通信系統(tǒng)仿真詳解

1、通信系統(tǒng)仿真詳解通信系統(tǒng)仿真實驗基于 SystemView 的 2PSK 系統(tǒng)仿真、系統(tǒng)仿真的目的：1、了解通信系統(tǒng)的組成、工作原理、信號傳輸、變換過程。2、掌握通信系統(tǒng)的設(shè)計方法與參數(shù)設(shè)置原則。3、掌握使用 SystemView 軟件仿真通信系統(tǒng)的方法。二、系統(tǒng)仿真任務(wù)：1、 系統(tǒng)輸入正弦波頻率：500 Hz;碼元傳輸速率：64kBd。2、設(shè)計一通信系統(tǒng)，并使用 SystemView 軟件進行仿真。3、獲取各點時域波形，波形、坐標、標題等要清楚;濾波器的單位 沖擊相應(yīng)和幅頻特性曲線。4、獲取主要信號的功率譜密度。5、各點波形：包括時域波形、眼圖、覆蓋圖、瀑布圖等。6、主要信號的功率譜密度。7

2、、濾波器的單位沖擊響應(yīng)及幅頻特性曲線。三、原理簡介：1 、 PCM 編碼與解碼：語音PCM的抽樣頻率為8kHz，每個量化樣值對應(yīng)一個8位二進 制碼，故話音數(shù)字編碼信號的速率為 8bits*8kHz=64kb/s。通常我們采用的是脈沖代碼調(diào)制編碼， 即PCM編碼。PCM 通過抽樣、 量化、編碼三個步驟將連續(xù)變化的模擬信號轉(zhuǎn)換為數(shù)字編 碼。為了增大輸入信號的動態(tài)范圍，這里采用采用 A 律壓擴實現(xiàn)非均勻量化2、并 串和串 并變換：ADC 采樣之后得到的是 8 位并行信號，為了將其變換成串行信號， 使用計數(shù)器和八選一數(shù)據(jù)選擇器來完成并行信號到串行信號的轉(zhuǎn)換。 由于是8位8kHz采樣的并行信號，因此計數(shù)

3、器的計數(shù)頻率為64kHz , 才能在一個采樣周期內(nèi)完成 8 位傳輸。而串行信號轉(zhuǎn)并行信號則是通過移位寄存器和鎖存器完成。 移位寄 存器將接收到的串行信號通過移位接收， 移滿 8位后將數(shù)據(jù)鎖存進入 鎖存器中。移位寄存器和鎖存器的時鐘信號應(yīng)設(shè)置為 64kHz和8kHz。 3、2PSK：(1) 2PSK 信號產(chǎn)生與調(diào)制2PSK 信號可以看作是雙極性基帶信號作用下的 DSB 調(diào)幅信號， 因此在本系統(tǒng)中使用雙極性基帶信號與載波相乘再經(jīng)過帶通濾波器 得到 2PSK 信號。(2) 2PSK 信號的解調(diào)2PSK 只能采用相干解調(diào)，使用 Cotas 環(huán)提取出同步載波與 2PSK 信號相乘，經(jīng)過一低通濾波器后再進

4、行抽樣判決即可解調(diào)出基帶 PCM 編碼信號。四、系統(tǒng)組成框圖、仿真模型、圖符參數(shù)設(shè)置： 本系統(tǒng)由三部分組成， 分別是 PCM 編碼與解碼、并 串和串 并變換、 2PSK 調(diào)制與解調(diào)。 系統(tǒng)組成框圖如下。 并數(shù)字4串H PCM輸,二 j ； E -T7r 【解碼頻輸 PCM編碼1、PCM編碼與解碼圖幅參數(shù)圖符號庫/名稱參數(shù)0Source:Si nu soidAmp = 1 vFreq = 500HzPhase = 0 degOutput 0 =Si ne t1 t2Output 1 =Cos ineMax Rate (Port 0)= 1.92e+6 Hz2Comm:Compa nderA-La

