【正文】 important。 Originally, this world, can produce a chemical reaction to an event, in addition to resolutely, have to do, and time. 原來(lái)，這個(gè)世界上，對(duì)某個(gè)事件能產(chǎn)生化學(xué)反應(yīng)的，除了非做不可的堅(jiān)決，還有，時(shí)間。也曾經(jīng)好像已經(jīng)下定了決心去做某件事，但更多的時(shí)候是最后又打起了退堂鼓。 Those were broken into various shapes of stationery。突然想到那件藍(lán)格子襯衫；那些被折成各種各樣形狀的信紙；那段從街角深巷伊始的友誼；還有那場(chǎng)還沒有開始就宣告了終結(jié)的邂逅計(jì)劃 …… 那些年那些天的非做不可，終于和青春一樣，都將在我們的人生中謝幕。t. Baumgartner still will free fall at a speed that would cause you and me to pass out, and no parachute is guaranteed to work higher than 25,000 feet (7,620 meters). cause there 。ll be traveling fast, so despite the distance, it will not be like diving into the deep end of a pool. It will be like he is diving into the shallow end. Skydiver preps for the big jump When he jumps, he is expected to reach the speed of sound 690 mph (1,110 kph) in less than 40 seconds. Like hitting the top of the water, he will begin to slow as he approaches the more dense air closer to Earth. But this will not be enough to stop him pletely. If he goes too fast or spins out of control, he has a stabilization parachute that can be deployed to slow him down. His team hopes it39。 Have declared the end of the encounter that haven39。那些曾經(jīng)所謂的非做不可，只是青蔥年華里自己給自己注射的一支強(qiáng)心劑，或者說(shuō)，是自以為是的精神寄托罷了。s time, your ideas are always special to clear. Want, want, line is clear, as if nothing could shake his. Also once seemed to be determined to do something, but more often is he backed out at last. Dislike his cowardice, finally found that there are a lot of love, there are a lot of miss, like shadow really have been doomed. Those who do, just green years oneself give oneself an arm injection, or is a selfrighteous spiritual. 一個(gè)人的時(shí)候，自己的想法總是特別地清晰。t want to give vent to out your inner voice can be in the high school children of the feelings in a period, but was eventually infarction when graduation party in the throat, later again stood on the pitch he has sweat profusely, looked at his thrown a basketball hoops, suddenly found himself has already can39。 The end of our life, and can meet many things really do? 而窮盡我們的一生，又能遇到多少事情是真正地非做不可？ During my childhood, think lucky money and new clothes are necessary for New Year, but as the advance of the age, will be more and more found that those things are optional。 May be back in the past, to oneself the paranoid weird belief disillusionment, these days, my mind has been very messy, in my mind constantly. Always feel oneself should go to do something, or write something. Twenty years of life trajectory deeply shallow, suddenly feel something, do it. 一字開頭的年齡已經(jīng)到了尾聲。s 21 win. Michel Platini, president of European football39。s antiracism taskforce, is in London for the Football Association39。