基于Multisim的鎖相環(huán)解調(diào)系統(tǒng)仿真
PLL Demodulation System Simulation Based on Multisim

摘要
實(shí)現(xiàn)調(diào)頻波解調(diào)的方法有很多，而鎖相環(huán)鑒頻是利用現(xiàn)代鎖相環(huán)技術(shù)來實(shí)現(xiàn)鑒頻，具有工作穩(wěn)定，失真小，信噪比高等優(yōu)點(diǎn)，所以被廣泛用在通信電路系統(tǒng)中。鎖相環(huán)其原理是通過鑒相檢測輸入信號和輸出信號的相位差，并將檢測出的相位差信號轉(zhuǎn)換成電壓信號輸出，該信號經(jīng)低通濾波器濾波后形成壓控振蕩器的控制電壓，對振蕩器輸出信號的頻率實(shí)施控制。
該文首先介紹了鎖相環(huán)技術(shù)發(fā)展的現(xiàn)狀、方向以及背景，并對PLL的原理進(jìn)行了闡述。在以上的基礎(chǔ)上，分別設(shè)計(jì)了2ASK、2PSK、2FSK的調(diào)制解調(diào)電路，其功能為數(shù)字基帶信號經(jīng)過調(diào)制輸出一個(gè)模擬信號，然后用鎖相環(huán)進(jìn)行解調(diào)，最后采用Multisim軟件進(jìn)行仿真。在對2ASK、2FSK、2PSK解調(diào)時(shí)，低通濾波器輸出的波形失真比較大，不過最后經(jīng)過抽樣判決電路整形后可以再生數(shù)字基帶脈沖。在整個(gè)電路設(shè)計(jì)中，力求要做到電路簡單，并完成任務(wù)書提到的要求。
關(guān)鍵詞：調(diào)制；解調(diào)； Multisim；鎖相環(huán)

Abstrack
There are many ways to realize frequency wave demodulation, and PLL frequency which has the advantages of stable operation, small distortion, high signal-to-noise ratio and so on is achieved by using modern PLL frequency technology, so it is widely used in communication circuit system. Phase-locked loop through the difference   of the phase detection of input signal and the output signal phase, and the detected phase difference signal into output voltage signal, the signal through a low pass filter. After the formation of the voltage control oscillator , the output signal of the oscillator frequency control.
This paper first introduces the present situation, development direction, phase-locked loop technology as well as the background, and the principle of PLL is discussed. On the basis of the above, the modulation and demodulation circuit of 2ASK, 2PSK, 2FSK which function is a digital baseband signal is modulated by an analog signal and output were designed, and then useing the PLL demodulation, finally using Multisim software simulation. In the 2ASK, 2FSK, 2PSK demodulation, the output of the low pass filter waveform distortion is relatively large, but finally it can regenerate digital baseband pulse sampling decision circuit after shaping. In the circuit design, and strive to do a simple circuit, and complete the task book mentioned requirements.
Keywords： modulate ；modulation ；PLL；Multisim

目 錄
第1章  緒論 1
1.1 研究背景 1
1.2 研究現(xiàn)狀 1
1.3 研究內(nèi)容介紹 2
第2章  基本原理 3
2.1  Multisim介紹 3
2.2  鎖相環(huán)基本原理 5
2.2.1鎖相環(huán)的基本組成 5
2.2.2 鎖相環(huán)的工作原理 5
第3章  調(diào)制解調(diào)電路設(shè)計(jì) 8
3.1  2FSK調(diào)制解調(diào)電路設(shè)計(jì) 8
3.1.1  2FSK調(diào)制電路設(shè)計(jì)原理 8
3.1.2  2FSK調(diào)制單元電路的設(shè)計(jì) 9
3.1.3  2FSK解調(diào)單元電路的設(shè)計(jì) 13
3.1.4  2FSK解調(diào)電路的整體設(shè)計(jì) 15
3.2  2PSK調(diào)制解調(diào)電路設(shè)計(jì) 17
3.2.1  2PSK調(diào)制解調(diào)電路設(shè)計(jì)原理 17
3.2.2  2PSK調(diào)制與解調(diào)電路的設(shè)計(jì)與仿真 18
3.3  2ASK調(diào)制解調(diào)電路設(shè)計(jì) 19
3.3.1  2ASK調(diào)制解調(diào)電路設(shè)計(jì)原理 19
3.3.2  2ASK調(diào)制與解調(diào)電路的設(shè)計(jì)與仿真 20
3.4  解調(diào)結(jié)果分析 22
總結(jié) 24
參考文獻(xiàn) 25
附錄：(外文翻譯) 26
致謝 50