本文關(guān)鍵詞： 頻率響應(yīng)遮蔽技術(shù) FIR數(shù)字濾波器 非線性優(yōu)化算法 非線性變換 可重構(gòu)濾波器組 助聽器　出處：《山東大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

【摘要】：數(shù)字濾波器被廣泛應(yīng)用在數(shù)字信號(hào)處理系統(tǒng)中,主要用來降噪和提取有用信息,濾波器的復(fù)雜度與濾波器的過渡帶寬成反比,當(dāng)過渡帶極窄時(shí),系統(tǒng)的復(fù)雜度會(huì)急劇增加,功耗也越大。頻率響應(yīng)遮蔽技術(shù)(FRM)使用了系數(shù)非常稀疏的子濾波器,可以大大降低窄過渡帶濾波器的復(fù)雜度。濾波器組也是數(shù)字信號(hào)處理系統(tǒng)和通信系統(tǒng)重要的組成部分,主要用來提取各個(gè)子帶信號(hào),為后續(xù)處理做準(zhǔn)備。目前比較常見的為余弦調(diào)制濾波器組、離散傅里葉變換調(diào)制濾波器組和多相濾波器組,用于軟件無線電收發(fā),數(shù)字通信,語(yǔ)音信號(hào)處理系統(tǒng)等,本文主要關(guān)注數(shù)字助聽系統(tǒng)中濾波器組的設(shè)計(jì)。本文重點(diǎn)研究了低復(fù)雜度濾波器設(shè)計(jì)和適用于助聽系統(tǒng)的低時(shí)延可重構(gòu)濾波器組設(shè)計(jì),主要工作如下：1、提出了新型二級(jí)FRM濾波器結(jié)構(gòu)和設(shè)計(jì)方法。FRM技術(shù)是設(shè)計(jì)具有窄過渡帶特性FIR濾波器的一種高效方法,當(dāng)濾波器的過渡帶比較窄的時(shí)候,可以用多級(jí)FRM進(jìn)一步減少其復(fù)雜度。對(duì)于傳統(tǒng)的二級(jí)FRM濾波器,存在以下兩個(gè)約束條件：1)原型濾波器的內(nèi)插因子必須是第二級(jí)遮蔽濾波器內(nèi)插因子的整數(shù)倍；2)第二級(jí)兩個(gè)遮蔽濾波器的內(nèi)插因子相同。本文提出的新型結(jié)構(gòu)打破了這兩個(gè)約束條件,采用新的計(jì)算方法確定各個(gè)子濾波器的設(shè)計(jì)參數(shù),并結(jié)合非線性優(yōu)化算法聯(lián)合優(yōu)化各個(gè)子濾波器。在新型結(jié)構(gòu)中,假如原型濾波器和第二級(jí)兩個(gè)遮蔽濾波器的內(nèi)插因子分別為M,P,Q,當(dāng)滿足P=Q, M=kP時(shí),得到的最優(yōu)解與傳統(tǒng)的二級(jí)FRM濾波器相同。當(dāng)有一個(gè)等式不滿足,改進(jìn)型結(jié)構(gòu)比傳統(tǒng)結(jié)構(gòu)復(fù)雜度更低,因此新型結(jié)構(gòu)在硬件實(shí)現(xiàn)中功耗更小。2、提出了適用于助聽器的低時(shí)延可重構(gòu)濾波器組。大部分學(xué)者在研究適用于助聽系統(tǒng)的濾波器組時(shí),主要集中于固定的濾波器組結(jié)構(gòu),這種結(jié)構(gòu)只能為聽力損失患者提供單一的聽力補(bǔ)償。由于不同的聽損患者具有不同的聽力損失特性,固定的濾波器組往往不能提供匹配的響度補(bǔ)償。本文提出了一種具有低時(shí)延特性的可重構(gòu)濾波器組。首先通過余弦調(diào)制低通FIR濾波器得到一個(gè)均勻?yàn)V波器組,然后采用非線性變換將均勻?yàn)V波器組映射為非均勻?yàn)V波器組,最后通過控制參數(shù),實(shí)現(xiàn)可重構(gòu)的濾波器組。該濾波器組可以提供四種不同的響度補(bǔ)償方式,并且無需改變?yōu)V波器組的結(jié)構(gòu)和任何子濾波器的系數(shù)。經(jīng)實(shí)例驗(yàn)證,與其他設(shè)計(jì)方法相比,該濾波器組具有較好的匹配性和較低的群時(shí)延。
[Abstract]:Digital filter is widely used in digital signal processing system, mainly used to reduce noise and extract useful information. The complexity of the filter is inversely proportional to the bandwidth of the filter, when the transition band is extremely narrow. The complexity of the system increases dramatically and the power consumption increases. FRM (Frequency response masking technique) uses subfilters with very sparse coefficients. The filter bank is also an important part of digital signal processing system and communication system, which is mainly used to extract each sub-band signal. In order to prepare for the subsequent processing. At present, the common filters are cosine modulation filter bank, discrete Fourier transform modulation filter bank and polyphase filter bank, which are used for software radio transceiver and digital communication. This paper focuses on the design of filter banks in digital hearing aid systems. This paper focuses on the design of low-complexity filters and low-delay reconfigurable filter banks for hearing aid systems. The main work is as follows: 1. The structure and design method of a new two-stage FRM filter. FRM technology is an efficient method to design FIR filter with narrow transition band characteristics. When the transition band of the filter is narrow, the complexity of the filter can be further reduced by multistage FRM. The interpolation factor of the prototype filter must be an integer multiple of the interpolation factor of the second level masking filter. 2) the interpolation factor of the second stage of the two filters is the same. The new structure in this paper breaks the two constraints and uses a new calculation method to determine the design parameters of each sub-filter. In the new structure, if the interpolation factor of the prototype filter and the second stage shadowing filter are MnP Q, respectively, the PQ is satisfied. The optimal solution is the same as the traditional two-stage FRM filter. When an equation is not satisfied, the complexity of the improved structure is lower than that of the traditional one. Therefore, the new structure has lower power consumption in hardware implementation. A low delay reconfigurable filter bank for hearing aids is proposed. Most of the researchers are studying the filter banks suitable for hearing aid systems. It mainly focuses on the fixed filter bank structure which can only provide a single hearing compensation for hearing loss patients because different hearing loss patients have different hearing loss characteristics. Fixed filter banks are often unable to provide matching loudness compensation. In this paper, a reconfigurable filter bank with low delay is proposed. First, a uniform filter bank is obtained by CoSine modulated low pass FIR filter. . Then the uniform filter bank is mapped to a non-uniform filter bank by nonlinear transformation. Finally, the reconfigurable filter bank is realized by controlling the parameters. The filter bank can provide four different loudness compensation methods. There is no need to change the structure of the filter bank and the coefficients of any subfilters. Compared with other design methods, the filter bank has better matching performance and lower group delay.
【學(xué)位授予單位】：山東大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TN713

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本文編號(hào)：1477752