基于单片机的数字滤波器设计外文文献翻译Word格式.docx

1、Abstract：With 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 processing in communications, voice, images, automatic control, radar, military, aerospace, medical and household a

2、ppliances, and many other fields widely applied. In the digital signal processing applications, the digital filter is important and has been widely applied. Keyword：SCM; Proteus, C language; Digital filter1、figures Unit on : Analog and digital filtersIn signal processing, the function of a filter is

3、 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. The following block diagram illustrates the basic idea. There are two main kinds of filter, analog and digital. They are quite diffe

4、rent 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 op amps 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 phys

6、ical 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 ty

8、pically 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. No

9、te that in a digital filter, the signal is represented by a sequence of numbers, rather than a voltage or current. The following diagram shows the basic setup of such a system. Unit refers to the input signals used to filter hardware or software. If the filter input, output signals are separated, th

10、ey are bound to respond to the impact of the Unit is separated, 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, dig

11、ital filters can be divided into two, namely, unlimited long 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 facil

12、itate simple. It is the shortcomings of the nonlinear phase; 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 m

13、argin characteristics. Impact from the digital filter response 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 filte

14、r function extremity fixed at the original point, it can only 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, I

15、IR filters must be network-wide calibration phase, the same section 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

16、of errors than IIR filter small number, and FIR filter can be 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

17、application of FIR filters, and IIR filters are not very strict 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 i

18、deals of the filter frequency characteristics :2、MATLAB introducedMATLAB is a matrix laboratory （Matrix Laboratory） is intended. In addition to an excellent value calculation capability, it also provides professional symbols terms, word processing, visualization modeling, simulation and real-time co

19、ntrol 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 other functions, in aerospace, mechanical manufacturing and construction f

20、ields 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 language is the most widely used programming language. Although MATLAB is a com

21、plete, 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 requirements and filter characteristics of the parameters, visual simple, gre

22、atly 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 harmonics of the system voltage and current signals （especially at D process

23、）, 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 filter. Digital filter design using traditional cumbersome formula, the need t

24、o 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 simulatioMATLAB is the basic unit of data matrix, with its directives Biaodashi mathematics, engineering, com

25、monly 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 the main pack and 30 types of tool kits （Toolbox）. kits can be divided into

26、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 is a stronger tool kits, tool kits control, signal processing tool kit, too

27、l 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 users through Yuanchengxu the construction of new procedures to prepare them

28、selves for kits.3、Digital filter design Digital filter design of the basic requirements Digital 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 applicatio

29、n. 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 function

30、 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 that the s

31、ystem 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 N-1）, th

32、e 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, system function or pulse response to describe. According to this description of hardware or software used to achieve it.4、Introduced FPGA Programmable logic device is a generic logic can use a variety of chips, which is to achieve ASIC ASIC （App