用matlab对2PSK调制进行仿真

clear

close all

fs=8e5 %抽样频率

fm=20e3 %基带频率

n=2*(6*fs/fm)

final=(1/fs)*(n-1)

fc=2e5 % 载波频率

t=0:1/fs:(final)

Fn=fs/2 %耐奎斯特频率

%用正弦波产生方波

twopi_fc_t=2*pi*fm*t

A=1

phi=0

x = A * cos(twopi_fc_t + phi)

% 方波

am=1

x(x>0)=am

x(x<0)=-1

figure(1)

plot(t,x)

axis([0 2e-4 -2 2])

title('等概二进制信源')

grid on

car=sin(2*pi*fc*t) %载波

psk=x.*car %载波调制

figure(2)

plot(t,psk)

axis([0 200e-6 -2 2])

title('2PSK信号')

grid on

figure(3)

plot(abs(fft(psk)))%产生2psk信号的频谱

grid on

title('2psk信号频谱')xlabel('f')

% file c10_MCQPSKrun.m

%

%

function BER_MC=c10_MCQPSKrun(N,Eb,No,ChanAtt,...

TimingBias,TimingJitter,PhaseBias,PhaseJitter)

fs = 1e+6

% sampling Rate (samples/second)

SymRate = 1e+5

% symbol rate (symbols/second)

Ts = 1/fs

% sampling period

TSym = 1/SymRate

% symbol period

SymToSend = 100%N

% symbols to be transmitted

ChanBW = 4.99e+5

% bandwidth of channel (Hz)

MeanCarrierPhaseError = PhaseBias

% mean of carrier phase

StdCarrierPhaseError = PhaseJitter

% stdev of phese error

MeanSymbolSyncError = TimingBias

% mean of symbol sync error

StdSymbolSyncError = TimingJitter

% stdev of symbol sync error

ChanGain = 10^(-ChanAtt/20)

% channel gain (linear units)

TxBitClock = Ts/2

% transmitter bit clock

RxBitClock = Ts/2

% reciever bit clock

%

%

Standard deviation of noise and signal amplitude at receiver input.

%

RxNoiseStd = sqrt((10^((No-30)/10))*(fs/2))

% stdev of noise

TxSigAmp = sqrt(10^((Eb-30)/10)*SymRate)

% signal amplitude

%

% Allocate some memory for probes.

%

SampPerSym = fs/SymRate

probe1 = zeros((SymToSend+1)*SampPerSym,1)

probe1counter = 1

probe2 = zeros((SymToSend+1)*SampPerSym,1)

probe2counter = 1

%

% Counters to keep track of how many symbols have have been sent.

%

TxSymSent = 1

RxSymDemod = 0

%

% Buffers that contain the transmitted and received data.

%

[unused,SourceBitsI] = random_binary(SymToSend,1)

[unused,SourceBitsQ] = random_binary(SymToSend,1)

%

% Differentially encode the transmitted data.

%

TxBitsI = SourceBitsI*0

TxBitsQ = SourceBitsQ*0

for k=2:length(TxBitsI)

TxBitsI(k) = or(and(not(xor(SourceBitsI(k),SourceBitsQ(k))),...

xor(SourceBitsI(k),TxBitsI(k-1))), ...

and(xor(SourceBitsI(k),SourceBitsQ(k)),...

xor(SourceBitsQ(k),TxBitsQ(k-1))))

TxBitsQ(k) = or(and(not(xor(SourceBitsI(k),SourceBitsQ(k))),...

xor(SourceBitsQ(k),TxBitsQ(k-1))), ...

and(xor(SourceBitsI(k),SourceBitsQ(k)),...

xor(SourceBitsI(k),TxBitsI(k-1))))

end

%

% Make a complex data stream of the I and Q bits.

%

TxBits = ((TxBitsI*2)-1)+(sqrt(-1)*((TxBitsQ*2)-1))

%

RxIntegrator = 0

% initialize receiver integrator

TxBitClock = 2*TSym

% initialize transmitter

%

% Design the channel filter, and create the filter state array.

%

[b,a] = butter(2,ChanBW/(fs/2))

b=[1]a=[1]

% filter bypassed

[junk,FilterState]=filter(b,a,0)

%

% Begin simulation loop.

%

while TxSymSent <SymToSend

%

% Update the transmitter's clock, and see

% if it is time to get new data bits

%

TxBitClock=TxBitClock+Ts

if TxBitClock >TSym

%

% Time to get new bits

%

TxSymSent=TxSymSent+1

%

% We don't want the clock to increase off

% to infinity, so subtract off an integer number

% of Tb seconds

%

clc

clear

fc=4800fs=12000fb=2400

%要调制的数字信号

a=randint(1,12,2)%随机产生12个“0”，“1”

s=zeros(1,60)

for i=1:12

for j=1:5

if(a(i)==0)

s(j+(i-1)*5)=0

else

s(j+(i-1)*5)=1

end

end

end

plot(s)xlabel('基带信号')

figure

pwelch(s)%功率谱

figure

%波形成形滤波器(平方根升余弦滚降)

h=firrcos(14,1200,1200,4800,'sqrt')

figure

stem(h)xlabel('成形滤波器的单位冲击响应')

[H,W]=freqz(h,1)

H=abs(H)

figure

plot(H)xlabel('成形滤波器的频率响应')

s=fftfilt(h,s)

figure

plot(s)xlabel('通过成形滤波器后的基带信号')

figure

pwelch(s)%经波形成形滤波器后的功率谱

%已调信号

e=dmod(a,4800,2400,12000,'psk',2)%调制

figure

plot(e)xlabel('已调信号')

enoise=e+randn(1,60)%enoise=e+.1*randn(1,60)不同功率的高斯白噪声

aa=ddemod(enoise,4800,2400,12000,'psk',2)%解调

figure

stem(aa)xlabel('解调后的数字信号')%解调后的数字信号

p=symerr(a,aa)/12 %误码率

%误码率曲线

figure

r=-6:3:12

rr=10.^(r/10)

pe1=1/2*exp(-rr)%相干解调的误码率曲线

hold on

plot(r,pe1,'r')grid on

pe2=(1-1/2*erfc(sqrt(rr))).*erfc(sqrt(rr))%差分相干解调的误码率曲线

plot(r,pe2,'b')xlabel('bpsk,dpsk误码率曲线')

set(gca,'XTick',-6:3:18)

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