scope:

The present document describes all the functions associated with the TETRA speech codec, except the specification of the codec by itself which is entirely defined in EN 300 395-2 [1]. Clause 4 of the present document provides a description of the functions associated with the speech encoder, while clause 5 is its counterpart for the speech decoder. Clause 6 describes the contents and the format of the signalling data block included in a stolen frame when used for transferring information relevant to the codec in a U-plane signalling message. In addition, annex A provides indications and preferred solutions for the implementation of optional features.