基于MATLAB的FIR數(shù)字濾波器的設(shè)計與仿真(英文翻譯)

1、畢業(yè)（設(shè)計）論文英 文 翻 譯系 別 電子信息工程系 專 業(yè) 電子信息工程 班 級 學(xué)生姓名 學(xué) 號 指導(dǎo)教師 英文原文 the simulation and the realization of the digital filterwith the information age and the advent of the digital world, digital signal processing has become one of todays most important disciplines and door technology. digital signal process

2、ing in communications, voice, images, automatic control, radar, military, aerospace, medical and household appliances, and many other fields widely applied. in the digital signal processing applications, the digital filter is important and has been widely applied.1、 figures uniton :analog and digita

3、l filtersin signal processing, the function of a filter is to remove unwanted parts of the signal, such as random noise, or to extract useful parts of the signal, such as the components lying within a certain frequency range. there are two main kinds of filter, analog and digital. they are quite dif

4、ferent in their physical makeup and in how they work. an analog filter uses analog electronic circuits made up from components such as resistors, capacitors and opamps to produce the required filtering effect. such filter circuits are widely used in such applications as noise reduction, video signal

5、 enhancement, graphic equalisers in hi-fi systems, and many other areas. there are well-established standard techniques for designing an analog filter circuit for a given requirement. at all stages, the signal being filtered is an electrical voltage or current which is the direct analogue of the phy

6、sical quantity (e.g. a sound or video signal or transducer output) involved. a digital filter uses a digital processor to perform numerical calculations on sampled values of the signal. the processor may be a general-purpose computer such as a pc, or a specialised dsp (digital signal processor) chip

7、. the analog input signal must first be sampled and digitised using an adc (analog to digital converter). the resulting binary numbers, representing successive sampled values of the input signal, are transferred to the processor, which carries out numerical calculations on them. these calculations t

8、ypically involve multiplying the input values by constants and adding the products together. if necessary, the results of these calculations, which now represent sampled values of the filtered signal, are output through a dac (digital to analog converter) to convert the signal back to analog form. n

9、ote that in a digital filter, the signal is represented by a sequence of numbers, rather than a voltage or current. unit refers to the input signals used to filter hardware or software. if the filter input, output signals are separated, they are bound to respond to the impact of the unit is separate

10、d, such as digital filters filter definition. digital filter function, which was to import sequences x transformation into export operations through a series y.according to figures filter function 24-hour live response characteristics, digital filters can be divided into two, namely, unlimited long

11、live long live the corresponding iir filter and the limited response to fir filters. iir filters have the advantage of the digital filter design can use simulation results, and simulation filter design of a large number of tables may facilitate simple. it is the shortcomings of the nonlinear phase;

12、linear phase if required, will use the entire network phase-correction. image processing and transmission of data collection is required with linear phase filters identity. and fir linear phase digital filter to achieve, but an arbitrary margin characteristics. impact from the digital filter respons

13、e of the units can be divided into two broad categories : the impact of the limited response (fir) filters, and unlimited number of shocks to (iir) digital filters.fir filters can be strictly linear phase, but because the system fir filter function extremity fixed at the original point, it can only

14、use the higher number of bands to achieve their high selectivity for the same filter design indicators fir filter called band than a few high-iir 5-10 times, the cost is higher, signal delay is also larger. but if the same linear phase, iir filters must be network-wide calibration phase, the same se

15、ction also increase the number of filters and network complexity. fir filters can be used to achieve non-digui way, not in a limited precision of a shock, and into the homes and quantitative factors of uncertainty arising from the impact of errors than iir filter small number, and fir filter can be

16、used fft algorithms, the computational speed. but unlike iir filter can filter through the simulation results, there is no ready-made formula fir filter must use computer-aided design software (such as matlab) to calculate. so, a broader application of fir filters, and iir filters are not very stric

17、t requirements on occasions.unit from sub-functions can be divided into the following four categories :(1) low-filter (lpf)(2) high-filter (hpf)(3) belt-filter (bpf)(4) to prevent filter (bsf)the following chart dotted line for the ideals of the filter frequency characteristics :a(f) a(f) 1 1 0 f f

18、0 f f (a) (b)a(f) a(f) 1 12、digital filter designdigital filter design of the basic requirementsdigital filter design must go through three steps :(1) identification of indicators : in the design of a filter, there must be some indicators. these indicators should be determined on the basis of the ap

