【正文】 輸入有關(guān)，而且與過(guò)去的輸出有關(guān)。 若有極點(diǎn)位于單位圓外將導(dǎo)致系統(tǒng)不穩(wěn)定 。對(duì)于 IIR 濾波器 ， 系統(tǒng)穩(wěn)定的條件如下 ： 若 | |1， 當(dāng) n→ 時(shí) ， h(n)→ 0， 系統(tǒng)穩(wěn)定 ； 若 | |1， 當(dāng) n→ 時(shí) ， h(n)→ ， 系統(tǒng)不穩(wěn)定 。 二階 IIR 濾波器，又稱(chēng)為二階基本節(jié)，分為直接 型、標(biāo)準(zhǔn)型和變換型。如圖 所示。 圖 直接 I型二階 IIR濾波器 直接型二階 IIR 濾波器還可以用圖 的結(jié)構(gòu)實(shí)現(xiàn)。可以證明上圖的結(jié)構(gòu)仍滿(mǎn)足二階 IIR 濾波器輸出方程。 圖 標(biāo)準(zhǔn)型二階 IIR濾波器 級(jí)聯(lián)型 30 級(jí)聯(lián)型結(jié)構(gòu)的系統(tǒng)函數(shù)為： 如圖 為 級(jí)聯(lián)型 IIR數(shù)字濾波器結(jié)構(gòu)框圖。 使用 DSP Builder 設(shè)計(jì) IIR 濾波器 4 階直接Ⅱ型 IIR 濾波器設(shè)計(jì) 在此需要設(shè)計(jì)一個(gè) 4階濾波器，給定濾波器的系統(tǒng)函數(shù)如下： 從系統(tǒng)函數(shù)我們可以提取各項(xiàng)系數(shù)如下： a0=1,a1=,a2=,a3=,a4=,b0=,b1=,b2=,b3=0,b4= 在 DSP Builder中，建立一個(gè)新模型，按照上述參數(shù)設(shè)計(jì)完成 4階 IIR濾波 器模型，如圖 。 Simulink仿真模塊“ Pulse Generator”（脈沖發(fā)生器）模擬了一個(gè)單位沖激函數(shù)。 修改 Simulink的仿真參數(shù)設(shè)置，設(shè)置“ Stop time”仿真停止時(shí)間為“ 50”，“ Solver options”中“ Type”為“ FixedStep”。仿真結(jié)果如圖。 生成的 VHDL 代碼如圖 所示。 圖 綜合后的 TCL文件 Quartus II 編譯 ： 單擊 SignalCompiler 中的步驟 3圖標(biāo)，調(diào)用 Quartus II完成編譯適配過(guò)程，生成編譯文件： 文件和 文件。 33 圖 4階級(jí)聯(lián)型 IIR濾波器 在上述模塊參數(shù)設(shè)置中， A11等增益模塊應(yīng)設(shè)置為 IIR濾波器的系數(shù)，這需要給定或者按照設(shè)計(jì)要求進(jìn)行計(jì)算。 打開(kāi) MATLAB中的 FDATool進(jìn)行濾波器系數(shù)計(jì)算，如圖 。如圖 IIR濾波器的相頻特性；圖 IIR濾波器的階躍響應(yīng)。對(duì)于級(jí)聯(lián)型 IIR濾波器，導(dǎo)出的系數(shù)分成兩個(gè)部分： SOS矩陣和 G增益，其中對(duì)于多個(gè)級(jí)聯(lián)的 IIR濾波器， SOS矩陣為一個(gè)二維矩陣。 G模塊的“ Gain Value”是 G（ 2）； B10模塊為 SOS（ 1,1）； B11模塊為 SOS（ 1,2）； B12模塊為 SOS（ 1,3）； A11模塊為 SOS（ 1,5）； A1模塊為 SOS（ 1,6）； B20模塊為 SOS（ 2,1）； B21模塊為 SOS（ 2,2）； B22模塊為 SOS（ 2,3）； A21模塊為 SOS（ 2,5）； A22模塊為 SOS（ 2,6）。 （ 4）設(shè)置系數(shù) 設(shè)置 Simulink仿真參 數(shù)“ Stop time( 停止時(shí)間 )”為 1e6, 類(lèi)型為“ Fixedstep”。由于 Step模塊生成了一個(gè)階躍函數(shù)，故仿真結(jié)果為 IIR濾波器的階躍響應(yīng)，如圖 。 生成的 VHDL 代碼如圖 所示。 37 圖 生成的 TCL文件 Quartus II 編譯 ： 單擊 SignalCompiler 中的步驟 3圖標(biāo)，調(diào)用 Quartus II完成編譯適配過(guò)程，生成編譯文件： 文件和文件 ，可以直接用于 FPGA 的編程配置 。從最初的茫然，到慢慢的進(jìn)入狀態(tài)，再到對(duì)思路逐漸的清晰，整個(gè)寫(xiě)作過(guò)程難以用語(yǔ)言來(lái)表達(dá)?；叵脒@段日子的經(jīng)歷和感受，我感慨萬(wàn)千，在這次畢業(yè)設(shè)計(jì)的過(guò)程中，我擁有了無(wú)數(shù)難忘的回憶和收獲。當(dāng)選 題報(bào)告，開(kāi)題報(bào)告定下來(lái)的時(shí)候，我當(dāng)時(shí)便立刻著手 資料的收集工作中，當(dāng)時(shí)面對(duì)浩瀚的書(shū)海真是有些茫然，不知如何下手， 我 很快 將這一困難告訴了導(dǎo)師，在導(dǎo)師細(xì)心的指導(dǎo) 之 下，終于 使我對(duì)自己 的工作方向和方法有了 大致的 掌握。我將收集到的資料仔細(xì)整理分類(lèi)，及時(shí)拿給導(dǎo)師進(jìn)行溝通。在寫(xiě)作過(guò)程中也不是一帆風(fēng)順的，我也遇到很多問(wèn)題，但是遇到困難我就及時(shí)和 導(dǎo)師聯(lián)系，并和同學(xué)互相交流，請(qǐng)教專(zhuān)業(yè)課老師。每一次遇到問(wèn)題的時(shí)候心情都會(huì)有點(diǎn)低落，但是每一次經(jīng)過(guò)自己的努力解決好了問(wèn)題就會(huì)感到十分的高興。 當(dāng)我終于完成了所有的任務(wù)后整個(gè)人都很累，但同時(shí)看著電腦熒屏上的畢業(yè)設(shè)計(jì)稿件我的心里是甜的，我覺(jué)得這一切都值了。在論文中我充分地運(yùn)用了大學(xué)期間所學(xué)到的知識(shí)。在了解和學(xué)習(xí)的同時(shí)不僅培養(yǎng)了我嚴(yán)肅認(rèn)真的做事作風(fēng)，還是一次意志的磨練，是對(duì)我實(shí)際能力的一次提升。 此次的經(jīng)歷會(huì)使我終身受益，我感受到要是真真正正用心去做一件事情，是真正的自己學(xué)習(xí)和研究的過(guò)程，沒(méi)有學(xué)習(xí)就不可能有研究的能力，沒(méi)有自己的研究，就不 會(huì)有所突破。 參考文獻(xiàn) [1]程佩青。 [2]潘松，黃繼業(yè)，王國(guó)棟。 [3]潘松，黃繼業(yè)。 [4]屈星，唐寧等。 [5]彭雪峰，汪臨偉，許建平。 [6]丁玉美，高西全。 [7]張志恒 。 [8]胡廣書(shū)。 Digital Singal Processing with Field Programmable Gate Arrays,清華大學(xué)出版社， 2020?；?VHDL 語(yǔ)言的八階 IIR 語(yǔ)音低通數(shù)字濾波器，桂林航天工業(yè)高等專(zhuān)科學(xué)校 電報(bào)， 2020。數(shù)字信號(hào)處理及其 MATLAB 實(shí)現(xiàn)，電子工業(yè)出版社， 1998?；?FPGA 的嵌入式系統(tǒng)設(shè)計(jì)，西安電子科技大學(xué)出版社， 2020。 boxing is a human bloodsport in which the intention is to hurt one39。 