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公开(公告)号：FR2418584A1
公开(公告)日：1979-09-21
申请号：FR7806562
申请日：1978-02-28
Applicant: IBM FRANCE , IBM FRANCE
Inventor： GODARD DOMINIQUE , DOMINIQUE GODARD
Abstract: Procédé pour déterminer la phase initiale de l'horloge du récepteur à partir d'un signal de synchronisation dont le spectre comprend deux raies a f1 = fc -1/2T et f2 = fC + 1/2T où fc est la fréquence porteuse et 1/T la cadence de signalisation. La phase initiale est obtenue en calculant la phase du coefficient à la fréquence 1/T de la transformée de Fourier discrète d'un nombre N prédéterminé d'échantillons du signal reçu élevé au carré s(ki). Application à la transmission de données.
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公开(公告)号：DE3478250D1
公开(公告)日：1989-06-22
申请号：DE3478250
申请日：1984-06-29
Applicant: IBM , IBM FRANCE
Inventor： GODARD DOMINIQUE
IPC: G01R27/28 , G01R25/00 , G01R29/02 , H04B17/00 , H04L1/20 , H04L7/00 , H04L25/02 , H04L27/00 , H04L1/24
Abstract: A sinusoidal test signal of a given frequency is applied by the generator 12 to the transmission channel 10. The output signal from the channel is sampled at 16 and fed to a Hilbert transformer 20 through an ADC 18. The sampled outputs from the Hilbert transformer are fed to a device 26 which derives therefrom the phase of the received signal. The phase of the test signal generated at 30-34 is subtracted from that of the output signal from device 26 and the resultant signal is fed to a phase filter 36, which removes therefrom the phase intercept and frequency shift components. The output from filter 36 is fed to a predictive filter 40 which removes the residual noise therefrom. A detector 42 measures the variations of the phase jitter values provided by predictive filter 40.
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公开(公告)号：DE3174147D1
公开(公告)日：1986-04-24
申请号：DE3174147
申请日：1981-11-30
Applicant: IBM , IBM FRANCE
Inventor： GODARD DOMINIQUE
Abstract: A method and apparatus for receiving a data signal modulated by means of a double sideband-quadrature carrier modulation technique in which the received signal is sampled at a rate higher than the signaling rate 1/T, passed through a compensating filter, and applied to a processing system which provides the detected data. The compensating filter is such that the amplitudes of the components at f1=fc-1/2T and f2=fc+1/2T, where fc is the carrier, are equal. An initializer enables a filter coefficient to be determined during the turn-on time of the receiver. An adjusting device allows this coefficient to be continually adjusted. The invention can be used in data transmission systems whose channel has an asymmetric amplitude-frequency response curve.
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公开(公告)号：FR2445078A1
公开(公告)日：1980-07-18
申请号：FR7836581
申请日：1978-12-20
Applicant: IBM FRANCE
Inventor： GODARD DOMINIQUE
Abstract: A method and a device which, in a receiver forming part of a data transmission system using DSB-QC modulation, permit detecting the beginning of a pseudo-random sequence of symbols pertaining to a first set of two symbols when this sequence is preceded by a sequence of successive alternations between two symbols pertaining to a second set, with the first and second sets being such that the beginning of said pseudo-random sequence will initiate a reversal of the phase of the components of the frequency spectrum of said sequence of alternations. In accordance with the method of the present invention, the received signal is demodulated, the DC component of the demodulated signal is determined, and the energy of that DC component is measured. The time at which said energy drops below its average value is indicative of the beginning of the pseudo-random sequence. In accordance with one aspect of the invention, the DC component of the demodulated signal is determined by passing the signal through a lowpass filter.
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公开(公告)号：DE3275052D1
公开(公告)日：1987-02-12
申请号：DE3275052
申请日：1982-06-25
Applicant: IBM , IBM FRANCE
Inventor： GODARD DOMINIQUE , MORLEC EMILE
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Patent Agency Ranking
公开(公告)号：DE3173306D1
公开(公告)日：1986-02-06
申请号：DE3173306
申请日：1981-09-08
Applicant: IBM , IBM FRANCE
Inventor： GODARD DOMINIQUE
Abstract: A listener echo canceller for a receiver made to receive data symbols an transmitted at regular time intervals T. The received wave is first conventionally decoded to derive the received symbols therefrom, said symbols are the subjected to a bulk delay which has been determined for shifting the listener echo impulse response to the time reference origin. The delayed symbols are then processed to generate an echo replica which replica is then fedback to the decoder input for being subtracted therefrom.
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公开(公告)号：FR2454732A1
公开(公告)日：1980-11-14
申请号：FR7910422
申请日：1979-04-17
Applicant: IBM FRANCE
Inventor： GODARD DOMINIQUE
Abstract: This invention relates to automatic adaptive equalizers used in those data transmission systems which rely upon a double sideband-quadrature carrier (DSB-QC) modulation technique. The term DSB-QC modulation is used here in a broad sense and includes all systems wherein the transmitted signal can be represented by superimposing two amplitude modulated quadrature carriers. Thus, the term DSB-QC includes, in particular, phase-shift keying, amplitude phase-shift keying and quadrature amplitude modulation. More particularly, this invention relates to a method and a device for training an adaptive equalizer by means of an unknown data signal sent to the receiver, and is especially useful in a data transmission system configured as a multipoint network.
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公开(公告)号：FR2333393A1
公开(公告)日：1977-06-24
申请号：FR7536910
申请日：1975-11-28
Applicant: IBM FRANCE
Inventor： GODARD DOMINIQUE , MILEWSK ANDRZEJ
Abstract: The invention provides a carrier detector for use in a multipoint communication system. In these systems a common communication link interconnects a master modem to a plurality of remote slave modems and a slave modem has to initialize itself without disturbing transmission of data between the master modem and another slave modem. Initialization is to be performed on such data, and the slave modem must be provided with a detector capable of detecting when data is being transmitted. The invention describes such a detector which is independent of the received signal power.
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公开(公告)号：DE3273552D1
公开(公告)日：1986-11-06
申请号：DE3273552
申请日：1982-06-25
Applicant: IBM , IBM FRANCE
Inventor： GODARD DOMINIQUE
Abstract: A device for detecting the presence of an alarm tone of a given frequency within a received signal carrying digital data in addition to said tone. The receiver comprises an analog-to-digital converter (42) the output of which is applied to a first recursive bandpass filter centered at the frequency of the alarm tone and the feedback loop of which includes a limiter. In addition, an input feedforward loop is provided for adding (at 58) the output signal from the converter (42), as multiplied by a coefficient gamma , to the output signal from the limiter. The output signal from the adder (58) is hard limited (at 44), then passed through a second bandpass filter. The energy of the signal obtained at the output of said second filter is then measured to provide indication of a tone's being received when said energy exceeds a predetermined threshold.
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公开(公告)号：FR2375773A1
公开(公告)日：1978-07-21
申请号：FR7639689
申请日：1976-12-23
Applicant: IBM FRANCE
Inventor： GODARD DOMINIQUE , MILEWSK ANDRZEJ
IPC: H04L27/22 , H04L27/233 , H04L27/20 , H04B3/04
Abstract: An adaptive phase detection method and apparatus is described which provides an estimated value phi n of the phase phi n transmitted at a signalling instant nT in a data transmission system using a M-phase PSK modulation technique. The system compensates for the effects of the intersymbol interference created by not more than one leading lobe of a succeeding signal and an arbitrary number of trailing lobes of preceding signals caused by the impulse response of the transmission channel. The method of the present invention mainly comprises the steps of:
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