Study on the Alternate Means of High Speed Telegraph - relay Network

转 报高速网备份手段的研究

Devices such as the telegraph and telephone relay messages by creating modulated electrical impulses or impulses that change in a systematic way .

电报 机与电话机等设备，通过产生调制电脉冲或以系统化方式变化的脉冲，来 传递信息。