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公开(公告)号：FR2536610A1
公开(公告)日：1984-05-25
申请号：FR8219562
申请日：1982-11-23
Applicant: CIT ALCATEL
Inventor： LEVY MICHEL , SURIE SERGE
Abstract: In a QPSK system using one cycle of a squared-off sinusoid per Baud period to represent the data dibits, the following are disclosed: (1) a direct detection circuit using samples taken only during the second and third quarters of the Baud period; (2) timing recovery by recognition of the opposite polarity of any QPSK signal compared to a half-Baud-delayed version of itself; and (3) an encoding scheme wherein only one of the two dibits is differentially encoded.
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公开(公告)号：DE3038574A1
公开(公告)日：1981-04-30
申请号：DE3038574
申请日：1980-10-13
Applicant: CIT ALCATEL
Inventor： LEVY MICHEL , POINAS CHRISTIAN
Abstract: A phase noise correction circuit for a synchronous data transmission system using symbols and including a decision circuit (33) at its receiving end for supplying an estimate of the transmitted symbols on the basis of the received symbols, wherein said correction circuit comprises a phase shifter circuit (36) located at the receiving end ahead of the decision circuit (33) and provided with a third-order phase-controlling feedback circuit (37) comprising: a phase shift angle generator (62) having an incrementation input and providing the phase shifter circuit (36) with the value of a phase shift angle updated at the rate at which the symbols are received, a phase error detector (60) providing the value of the phase error between the received and the estimated symbols appearing at the terminals of the decision symbols, likewise at the rate at which the symbols are received; and a filter (61) interposed between the output of the phase error detector (60) and the incrementation input of the phase shift angle generator (62), the said filter (61) having a transfer function expressed as follows using the z transform: where a, b, c and d are positive non-zero coefficients. This circuit is particularly intended for use with quadrature amplitude modulation.
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公开(公告)号：IT7968785D0
公开(公告)日：1979-09-07
申请号：IT6878579
申请日：1979-09-07
Applicant: CIT ALCATEL
Inventor： LEVY MICHEL
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公开(公告)号：DE3378946D1
公开(公告)日：1989-02-16
申请号：DE3378946
申请日：1983-11-17
Applicant: CIT ALCATEL
Inventor： LEVY MICHEL , SURIE SERGE
IPC: H04L25/49
Abstract: In a QPSK system using one cycle of a squared-off sinusoid per Baud period to represent the data dibits, the following are disclosed: (1) a direct detection circuit using samples taken only during the second and third quarters of the Baud period; (2) timing recovery by recognition of the opposite polarity of any QPSK signal compared to a half-Baud-delayed version of itself; and (3) an encoding scheme wherein only one of the two dibits is differentially encoded.
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公开(公告)号：IT1128776B
公开(公告)日：1986-06-04
申请号：IT6766080
申请日：1980-04-24
Applicant: CIT ALCATEL
Inventor： LEVY MICHEL , POINAS CHRISTIAN
Abstract: Data in the form of multi-value symbols is transmitted at a symbol rate 1/ DELTA T. At the receiver a decision circuit supplies estimates of the transmitted symbols on the basis of the received symbols. The present invention concerns compensating phase noise after equalization, if any, of the received symbols and before application of the received symbols to the decision circuit (38, 39). The received symbols are in complex form with in-phase and quadrature components yk' and yk'' respectively. Phase noise is compensated by complex multiplication in a multiplier (36) of the received symbols by a complex coefficient mk mk+1=[mk- lambda (vk-ak)yk*]exp[-iFk( epsilon j)] where: lambda is a real coefficient; yk* is the complex conjugate of the symbol received at instant k DELTA T+to (where to is the instant taken as the origin of time measurements); vk is the symbol applied to the decision circuit at said instant; ak is the estimated value of the received symbol; epsilon j is an error signal derived from the phase difference between the symbol applied to the decision circuit and the symbol estimated by the decision circuit at instant j DELTA T+to; and Fk( epsilon j) is a linear function of at least the error signals epsilon j. The invention is particularly applicable to quadrature modulation systems, but if only one channel is transmitted the quadrature channel can be simulated using the Hilbert transform of the one channel.
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Patent Agency Ranking
公开(公告)号：CA1191561A
公开(公告)日：1985-08-06
申请号：CA441694
申请日：1983-11-22
Applicant: CIT ALCATEL
Inventor： LEVY MICHEL , SURIE SERGE
Abstract: L'équipement de transmission synchrone de données reçoit les données sous forme d'informations binaires et les assemble par groupes successifs de deux qu'il transmet l'un après l'autre au cours d'intervalles de temps égaux et successifs de durée T dits temps Baud au moyen d'éléments de signal occupant chacun en temps Baud et pouvant prendre une parmi quatre formes possibles définies par les fonctions : Il comporte en réception un circuit de détection directe avec des bascules assurant l'échantillonnage des éléments de signal au cours des deuxième et troisième quarts de temps Baud et un circuit logique assurant la reconnaissance des formes des éléments de signal. Un circuit de récupération de rythme Baud de l'équipement de transmission procède à partir d'une comparaison de deux versions des éléments de signal reçus retardées l'une par rapport à l'autre d'un délai égal à un demi temps Baud.