he then had half a minute39。s hands, protected only by having been soaked in brine. With their bination of boxing and wrestling moves, early contests were literally ‘no holds barred’。s Rules of 1743 eradicated some of the barbarism by outlawing the hitting of a man when he was down, and the seizing of hair or the body below the waist, but they still permitted butting. Yet it was not the brutality of the prizering which brought its demise, but the corruption with which it became associated. The revival of the sport as boxing in late Victorian Britain saw several changes designed to render it more civilized. Although some of the old practices continued for a while — even the famous Queensbury Rules initially allowed endurance contests — by the turn of the century the general picture was one of boxing in gloves, limitedtime rounds, points decisions after a fixed number of rounds had elapsed, and weight divisions, though the latter have accentuated problems of dehydration as fighters struggle to ‘make the weight’. For much of the twentieth century the history of boxing has been one of crumbling resistance to changes intended to protect further the brains and bodies of participants. Between 1984 and 1993 eight boxers had died soon after fights in the UK。s condition between rounds and may remend that the contest be stopped. Doctors also examine each boxer at the conclusion of fights and paramedic teams must be on hand at all boxing bills. The medical profession in several countries has increasingly adopted an antiboxing stance, citing irreversible brain damage as its major objection to the sport. This is a key point for, in absolute terms of deaths and serious injuries, other sports such as horseracing, mountaineering, rugby, and even cricket appear more dangerous, but in none of them is deliberate and repeated striking of an opponent part of the rules of the game. In contrast a boxer has a licence for physical assault. The evidence is clear that repeated pummelling to the head can cause cumulative damage to the brain: here time is no great healer. Occasionally, acute brain injury can occur during a fight. The greatest danger es towards the end when a tired man with a loose neck has his head flipped back rapidly by a punch. This can tear a vein outside or inside the brain, which then leaks blood, causing pressure on the brain and eventually leading to a a. Only if the clot is removed rapidly can the fighter survive. Fighters now train harder。 antiboxing Bills proposed in parliament have failed to reach the statute books. Most schools, both state and public, however, have dropped boxing from their physical education curriculum. Yet it should be noted that amateur boxing is exceptionally well regulated: not more than four rounds are fought, headguards are worn, and the referee is allowed to stop a fight to prevent serious injury. However, headguards, whilst absorbing energy from punches, present an even larger target to be hit and thus the number of blows striking home may well increase. Indeed, studies have shown that nonboxing sportsmen outperform even amateur fighters in neurological tests and, notwithstanding the safety precautions, three amateur fighters have suffered serious brain injury in British rings since 1988. For centuries boxing has been the epitome of overt masculinity, a demonstration of manliness a