t agree with the disciplinary action your employer has taken against you ? your employer dismisses you and you think that you have been dismissed unfairly. For more information about dismissal and unfair dismissal, see Dismissal. You can make a claim to an employment tribunal, even if you haven39。還有，在設(shè)計(jì)過(guò)程中感謝井教員給我提供微機(jī)等便利的條件，使得我們能夠順利的完成畢業(yè)設(shè)計(jì)。 致謝 至此，畢業(yè)設(shè)計(jì)已接近尾聲。設(shè)計(jì)不僅是對(duì)所學(xué)理論知識(shí)的考核，更是對(duì)把所學(xué)習(xí)理論知識(shí)運(yùn)用的實(shí)踐操作中的一次檢驗(yàn)。 （ 2）遇到困難，迎難而上。從接到題目到設(shè)計(jì)結(jié)束的過(guò)程中經(jīng)歷了很多，總的來(lái)說(shuō)可以概括為以下幾點(diǎn)。的相位模糊，所以 2PSK 信號(hào)的相干解調(diào)存在隨機(jī)的 倒π 現(xiàn)象，從而使得 2PSK 方式在實(shí)際中很少采用。在相干解調(diào)過(guò)程中需要用到與接收的 2PSK 信號(hào)同頻同相的相干載波，當(dāng)恢復(fù)的相干載波產(chǎn)生 180176。 3) 經(jīng)過(guò)以上參數(shù)的設(shè)置后就可以進(jìn)行系統(tǒng)的仿真，其各點(diǎn)的時(shí)間波形如圖 425所示 圖 425 2FSK 信號(hào)經(jīng)調(diào)制后各點(diǎn)的時(shí)間波形 由上圖可以看出經(jīng)過(guò) f1 和 f2 兩個(gè)載波的調(diào)制， 2FSK 信號(hào)有明顯的頻率上的差別 4． 解調(diào)仿真 2FSK 的解調(diào)分為相干解調(diào)和非相干解調(diào)法，下面采用相干解調(diào)法對(duì) 2FSK 信號(hào)進(jìn)行解調(diào) 解調(diào)方框圖 如圖 426 所示 圖 426 2FSK 信號(hào)解調(diào)方框圖 其中 From File 是一個(gè)封裝模塊，就是 2FSK 信號(hào)的調(diào)制模塊，兩個(gè)帶通濾波器分別將 2FSK 信號(hào)上下分頻 f1 和 f2 ,后面就和 2ASK 信號(hào)的解調(diào)過(guò)程相同，各參數(shù)設(shè)置如下： 圖 427 2FSK 信號(hào) f1 帶通濾波器參數(shù)設(shè)置 圖 428 2FSK 信號(hào) f2 帶通濾波器參數(shù)設(shè)置 經(jīng)過(guò)以上參數(shù)的設(shè)置后就可以進(jìn)行系統(tǒng)的仿真， 2FSK 信號(hào)經(jīng)解調(diào)后各點(diǎn)的時(shí)間波形如圖 429 所示 圖 429 2FSK 信號(hào)經(jīng)相干解調(diào)后各點(diǎn)的時(shí)間波形 經(jīng)過(guò)系統(tǒng)的仿真可以觀察出系統(tǒng)的誤碼率為 ，如下圖所示 4． 3 2PSK 的調(diào)制與解調(diào)仿真 1 2PSK 調(diào)制仿真 1） 建立模型方框圖 2PSK 信號(hào)調(diào)制的 Simulink 模型方框圖如圖圖 431 所示 圖 431 2PSK 信號(hào)調(diào)制的 Simulink 的模型圖 其中 Sine wave 和 Sine wave1 是反相的載波，正弦脈沖作為信號(hào)源。 4． 2 2FSK 的調(diào)制與解調(diào)仿真 4． 2． 1 調(diào)制仿真 1） 建立模型方框圖 2FSK信號(hào)是由頻率分別為 f1和 f2的兩個(gè)載波對(duì)信號(hào)源進(jìn)行頻率上的控制而形成的，其中 f1 和 f2 是兩個(gè)頻率有明顯差別的且都遠(yuǎn)大于信號(hào)源頻率的載波信號(hào)， 2FSK 信號(hào)產(chǎn)生的 Simulink 仿真模型圖如圖 421 所示 圖 421 2FSK 信號(hào)的 simulink 模型方框圖 其中 sine wave1 和 sine wave 是兩個(gè)頻率分別為 f1 和 f2 的載波， Pulse Generator 模塊是信號(hào)源， NOT 實(shí)現(xiàn)方波的反相， 最后經(jīng)過(guò)相乘器和相加器生成 2FSK 信號(hào)。 2） 參數(shù)設(shè)置 建立好模型之后就要設(shè)置系統(tǒng)參數(shù)，以達(dá)到系統(tǒng)的最佳仿真。這種現(xiàn)象通常稱為 倒π 現(xiàn)象。 (a) (b) 圖 342 二進(jìn)制移相鍵控信號(hào)的調(diào)制原理圖 3． 4． 2 2PSK 的解調(diào) 2PSK 信號(hào)的解調(diào)通常都是采用相干解調(diào)，解調(diào)器原理圖如圖 243 所示。若用 表示第 n個(gè)符號(hào)的絕對(duì)相位，則有 （ 322） 這種以載波的不同相位直接表示相位二進(jìn)制數(shù)字信號(hào)的調(diào)制方式，稱為二進(jìn)制絕對(duì)相移方式。它們是利用載波振蕩相位的變化來(lái)傳送數(shù)字信息的。則系統(tǒng)的誤碼率為 （ 317） 由上式公式可見，包絡(luò)解調(diào)時(shí) 2FSK 系統(tǒng)的誤碼率將隨輸入信噪比的增加而形成指數(shù)規(guī)律下降。 圖 333 2FSK 信號(hào)的包絡(luò)檢測(cè)方框圖 （ 2）同步檢測(cè)波法 原理方框圖如圖 334 所示。線性鑒頻法有模擬鑒頻法、過(guò)零檢測(cè)法、差分檢測(cè)法，分離濾波法又包括相干檢測(cè)法、非相干檢測(cè)法以及動(dòng)態(tài)濾波法等。若以二進(jìn)制頻移鍵控信號(hào)功率譜第一個(gè)零點(diǎn)之間的頻率間隔計(jì)算二進(jìn)制頻移鍵控信號(hào)的帶寬 ，則二進(jìn)制頻移鍵控信號(hào)的帶寬 為 （ 316） 其中 圖 332 為相位不連續(xù)二進(jìn)制頻移鍵控信號(hào)的功率譜示意圖。若二進(jìn)制基帶信號(hào)的 1 符號(hào)對(duì)應(yīng)于載波頻率的 f1， 0 符號(hào)對(duì)應(yīng)于載波頻率的 f2，則二進(jìn)制頻移鍵控信號(hào)的時(shí)域表達(dá)式為 （ 311）