Code-excited linear prediction

About: Code-excited linear prediction is a research topic. Over the lifetime, 2025 publications have been published within this topic receiving 28633 citations. The topic is also known as: CELP.

A Low-Rate Digital Formant Vocoder

Abstract: A complete algorithm of a 1200-bits/s digital formant vocoder system is described. This vocoder algorithm draws heavily on the results of recent research in linear predictive coding. The transmitting parameters are frequencies and amplitudes of the first three formants, the pitch period, voiced/unvoiced decision, and the gain. Formant bandwidths are estimated at the synthesizer by using the amplitude information. The synthesizer structure is in the parallel form. The synthetic speech quality at 1200 bits/s is reasonably good; most of the speech is intelligible and speaker-recognizable.

Robust VB 2D-CELP image transmission over CDMA Rayleigh fading channels

Abstract: This paper describes a new error resilient analysis-by-synthesis coding scheme and its application for robust still image transmission over CDMA Rayleigh fading channels. For the purpose of providing reliable transmission, a type-I hybrid ARQ protocol is used in a concatenated Reed–Solomon/convolutional coding scheme. However, for delay-constrained applications, the protocol is used with a limited number of retransmissions in addition to limited RS interleaving. Results of coded images are provided for the uplink of a communication system, where a slowly Rayleigh fading channel is considered.

Digital speech transmission for highly encrypted and paramilitary operated land mobile radio communications over a narrowband UHF channel

Abstract: The functional, technical and operational requirements which determine the design of the speech order are specified. Compression methods including both waveform coding and source coding are reviewed, and their performance together with implementation practicability are discussed. The importance of the type of modulation and encryption methods to be used in conjunction with the encoder is emphasised. It is concluded that robust linear predictive coding algorithms would provide some pragmatic solutions in the future for digital secure voice transmission over narrowband radio channels in the light of rapid development of digital signal processing techniques and very large scale integrated (VLSI) circuits technology. Specifically, code excited linear predicted (CELP) with line spectral pair (LSP) coefficients has shown considerable promise for good quality coding of speech at low bit rates with reduced complexity which is suitable for land mobile communications. >

Implementation of a real-time HY-2 channel vocoder algorithm

Abstract: This paper describes the proprietary implementation of a real-time software based HY-2 compatible channel vocoder algorithm. The HY-2 algorithm was used prior to linear predictive coding (LPC) vocoders for low bit rate voice communications at 2400 bps. This implementation is a unique and instructive implementation of a parametric vocoder, producing high quality speech.