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    1.
    发明专利
    未知

    公开(公告)号：DE69328356T2

    公开(公告)日：2000-10-19

    申请号：DE69328356

    申请日：1993-04-29

    Applicant: IBM

    Inventor： CESARO CLAUDE ,  RICHTER GERARD

    IPC: H04Q1/45 ,  H04Q1/457

    Abstract: Tone-detection method for a call-progress process which detects at least one tone in a multifrequency dual-tone signal in a telecommunication apparatus having digital signal processing resources. The method involves the step of: computing (201) the value of the energy of the signal, processing (201) said received signal to determine the existence of one or two tones in said signal, applying a second-order or fourth-order autoregressive process in response to said determination and performing (203, 208) a first estimation of the autoregressive parameters of said received signal, performing a digital band-pass filtering operation (205,210) adjusted to the result of the estimation of said autoregressive parameters to provide a partial elimination of the noise existing on said received signal, reapplying (205, 210) a second-order or fourth-order autoregressive process in response to said determination and performing a final estimation of the autoregressive parameters of said received signal, computing (206, 211) the values of the frequencies each tone from the value of said estimated parameters. The determination of the number of tones existing in the signal is achieved by the computation of the ratio: which is theorically equal to 2 in the case of a unique tone, and conversely should be 4 in that of a dual tone. The first and final second-order autoregressive process are based on the predicting function having the z-transfer function: and which is associated with a Least Mean Square algorithm continuously adapting the parameters of the predictor in a sense allowing the minimizing of an error signal. On the other hand, the first and final fourth-order autoregressive process are based on the predicting function having the z-transfer function: To increase the accuracy of the tone-detection mechanism, the second-order autoregressive function is performed with the value of a2 parameter being constantly fixed to -1. Similarly, the fourth-order autoregressive process is performed with the values of a3 and a4 being respectively equal to a1 and - 1. The digital filter which provides the suppression of most of the noise existing in the signal having an unique tone is based on the z-transfer function: In the case of a dual-tone, the filtering is based on the function:

    3.
    发明专利
    未知

    公开(公告)号：DE69120924T2

    公开(公告)日：1997-01-30

    申请号：DE69120924

    申请日：1991-01-15

    Applicant: IBM

    Inventor： ABBIATE JEAN-CLAUDE ,  RICHTER GERARD

    IPC: H03M3/02 ,  H04B14/06 ,  H03M1/60

    Abstract: Sigma-delta converter for converting an analog input signal into a sigma-delta code. The converter includes a threshold device (222) for generating an output and feedback signal, a filter receiving said analog input signal and said feedback signal by means of at least one feedback loop. The sigma-delta converter further includes means (221, 222) located in said at least feedback loop for performing a return-to-zero of the sigma-delta code generated by said threshold device at every period of the sigma delta clock whereby said sigma-delta converter is insensitive to the asymmetry of the rise and fall time of the thresholds device. That results in an increase of the signal-to-noise ratio and the linearity of the converter allowing the manufacture of a sigma-delta convertors with discrete components without requiring the development of an integrated circuit using switched capacitor technology.

    4.
    发明专利
    未知

    公开(公告)号：DE68913967D1

    公开(公告)日：1994-04-21

    申请号：DE68913967

    申请日：1989-07-12

    Applicant: IBM

    Inventor： FERRY MICHEL ,  PANTANI JEAN-PIERRE ,  ORENGO GERARD ,  RICHTER GERARD

    IPC: H03M3/02

    Abstract: A sigma-delta converter including a switching component (313) controlled by a first clock (308) having determined transitions for generating a train of sigma-delta code pulses corresponding to an analog input value. The sigma-delta includes means (306, 310, 311) for generating a second clock (350) of a same frequency than the first clock and having a negative transition followed after a defined period of time (d2) by a positive transition. The determined transitions of the first clock controlling the swithing element occur during said defined period of time. There is also included means (305) controlled by the sigma-delta code pulse train and said second clock for generating a train of sigma-delta pulses being insensitive to the mismatch of the rise and fall times of said switching element (313) whereby improving the linearity and the signal-to-noise ration of the converter. The control of the said period of time allows the varying of the energy of the pulses in order to provide pulses train which, when applied to a sigma-delta decoder, provides an analog output value representative but attenuated with respect to the analog input value.