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公开(公告)号：FR2460075A1
公开(公告)日：1981-01-16
申请号：FR7916087
申请日：1979-06-22
Applicant: CIT ALCATEL
Inventor： LEVY MICHEL , HAAG JEAN-PHILIPPE
Abstract: An echo canceller for a full-duplex carrier modulation transmission system terminal. The echo canceller includes a digital time-domain complex transversal filter with controlled weighting coefficients and an offset equal to a submultiple l of a Baud period DELTA related to a rate at which a stream of complex symbols is received at the input of the filter. These complex symbols include complex symbols outputted by a coder of a transmitter of the terminal at the rate l/ DELTA interleaved with l-1 null symbols. The transversal filter output is connected to a digital modulator operated at the transmitter carrier frequency with instantaneous values updated at intervals equal to the Baud period to generate a passband echo copy signal. The invention is of particular benefit in transmission systems in which the product of the transmission carrier frequency and the Baud period is an integral multiple of l/4, as digital implementation of the modulator is then extremely simple.
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公开(公告)号：DE3022553A1
公开(公告)日：1981-01-08
申请号：DE3022553
申请日：1980-06-16
Applicant: CIT ALCATEL
Inventor： LEVY MICHEL , HAAG JEAN-PHILIPPE
Abstract: An echo canceller for a full-duplex carrier modulation transmission system terminal. The echo canceller includes a digital time-domain complex transversal filter with controlled weighting coefficients and an offset equal to a submultiple l of a Baud period DELTA related to a rate at which a stream of complex symbols is received at the input of the filter. These complex symbols include complex symbols outputted by a coder of a transmitter of the terminal at the rate l/ DELTA interleaved with l-1 null symbols. The transversal filter output is connected to a digital modulator operated at the transmitter carrier frequency with instantaneous values updated at intervals equal to the Baud period to generate a passband echo copy signal. The invention is of particular benefit in transmission systems in which the product of the transmission carrier frequency and the Baud period is an integral multiple of l/4, as digital implementation of the modulator is then extremely simple.
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公开(公告)号：FR2455408A1
公开(公告)日：1980-11-21
申请号：FR7910808
申请日：1979-04-27
Applicant: CIT ALCATEL
Inventor： LEVY MICHEL , POINAS CHRISTIAN
Abstract: Data in the form of multi-value symbols is transmitted at a symbol rate 1/ DELTA T. At the receiver a decision circuit supplies estimates of the transmitted symbols on the basis of the received symbols. The present invention concerns compensating phase noise after equalization, if any, of the received symbols and before application of the received symbols to the decision circuit (38, 39). The received symbols are in complex form with in-phase and quadrature components yk' and yk'' respectively. Phase noise is compensated by complex multiplication in a multiplier (36) of the received symbols by a complex coefficient mk mk+1=[mk- lambda (vk-ak)yk*]exp[-iFk( epsilon j)] where: lambda is a real coefficient; yk* is the complex conjugate of the symbol received at instant k DELTA T+to (where to is the instant taken as the origin of time measurements); vk is the symbol applied to the decision circuit at said instant; ak is the estimated value of the received symbol; epsilon j is an error signal derived from the phase difference between the symbol applied to the decision circuit and the symbol estimated by the decision circuit at instant j DELTA T+to; and Fk( epsilon j) is a linear function of at least the error signals epsilon j. The invention is particularly applicable to quadrature modulation systems, but if only one channel is transmitted the quadrature channel can be simulated using the Hilbert transform of the one channel.
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公开(公告)号：IT8067973D0
公开(公告)日：1980-06-20
申请号：IT6797380
申请日：1980-06-20
Applicant: CIT ALCATEL
Inventor： LEVY MICHEL , HAAG JEAN PHILIPPE
Abstract: An echo canceller for a full-duplex carrier modulation transmission system terminal. The echo canceller includes a digital time-domain complex transversal filter with controlled weighting coefficients and an offset equal to a submultiple l of a Baud period DELTA related to a rate at which a stream of complex symbols is received at the input of the filter. These complex symbols include complex symbols outputted by a coder of a transmitter of the terminal at the rate l/ DELTA interleaved with l-1 null symbols. The transversal filter output is connected to a digital modulator operated at the transmitter carrier frequency with instantaneous values updated at intervals equal to the Baud period to generate a passband echo copy signal. The invention is of particular benefit in transmission systems in which the product of the transmission carrier frequency and the Baud period is an integral multiple of l/4, as digital implementation of the modulator is then extremely simple.
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