The authors present a linear prediction (LP) based vocoder in which speech waveforms are considered as having a time envelope, the shape of which contains important perceptual information. By ensuring that the time en...
详细信息
The authors present a linear prediction (LP) based vocoder in which speech waveforms are considered as having a time envelope, the shape of which contains important perceptual information. By ensuring that the time envelope of the synthetic speech closely matches that of the original, natural sounding synthetic speech can be achieved at 1.6kbit/s.
A method for optimising LPC filters in linear prediction based speech coders is described. The optimisation process compensates for errors incurred through coding the excitation signal, providing an improvement in the...
详细信息
A method for optimising LPC filters in linear prediction based speech coders is described. The optimisation process compensates for errors incurred through coding the excitation signal, providing an improvement in the quality of the decoded speech, with no increase in bit rate.
Low-delay techniques are proposed for coding 7 kHz speech using subband code-excited linear predictive coding (CELP). The use of separate and joint index codebooks is compared. Specifically, the joint-index-subband CE...
详细信息
Low-delay techniques are proposed for coding 7 kHz speech using subband code-excited linear predictive coding (CELP). The use of separate and joint index codebooks is compared. Specifically, the joint-index-subband CELP (JISBC) algorithm is found to provide good quality with processing delay in the range 2.375-3.375 ms at corresponding bit rates of 16-8 k bit/s.
This paper provides an analytical derivation of a simple noniterative technique for extracting a multiple impulse excitation model for synthesized speech directly from the LPC residual sequence. While suboptimal with ...
详细信息
This paper provides an analytical derivation of a simple noniterative technique for extracting a multiple impulse excitation model for synthesized speech directly from the LPC residual sequence. While suboptimal with respect to "multipulse" techniques, this method is very applicable for speech enhancement where processor capability is limited. The results suggest an additional "orthogonality" requirement between the excitation sequence and the resulting prediction error, which aids in the intuitive understanding of the method.
Nonlinearity in communication satellite payloads often severely degrades the downlink signal quality in such systems. A digital pre-compensation technique to enhance digital predistortion performance in multicarrier s...
详细信息
Nonlinearity in communication satellite payloads often severely degrades the downlink signal quality in such systems. A digital pre-compensation technique to enhance digital predistortion performance in multicarrier satellite communication systems is presented. The proposed technique has been validated by simulations with an appropriate platform where excellent performance improvements have been measured. In addition, the implementation feasibility of this technique has been briefly demonstrated by means of a real-time FPGA implementation.
A novel codebook generation scheme for vector quantisation is presented. The proposed scheme is of comparable computational complexity to the Linde-Buzo-Gray (LBG) algorithm, but its performance is shown to be superior.
A novel codebook generation scheme for vector quantisation is presented. The proposed scheme is of comparable computational complexity to the Linde-Buzo-Gray (LBG) algorithm, but its performance is shown to be superior.
We present an architecture called the modular neural predictivecoding architecture (Modular NPC). The Modular NPC is used for discriminative feature extraction (DFE). It provides an architecture based on phonetics kn...
详细信息
We present an architecture called the modular neural predictivecoding architecture (Modular NPC). The Modular NPC is used for discriminative feature extraction (DFE). It provides an architecture based on phonetics knowledge applied to phoneme recognition. The phonemes are extracted from the Darpa-Timit speech database. Comparisons with coding methods (LPC, MFCC, PLP) are presented: they put in obviousness an improvement of the recognition rates.
An autocorrelator for speech analysis has been integrated in CMOS technology. The CMOS integrated circuit is composed of analog, switched-capacitor, and digital circuitry. The autocorrelator uses a time-multiplexed mu...
详细信息
An autocorrelator for speech analysis has been integrated in CMOS technology. The CMOS integrated circuit is composed of analog, switched-capacitor, and digital circuitry. The autocorrelator uses a time-multiplexed multiplying digital-to-analog converter and three multiplexed switched-capacitor filter sections. Each multiplexed filter section consists of ten channels so that ten autocorrelation lags are computed. Practical problems associated with the integration of the multiplexed filters are discussed, and experimental data are given for the filters and the complete autocorrelator.
This paper presents a theoretical analysis of high-rate vector quantization (VQ) systems that use suboptimal, mismatched distortion measures, and describes the application of the analysis to the problem of quantizing ...
详细信息
This paper presents a theoretical analysis of high-rate vector quantization (VQ) systems that use suboptimal, mismatched distortion measures, and describes the application of the analysis to the problem of quantizing the linear predictive coding (LPC) parameters in speech coding systems, First, it is shown that in many high-rate VQ systems the quantization distortion approaches a simple quadratically weighted error measure, where the weighting matrix is a ''sensitivity matrix'' that is an extension of the concept of the scalar sensitivity. The approximate performance of VQ systems that train and quantize using mismatched distortion measures is derived, and is used to construct better distortion measures, Second, these results are used to determine the performance of LPC vector quantizers, as measured by the log spectral distortion (LSD) measure, which have been trained using other error measures, such as mean-squared (MSE) or weighted mean-squared error (WMSE) measures of LPC parameters, reflection coefficients and transforms thereof, and line spectral pair (LSP) frequencies, Computationally efficient algorithms for computing the sensitivity matrices of these parameters are described. In particular, it is shown that the sensivity matrix for the LSP frequencies is diagonal, implying that a WMSE measure of LSP frequencies converges to the LSD measure in high-rate VQ systems, Experimental results to support the theoretical performance estimates are provided.
Distributed space-time block coding (STBC) is a promising technique for future broadband wireless communication system, because of its substantially improving the reliability of wireless channel by exploiting cooperat...
详细信息
Distributed space-time block coding (STBC) is a promising technique for future broadband wireless communication system, because of its substantially improving the reliability of wireless channel by exploiting cooperative spatial diversity. In this study, the authors propose a novel two time slots distributed time-reversal STBC scheme for amplify-and-forward relay-assisted single-carrier (SC) block transmissions over frequency-selective fading channel. They first exploit the discrete Fourier transform extended properties to construct a linear precoding matrix. They then employ a low-complexity suboptimal frequency domain decision feedback equalisation (FD-DFE) to collect potential multipath diversity at high signal-to-noise ratio. Simulation results demonstrate that the proposed scheme provides better performance than the conventional distributed SC-STBC scheme with minimum-mean-square error FD linear equalisation.
暂无评论