2PSK与PCM仿真实验··西电

1、通信原理研究报告名称：基于2PSK仿真与PCM仿真研究结果与测量分析姓 名： 班 级： 目的（1）深入理解（ ）通信系统的工作原理、电路组成和信息传输特点；（2）熟悉上述通信系统的设计方法与参数选择原则；（3）掌握在SYSTEMVIEW环境中使用参数化图符模块构建通信系统模型的设计仿真方法；（4）熟悉系统中各信号时域波形特点；（5）熟悉系统中各信号频域的功率谱特点。内容（一）（1）使用m序列为数字系统输入调试信号，码速率参见附表；（2）采用模拟调制或数字键控实现2PSK调制；（3）通过相干解调完成2PSK解调，恢复初始m序列；（4）从时域观测各信号点波形，获得接收端信号眼图；（5）观测各信号功

2、率谱；内容（二）（6）通过不少于三个频率正弦信号叠加而成的模拟信号作为系统真实输入信号，并采用PCM编码方法实现模数转换；（7）模拟输入信号转换形成的数字信号通过2PSK调制解调系统实现数字频带传输；（8）通过PCM解码恢复初始模拟信号；（9）从时域重点观测模拟信号点波形；（10）从频域重点观察模拟信号功率谱。方案模拟信号的数字传输通信系统的组成框图如下图所示。系统输入的模拟随机信号 m(t)，经过该通信系统后要较好地得到恢复。模拟信息源抽样、量化和编码数字通信系统译码和低通滤波m(t)skskm(t)模拟随机信号数字随机序列数字随机序列模拟随机信号具体方案建议：PCM + 2PSK (BPS

3、K)在2PSK中，通常用初始相位0和p分别表示二进制“1”和“0”。因此，2PSK信号的时域表达式为： 式中，jn表示第n个符号的绝对相位： 上式可以改写为：2PSK信号的调制器原理方框图模拟调制的方法： 键控法：即发送二进制符号“1”时（an取+1），e2PSK(t)取0相位；发送二进制符号“0”时（ an取 -1）， e2PSK(t)取p相位（也可以反之）。这种以载波的不同相位直接去表示相应二进制数字信号的调制方式，称为二进制(绝对)相移方式. 已调信号e2PSK(t)典型波形如下图：2PSK信号的解调器（想干解调）原理方框图和波形图：（一） 2psk仿真 波形输出结果及分析：电路连接图时

4、域波形：输入信号信号通过开关之后信号通过带通滤波器信号通过低通滤波器后输出信号各信号功率谱密度输入信号经过开关带通滤波器输出低通滤波器输出最终输出接收端眼图N=0N=1N=0.5瀑布图Token 28 带通滤波器的幅频特性曲线Token 25低通滤波器的幅频特性曲线图符参数设置表编号名称参数26Comm: PN GenReg Len = 5Taps = 2- 5Seed = -1Threshold = 0True = 1False = -1Max Rate = 440e+3 Hz22Source: Pulse TrainAmp = -1 vFreq = 22e+3 HzPulseW = 22.

5、7273e-6 secOffset = 500e-3 vPhase = 0 degMax Rate = 440e+3 Hz29Logic: SPDTSwitch Delay = 0 secThreshold = 0 vInput 0 = t30 Output 0Input 1 = t12 Output 0Control = t26 Output 0Max Rate = 440e+3 Hz12Source: SinusoidAmp = 1 vFreq = 44e+3 HzPhase = 0 degOutput 0 = Sine t30 t29Output 1 = CosineMax Rate (

6、Port 0) = 440e+3 Hz30Operator: NegateMax Rate = 440e+3 Hz2Adder: Non ParametricInputs from t9p0 t29p0Outputs to 28Max Rate = 440e+3 Hz9Source: Gauss NoiseStd Dev = 0 vMean = 0 vMax Rate = 440e+3 Hz28Operator: Linear SysButterworth Bandpass IIR3 PolesLow Fc = 22e+3 HzHi Fc = 66e+3 HzQuant Bits = None

7、Init Cndtn = TransientDSP Mode DisabledMax Rate = 440e+3 Hz27Source: SinusoidAmp = 1 vFreq = 44e+3 HzPhase = 0 degOutput 0 = Sine t13Output 1 = CosineMax Rate (Port 0) = 440e+3 Hz13Multiplier: Non ParametricInputs from t27p0 t28p0Outputs to 25Max Rate = 440e+3 Hz25Operator: Linear SysButterworth Low