19、plication. in many practical applications, digital filters are often used to achieve the frequency operation. therefore, indicators in the form of general jurisdiction given frequency range and phase response. margins key indicators given in two ways. the first is absolute indicators. it provides a

20、function to respond to the demands of the general application of fir filter design. the second indicator is the relative indicators. its value in the form of answers to decibels. in engineering practice, the most popular of such indicators. for phase response indicators forms, usually in the hope th

21、at the system with a linear phase frequency bands human. using linear phase filter design with the following response to the indicators strengths：it only contains a few algorithms, no plural operations；there is delay distortion, only a fixed amount of delay; the filter length n (number of bands for

22、n-1), the volume calculation for n/2 magnitude.(2) model approach : once identified indicators can use a previous study of the basic principles and relationships, a filter model to be closer to the target system.(3) achieved : the results of the above two filters, usually by differential equations,

23、system function or pulse response to describe. according to this description of hardware or software used to achieve it.3、 matlab introducedmatlab is a matrix laboratory (matrix laboratory) is intended. in addition to an excellent value calculation capability, it also provides professional symbols t

24、erms, word processing, visualization modeling, simulation and real-time control functions. matlab as the worlds top mathematical software applications, with a strong engineering computing, algorithms research, engineering drawings, applications development, data analysis and dynamic simulation, and

25、other functions, in aerospace, mechanical manufacturing and construction fields playing an increasingly important role. and the c language function rich, the use of flexibility, high-efficiency goals procedures. high language both advantages as well as low level language features. therefore, c langu

26、age is the most widely used programming language. although matlab is a complete, fully functional programming environment, but in some cases, data and procedures with the external environment of the world is very necessary and useful. filter design using matlab, could be adjusted with the design req

27、uirements and filter characteristics of the parameters, visual simple, greatly reducing the workload for the filter design optimization.in the electricity system protection and secondary computer control, many signal processing and analysis are based on are certain types yeroskipou and the second ha

28、rmonics of the system voltage and current signals (especially at d process), are mixed with a variety of complex components, the filter has been installed power system during the critical components. current computer protection and the introduction of two digital signal processing software main filt

29、er. digital filter design using traditional cumbersome formula, the need to change the parameters after recalculation, especially in high filters, filter design workload. uses matlab signal processing boxes can achieve rapid and effective digital filter design and simulation.matlab is the basic unit

30、 of data matrix, with its directives biaodashi mathematics, engineering, commonly used form is very similar, it is used to solve a problem than in matlab c, fortran and other languages end precision much the same thing. the popular matlab 5.3/simulink3.0 including hundreds of internal function with

31、the main pack and 30 types of tool kits (toolbox). kits can be divided into functional tool kits and disciplines toolkit. matlab tool kit used to expand the functional symbols terms, visualization simulation modelling, word processing and real-time control functions. professional disciplines toolkit

32、 is a stronger tool kits, tool kits control, signal processing tool kit, tool kits, etc. belonging to such communicationsmatlab users to open widely welcomed. in addition to the internal function, all the packages matlab tool kits are readable document and the document could be amended, modified or

33、users through yuanchengxu the construction of new procedures to prepare themselves for kits.中文翻譯數(shù)字濾波器的仿真與實現(xiàn)隨著信息時代和數(shù)字世界的到來，數(shù)字信號處理已成為當(dāng)今一門極其重要的學(xué)科和技術(shù)領(lǐng)域。數(shù)字信號處理在通信、語音、圖像、自動控制、雷達、軍事、航空航天、醫(yī)療和家用電器等眾多領(lǐng)域得到了廣泛的應(yīng)用。在數(shù)字信號處理應(yīng)用中，數(shù)字濾波器十分重要并已獲得廣泛應(yīng)用。1、數(shù)字濾波器介紹：模擬和數(shù)字濾波器 在信號處理、過濾功能是一個不排除部分信息，如隨機噪音，提取有用的信號部分，如部分地勢在一定的頻率范圍。

34、有兩大類型的過濾，模擬以及數(shù)字。他們是完全不同的物理結(jié)構(gòu)，如何工作。類比電子電路模擬用的濾波部分組成，例如由電阻、電容和生產(chǎn)所需的濾波效果。這種濾波器被廣泛使用的電路減少噪音等方面的應(yīng)用，提高視頻信號、圖像均衡的高科技傳真系統(tǒng)等眾多領(lǐng)域。有完善的技術(shù)標(biāo)準(zhǔn)設(shè)計的模擬電路進行濾波的特定要求。在各個階段，是一個信號，是電機電壓和過濾，目前直接的物理模擬量(例如聲音或視頻信號和變頻器生產(chǎn))處理。數(shù)字濾波器用數(shù)字進行數(shù)值計算處理器的信號抽樣值。處理器的可能通用計算機等pc或?qū)I(yè)發(fā)展計劃圖(數(shù)字信號處理器)芯片。模擬信號必須先投入使用的取樣和a/d轉(zhuǎn)換器(模擬到數(shù)字轉(zhuǎn)換器)。由此二元多,占抽樣連續(xù)輸入信號