5、wMax Input = 5Max Rate =1.92e+6 Hz3Logic: ADCTwos Compleme ntGate Delay = 0 secThreshold =500e-3 vTrue Output=1 vFalse Output=0 vNo. Bits = 8Min Input =-5 vMax Input =5 vRise Time = 0secAn alog = t2Output 0Clock = t5Output 0Output 0 =Q-0 t6Output 1 =Q-1 t6Output 2 =Q-2 t6Output 3 =Q-3 t6Output 4 =Q-

6、4 t6Output 5 =Q-5 t6Output 6 =Q-6 t6Output 7 =Q-7 t6Output 8 =Q-8Output 9 =Q-9Output 10 =Q-10Output 11 =Q-11Output 12 =Q-12Output 13 =Q-13Output 14 =Q-14Output 15 =Q-15Max Rate (Port 0)= 1.92e+6 Hz5Source:Pulse TrainAmp = 1 vFreq = 8e+3HzPulseW =80e-6 secOffset =-500e-3 vPhase = 0 degMax Rate =1.92e

7、+6 Hz28Logic: DACTwos Compleme ntGate Delay = 0 secThreshold = 500e-3 vNo. Bits = 8Min Output = -5 vMax Output=5 vD-0 = t26Output 7D-1 = t26Output 6D-2 = t26Output 5D-3 = t26Output 4D-4 = t26Output 3D-5 = t26Output 2D-6 = t26Output 1D-7 = t26Output 0D-8 = NoneD-9 = NoneD-10 = NoneD-11 = NoneD-12 = N

8、oneD-13 = NoneD-14 = NoneD-15 = NoneMax Rate =1.92e+6 Hz31Comm:DeCompa ndA-LawMax Input = 5Max Rate =1.92e+6 Hz32Operator: Lin ear SysButterworthLowpass IIR3 PolesFc = 3.4e+3HzQua nt Bits = NoneInit Cndtn = Tran sie ntDSP Mode DisabledMax Rate =1.92e+6 Hz2、并串和串并變換SytemVie by ELANIX *S-yEtemViw by EL

9、ANIX圖符號庫/名稱參數(shù)6Logic:Mux-D-8Gate Delay = 0 secThreshold =500e-3 vTrue Output=1 vFalse Output=-1 vRise Time = 0secFall Time = 0secS-0 = t7Output 0S-1 = t7Output 1S-2 = t7Output 2I-0 = t3Output 0I-1 = t3Output 11-2 = t3Output 21-3 = t3Output 31-4 = t3Output 41-5 = t3Output 51-6 = t3Output 61-7 = t3Outp

10、ut 7En able* = t10Output 0Output 0 = Zt11t13Output 1 =Z*Max Rate (Port 0)= 1.92e+6 Hz7Logic:Cn tr-U/DGate Delay = 0 secThreshold =500e-3 vTrue Output=1 vFalse Output=0 vRise Time = 0secFall Time = 0secP-0 = NoneP-1 = NoneP-2 = NoneP-3 = NonePL* = t8Output 0U*/D = NoneCE* = NoneClock = t9Output 0Outp

11、ut 0 =Q-0 t6Output 1 =Q-1 t6Output 2 =Q-2 t6Output 3 =Q-3Output 4 =TCOutput 5 =RC*Max Rate (Port 0)= 1.92e+6 Hz8Source: StepAmp = 1vFctStart = 0 secOffset = 0 vMax Rate =1.92e+6 Hz9Source: PulseTrainAmp = 1vFreq = 64e+3HzPulseW =2e-6 secOffset = 0 vPhase = 0 degMax Rate =1.92e+6 Hz10Source: StepFctA

12、mp = 0 vStart = 0 secOffset = 0 vMax Rate =1.92e+6 Hz23Source: StepFctAmp = 1v Start = 0 sec Offset = 0 v Max Rate =1.92e+6 Hz24Logic:Shft-8inGate Delay = 0 secThreshold =500e-3 vTrue Output=1 vFalse Output=0 vRise Time = 0secFall Time = 0 secIn put A = t22Output 0In put B = t22Output 0Clock = t25Ou

