选择呼叫发射机主要用于飞机选择呼叫系统的测试,需要按照测试要求产生与实际相符的信号.系统采用DDS技术,设计选择呼叫信号的数字合成、载波信号频率控制和调幅射频放大3部分电路,并将其集成到系统内部,是一套完整的选择呼叫信号发射机.研制的系统实验指标达到设计标准,产生的信号准确稳定,能够按照设定同时发送3路甚高频选择呼叫射频信号,可以直接用于对飞机选择呼叫接收机的测试.%The selective call (SEL CAL) transmitter is mainly used for the system testing of the aircraft, which should generate signal consistent with the actual signal in accordance with the testing requirements. Three parts circuits namely digital selective call signal synthesis, frequency control and amplitude modulated RF signal am plifier are designed by using DDS technology and are integrated within the system. It is a complete call signal transmitter. The experimental indexes meet the design standards. The product can transmit 3-way SEL CAL sig nals in different frequencies accurately and steadily. It can be directly used for the testing of aircraft selective call receiver.
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