    6.
    发明专利
    未知

    公开(公告)号：DE69120924D1

    公开(公告)日：1996-08-22

    申请号：DE69120924

    申请日：1991-01-15

    Applicant: IBM

    Inventor： ABBIATE JEAN-CLAUDE ,  RICHTER GERARD

    IPC: H03M3/02 ,  H04B14/06 ,  H03M1/60

    Abstract: Sigma-delta converter for converting an analog input signal into a sigma-delta code. The converter includes a threshold device (222) for generating an output and feedback signal, a filter receiving said analog input signal and said feedback signal by means of at least one feedback loop. The sigma-delta converter further includes means (221, 222) located in said at least feedback loop for performing a return-to-zero of the sigma-delta code generated by said threshold device at every period of the sigma delta clock whereby said sigma-delta converter is insensitive to the asymmetry of the rise and fall time of the thresholds device. That results in an increase of the signal-to-noise ratio and the linearity of the converter allowing the manufacture of a sigma-delta convertors with discrete components without requiring the development of an integrated circuit using switched capacitor technology.

    8.
    发明专利
    未知

    公开(公告)号：DE69230969D1

    公开(公告)日：2000-05-31

    申请号：DE69230969

    申请日：1992-07-10

    Applicant: IBM

    Inventor： RICHTER GERARD

    IPC: H03H21/00 ,  H03H15/00 ,  H03H17/00 ,  H04B3/14 ,  H04L25/03

    Abstract: Adaptive equalization system for allowing the equalization of a base-band line of a DCE, said system including an adaptive filter (319) for ajusting (307) its coefficients in accordance with an adaptive algorithm. The equalizer (312) includes means, during an initial phase to work in an adaptive or non-adaptive mode according to the convergence of the recursive process. The algorithm is triggered (315) depending on whether the equalized signal (317) belong or not to one of predefined intervals of convergence. After this preliminary period, when the mean square of the residual error (314) is considered small enough to ensure the convergence of the adaptive process the algorithm is computed on a continuous mode (313). An efficient and very simple equalization process is therefore provided which is ensured to converge whatever the characteristics of the transmission line and without training sequence.

    9.
    发明专利
    未知

    公开(公告)号：DE69328356D1

    公开(公告)日：2000-05-18

    申请号：DE69328356

    申请日：1993-04-29

    Applicant: IBM

    Inventor： CESARO CLAUDE ,  RICHTER GERARD

    IPC: H04Q1/45 ,  H04Q1/457

    Abstract: Tone-detection method for a call-progress process which detects at least one tone in a multifrequency dual-tone signal in a telecommunication apparatus having digital signal processing resources. The method involves the step of: computing (201) the value of the energy of the signal, processing (201) said received signal to determine the existence of one or two tones in said signal, applying a second-order or fourth-order autoregressive process in response to said determination and performing (203, 208) a first estimation of the autoregressive parameters of said received signal, performing a digital band-pass filtering operation (205,210) adjusted to the result of the estimation of said autoregressive parameters to provide a partial elimination of the noise existing on said received signal, reapplying (205, 210) a second-order or fourth-order autoregressive process in response to said determination and performing a final estimation of the autoregressive parameters of said received signal, computing (206, 211) the values of the frequencies each tone from the value of said estimated parameters. The determination of the number of tones existing in the signal is achieved by the computation of the ratio: which is theorically equal to 2 in the case of a unique tone, and conversely should be 4 in that of a dual tone. The first and final second-order autoregressive process are based on the predicting function having the z-transfer function: and which is associated with a Least Mean Square algorithm continuously adapting the parameters of the predictor in a sense allowing the minimizing of an error signal. On the other hand, the first and final fourth-order autoregressive process are based on the predicting function having the z-transfer function: To increase the accuracy of the tone-detection mechanism, the second-order autoregressive function is performed with the value of a2 parameter being constantly fixed to -1. Similarly, the fourth-order autoregressive process is performed with the values of a3 and a4 being respectively equal to a1 and - 1. The digital filter which provides the suppression of most of the noise existing in the signal having an unique tone is based on the z-transfer function: In the case of a dual-tone, the filtering is based on the function:

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