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数据通信是电子计算机技术和现代通信技术相结合的产物。是继电话、电报之后的另一种新颖的通信方式。普通电话与电报在传递过程中都需要有人参与,属于“人—人”通信。数据通信由是一种在电子计算机之间、计算机与终端或终端与终端之间的通信,属于“机—机”通信。借助于它,可使计算机的资源得到共享。与普通数字通信一样,就广义而文,数据通信系统也由三部分组成:信源、信道和信宿。在数字通信中,信源送出的是模拟信号,经模/数转换后,变成在时域和幅域上都是离散值的数字信号,到了接收端,经数/模转换还原成相应的模拟信号。数据通信与此不同,信源送出的和信宿收到的都是数字信号。这种信号是表征字母、数字和符号的数字信号,因此又称为“数据信号”。电报信号就是一种数据信号,电报通信可以看作是低速的数据通信。
Data communication is the product of the combination of electronic computer technology and modern communication technology. Is another telephone, after telegraph another novel communication. Ordinary telephone and telegraphy need someone to participate in the transmission process, belonging to “people - person ” communication. Data communication is a kind of communication between computers, computers and terminals or between terminals and terminals, belonging to “machine-machine ” communication. With it, your computer’s resources can be shared. As with ordinary digital communications, the broad sense of the word, data communications systems are also composed of three parts: source, channel and sink. In digital communications, the source sends the analog signal, the analog / digital conversion, into a discrete value in the time domain and domain digital signal to the receiving end, the digital / analog conversion back to the corresponding Analog signal. Data communication is different from this. Source and sink are both digital signals. This signal is a digital signal that characterizes letters, numbers and symbols and is therefore also called “data signal.” Telegram signal is a kind of data signal, telegram communication can be regarded as the low speed data communication.