13、tput 0MR* = t23Output 0Output 0 =Q-0t26Output 1 =Q-1t26Output 2 =Q-2t26Output 3 =Q-3t26Output 4 =Q-4t26Output 5 =Q-5t26Output 6 =Q-6t26Output 7 =Q-7t26Max Rate (Port 0)= 1.92e+6 Hz25Source: PulseTrainAmp = 1vFreq = 64e+3HzPulseW =10e-6 secOffset = -500e-3 vPhase = 0 degMax Rate =1.92e+6 Hz26Logic:La

14、tch-8TGate Delay = 0 secThreshold =500e-3 vTrue Output=1 vFalse Output=0 vRise Time = 0 secFall Time = 0 secData D-0 = t24 Output 0Data D-1 = t24 Output 1Data D-2 = t24 Output 2Data D-3 = t24 Output 3Data D-4 = t24 Output 4Data D-5 = t24 Output 5Data D-6 = t24 Output 6Data D-7 = t24 Output 7L-E nabl

15、e = t27 Output 0Output 0 =Q-0t28Output 1 =Q-1t28Output 2 =Q-2t28Output 3 =Q-3t28Output 4 =Q-4t28Output 5 =Q-5t28Output 6 =Q-6t28Output 7 =Q-7t28Max Rate (Port 0)= 1.92e+6 Hz27Source: PulseTrainAmp = 1 vFreq = 8e+3HzPulseW =4e-6 secOffset =-500e-3 vPhase = 315 degMax Rate =1.92e+6 Hz3、2PSK調(diào)制與解調(diào)圖符號庫/名

16、稱參數(shù)13Multiplier:NonParametricIn puts from t14p0 t6p0Outputs to1215Max Rate =1.92e+6 Hz14Source:Si nu soidAmp = 1vFreq =192e+3 HzPhase = 0 degOutput 0 =Si ne t13Output 1 =Cos ineMax Rate (Port 0)= 1.92e+6 Hz15Operator: Lin ear SysLin ear PhaseBan dpass IIR3 PolesLow Fc = 128e+3 HzHi Fc =256e+3 HzQua

17、nt Bits =NoneInit Cndtn =0DSP Mode DisabledMax Rate =1.92e+6 Hz16Comm:VCO Freq =Costas192e+3 HzVCO Phase = 0 degMod Gai n = 1Hz/vLoop Fltr = 1+ 1/s + 1/sA2Output 0 =BasebandIn PhaseOutput 1 =BasebandQuadratureOutput 2 =VCO In PhaseOutput 3 =VCOQuadrature t17Max Rate(Port 3)=1.92e+6 Hz17Multiplier:No

18、nParametricIn puts from t15p0 t16p3Outputs to18Max Rate =1.92e+6 Hz18Operator: Lin ear SysLin ear Phase Lowpass IIR3 PolesFc = 64e+3HzQua nt Bits = NoneInit Cndtn = Tran sie ntDSP Mode DisabledMax Rate =1.92e+6 Hz20Operator:SamplerIn terpolat ingRate = 64e+3HzAperture = 0 secApertureJitter = 0 secMa

19、x Rate =64e+3 Hz21Operator: HoldLast ValueGai n = 1Out Rate = 1.92e+6 HzMax Rate =1.92e+6 Hz22Logic: BufferGate Delay =0 secThreshold = 0vTrue Output=1 vFalse Output=0 vRise Time = 0secFall Time = 0 secMax Rate =1.92e+6 Hz五、仿真波形:1、輸入正弦波信號if2=e-i5e-35e-302&S-3136-3Tme n S&arcs2、A律壓縮信號SySWflPiTHW25ft-3!3t-31AMpnrle?10-5006-3.3、基帶信號（局部放大）ZCS&cTime r Sescrda4、2PSK調(diào)制信號（局部放大）4、2psk調(diào)制信號5jWW 軸11IK-613MO13Oen&130C-620SMs3Ce-6205ES4U1 二律 45、提取載波信號（局部放大）acESB?TM4-6Time in seooHd5、通過帶通濾波器后信號MH4KW-R6、接收低通濾波器后信號（局部放大）呂二一y7、采樣器輸出信號（局部放大）8、保持器輸出信號（局部放大）9、緩沖器輸出（局部放大）10、DA輸出信號rA1 J1k丿11 /112