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通信系統(tǒng)中數(shù)字調(diào)制系統(tǒng)的matlab仿真論文--畢業(yè)設(shè)計(jì)-wenkub.com

2025-01-14 02:43 本頁面
   

【正文】 )。)。SNRdB39。 %關(guān)閉模型FKKfor i=1:11 A=x(i)。)。)。EsNodB39。dpkk % 打開模型for i=1:11 A=x(i)+26。 sys=1。x0 = [0]。 = 1。endfunction [sys,x0,str,ts]=mdlInitializeSizessizes = simsizes。 case{1,2,4, 9}, sys=[]。本系統(tǒng)可以編譯成可執(zhí)行文件,脫離Matlab環(huán)境運(yùn)行,這樣該仿真系統(tǒng)的應(yīng)用將更加廣泛。仿真這幾種理論已經(jīng)很成熟的數(shù)字調(diào)制方式,一方面,可以更容易將仿真結(jié)果與成熟的理論進(jìn)行比較,從而驗(yàn)證仿真的合理性;另一方面,也可以以此為基礎(chǔ)將仿真系統(tǒng)進(jìn)行改進(jìn)擴(kuò)展,使其成為仿真更多的數(shù)字調(diào)制方式的模板。同時(shí),競爭局面的形成,促使運(yùn)營企業(yè)積極拓展新業(yè)務(wù)、新應(yīng)用,向用戶提供豐富的選擇,以滿足用戶多方面、多層次的需求?;仡櫼苿油ㄐ诺陌l(fā)展歷程,調(diào)制解調(diào)技術(shù)和個(gè)人通信的移動性以及無縫隙覆蓋多媒體綜合業(yè)務(wù)需求將愈來愈突出。泛歐的數(shù)字移動通信采用的是GMSK調(diào)制,而美國和日本的數(shù)字移動通信則采用QPSK調(diào)制技術(shù)。隨著調(diào)制技在不斷的發(fā)展,新的調(diào)制技術(shù)將可以帶來更好的頻譜效率和更高的功率效率。文章針對三種基本調(diào)制解調(diào)技術(shù)及其改進(jìn)調(diào)制技術(shù)進(jìn)行了詳細(xì)的仿真和分析,可見,選擇一種調(diào)制技術(shù)是根據(jù)信道特性和應(yīng)用來確定的。近年來,我們移動通信業(yè)務(wù)迅猛發(fā)展,已深入到社會生活的各個(gè)方面,面對移動用戶群的持續(xù)增長和新業(yè)務(wù)的層出不窮,移動通信體系要及時(shí)適應(yīng)甚至超前于市場需求的步伐。s mobile munication and the Internet development is extremely rapid, but our country at present mobile phone and the network user popular rate very are also low, facing our country 1,300,000,000 populations, our country has the very big development space in the network scale and the capacity the same time, the petition aspect formation, urges the operation enterprise to develop the new service, the new application positively, provides the rich choice to the user, satisfies the user variously, the multilevel , also has the very big development potential on the mobile munication and the Internet application must promote the wireless domain advance in technology, the technological innovation positively, for the realization rely on science and education to rejuvenate the nation strategy, strengthens the Chinese nation the prehensive national strength, contributes the strength positively for the global informationization and under the economical globalization environment international society and universe39。 仿真模型性能與理論性能的比較4 外文翻譯 原文In the last few years, in the mobile munication modulates the demodulation technology superiority in the development speed and the new application number aspect, for human extremely profound with the social economy development, the modulating technology modulating technique renews continuously again and is consummating, at the same time, the mobile munication has passed through the first generation of mobile munication, the second generation of mobile munication and soon enters the third generation mobile、 this, the modulating technology modulating technique development is playing the extremely vital role in inside.In recent years, our mobile munication service swift and violent development, penetrated into social life each aspect, facing the motion user group continually growth and new service emerging one after another incessantly, the mobile munication system must adapt promptly even in advance in the market demand took of a digital modulating technology modulating technique mobile munication core technologies is the realization high speed, the highly effective mobile munication system important digital