Rudolf Hofmann

Speech codec for the European mobile radio system

In 1991 a digital mobile radio system will be introduced in Europe. The speech codec to be used as the standard is presented. The coding scheme which has been selected by the CEPT Groupe-Speciale-Mobile (GSM) as a result of formal subjective listening tests, is based on the regular-pulse excitation LPC technique (RPE-LPC) combined with long-term prediction (LTP). The so-called RPE-LTP codec has a net bit rate of 13 kbit/s. The algorithm and the experimental implementations based on different VLSI signal processors are described and demonstrated.<<ETX>>

Device for the digital recording and reproduction of speech signals

Devices for the digital recording and reproduction of speech signals are used, for example in answering apparatus. In order to reduce the quantity of data to be stored without noticeably affecting the acoustic quality of the speech, it is proposed to encode speech signals by means of a residual signal speech encoder.

A regular-pulse excited linear predictive codec

Abstract A 16 kbit/s speech codec with low complexity and low signal delay is presented which is a special version of the Regular-Pulse Excitation LPC approach (RPE-LPC). This proposal is the basis for the codec standard which will be used in the future Pan-European digital mobile telephone system. An experimental hardware model is described.