手机经过射频电波(一种与调频电波和微波类似的能量方式)，将信号发送至左近的信号塔。

Cellphones send signals to nearby towers via radio frequency waves, a form of energy similar to FM radio waves and microwaves.

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常用的调制方式使用正弦波作为载波并对其进行幅度调制(AM)和角度调制即调频(FM)或调相(PM)。

In frequently used methods, sine wave is used as carrier with amplitude modulation (am), frequency modulation (FM) and phase modulation (PM) implied.

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主控芯片采用AT89C51单片机，通信方式采用抗干扰能力强、可靠性高的DTMF信号和单工调频的无线通信方式。

The master control chip uses AT89C51, the communication mode adopts DTMF signal with strong anti-interference and high reliability, and simplex frequency modulation.

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主控芯片采用AT89C51单片机，通信方式采用抗干扰能力强、可靠性高的DTMF信号和单工调频的无线通信方式。

The master control chip uses AT89C51, the communication mode adopts DTMF signal with strong anti-interference and high reliability, and simplex frequency modulation.

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