SSH EN 300 961 V8.1.1:2000

Sistemi i telekomunikacionit dixhital celular (Faza 2+) (GSM); Fjalimi me vlerë të plotë; Ndërkodimi (GSM 06.10 versioni 8.1.1 Publikimi 1999)

Digital cellular telecommunications system (Phase 2+) (GSM); Full rate speech; Transcoding (GSM 06.10 version 8.1.1 Release 1999)

Scope

The transcoding procedure specified in the present document is applicable for the full-rate Traffic Channel (TCH) in the
digital cellular telecommunications system. The use of this transcoding scheme for other applications has not been
considered.
In GSM 06.01, a reference configuration for the speech transmission chain of the digital cellular telecommunications
system is shown. According to this reference configuration, the speech encoder takes its input as a 13 bit uniform PCM
signal either from the audio part of the mobile station or on the network side, from the PSTN via an 8 bit/A- or µ-law
(PCS 1900) to 13 bit uniform PCM conversion. The encoded speech at the output of the speech encoder is delivered to a
channel encoder unit which is specified in GSM 05.03. In the receive direction, the inverse operations take place.
The present document describes the detailed mapping between input blocks of 160 speech samples in 13 bit uniform
PCM format to encoded blocks of 260 bits and from encoded blocks of 260 bits to output blocks of 160 reconstructed
speech samples. The sampling rate is 8000 sample/s leading to an average bit rate for the encoded bit stream of 13
kbit/s. The coding scheme is the so-called Regular Pulse Excitation - Long Term prediction - Linear Predictive Coder,
here-after referred to as RPE-LTP.
The present document also specifies the conversion between A- and µ-law (PCS 1900) PCM and 13 bit uniform PCM.
Performance requirements for the audio input and output parts are included only to the extent that they affect the
transcoder performance. The present document also describes the codec down to the bit level, thus enabling the
verification of compliance to the present document to a high degree of confidence by use of a set of digital test
sequences. These test sequences are described and are contained in archive en_300961v080101p0.ZIP which
accompanies the present document.