This paper briefly introduces the classification of low bit rate speech encoding algorithm in two criterion and pays more attention to three classical low bit rate speech encoding algorithm and their traits,so the pursuer can commendably grasp the classification of low bit rate speech encoding and the system of algorithm.

An improved algorithm based on G.729 speech coding;

Simulation of the FS-1016 speech coding algorithm;

Efficient LSP quantization algorithm for very low bit rate speech coding;

G.729 Speech Code Research Based on DSP;

Full specification of the speech codes used in the TETRA (Trans-European Truncked Radio) system is presented.

This thesis realized and described speech code based on the issue of ITU-T pronunciation code standard G723.

This paper expounds the voice coding technology and its development, and particularly discusses the two most popular fields of voice coding—LPC and SBC.

729(8kbit/s)are the low bit rate of voice coding standard provided by ITU-T, which can be used for network ,wireless and satellite communication.

Intercommunication(including voice and data) between the virtual simulation radio and multi-type semi-simulation radio was materialized systematically,mainly depending on voice coding,real-time de-noising,formats reciprocating and so on.