modulation demodulation technology holds the extremely important status in the digital munication, the monly used digital modulation includes: Frequency shift keying (FSK) and phaseshift keying (PSK) and so on. At present has used in the mobile munication system the modulating technology modulating technique being possible to divide into two big kinds: The linear modulation technology and the permanent enveloping modulating technology modulating technique linear modulation technology mainly has: PSKBPSK、QPSK OQPSK/4 – QPSK、QAM、16QAM、64QAM、256QAM .the permanent envelope modulating technology modulating technique mainly has: MSK TFM GMSK.The article in view of the three kind of basicial modulation demodulation technology has carried on the detailed simulation and the analysis, obviously, chooses one kind of modulating technology modulating technique is determined according to the channel characteristic and the power efficiency and the frequency spectrum efficiency cannot be satisfactory to both sides generally uneven high frequency spectrum efficiency needs to sacrifice certain power efficiency to obtain。這里我們比較2FSK、 2DPSK和 MSK三種模型的調(diào)制性能,因?yàn)椋?ASK在現(xiàn)實(shí)中用的很少,討論它的性能的意義不大。假設(shè)K比特碼元的持續(xù)時(shí)間仍為,則M相調(diào)制波形可以表示為,式中 通常,多相制中使用最廣泛的是四相制和八相制,即M=4或8。其帶寬與多電平雙邊帶調(diào)制相同。 設(shè)計(jì)MFSK仿真模型如圖 所示。其第一零點(diǎn)帶寬為fM -f1 + 2fs。在工程實(shí)踐中應(yīng)權(quán)衡二者的關(guān)系。相同的發(fā)射功率下,信號空間中元數(shù)越多,各個(gè)信號之間的距離越小,抗干擾能力越差。 多元數(shù)字調(diào)制是提高通信系統(tǒng)的頻帶利用率一個(gè)重要途徑。 (a) (b) BPSK調(diào)制系統(tǒng)的星座圖和頻譜圖 (a) (b) QPSK調(diào)制系統(tǒng)的星座圖和頻譜圖 (a) (b) oQPSK調(diào)制系統(tǒng)的星座圖和頻譜圖 仿真結(jié)果說明在相同傳輸條件下,QPSK、OQPSK調(diào)制以比BPSK調(diào)制高1倍的速率傳輸信息,QPSK誤碼率高于BPSK約30倍,由于是相位調(diào)制,頻譜反映了具有不同相位特性的同一載波,因此頻譜特性一致。,由隨機(jī)整數(shù)產(chǎn)生器,頻譜儀,基帶BPSK調(diào)制與解調(diào)器,加性高斯白噪聲信道,誤碼率計(jì)算器,離散時(shí)間星座圖儀及顯示器構(gòu)成。的相位跳變,信號通過BPF后包絡(luò)起伏小,性能得到了改善,因此受到了廣泛重視。除此之外,其它均與QPSK作用相同。的相位跳變。因此,OQPSK信號相位只能跳變0176。OQPSK也稱為偏移四相相移鍵控(offsetQPSK),是QPSK的改進(jìn)型。這種形式的已調(diào)波具有兩個(gè)主要特點(diǎn),其一是包絡(luò)恒定或起伏很??;其二是已調(diào)波頻譜具有高頻快速滾降特性,或者說已調(diào)波旁瓣很小,甚至幾乎沒有旁瓣。這種相位跳變引起包絡(luò)起伏,當(dāng)通過非線性部件后,使已經(jīng)濾除的帶外分量又被恢復(fù)出來,導(dǎo)致頻譜擴(kuò)展,增加對相鄰波道的干擾。的相位跳變,在QPSK基礎(chǔ)上提出的。按照串/并變換器輸出的雙比特碼元的不同,邏輯選相電路輸出相應(yīng)相位的載波。雙極性的和脈沖分別對同相載波及正交載波進(jìn)行二相調(diào)制,得到虛線矢量如圖。此時(shí),上式恰好表示兩個(gè)正交的二相調(diào)制信號的合成。由于每一種載波相位代表兩個(gè)比特信息,故每個(gè)四進(jìn)制碼元又被稱為雙比特碼元。只有2DPSK信號才能采用這種方法解調(diào),因?yàn)樗且郧耙粋€(gè)碼元的載波相位作為參考相位,而不是未調(diào)載波的相位。 2PSK信號的相干解調(diào)框圖2DPSK信號的產(chǎn)生框圖: 2DPSK信號的調(diào)制方框圖圖中,波形變換器用來完成單極性不歸零波形到雙極性波形的變換,其變換關(guān)系為,因?yàn)椋杂?。所以,?shí)際中不采用2PSK方式,而采用一種所謂的相對(差分)移相(2DPSK)方式。 2PSK 、QPSK、OQPSK二進(jìn)制移相鍵控(2PSK)方式是受鍵控的載波相位按基帶脈沖而改變的一種數(shù)字調(diào)制方式。位置:Communications Blockset\Channels 加性高斯白噪聲信道的主要參數(shù)參數(shù)名稱參數(shù)值 FSK MSK GMSKInitial seed (初始化種子)18233Mode (模式)Signal to noise ration (SNR)(信噪比)SNR(信噪比)3 6 6Input signal power(輸入信號功率)1 加性高斯白噪聲信道的主要參數(shù)4. Error Rate Calculation(誤碼率計(jì)算)比較輸入輸出的誤碼率。所以高斯低通濾波器必須滿足:(1) 帶寬窄,且是銳截止的(2) 具有較低的過沖脈沖響應(yīng)(3) 保持輸出脈沖的面積不變: FSK基帶調(diào)制仿真系統(tǒng)框圖FSK基帶調(diào)制仿真系統(tǒng)的框圖由伯努利二進(jìn)制隨機(jī)數(shù)產(chǎn)生器,頻譜儀,基帶MFSK調(diào)制與解調(diào)器,加性高斯白噪聲信道,誤碼率計(jì)算器及顯示器構(gòu)成。由(1)式知,當(dāng)=+1時(shí),信號的頻率為當(dāng)=1時(shí),信號的頻率為由此可得 MSK信號在碼元轉(zhuǎn)化時(shí)信號的相位是連續(xù)的,根據(jù)這個(gè)要求,相位應(yīng)該滿足下面的條件:
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