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    STARTING-UP METHOD FOR AN ECHO CANCELLER FILTER, AND COMMUNICATION SYSTEM USING THIS METHOD
    2.
    发明专利
    STARTING-UP METHOD FOR AN ECHO CANCELLER FILTER, AND COMMUNICATION SYSTEM USING THIS METHOD 未知

    公开(公告)号：DE3376943D1

    公开(公告)日：1988-07-07

    申请号：DE3376943

    申请日：1983-06-30

    Applicant: IBM ,  IBM FRANCE

    Inventor： DESBLACHE ANDRE ,  GALAND CLAUDE ,  VERMOT-GAUCHY ROBERT

    IPC: H04B3/23

    Abstract: In an echo filter with a 128-tap delay line, successive sequences of real and imaginary components of samples of flat-spectrum signal are sent along the echo path. From the echo a sequence of samples (z(n)) is received and stored, and the terms of its fast Fourier transform (FFT) are calculated. Each term is rotated through a predetermined angle in accordance with its rank, and an inverse FFT is performed on the rotated terms. The results (h(n)) are sorted for location and measurement of the max. term in the inverse transform, on each side of which a given number of terms are selected and measured for the initial coeffts.

    4.
    发明专利
    未知

    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.

    5.
    发明专利
    未知

    公开(公告)号：FR2296322A1

    公开(公告)日：1976-07-23

    申请号：FR7443560

    申请日：1974-12-27

    Applicant: IBM FRANCE

    Inventor： CROISIER ALAIN ,  DESBLACHE ANDRE

    IPC: H04L27/38 ,  H04L27/00

    Abstract: A data transmitting and receiving system in which data is transmitted by varying the phase and amplitude of a carrier, including a receiver which detects the data in a received signal while reducing the effects of noise components which alter the phase and amplitude of the received signal. An in-phase component and a quadrature component are derived from the received signal and are then rotated an angular amount which is a function of an estimated value of the phase error in the received signal. The rotated components are then compared with two sets of reference coordinates for selecting a pair of reference coordinates which have values closest to the values of the rotated in-phase and quadrature components, respectively. The estimated value of the phase error is derived as a trigonometric function of the rotated components and selected reference coordinates. The selected reference coordinates are indicative of the transmitted data.

    VOICE ACTIVITY DETECTION PROCESS AND MEANS FOR IMPLEMENTING SAID PROCESS
    6.
    发明专利
    VOICE ACTIVITY DETECTION PROCESS AND MEANS FOR IMPLEMENTING SAID PROCESS 未知

    公开(公告)号：CA1231473A

    公开(公告)日：1988-01-12

    申请号：CA454771

    申请日：1984-05-18

    Applicant: IBM

    Inventor： DESBLACHE ANDRE ,  GALAND CLAUDE ,  VERMOT-GAUCHY ROBERT

    IPC: G10L11/02 ,  H04J3/16 ,  H04J3/17

    Abstract: In a transmission system for transmitting voice signals each signal being sampled and coded to derive therefrom blocks of samples and short term power spectrum characteristics or each block, a voice activity detection process is proposed wherein an energy representative information is derived from each block of sample, which energy representative information is compared with a predetermined threshold and said threshold is adjusted accordingly. Then an active/ambiguous decision is taken based on the relative magnitude of the energy information with respect to the adjusted threshold, which ambiguity is then eventually resolved through analysis of the magnitude of variation of the short term power spectrum characteristics.

    7.
    发明专利
    未知

    公开(公告)号：FR2407621A1

    公开(公告)日：1979-05-25

    申请号：FR7733121

    申请日：1977-10-27

    Applicant: IBM FRANCE

    Inventor： DESBLACHE ANDRE

    IPC: H04B1/10 ,  G08C19/12 ,  G08C25/00 ,  H04L1/00 ,  H04L27/00 ,  H04L27/18 ,  H04L27/227

    Abstract: A method and device for measuring the slope of the envelope delay characteristic of a transmission channel and deriving the phase intercept value therefrom. A measurment signal having a frequency spectrum including three rays at frequencies fo, f1 and f2 is sent over the transmission channel. Frequency fo is the carrier frequency and frequencies f1 and f2 are defined as f1=fo-1/2T and f2=fo+1/2T, where 1/T is the signaling rate. At the output of the channel, the three components at frequencies fo, f1 and f2 are extracted from the received measurement signal, and the instantaneous phases psi o, psi 1 and psi 2 of these three components are then measured. The value of the slope S of the envelope delay characteristic is obtained in accordance with the relation where phi o', phi 1' and phi 2' are the phases of the three rays at frequencies fo, f1 and f2 of the measurement signal sent over the channel. The value of the phase intercept phi i for a given sampling phase phi s is determined in accordance with the relation phi i= phi o-K S where phi i is the phase of the component at frequency fo received at the instant K is a proportionality constant lying between 0 and 1, and S is the slope expressed in milliseconds.

    10.
    发明专利
    未知

    公开(公告)号：FR2336005A1

    公开(公告)日：1977-07-15

    申请号：FR7539629

    申请日：1975-12-18

    Applicant: IBM FRANCE

    Inventor： DESBLACHE ANDRE

    IPC: H03H17/04 ,  H04B3/04 ,  H04L27/00 ,  H04L27/227 ,  H03H21/00 ,  H03K ,  H03K5/00 ,  H03H5/00

    Abstract: A new adaptive digital tuning filter for tracking a sinusoidal signal within a frequency band is described. The input signal representative of both said sinusoidal signal and noise is fed to a Hilbert transformer which provides the in-phase and quadrature components, xk and xk, respectively, of said sinusoidal signal. These components are applied to the input of a filter having a transfer function K where WHERE phi = 2 pi FT, f is the tuned frequency of the filter, T is the signal sampling period and a is a constant close to unity.

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