This paper describes the basic theory of speech compression encoding and decoding algorithm in TETRA (terrestrial trunked radio) system.

研究了陆地集群无线通信（TETRA）数字集群移动通信系统的语音压缩编解码算法的基本原理。

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Each probe can pick up GPS signals and signals from eLoran, an enhanced version of Loran, the ground-based terrestrial radio-navigation system first used by the American and British navies during the second world war.

ECONOMIST: GPS jamming