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无线电信号传输的软件调制有多种优点,软件调制由计算机软件控制,根据所传输信号的高、低电平,分别发出两种频率。关键是这些频率的产生。由计算机运行指令时所产生的延时时间。有规律地向输出口发送高电平或低电平来达到。指令运行时钟周期所延时的时间等于所需频率的周期。该方法在TRS-80.APPLE ⅡKC-85及单片机均适用。文章以IBM-PC/XT为例,对实现软件调制作了探讨。证明方法可行、步骤精度与计算值基本相同,运用方便、简捷。
There are several advantages to software modulation of radio signal transmission. Software modulation is controlled by computer software. Two kinds of frequencies are respectively transmitted according to the high and low level of the transmitted signal. The key is the generation of these frequencies. The delay time generated when the computer is running a command. Regularly sent to the output port to send high or low to achieve. The period during which the instruction run clock cycle is delayed by the required frequency. The method is TRS-80.APPLE Ⅱ KC-85 and SCM are applicable. Taking IBM-PC / XT as an example, this paper discusses the software modulation. Prove that the method is feasible, the accuracy of the step and the calculated value are basically the same, the use is convenient and simple.