Patent EP0244057A2 successfully refreshed from Google Patents.
EP0244057A2
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EP
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Communication system, receiver and transmitter and method of data retrieval
Assignee: AT&T Inc
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Filing: 1987-02-23
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Granted: —
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Expires: 2007-02-23
Abstract
Abstract A bandwith reduction technique is disclosed for use in digital systems wherein a pair of data signal elements modulate quadrature-related carriers. This modulation, re ferred to as quadrature amplitude modulation (QAM), phase shift keying (PSK) or amplitude and phase shift keying (APSK), generates a double-sideband signal which is transmitted in a variety of communications systems. In accordance with the present invention, the above-described double-sideband signal is filtered (103) to form either a single sideband or vestigial sideband signal prior to transmission. While this use of a vestigial or single-sideband signal, in lieu of a double-sideband signal, permits the transmission of more information in a given frequency interval, the filtering process contaminates the data signal elements. To recover the data signal elements at the receiver, a pair of received signal elements (110, 111) is formed by extracting the carrier signals. One of these received signal elements is then altered (118) at selected times to recover an associated one of the data signal elements (150) at each selected time. Finally, this associated data signal element at certain ones of the selected times is combined (119) with the other one of the received signal elements at an associated time to form the remaining - data signal element (151).
Inventors
- 👤 Peter Dimitrios Karabinis
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-25 14:57
CPC Classifications
H; H04; H04L; H04L27/00; H04L27/32; H04L27/34
Claims Analysis
Total Claims: 28
Claim 1
Independent Claim
156 words
_ receiver apparatus for use in a digital transmission system wherein a pair of data signal elements modulate quadrature-related carriers, and wherein the modulated carriers are transformed into a signal having one sideband and another suppressed sideband, said receiver apparatus CHARACTERIZED BY means for demodulating said transformed carriers to form a pair of received signal elements by extracting said quadrature-related carriers, each of said received signal elements comprising an associated one of said data signal elements and an inferfering signal caused by the transformation of said carriers; means for altering one of said received signal elements at selected times to form said associated data signal element at each of said selected times; and means for combining said associated data signal element formed by said altering means at certain ones of said selected times and the other one of said received signal elements at an associated time to form the other one of said data signal elements.
Claim 2
Dependent Claim
156 words
_ receiver apparatus for use in a digital transmission system wherein a pair of data signal elements modulate quadrature-related carriers, and wherein the modulated carriers are transformed into a signal having one sideband and another suppressed sideband, said receiver apparatus CHARACTERIZED BY means for demodulating said transformed carriers to form a pair of received signal elements by extracting said quadrature-related carriers, each of said received signal elements comprising an associated one of said data signal elements and an inferfering signal caused by the transformation of said carriers; means for altering one of said received signal elements at selected times to form said associated data signal element at each of said selected times; and means for combining said associated data signal element formed by said altering means at certain ones of said selected times and the other one of said received signal elements at an associated time to form the other one of said data signal elements.
Claim 3
Dependent Claim
17 words
The apparatus of claim 1 CHARACTERIZED IN THAT said associated time is one of said selected times.
Claim 4
Dependent Claim
21 words
The apparatus of claim 2 CHARACTERIZED IN THAT said certain ones of said selected times precede and succeed said associated time.
Claim 5
Dependent Claim
26 words
The apparatus of claim 2 CHARACTERIZED IN THAT said certain ones of said selected times are one time preceding and one time succeeding said associated time.
Claim 6
Dependent Claim
32 words
The apparatus of claim 1 CHARACTERIZED IN THAT said altering means alters said one received signal element at each selected time by a preselected quantity which varies with said received signal element.
Claim 7
Dependent Claim
36 words
The apparatus of claim 5 CHARACTERIZED IN THAT said data signal elements have assigned values and the assigned values for one data signal element are different from the assigned values for the other data signal element.
Claim 8
Dependent Claim
18 words
The apparatus of claim 6 CHARACTERIZED IN THAT said preselected quantity is a function of the assigned values.
Claim 9
Dependent Claim
24 words
The apparatus of claim 1 CHARACTERIZED IN THAT said interfering signal is a nonzero function of an unassociated one of said data signal elements.
Claim 10
Dependent Claim
15 words
The apparatus of claim 8 CHARACTERIZED IN THAT said nonzero function is the Hilbert transform.
Claim 11
Dependent Claim
38 words
The apparatus of claim 6 CHARACTERIZED IN THAT said preselected quantity lies in a set of numbers found by taking an algebraic combination of all possible permutations of said assigned values of one of said data signal elements.
Claim 12
Dependent Claim
15 words
The apparatus of claim 1 CHARACTERIZED IN THAT said transformed carriers are a single-sideband signal.
Claim 13
Dependent Claim
17 words
.12. The apparatus of claim 1 CHARACTERIZED IN THAT said transformed carriers are a vestigial sideband signal.
Claim 14
Dependent Claim
38 words
The apparatus of claim 1 CHARACTERIZED IN THAT the alteration of said one received signal element at any one of said selected times is independent of the alterations of said one received signal element at other selected times.
