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公开(公告)号：CA1209666A
公开(公告)日：1986-08-12
申请号：CA425790
申请日：1983-04-13
Applicant: IBM
Inventor： GODARD DOMINIQUE
Abstract: A TONE RECEIVER FOR DIGITAL DATA COMMUNICATION SYSTEMS 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 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 the output signal from the converter, as multiplied by a coefficient ?, to the output signal from the limiter. The output signal from the adder is hard limited, 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 being received when said energy exceeds a predetermined threshold,
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公开(公告)号：CA1188369A
公开(公告)日：1985-06-04
申请号：CA412956
申请日：1982-10-06
Applicant: IBM
Inventor： GODARD DOMINIQUE
Abstract: METHOD AND APPARATUS FOR RECEIVING A DATA SIGNAL MODULATED BY MEANS OF A DOUBLE SIDEBAND-QUADRATURE CARRIER MODULATION TECHNIQUE 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 amplitudefrequency response curve.
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公开(公告)号：BR8303365A
公开(公告)日：1984-02-07
申请号：BR8303365
申请日：1983-06-23
Applicant: IBM
Inventor： GODARD DOMINIQUE , MORLEC EMILE
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Patent Agency Ranking
公开(公告)号：BR8303260A
公开(公告)日：1984-02-07
申请号：BR8303260
申请日：1983-06-20
Applicant: IBM
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：AU1614683A
公开(公告)日：1984-01-05
申请号：AU1614683
申请日：1983-06-22
Applicant: IBM
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：DE3064001D1
公开(公告)日：1983-08-11
申请号：DE3064001
申请日：1980-02-07
Applicant: IBM
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：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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公开(公告)号：FR2309089A1
公开(公告)日：1976-11-19
申请号：FR7514020
申请日：1975-04-25
Applicant: IBM FRANCE
Inventor： CARON FRANCOIS , DESBLACHE ANDRE , GODARD DOMINIQUE , MADDENS FRANCIS
IPC: H04L25/40 , H03K5/00 , H03L7/00 , H03L7/06 , H03L7/08 , H04L7/027 , H04L7/033 , H04L7/04 , H04L27/06 , H04L7/02
Abstract: 1492165 APC systems INTERNATIONAL BUSINESS MACHINES CORP 24 March 1976 [25 April 1975] 11806/76 Heading H3A A synchronization arrangement for adjusting the phase of clock signals defining the sampling instants of a received digital data i.e. a modulated carrier fc comprises a controlled oscillator 14 for producing the clock signals and a control circuit 15 including (see Fig. 3) a first filter 16 for extracting from the received signal an upper sideband component of phase # 1 and frequency fc + 1/2T, where 1/T is the data rate, a second filter 18 for extracting a lower sideband component of phase # 2 and frequency fc-1/2T, a circuit 17, 19, 20 for producing from the two components a signal representing # 2 -# 1 for controlling the clock signals. The oscillator may be a quartz oscillator providing a squared output and applied to a set of dividers whose division ratio is varied by the error control signal produced by circuit 15 so that the clock sampling instants at 4 correspond to specific instants in the received data and associated with particular sideband information. The sampled data may be applied via an A/D converter 6 or direct to the control circuit 15. The filters 16, 18 may be narrow-band recursive digital filters (Figs. 4, 8, not shown). The filtered outputs are multiplied at 17 and low pass filtered at 19 and applied via a circuit 20 to obtain a sinusoidal function of the phase error. The need for a low-pass filter may be obviated by employing filters 16, 18 which produce quadrature outputs (Figs. 6, 9, not shown). A second order feed-back loop (Fig. 7, not shown) provides better frequency drift correction. For synchronizing the receiver and transmitter clocks, an initialization sequence may be transmitted before the data and the receiver may be modified (Fig. 9, not shown) to selectively respond to the sequence and the following data. Further sync information may be sent at regular intervals before and after each data transmission.
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