【正文】 tions, 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. Note 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, they 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 24hour live response characteristics, digital 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 facilitate simple. It is the shortings of the nonlinear phase。 Secondly, the size and FPGA devices allow automation needs plugins, reducing the manufacturing system to lower costs。s digital age background, the DSP has bee the munications, puter, and consumer electronics products, and other fields based device. Digital signal processors and digital signal processing is inseparably, we usually say DSP can also mean the digital signal processing (Digital Signal Processing), is that in this digital signal processors Lane. Digital signal processing is a cover many disciplines applied to many areas and disciplines, refers to the use of puters or specialized processing equipment, the signals in digital form for the collection, conversion, recovery, valuation, enhancement, pression, identification, processing, the signals are pliant form. Digital signal processors for digital signal processing devices, it is acpanied by a digital signal processing to produce. DSP development process is broadly divided into three phases : the 20th century to the 1970s theory that the 1980s and 1990s for the development of products. Before the emergence of the digital signal processing in the DSP can only rely on microprocessors (MPU) to plete. However, the advantage of lower highspeed realtime processing can not meet the requirements. Therefore, until the 1970s, a talent made based DSP theory and algorithms. With LSI technology development in 1982 was the first recipient of the world gave birth to the DSP chip. Years later, the second generation based on CMOS 工藝 DSP chips have emerged. The late 1980s, the advent of the third generation of DSP chips. DSP is the fastestgrowing 1990s, there have been four successive fivegeneration and the generation DSP devices. After 20 years of development, the application of DSP products has been extended to people39。 (3) beltfilter (BPF)。 (4) to prevent filter (BSF). The following chart dotted line for the ideals of the filter frequency characteristics : MATLAB introduced MATLAB 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 realtime control functions. MATLAB as the world39。s learning, work and all aspects of life and gradually bee electronics products deter。 ③ the filter length N (number of bands for N1), 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, system function or pulse response to describe. According to this description of hardware or software used to achieve it. Introduced FPGA Programmable logic device is a generic logic can use a variety of chips, which is to achieve ASIC ASIC (Application Specific Integrated Circuit) semicustomized device, Its emergence and development of electronic systems designers use CAD tools to design their own laboratory in the ASIC device. Especially FPGA (Field Programmable Gate Array) generated and development, as a microprocessor, memory, the figures for electronic system design and set a new industry standard (that is based on standard product sales catalogue in the market to buy). Is a digital system for microprocessors, memories, FPGA or three standard building blocks constitute their integration direction. Digital circuit design using FPGA devices, can not only simplify the design process and can reduce the size and cost of the entire system, increasing system reliability. They do not need to spend the traditional sense a lot of time and effort required to create integrated circuits, to avoid the investment risk and bee the fastestgrowing industries of electronic devices group. Digital circuit design system FPGA devices using the following main advantages (1) Design flexible Use FPGA devices may not in the standard series device logic functional limitations. And changes in system design and the use of logic in any one stage of the process, and only through the use of reprogramming the FPGA device can be pleted, the system design provides for great flexibility. (2) Increased functional density Functional density in a given space refers to the number of functional integration logic. Programmable logic chip ponents doors several high, a FPGA can replace several films, film scores or even hundreds of smallscale digital IC chip illustrated in the film. FPGA devices using the chip to use digital systems in small numbers, thus reducing the number of chips u