可变频带数字带通滤波器设计方法研究

发布时间：2018-01-17 21:16

本文关键词：可变频带数字带通滤波器设计方法研究　出处：《内蒙古大学》2015年硕士论文　论文类型：学位论文

【摘要】：信号进行发送传播的过程中都一定程度的产生其他的无用信号成分。所以我们面临带有噪声的原始信号中提取有效信号是滤波技术的核心所在,也是现代通信信号处理中涉及的必要环节。现代通信领域中滤波器是非常广泛应用的器件之一,滤波器进行设计时一般用硬件、算法、软件来实现。数字滤波器与模拟滤波器相比有很多优点,比如精度高、稳定性好、体积小、成本低、工作效率高等。有限长脉冲响应滤波器的稳定性好。本论文研究了可变频带有限长脉冲响应滤波器的设计法。它跟普通的数字FIR滤波器相比灵活性高,且不用反复离线设计新的滤波器也能得到所需理想的频域特性,这也是可变频带数字带通滤波器的非常重要的优点。所以研究可变频带数字FIR滤波器设计法有很大的研究价值。在设计可变频带数字带通滤波器时,首先估计接受信号的带宽和中心频率。其次,根据接受信号的中心频率和带宽来计算FIR滤波器的参数。最后,掌握参数以后选用合适的滤波器设计法来设计所需的滤波器。因为每次估计的带宽和中心频率不同所以计算出的滤波参数也不同。以上的三个步骤是本文所设计的可变频带滤波器的整个过程。本文进行分析了几种常用的中心频率和带宽估计法后发现这几种估计法都有一定的局限性,且低信噪比的情况下估计准确度都不高。所以研究了基于迭代方法的改进的中心频率估计法、Welch方法的带宽估计法。Welch的带宽估计法比修正协方差法和MUSIC法等常用法比起来稳定性好,精度高。基于迭代法的中心频率估计法跟其他常用法相比测量的频率范围广、运算简单、低信噪比的情况下也精确估计带宽等优点。所以可变频带数字带通FIR滤波器有很广的应用前景。而且,随着通信信号处理的持续发展和新结构、新算法的不断提出,数字滤波器满足更高的应用要求且性能也将变得越来越好。
[Abstract]:In the process of signal transmission and propagation, other useless signal components are produced to a certain extent, so we are faced with the original signal with noise to extract the effective signal is the core of the filtering technology. Filter is one of the most widely used devices in the field of modern communication. The filter is generally used in hardware and algorithm when it is designed. Compared with analog filter, digital filter has many advantages, such as high precision, good stability, small size and low cost. The finite length impulse response filter has good stability. In this paper, the design method of variable band finite length pulse response filter is studied. It is more flexible than the conventional digital FIR filter. Moreover, the desired frequency domain characteristics can be obtained without repeated off-line design of new filters. This is also a very important advantage of the frequency band digital band-pass filter, so it is of great value to study the design method of the variable-band digital FIR filter. In the design of the variable-band digital band-pass filter. First, the bandwidth and the central frequency of the received signal are estimated. Secondly, the parameters of the FIR filter are calculated according to the center frequency and bandwidth of the received signal. After mastering the parameters, choose the appropriate filter design method to design the required filter. Because the bandwidth and center frequency of each estimation are different, the filter parameters calculated are different. The above three steps are designed in this paper. In this paper, we analyze several common methods of center frequency and bandwidth estimation, and find that these methods have some limitations. And the estimation accuracy is not high in the case of low SNR. Therefore, an improved center frequency estimation method based on iterative method is studied. The bandwidth estimation method of Welch method. Welch's bandwidth estimation method is more stable than that of modified covariance method and MUSIC method. Compared with other common methods, the center frequency estimation method based on iterative method has a wide frequency range and simple operation. In the case of low signal-to-noise ratio (SNR), the bandwidth can be estimated accurately. Therefore, the frequency-band digital band-pass FIR filter has a wide application prospect. Moreover, with the continuous development of communication signal processing and new structure. With the development of new algorithms, digital filters can meet higher application requirements and the performance will become better and better.
【学位授予单位】：内蒙古大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN713.5

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