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公开(公告)号：DE3784490T2
公开(公告)日：1993-09-16
申请号：DE3784490
申请日：1987-04-22
Applicant: IBM
Inventor： BELLOC JACQUES , MORLEC EMILE , GODARD DOMINIQUE , QUINTIN MICHEL
Abstract: Echo cancelling device for providing an echo-free incoming data signal with a phase-roll tracking device comprising phase rotating means (58) for rotating the phase of the generated echo signal by a value X which is the estimated phase-roll value, thereby providing a complex phase-roll corrected echo signal a multiplier (124) for multiplying the error signal between the incoming signal and the real component (112) of the phase-roll corrected echo signal by the imaginary component (120) of the same signal, thereby providing a value Y function of the variation of the phase-roll; a phase-roll variation estimator (128) providing an estimation Z of the phase-roll variation X in half duplex mode or in full duplex mode, in response to value Y; and a phase filter (126) providing the estimated phase-roll value X in response to the estimation Z.
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公开(公告)号：DE2962162D1
公开(公告)日：1982-03-25
申请号：DE2962162
申请日：1979-01-04
Applicant: IBM
Inventor： GODARD DOMINIQUE
Abstract: In a synchronous data transmission system wherein data transmission is achieved by modulating a carrier wave of frequency fc at the signaling rate 1/T, a method for determining the initial phase value by which the phase of the receiver clock is to be varied during an initial synchronization operation during which a synchronization signal, the spectrum of which includes two distinct lines at frequencies f1=fc-1/2T and f2=fc+1/2T, is transmitted comprising the steps of: (a) sampling the synchronization signal fed into the receiver at the rate 1/ tau which is a multiple of the signaling rate, to provide a signal x(k tau ) where k=a, 1, . . . , (b) multiplying the signal X( tau ) by itself to provide a signal s(k tau ). (c) computing the coefficient Co, which corresponds to the frequency 1/T, of the discrete Fourier transform of signal s(k tau ) from N samples thereof, the number N being determined from the resolution R=1/N tau required to overcome the effects of the frequency components, other than the component at frequency 1/T, of signal s(k tau ), and (d) computing the phase of coefficient Co that represents the initial phase value by which the phase of the receiver clock is to be varied.
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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：DE3783605T2
公开(公告)日：1993-07-15
申请号：DE3783605
申请日：1987-04-22
Applicant: IBM
Inventor： BELLOC JACQUES , MORLEC EMILE , GODARD DOMINIQUE , QUINTIN MICHEL
Abstract: Echo cancelling device for cancelling echoes affecting the incoming signal received over a two-wire telephone line, comprising near echo canceller 20, far echo canceller 22 and an adder 26 providing the estimated echo signal. A circuit path including a digital-to-analog converter 48 for converting the digital estimated echo signal into analog form and a subracter 52 for subtracting the resulting analog signal from the analog incoming signal, is separated from a circuit path including an analog-to-digital converter 42 for converting the analog incoming signal into digital form and a subtracter 44 for subtracting the digital estimated echo signal from the resulting digital incoming signal thereby providing a digital signal used as a control signal for adjusting the echo cancellers 20 and 22.
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公开(公告)号：DE3784490D1
公开(公告)日：1993-04-08
申请号：DE3784490
申请日：1987-04-22
Applicant: IBM
Inventor： BELLOC JACQUES , MORLEC EMILE , GODARD DOMINIQUE , QUINTIN MICHEL
Abstract: A multiplier (58) phase rotates a generated echo signal by a value X which is the estimated phase-roll value to provide a complex phase-roll connected signal. The error signal differenced between the incoming signal and the real component (112) of the corrected signal is then multipled (124) by the imaginary component (120) to provide a value Y. A phase variation estimator (128) determines the phase roll value Z in half-duplex mode, as well as in full-duplex mode, in response to this value Y. A phase filter (126) provides the estimated value X in response to the phase-roll value Z. Pref. the estimator (128) includes a third multiplier providing a value proportional to the value Y and a fourth multiplier multiplying the sign bits to provide a low-value estimate of the value Z.
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Patent Agency Ranking
公开(公告)号：CA1227246A
公开(公告)日：1987-09-22
申请号：CA479574
申请日：1985-04-19
Applicant: IBM
Inventor： GODARD DOMINIQUE
IPC: G01R27/28 , G01R25/00 , G01R29/02 , H04B17/00 , H04L1/20 , H04L7/00 , H04L25/02 , H04L27/00 , H04L1/24
Abstract: METHOD AND DEVICE FOR MEASURING PHASE JITTER ON A TRANSMISSION SUNNILY A sinusoidal test signal of a given frequency is applied by a generator to a transmission channel. The output signal from the channel is sampled and fed to a Hilbert transformer. From the sampled outputs of the Hilbert transformer the phase of the received signal is derived. The phase of a test signal is subtracted from that of the output signal and the resultant signal is fed to a phase filter, which removes therefrom the phase intercept and frequency shift components. The output from filter is fed to a predictive filter which removes the residual noise therefrom. A detector measures the variations of the phase jitter values provided by the predictive filter.
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公开(公告)号：DE2967301D1
公开(公告)日：1985-01-03
申请号：DE2967301
申请日：1979-05-07
Applicant: IBM
Inventor： GODARD DOMINIQUE , THIRION PHILIPPE
Abstract: A method and a device for training the equalizer of a receiver used in a QAM transmission system, by means of an unknown data signal, thereby enabling in particular said equalizer to be trained in the cases described above. In accordance with the method of the present invention, in a data receiver wherein, under normal operating conditions, the data is detected with respect to a first constellation, the equalizer is trained by detecting the data with respect to a second constellation which comprises fewer points than said first constellation and by adjusting the coefficients of the equalizer by means of an error signal produced as a result of the detection operation performed with respect to the second constellation. In accordance with a first embodiment of the present invention, the second constellation is comprised of those points of the first constellation that are farthest from its center. In accordance with a second embodiment of the invention, the points of the second constellation are obtained as follows: the first constellation is divided into L sets of points Sl, l=1, 2, . . . , L and a point bl of the second constellation is associated with each set Sl in accordance with the relation where the ak's are those points of the first constellation that belong to the set Sl.
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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：AT24812T
公开(公告)日：1987-01-15
申请号：AT82430017
申请日：1982-06-25
Applicant: IBM
Inventor： GODARD DOMINIQUE , MORLEC EMILE
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