Claim 15
Independent Claim
145 words
A method of retrieving a pair of data signal elements wherein said elements modulate quadrature-related carriers, and wherein the modulated carriers are then transformed into a signal having one sideband and another suppressed sideband, said method CHARACTERIZED BY demodulating said transformed carriers to form received signal elements by extracting said quadrature- ; related carriers, each of said received signal elements comprising an associated one of said data signal elements and an interfering signal created by the transformation of said carriers; altering one of said received signal elements at selected times to form said associated data signal element at each of said selected times; and combining said associated data signal element formed by said altering means at certain ones of said selected times and the other one of said received signal elements at an associated time to form the other one of said data signal elements.
Claim 16
Independent Claim
145 words
A method of retrieving a pair of data signal elements wherein said elements modulate quadrature-related carriers, and wherein the modulated carriers are then transformed into a signal having one sideband and another suppressed sideband, said method CHARACTERIZED BY demodulating said transformed carriers to form received signal elements by extracting said quadrature- ; related carriers, each of said received signal elements comprising an associated one of said data signal elements and an interfering signal created by the transformation of said carriers; altering one of said received signal elements at selected times to form said associated data signal element at each of said selected times; and combining said associated data signal element formed by said altering means at certain ones of said selected times and the other one of said received signal elements at an associated time to form the other one of said data signal elements.
Claim 17
Dependent Claim
16 words
The method of claim 14 CHARACTERIZED IN THAT said transformed carriers form a vestigial sideband signal.
Claim 18
Dependent Claim
15 words
The method of claim 14 CHARACTERIZED IN THAT said transformed carriers form a single-sideband signal.
Claim 19
Dependent Claim
38 words
The method of claim 14 CHARACTERIZED IN THAT the alteration of said one received signal element at any one of said selected times is independent of the alterations of said one received signal element at other selected times.
Claim 20
Dependent Claim
55 words
A transmitter for use in communication systems CHARACTERIZED BY means for modulating quadrature-related carrier signals with elements of a data signal to form a double-sideband signal, each of said elements representing information which is independent of the other, and means for transforming said double-sideband signal into a signal having a sideband and another suppressed sideband.
Claim 21
Dependent Claim
55 words
A transmitter for use in communication systems CHARACTERIZED BY means for modulating quadrature-related carrier signals with elements of a data signal to form a double-sideband signal, each of said elements representing information which is independent of the other, and means for transforming said double-sideband signal into a signal having a sideband and another suppressed sideband.
Claim 22
Dependent Claim
20 words
The transmitter of claim 18 CHARACTERIZED IN THAT said transforming means transforms said double-sideband signal into a vestigial sideband signal.
Claim 23
Dependent Claim
19 words
The transmitter of claim 18 CHARACTERIZED IN THAT said transforming means transforms said double-sideband signal into a single-sideband signal.
Claim 24
Dependent Claim
169 words
A communications system CHARACTERIZED BY a transmitter and a receiver wherein said transmitter comprises means for modulating quadrature-related carrier signals with a pair of data signal elements to form a double-sideband signal, and means for transforming said double-sideband signal into a signal having a sideband and another suppressed sideband, and said receiver comprising means for. demodulating said transformed double-sideband signal to form a pair of received signal elements by extracting said quadrature-related carriers, each of said received signal elements comprising an associated one of said data signal elements and an interfering signal created by the transformation of said double-sideband signal, means for altering one of said received signal elements at selected times to form said associated data signal element at each of said selected times; and means for combining said associated data signal element formed by said altering means at certain ones of said selected times and the other one of said received signal elements at an associated time to form the other one of said data signal elements.
Claim 25
Dependent Claim
169 words
A communications system CHARACTERIZED BY a transmitter and a receiver wherein said transmitter comprises means for modulating quadrature-related carrier signals with a pair of data signal elements to form a double-sideband signal, and means for transforming said double-sideband signal into a signal having a sideband and another suppressed sideband, and said receiver comprising means for. demodulating said transformed double-sideband signal to form a pair of received signal elements by extracting said quadrature-related carriers, each of said received signal elements comprising an associated one of said data signal elements and an interfering signal created by the transformation of said double-sideband signal, means for altering one of said received signal elements at selected times to form said associated data signal element at each of said selected times; and means for combining said associated data signal element formed by said altering means at certain ones of said selected times and the other one of said received signal elements at an associated time to form the other one of said data signal elements.
Claim 26
Dependent Claim
38 words
The system of claim 21 CHARACTERIZED IN THAT the alteration of said one received signal element at any one of said selected times is independent of the alterations of said one received signal element at other selected times.
Claim 27
Dependent Claim
21 words
3. The system of claim 21 CHARACTERIZED IN THAT said transforming means transforms said double-sideband signal into a single sideband signal.
Claim 28
Dependent Claim
20 words
The system of claim 21 CHARACTERIZED IN THAT said transforming means transforms said double-sideband signal into a vestigial sideband signal.
References Cited (Backward Citations)
No citation records indexed.
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