulation-demodulation method of claim 21, wherein said step of subdividing the signal constellation includes providing the subsets with a plurality of the multilevel symbols, said step of expanding the information bit sequence includes providing the expanded bit sequence with an uncoded bit group portion, said step of modulating a carrier signal including selecting one of the multilevel symbols for modulation from the selected subset in response to the uncoded bit group portion.

Claim 27

Dependent Claim 22 words

The modulation-demodulation method of claim 21, wherein said step of subdividing the signal constellation includes providing each subset with only one point.

Claim 28

Dependent Claim 24 words

The modulation-demodulation method of claim 21, further including removing said adverse angular rotations from an output signal derived from the received modulated carrier signal.

Claim 29

Dependent Claim 24 words

The modulation-demodulation method of claim 17, further including removing said adverse angular rotations from an output signal derived from the received modulated carrier signal.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1989-07-14	1990-01-13	1990-07-15	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1993-07-14	1994-01-13	1994-07-15	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1997-07-14	1998-01-13	1998-07-15	$7700.00	Window Closed / Lapsed

Carrier-phase adjustment using absolute phase detector

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