Process and device for blind equalization of the effects of a transmission channel on a digital speech signal
First Claim
1. Process for the blind equalisation of the effects of a transmission channel on a digital speech signal ({sn (t)}) passing through said transmission channel, said process involving at least:
- transforming said digital speech signal into a set of cepstral vectors, the set of cepstral vectors being representative of said digital speech signal over a given horizon;
calculating a reference cepstrum ({Rn (i)}) representative, for each of the cepstral vectors of said set of cepstral vectors of the long-term cepstrum of said speech signal, said reference cepstrum ({Rn (i)}) consisting of a constant cepstrum signal for each of the cepstral vectors representative in the digital speech signal and in the set of cepstral vectors of the long-term cepstrum in the speech signal;
subjecting each of the cepstral vectors to adaptive filtering on the basis of said reference cepstrum, in order to generate a set of equalised cepstral vectors ({Cn (i)}) in which the effects of said transmission channel are substantially suppressed, said set of equalised cepstral vectors being representative of an equalised digital speech signal.
1 Assignment
0 Petitions
Accused Products
Abstract
A process and device for blind equalization of the effects of a transmission channel on a speech signal. The speech signal is transformed into cepstral vectors which are representative of the speech signal over a given horizon. A reference cepstrum consisting of a constant cepstrum signal representative of the long-term cepstrum of the speech signal is calculated for each cepstral vector. Each of the cepstral vectors is subjected to adaptive filtering by LMS on the basis of the reference cepstrum so as to generate a set of equalized cepstral vectors on the basis of the calculation of an error signal between the reference cepstrum and equalized cepstral vectors. The error signal is expressed as the difference between the reference cepstrum component of a given rank and the component of the same rank of the equalized cepstral vector.
56 Citations
7 Claims
-
1. Process for the blind equalisation of the effects of a transmission channel on a digital speech signal ({sn (t)}) passing through said transmission channel, said process involving at least:
-
transforming said digital speech signal into a set of cepstral vectors, the set of cepstral vectors being representative of said digital speech signal over a given horizon; calculating a reference cepstrum ({Rn (i)}) representative, for each of the cepstral vectors of said set of cepstral vectors of the long-term cepstrum of said speech signal, said reference cepstrum ({Rn (i)}) consisting of a constant cepstrum signal for each of the cepstral vectors representative in the digital speech signal and in the set of cepstral vectors of the long-term cepstrum in the speech signal; subjecting each of the cepstral vectors to adaptive filtering on the basis of said reference cepstrum, in order to generate a set of equalised cepstral vectors ({Cn (i)}) in which the effects of said transmission channel are substantially suppressed, said set of equalised cepstral vectors being representative of an equalised digital speech signal. - View Dependent Claims (2, 3, 4)
-
-
5. Device for the blind equalisation of the effects of a transmission channel on a digital speech signal ({sn (t)}) passing through said transmission channel, comprising at least:
-
means for transforming said digital speech signal into a set of cepstral vectors, said set of cepstral vectors being representative of said digital speech signal over a given horizon; means for generating a reference cepstrum that is representative, for each of the cepstral vectors of said set of cepstral vectors, of the long-term cepstrum of this speech signal; means for adaptive filtering, on the basis of said reference cepstrum, of each of the cepstral vectors enabling generation of a set of equalised cepstral vectors in which the effect of said transmission channel are substantially suppressed, said set of equalised cepstral vectors being representative of an equalised digital speech signal, said means for adaptive filtering comprising at least for each cepstral vector ({Cn (i)}), iε and
for a reference cepstrum ({Rn (i)}) representative, for each of the cepstral vectors, of the long-term cepstrum of this speech signal,means for calculating an error signal (E(i)) between each component of rank i (Cn (i)) of each equalised cepstral vector ({Cn (i)}) and the corresponding component of identical rank (Rn (i)) of the reference cepstrum ({Rn (i)}), E(i)=R n (i)-Cn (i)); and means for equalisation of said cepstral vector ({Cn (i)}) transmitting a component (Cn (i)) of the equalised cepstral vector ({Cn (i)}) on the basis of each component (Cn (i)) of each cepstral vector ({Cn (i)}) and said error signal (E(i)). - View Dependent Claims (6, 7)
-
Specification