US5705958A
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US
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Apparatus for correcting quadrature error in a modulator and/or in a demodulator for a signal having a plurality of phase states, a corresponding transmitter, and a corresponding receiver
Assignee: Alcatel CIT SA
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Filing: 1996-09-26
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Granted: 1998-01-06
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Expires: 2016-09-26
Abstract
Abstract Apparatus for correcting quadrature error in a quadrature modulator and/or in a demodulator for a signal having a plurality of phase states, or of amplitude and phase states. The correction apparatus comprises a processor (51) which, when the apparatus is used to correct quadrature error in a demodulator, transforms the levels P and Q of the digital signals output by the demodulation stage into corrected levels P' and Q' that satisfy any one of the following eight relationships: ##STR1## These corrected levels are then applied to decision element (72), optionally after their maximum levels have equalized. The apparatus combines correction accuracy with cheapness, and it enables any quadrature error to be corrected.
Inventors
- 👤 Patrick Janer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 22:40
CPC Classifications
H; H04; H04L; H04L27/00; H04L27/32; H04L27/34; H04L27/38; H04L27/3845; H04L27/3854; H04L27/3863; H04L27/36; H04L27/362; H04L27/364; H04L27/0014; H04L2027/0016
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
132 words
Apparatus for correcting quadrature error in a demodulation stage (2) supplying a digital signal constituted, at each symbol time, by a symbol of a constellation having a plurality of phase states or of amplitude and phase states, each symbol of said constellation being determined by two amplitude levels P and Q output by said demodulation stage (2); said apparatus being characterized in that it comprises processing means (51) supplying two corrected amplitude levels P' and Q' on the basis of said amplitude levels P and Q, said corrected amplitude levels P' and Q' being respectively equal to the values in any one of the following pairs of values: P+Q and Q-P P+Q and P-Q -P-Q and Q-P -P-Q and P-Q Q-P and P+Q P-Q and P+Q Q-P and -P-Q P-Q and -P-Q.
Claim 2
Dependent Claim
132 words
Apparatus for correcting quadrature error in a demodulation stage (2) supplying a digital signal constituted, at each symbol time, by a symbol of a constellation having a plurality of phase states or of amplitude and phase states, each symbol of said constellation being determined by two amplitude levels P and Q output by said demodulation stage (2); said apparatus being characterized in that it comprises processing means (51) supplying two corrected amplitude levels P' and Q' on the basis of said amplitude levels P and Q, said corrected amplitude levels P' and Q' being respectively equal to the values in any one of the following pairs of values: P+Q and Q-P P+Q and P-Q -P-Q and Q-P -P-Q and P-Q Q-P and P+Q P-Q and P+Q Q-P and -P-Q P-Q and -P-Q.
Claim 3
Dependent Claim
17 words
Apparatus according to claim 1, characterized in that said corrected amplitude levels are applied to decision means.
Claim 4
Dependent Claim
36 words
Apparatus according to claim 1, characterized in that said processing means (51) are preceded by automatic gain control amplification means (49, 50) ensuring that the maximum levels of said amplitude levels P and Q are equal.
Claim 5
Dependent Claim
37 words
Apparatus according to claim 1, characterized in that said processing means (51) are followed by automatic gain control amplification means (70, 71) ensuring that the maximum levels of said corrected amplitude levels P' and Q' are equal.
Claim 6
Dependent Claim
141 words
Apparatus for correcting quadrature error in a modulation stage (1) to which a digital-type modulating signal is applied, the signal being constituted, at each symbol time, by a symbol of a constellation having a plurality of phase states or of amplitude and phase states, each symbol of said constellation being determined by two amplitude levels P and Q; said apparatus being characterized in that it comprises processing means (51) supplying two corrected amplitude levels P' and Q' on the basis of said amplitude levels P and Q, said corrected amplitude levels P' and Q' being applied to said modulation stage (1) and being respectively equal to the values in any one of the following pairs of values: P+Q and Q-P P+Q and P-Q -P-Q and Q-P -P-Q and P-Q Q-P and P+Q P-Q and P+Q Q-P and -P-Q P-Q and -P-Q.