35、的取值傳送到處理器,進行數(shù)字計算。這些計算通常涉及多方面的投入和增加產(chǎn)品取值的共同因素。如有必要,這些計算結(jié)果,現(xiàn)在是抽樣信號值的濾波,產(chǎn)出通過d/a轉(zhuǎn)換器來把信號轉(zhuǎn)換回模擬形式?？吹揭粋€數(shù)字濾波器,信號是由一系列數(shù)字組成,而不是電壓或電流。濾波器是指用來對輸入信號進行濾波的硬件或軟件。如果濾波器的輸入、輸出都是離散信號，則該濾波器的沖擊響應(yīng)也必然是離散的，這樣的濾波器定義為數(shù)字濾波器。數(shù)字濾波器的功能，就是把輸入序列x通過一定的運算變換成輸出序列y。根據(jù)數(shù)字濾波器沖激響應(yīng)函數(shù)的時域特性，可將數(shù)字濾波器分為兩種，即無限長沖激相應(yīng)（iir）濾波器和有限長沖激響應(yīng)（fir）濾波器。iir數(shù)字濾波器

36、的優(yōu)點是可以利用模擬濾波器設(shè)計的結(jié)果，而模擬濾波器的設(shè)計有大量圖表可查，方便簡單。它的缺點是相位的非線性；若需要線性相位，則要采用全通網(wǎng)絡(luò)進行相位校正。圖象處理以及數(shù)據(jù)采集傳輸都要求濾波器具有線性相位特性。而fir數(shù)字濾波器可以實現(xiàn)線性相位，又可具有任意幅度特性。從數(shù)字濾波器的單位沖擊響應(yīng)來看，可分為兩大類：有限沖擊響應(yīng)（fir）數(shù)字濾波器和無限沖擊響應(yīng)（iir）數(shù)字濾波器。fir濾波器卻可以得到嚴格的線性相位，然而由于fir濾波器的系統(tǒng)函數(shù)的極點固定在原點，所以只能用較高的階數(shù)來實現(xiàn)其高選擇性，對于同樣的濾波器設(shè)計指標(biāo)，fir濾波器所要求的階數(shù)要比iir高5至10倍，所以成本較高，信號延遲也

37、較大。但是如果要求相同的線性相位，則iir濾波器就必須加全通網(wǎng)絡(luò)進行相位校正，同樣也要增加濾波器網(wǎng)絡(luò)的節(jié)數(shù)和復(fù)雜性。fir濾波器可以用非遞歸的方法實現(xiàn)，在有限精度下不會產(chǎn)生振蕩，同時由于量化舍入以及系數(shù)的不確定性所引起的誤差的影響要比iir濾波器小的多，并且fir濾波器可以采用fft算法，運算速度快。但是不象iir濾波器可以借助模擬濾波器的成果，fir濾波器沒有現(xiàn)成的計算公式，必須要用計算機輔助設(shè)計軟件（如matlab）來計算。由此可知，fir濾波器應(yīng)用比較廣，而iir濾波器則用在相位要求不是很嚴格的場合。濾波器從功能上分又可分為如下4類:(1)低通濾波器(lpf)；(2)高通濾波器(hpf )；(3)帶通濾波器(bpf )；(4)帶阻濾波器(bsf)。a(f) a(f) 1 1 0 f f 0 f f (a) (b)a(f) a(f) 1 1 0 f f f 0 f f f (c) (d)圖中四類濾波器的幅頻特性(a)低通 (b)高通 (c)帶通 (d)帶阻2、數(shù)字濾波器的設(shè)計數(shù)字濾波器設(shè)計的基本要求，數(shù)字濾波器設(shè)計要經(jīng)過三個步驟：（1）確定指標(biāo)：在設(shè)計一個濾波器前，必須有一些指標(biāo)。這些指標(biāo)要根據(jù)應(yīng)用確定。在很多實際應(yīng)用中，數(shù)字濾波器常常被用來實現(xiàn)選頻操