telephone time signal

FSK caller signal automatically refresh existing system date and time, DTMF telephone signal to the original system, the time and date settings had no effect.

FSK来电信号自动刷新原有的系统日期时间，DTMF来电信号对原系统的时间，日期的设置无影响。

For the requirements of the signal-to-noise ratio of lower in part of telephone channel the algorithm to convergence in the time domain and frequency domain step by step.

针对部分线路上语音信噪比较低的实际，引入谱熵进行分级检测，将算法在时域和频域逐级进行收敛。

With regard to communication security, the safekeeping of password and real-time processing in speech signal encryption based on triple Data Encryption Standard ( 3DES) were analyzed. In addition, the basic framework of speech encryption and the hardware system design in encryption telephone were presented.

针对通信安全性问题，分析了三重数据加密的密钥保管问题和语音加密的实时处理技术，提出了将算法移植到电话中加密语音信号的系统结构并进行了硬件设计。