With the application of MATLAB software, this design used a cycle of m sequence to simulate and analyze a certain cycle of square wave signals. The relevant knowledge of spread spectrum communication was elaborated from various aspects, such as the composition principles and characteristics of spread spectrum communication system, its major performance index and its direct sequence, pseudo random sequence and the methods of implementing spread spectrum; particular emphasis was focused on the theoretical analysis and simulation study of the performance of DS spread spectrum system.
設計從理論上分析了直接序列擴頻通信系統的系統框圖、直接序列擴頻信號的產生原理及其解調、窄帶幹擾對解擴的影響，並通過編輯MATLAB中的代碼實現了擴頻通信系統的仿真。將方波信號擴頻，而後進行調制與解調，最後使信號通過低通濾波器，過濾掉它的高頻部分，從而恢復出所期望的信號，並與原始方波信號進行對照。
This design theoretically analyzed the system chart of DS spread spectrum system, its signal’s generation principles and demodulation, the impact of narrowband interference on de-spreading, and the realization of the spread spectrum communication system simulation by editing the MATLAB codes. Then, spread spectrum was conducted on the square wave signals, followed by modulation and demodulation, and finally, the signals were filtered to remove the high frequency parts by low pass filter, so as to regenerate the desired signals and to compare them with the original square wave signals.
結果顯示，兩者具有壹致性，信號頻譜基本相同，達到了預期的效果。
The result shows that there is consistency in both signals, their frequency spectrums are basically the same and the expected result is achieved.
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