【作者】 张海波；

【导师】 高燕梅；

【作者基本信息】 吉林大学 ， 信号与信息处理， 2011， 硕士

【摘要】 当前模拟音频处理技术逐渐被数字音频处理技术取代,数字音频处理技术得到了迅速的普及和发展。数字滤波技术对采集到的音频信号进行变换处理后,就实现了音频处理的数字化。数字滤波是业内人士的研究热点,是数字信号处理技术中的关键技术之一。由于采用的乘法器结构庞大,传统的数字滤波器的音频处理系统在体积和处理速度上存在着不足。随着可编程逻辑器件的发展,FPGA在性能、成本、灵活性和功耗等方面具有明显的优势,在信号处理领域中基于FPGA的信号处理器已经被广泛的应用。本论文研究了数字滤波器的基本理论、数字音频处理方法和全相位数据预处理方法,完成了基于FPGA的IIR数字音频滤波器的设计与实现。首先,全相位数据预处理方法应用于数字音频处理中存在减小截断效应的优势,以N=4时无窗全相位数据预处理为例,对音频信号进行了预处理,结果表明,音频信号首尾波形平滑,都保持了连续性,另外缩小了旁谱泄露范围,减小谱间干扰,波形失真和泄露抑制得到了很好的改善,从而减小了截断误差。改进了IIR并行处理的实现方法,由二路并行处理改进为四路并行处理,提供一种基于FPGA的并行处理滤波器的实现方案,采用四路并行处理方法设计数字滤波器,并把经过无窗全相位数据预处理后的音频信号作为四路并行处理滤波器的输入。提出采用八路并行处理方法设计数字滤波器的设想,证明四路、八路并行处理的正确性与可实现性,应用硬件描述语言VHDL实现了设计。QuartusⅡ软件除了具有强大的编译综合功能外,还提供了一定的波形仿真功能。由于其输入和输出均以波形的形式给出,难以对结果进行定量分析。为了加强QuartusⅡ软件的仿真功能,提高设计效率,本论文主要采取MATLAB及QuartusⅡ联合仿真的方式,以经过无窗全相位数据预处理后的音频信号作为输入信号,对所设计的滤波器的滤波效果进行测试验证。实验系统测试结果表明,本论文所设计的IIR音频滤波器时钟频率得到增强,滤波速度得到了提高,其中四路并行处理IIR滤波器的时钟频率是98.41MHz,二路并行处理IIR滤波器的时钟频率是95.29MHz,前者要高于后者3.12MHz,达到了设计的要求。更多还原

【Abstract】 In the current, analog audio processing technology is gradually replaced by digital audio processing technology, which has obtained a rapid popularization and development. Digital filtering technology can realize the digitization of audio processing through transforming the collected audio signal. Digital filter is the study hotspot inside the industry, and is one of key signal processing technology. Because the structure of multiplier is huge, the audio processing system of traditional digital filter is inadequate in volume and processing speed. With the development of programmable logic device, FPGA has obvious advantages in performance, cost, flexibility and power. The signal processor based on FPGA already has been widely used in signal processing field.This paper studied the basic theory of digital filter, digital audio processing method and all phase data pretreatment method, and completed the IIR digital audio filter of design and implementation based on FPGA.Firstly, all phase data pretreatment method had the advantage of reducing truncated effect when it was applied to digital audio processing. Take all phase windowless data preprocessing as an example when N=4, and do the pretreatment for audio signal. The results show that the head and tail waveforms of audio signal are smooth; maintain the continuity; narrow the leaked scope of side spectrum; reduce the interference between spectrum. Waveform distortion and leak inhibition have got a very good improvement, thus reduce truncation errors.The realization method of IIR parallel processing is improved, from the two parallel processing improvement to four ways of parallel processing. This paper offers a parallel processing implementation scheme of the filter based on FPGA, using four ways of parallel processing method to design digital filter, and put audio signal after the pretreatment through windowless all phase data as the input for four ways parallel processing filter. Eight ways parallel processing method is proposed to design digital filter, then we proof the validity and practicality of four and eight parallel processing by VHDL realized the design.QuartusⅡsoftware not only has strong compile comprehensive functions, but also provides certain waveform simulation function. Because its input and output are given in the form of waveform, it is difficult to get quantitative analysis of results. In order to strengthen QuartusⅡsimulation function and improve the design efficiency, this paper mainly take MATLAB and QuartusⅡjoint simulation way. With the audio signal after pretreatment by windowless all phase data as the input signal, the filter effect of designed filters is tested.Experimental results show that the clock frequency of designedⅡR audio filter is increased, and the filtering speed is improved. The clock frequency of four ways parallel processingⅡR filter is 98.41 MHz, and two parallel processingⅡR filter is 95.29 MHz; the former than the latter 3.12 MHz and meet the design requirements.更多还原