采用DSP处理器的甚高频全向信标/仪表着陆系统标准信号源

Standard Signal Source for VHF Omni Direction Beacon/Instrument Landing System Based on DSP

甚高频全向信标/仪表着陆系统标准信号源中,需要进行复杂低频信号的合成。较为详细地阐述了系统采用DSP处理器实现复杂信号合成的原理,即通过利用DSP处理器内部丰富的硬件资源,采用DDS的技术原理,在DSP内部构建DDS的框架电路;并利用DSP内部各单元灵活的可编程特性,使内建的DDS各电路可以分时复用。信号合成时首先使用DDS技术分时合成单一信号,然后再通过数据相加的办法,合成所需的复杂信号。信号合成过程中发挥DDS、DSP的技术优势,同时实现了信号的调幅、调频,高精度相位、幅度预置。最后通过高精度D/A转换器实现信号的模拟输出。最后以电路实际输出的合成信号的波形图与实测结果的形式,验证了所讲述原理的正确性。

Complicated low frequency＇s synthesis is needed in the design of the standard signal source for Very-High-Frequency omni direction beacon/Instrument Landing System （ILS）. The paper introduces the technical principle in detail for using DSP processor to realize complicated signal synthesis in the system. The signal synthesis method is to use DDS technique to build DDS frame circuits with the hardware source inside DSP, and to make these inbuilt circuits be time-sharing multiplexed by using the flexible programmability of DSP units. When signals are synthesized, signals are first generated separately by the DDS frame circuits, and then synthesized to the needed complicated signals by means of data adding. The signal synthesis process makes use of the advantages of DDS and DSP to realize amplitude/frequency modulation and precise phase/amplitude presetting. The analog signal was output from a D/A converter with high precision. The paper provides the real synthesis signal waveform and measured result from the circuit to validate the principle correctness in the end.