8、pass IIR3 PolesFc = 22e+3 HzQuant Bits = NoneInit Cndtn = TransientDSP Mode DisabledMax Rate = 440e+3 Hz3Operator: DelayNon-InterpolatingDelay = 0 sec= 0.0 smpOutput 0 = Delay t17Output 1 = Delay - dTMax Rate (Port 0) = 440e+3 Hz17Operator: SamplerInterpolatingRate = 440e+3 HzAperture = 0 secApertur

9、e Jitter = 0 secMax Rate = 440e+3 Hz18Operator: HoldLast ValueGain = 1Out Rate = 440e+3 HzMax Rate = 440e+3 Hz20Logic: BufferGate Delay = 0 secThreshold = 0 vTrue Output = 1 vFalse Output = 0 vRise Time = 0 secFall Time = 0 secMax Rate = 440e+3 Hz 结果分析：我们采用的是树枝键控实现2PSK调制，利用数字信号的离散取值特点通过开关键控载波，从而实现数字

10、调制。由结果可知，如果两个频率相同的载波同时开始振荡，这两个频率同时达到正最大值，同时达到零值，同时达到负最大值，它们应处于"同相"状态；如果其中一个开始得迟了一点，就可能不相同了。如果一个达到正最大值时，另一个达到负最大值，则称为"反相"。一般把信号振荡一次（一周）作为360度。如果一个波比另一个波相差半个周期，我们说两个波的相位差180度，也就是反相。当传输数字信号时，"1"码控制发0度相位，"0"码控制发180度相位。载波的初始相位就有了移动，也就带上了信息。结合图，与上述结果一致。而且从三个眼图知，随着信噪

11、比的增加，眼图质量越来越好 遇到的问题：一开始实验产生的功率谱图不好看，太稀，经老师指导后，知道了可以把“stop time”调的大一点图就看上去就好看多了。（二） Pcm仿真 波形输出结果及分析：电路连接图时域波形：输入信号输出信号主要信号的功率谱密度：输入信号输出信号瀑布图：Token 12 低通滤波器幅频特性Token 63 带通滤波器幅频特性Token 60 低通滤波器幅频特性图符参数设置表编号名称参数0Source: SinusoidAmp = 1 vFreq = 100 HzPhase = 0 degOutput 0 = Sine t3Output 1 = CosineMax Ra

12、te (Port 0) = 440e+3 Hz1Source: SinusoidAmp = 1 vFreq = 200 HzPhase = 0 degOutput 0 = Sine t3Output 1 = CosineMax Rate (Port 0) = 440e+3 Hz2Source: SinusoidAmp = 1 vFreq = 300 HzPhase = 0 degOutput 0 = Sine t3Output 1 = CosineMax Rate (Port 0) = 440e+3 Hz3Adder: Non ParametricInputs from t0p0 t1p0 t

13、2p0Outputs to 4 6Max Rate = 440e+3 Hz6Comm: CompanderA-LawMax Input = ±5Max Rate = 440e+3 Hz8Logic: ADCTwo's ComplementGate Delay = 0 secThreshold = 500e-3 vTrue Output = 1 vFalse Output = 0 vNo. Bits = 8Min Input = -5 vMax Input = 5 vRise Time = 0 secAnalog = t6 Output 0Clock = t14 Output

14、0Output 0 = Q-0 t24Output 1 = Q-1 t25Output 2 = Q-2 t26Output 3 = Q-3 t27Output 4 = Q-4 t28Output 5 = Q-5 t29Output 6 = Q-6 t30Output 7 = Q-7 t31Output 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) = 440e+3 Hz14

15、Source: Pulse TrainAmp = 1 vFreq = 2.75e+3 HzPulseW = 181.818e-6 secOffset = -500e-3 vPhase = 0 degMax Rate = 440e+3 Hz16Operator: SamplerInterpolatingRate = 55e+3 HzAperture = 0 secAperture Jitter = 0 secMax Rate = 55e+3 Hz41Comm: TD MuxNo. Inputs = 8Time per Input = 363.636e-6 secTime Slot 0 = t32