Claim 7
Dependent Claim
141 words
Apparatus for correcting quadrature error in a modulation stage (1) to which a digital-type modulating signal is applied, the signal being constituted, at each symbol time, by a symbol of a constellation having a plurality of phase states or of amplitude and phase states, each symbol of said constellation being determined by two amplitude levels P and Q; said apparatus being characterized in that it comprises processing means (51) supplying two corrected amplitude levels P' and Q' on the basis of said amplitude levels P and Q, said corrected amplitude levels P' and Q' being applied to said modulation stage (1) and being respectively equal to the values in any one of the following pairs of values: P+Q and Q-P P+Q and P-Q -P-Q and Q-P -P-Q and P-Q Q-P and P+Q P-Q and P+Q Q-P and -P-Q P-Q and -P-Q.
Claim 8
Dependent Claim
157 words
A receiver for receiving signals, each of which has a plurality of phase states or of amplitude and phase states, said receiver being characterized in that it includes apparatus for correcting quadrature error in a demodulation stage supplying a digital signal constituted, at each symbol time, by a symbol of a constellation having a plurality of phase states or of amplitude and phase states, each symbol of said constellation being determined by two amplitude levels P and Q output by said demodulation stage, said apparatus being characterized in that it comprises processing means supplying two corrected amplitude levels P' and Q' on the basis of said amplitude levels P and Q, said corrected amplitude levels P' and Q' being respectively equal to the values in any one of the following pairs of values: P+Q and Q-P P+Q and P-Q -P-Q and Q-P -P-Q and P-Q Q-P and P+Q P-Q and P+Q Q-P and -P-Q P-Q and -P-Q.
Claim 9
Dependent Claim
157 words
A receiver for receiving signals, each of which has a plurality of phase states or of amplitude and phase states, said receiver being characterized in that it includes apparatus for correcting quadrature error in a demodulation stage supplying a digital signal constituted, at each symbol time, by a symbol of a constellation having a plurality of phase states or of amplitude and phase states, each symbol of said constellation being determined by two amplitude levels P and Q output by said demodulation stage, said apparatus being characterized in that it comprises processing means supplying two corrected amplitude levels P' and Q' on the basis of said amplitude levels P and Q, said corrected amplitude levels P' and Q' being respectively equal to the values in any one of the following pairs of values: P+Q and Q-P P+Q and P-Q -P-Q and Q-P -P-Q and P-Q Q-P and P+Q P-Q and P+Q Q-P and -P-Q P-Q and -P-Q.
Claim 10
Dependent Claim
157 words
A transmitter for transmitting signals, each of which has a plurality of phase states or of amplitude and phase states, said transmitter being characterized in that it includes apparatus for correcting quadrature error in a demodulation stage supplying a digital signal constituted, at each symbol time, by a symbol of a constellation having a plurality of phase states or of amplitude and phase states, each symbol of said constellation being determined by two amplitude levels P and Q output by said demodulation stage, said apparatus being characterized in that it comprises processing means supplying two corrected amplitude levels P' and Q' on the basis of said amplitude levels P and Q, said corrected amplitude levels P' and Q' being respectively equal to the values in any one of the following pairs of values: P+Q and Q-P P-Q and P-Q -P-Q and Q-P -P-Q and P-Q Q-P and P+Q P-Q and P+Q Q-P and -P-Q P-Q and -P-Q.
Claim 11
Dependent Claim
157 words
A transmitter for transmitting signals, each of which has a plurality of phase states or of amplitude and phase states, said transmitter being characterized in that it includes apparatus for correcting quadrature error in a demodulation stage supplying a digital signal constituted, at each symbol time, by a symbol of a constellation having a plurality of phase states or of amplitude and phase states, each symbol of said constellation being determined by two amplitude levels P and Q output by said demodulation stage, said apparatus being characterized in that it comprises processing means supplying two corrected amplitude levels P' and Q' on the basis of said amplitude levels P and Q, said corrected amplitude levels P' and Q' being respectively equal to the values in any one of the following pairs of values: P+Q and Q-P P-Q and P-Q -P-Q and Q-P -P-Q and P-Q Q-P and P+Q P-Q and P+Q Q-P and -P-Q P-Q and -P-Q.
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