摘要
本文对基带信号的成形和射频信号的多速率处理进行了研究。首先给出了成形滤波函数的数学模型,讨论了几种常用成形滤波函数的传输特性以及对传输系统信号误码率的影响。接着介绍了成形滤波器的几种实现方法,包括FIR算法、FFT-IFFT算法和码元滑动窗算法,并将遗传算法用于确定成形滤波器的系数。仿真结果表明,遗传算法在滤波器的设计中确实是有效的。然后介绍了数字成形滤波器多相结构的FPGA实现方法,运用查询系数ROM的方法可以省去实现滤波器的乘法器结构,并对此实现方法进行软件仿真和硬件电路板测试,测试结果达到了较理想的效果。最后讨论了多速率信号处理中两种重要的信号处理——内插和抽取,对它们的实现方法进行了软件仿真,同时给出了它们的FPGA实现。
This paper investigates the problems about the base-band signal shaping and the multi-rate signal processing of the radio-frequency signal. Firstly, the paper gives the mathematical model of the shaping-filter functions and discusses their transmission characteristics. Secondly, the methods to realize the shaping-filter are introduced, which include the FIR algorithm, the FFT-IFFT algorithm and the symbol sliding-window algorithm. The genetic algorithm (GA) is used to optimize the filter coefficients. Computer simulation shows the GA is effective in the filter's design. In addition, the paper presents filter multi-phase structure for the shaping-filter design and its FPGA implementation, where multipliers can be omitted by using the look-up table of the filter coefficients ROM . Test of the prototype circuit board shows the method is perfect. Finally, two important theories of the multi-rate signal processing, interpolation and decimation, are discussed. The paper also gives their computer simulation results and FPGA implementation.
引文
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