16、 Output 0Time Slot 1 = t33 Output 0Time Slot 2 = t34 Output 0Time Slot 3 = t35 Output 0Time Slot 4 = t36 Output 0Time Slot 5 = t37 Output 0Time Slot 6 = t38 Output 0Time Slot 7 = t39 Output 0Max Rate = 440e+3 Hz43Operator: HoldLast ValueGain = 1Out Rate = 440e+3 HzMax Rate = 440e+3 Hz68Logic: Buffer

17、Gate Delay = 0 secThreshold = 500e-3 vTrue Output = 1 vFalse Output = -1 vRise Time = 0 secFall Time = 0 secMax Rate = 440e+3 Hz64Logic: SPDTSwitch Delay = 0 secThreshold = 0 vInput 0 = t65 Output 0Input 1 = t52 Output 0Control = t68 Output 0Max Rate = 440e+3 Hz52Source: SinusoidAmp = 1 vFreq = 44e+

18、3 HzPhase = 0 degOutput 0 = Sine t65 t64Output 1 = CosineMax Rate (Port 0) = 440e+3 Hz65Operator: NegateMax Rate = 440e+3 Hz49Source: Gauss NoiseStd Dev = 0 vMean = 0 vMax Rate = 440e+3 Hz47Adder: Non ParametricInputs from t49p0 t64p0Outputs to 63Max Rate = 440e+3 Hz63Operator: Linear SysButterworth

19、 Bandpass IIR3 PolesLow Fc = 22e+3 HzHi Fc = 66e+3 HzQuant Bits = NoneInit Cndtn = TransientDSP Mode DisabledMax Rate = 440e+3 Hz53Multiplier: Non ParametricInputs from t62p0 t63p0Outputs to 60Max Rate = 440e+3 Hz62Source: SinusoidAmp = 1 vFreq = 44e+3 HzPhase = 0 degOutput 0 = Sine t53Output 1 = Co

20、sineMax Rate (Port 0) = 440e+3 Hz60Operator: Linear SysButterworth Lowpass IIR3 PolesFc = 22e+3 HzQuant Bits = NoneInit Cndtn = TransientDSP Mode DisabledMax Rate = 440e+3 Hz48Operator: DelayNon-InterpolatingDelay = 0 sec= 0.0 smpOutput 0 = Delay t55Output 1 = Delay - dTMax Rate (Port 0) = 440e+3 Hz

21、55Operator: SamplerInterpolatingRate = 440e+3 HzAperture = 0 secAperture Jitter = 0 secMax Rate = 440e+3 Hz56Operator: HoldLast ValueGain = 1Out Rate = 440e+3 HzMax Rate = 440e+3 Hz57Logic: BufferGate Delay = 0 secThreshold = 0 vTrue Output = 1 vFalse Output = 0 vRise Time = 0 secFall Time = 0 secMa

22、x Rate = 440e+3 Hz69Operator: DelayNon-InterpolatingDelay = 318.182e-6 sec= 140.0 smpOutput 0 = Delay t45Output 1 = Delay - dTMax Rate (Port 0) = 440e+3 Hz45Comm: TD DeMuxNo. Outputs = 8Time per Output = 363.636e-6 secOutput 0 = Time Slot 0 t44 t9Output 1 = Time Slot 1 t9Output 2 = Time Slot 2 t9Out

23、put 3 = Time Slot 3 t9Output 4 = Time Slot 4 t9Output 5 = Time Slot 5 t9Output 6 = Time Slot 6 t9Output 7 = Time Slot 7 t9Max Rate (Port 0) = 55e+3 Hz9Logic: DACTwo's ComplementGate Delay = 0 secThreshold = 500e-3 vNo. Bits = 8Min Output = -5 vMax Output = 5 vD-0 = t45 Output 0D-1 = t45 Output 1D-2 = t45 Output 2D-3 = t45 Output 3D-4 = t45 Output 4D-5 = t45 Output 5D-6 = t45 Output 6D-7 = t45 Output 7D-8 = NoneD-9 = NoneD-10 = NoneD-11 = NoneD-12 = NoneD-13 = NoneD-14 = NoneD-15 = NoneMax Rate = 55e+3 Hz7Comm: DeCompandA-LawMax Input = ±5Max Rate = 55e+3 Hz12Operator: Linear S