Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
219 words
A multi-pulse excitation linear-predictive coder for processing digital speech signals partitioned into segments, comprising: -a linear prediction analyzer responsive to the speech signal of each segment for generating prediction parametesr characterizing the short-time spectrum of the speech signal, -an excitation generator for generating a multi-pulse excitation signal partitioned into intervals, each excitation interval containing a sequence of at least one and at most a predetermined number of pulses, -means for forming an error signal representative of the difference between the speech signal and - a synthetic speech signal constructed on the basis of the multi-pulse excitation signal and the prediction parameters, -means for perceptually weighting the error signal, -means responsive to the weighted error signal for generating in each excitation interval pulse parameters controlling the excitation generator to minimize, in a time interval at least equal to the excitation interval, a predetermined function of the weighted error signal, characterized in that -the excitation generator is arranged for generating an excitation signal which in each excitation interval consists of a pulse pattern having a grid of a predetermined number of equidistant pulses, and -the means for controlling the excitation generator are arranged for generating pulse parameters characterizing the position of the grid relative to the beginning of the excitation interval and the variable amplitudes of the pulses of the grid.
Claim 2
Dependent Claim
219 words
A multi-pulse excitation linear-predictive coder for processing digital speech signals partitioned into segments, comprising: -a linear prediction analyzer responsive to the speech signal of each segment for generating prediction parametesr characterizing the short-time spectrum of the speech signal, -an excitation generator for generating a multi-pulse excitation signal partitioned into intervals, each excitation interval containing a sequence of at least one and at most a predetermined number of pulses, -means for forming an error signal representative of the difference between the speech signal and - a synthetic speech signal constructed on the basis of the multi-pulse excitation signal and the prediction parameters, -means for perceptually weighting the error signal, -means responsive to the weighted error signal for generating in each excitation interval pulse parameters controlling the excitation generator to minimize, in a time interval at least equal to the excitation interval, a predetermined function of the weighted error signal, characterized in that -the excitation generator is arranged for generating an excitation signal which in each excitation interval consists of a pulse pattern having a grid of a predetermined number of equidistant pulses, and -the means for controlling the excitation generator are arranged for generating pulse parameters characterizing the position of the grid relative to the beginning of the excitation interval and the variable amplitudes of the pulses of the grid.
Claim 3
Dependent Claim
46 words
A multi-pulse excitation linear-predictive coder as claimed in Claim 1, characterized in that the means for perceptually weighting the error signal are constituted by a fixed weighting filter having a recursive structure and having a filter co efficients related to the long-time average of speech signals.
Claim 4
Dependent Claim
52 words
A multi-pulse excitation linear-predictive coder as claimed in Claim 1 or 2, characterized in that the means for perceptually weighting the error signal are arranged for truncating their impulse response at a length which is at most equal to the spacing between two equidistant pulses in the grid of the excitation signal.
Claim 5
Dependent Claim
50 words
4 . A multi-pulse excitation linear-predictive coder as claimed in Claim 2, characterized in that the auto-correlation function of the impulse response of the weighting filter is zero for delays equal to the spacing between two equidistant pulses in the excitation signal grid, and to integral multiples of this spacing.