Patents by Inventor Andreas H. Weirich

Andreas H. Weirich has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 4592070
    Abstract: An ADPCM encoder and decoder includes an adaptive quantizer and an adaptive predictor. A quantizing-step-size adaptation circuit determines a quantizing-step-size for the adaptive quantizer in dependence upon the ADPCM signal. When the quantizing-step-size is small, updating of predictor coefficients, produced in the adaptive predictor, in dependence upon a reconstructed signal and a reconstructed error signal derived from the ADPCM signal, is inhibited, the predictor coefficients being updated only in dependence upon a leakage function. This enables improved tracking to be achieved by the ADPCM arrangement.
    Type: Grant
    Filed: November 28, 1983
    Date of Patent: May 27, 1986
    Assignee: Northern Telecom Limited
    Inventors: Peter E. Chow, Andreas H. Weirich, Leo Strawczynski
  • Patent number: 4549304
    Abstract: In an ADPCM transmission system, signalling frames of an incoming multiplexed PCM signal are identified and signalling bits extracted therefrom. During each signalling frame, an ADPCM encoder/decoder is controlled by the signalling frame signal to operate entirely for 3-bit ADPCM, instead of the regular 4-bit ADPCM, to which 3-bit ADPCM the extracted signalling bits are added for transmission. The deliberate alteration from 4-bit to 3-bit ADPCM at the encoder and decoder of the system in each signalling frame ensures proper adaptation and consequently no loss of tracking between the encoder and the decoder.
    Type: Grant
    Filed: November 28, 1983
    Date of Patent: October 22, 1985
    Assignee: Northern Telecom Limited
    Inventors: Andreas H. Weirich, Leo Strawczynski
  • Patent number: 4542516
    Abstract: An ADPCM encoding/decoding arrangement produces n-bit ADPCM codes which have 2.sup.n -1 possible codes, excluding the all-zeroes code. A range of error signals about zero is quantized by the encoder as a non-zero ADPCM code. In order to avoid such non-zero codes resulting in undesired changes of predictor coefficients of an adaptive predictor of the arrangement, updating of the predictor coefficients in dependence upon a reconstructed error signal derived from the ADPCM signal is inhibited when each such non-zero code occurs.
    Type: Grant
    Filed: November 28, 1983
    Date of Patent: September 17, 1985
    Assignee: Northern Telecom Limited
    Inventor: Andreas H. Weirich