IMBE (Improved Multi - Band Excitation) and AMBE (Advanced Multi - Band Excitation) both based on the proprietary MBE (Multi - Band Excitation) speech compression algoritym are intemationally recognized as the best speech compression algorithms in the world , and AMBE has been built in DVSI's AMBE2000 speech compression vocoder. The locomotive voice compression recorder based on AMBE2000 chip possesses the characteristics of intelligibility , full - electronics ,long - time recording and high reliability. The recorder , which has been gradually equipped throughout the railway system , is an important equipment by which railway transportation safety can be realized.