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⛄ 内容介绍
This paper mainly discusses about three basic digital modulation process ASK, FSK, PSK. These modulation schemes can be characterized by their transmitted symbols which consist of a discrete set of values occurring at gradually spaced intervals. The selection of a digital modulation technique for a specific application depend not only the bandwidth efficiency and implementation complexity but also error rate occurred in a bit (BER) and signal to noise ratio. Binary modulation methods use two level symbols and are facile to implement, provide good error substantiation. BER is a key parameter that used for assessing systems that transmit signal data from one location to another. SNR is well known measure of how the signal and noise power compare against each other. It directly affects the probability of error performance of a system. In this paper, we have implemented ASK, FSK and PSK using MATLAB.
⛄ 完整代码
clc
clear all
msglen=1000;
%msglen= number of bits to be transmitted
%take msglen=10000, or 20000 for more accuracy
%%===============================================
n=msglen;
b=randi(1,n);
f1=1;f2=2;
t=0:1/30:1-1/30;
%ASK
sa1=sin(2*pi*f1*t);
E1=sum(sa1.^2);
sa1=sa1/sqrt(E1); %unit energy
sa0=0*sin(2*pi*f1*t);
%FSK
sf0=sin(2*pi*f1*t);
E=sum(sf0.^2);
sf0=sf0/sqrt(E);
sf1=sin(2*pi*f2*t);
E=sum(sf1.^2);
sf1=sf1/sqrt(E);
%PSK
sp0=-sin(2*pi*f1*t)/sqrt(E1);
sp1=sin(2*pi*f1*t)/sqrt(E1);
%MODULATION
ask=[];psk=[];fsk=[];
for i=1:n
if b(i)==1
ask=[ask sa1];
psk=[psk sp1];
fsk=[fsk sf1];
else
ask=[ask sa0];
psk=[psk sp0];
fsk=[fsk sf0];
end
end
figure(1)
subplot(411)
stairs(0:10,[b(1:10) b(10)],'linewidth',1.5)
axis([0 10 -0.5 1.5])
title('Message Bits');grid on
subplot(412)
tb=0:1/30:10-1/30;
plot(tb, ask(1:10*30),'b','linewidth',1.5)
title('ASK Modulation');grid on
subplot(413)
plot(tb, fsk(1:10*30),'r','linewidth',1.5)
title('FSK Modulation');grid on
subplot(414)
plot(tb, psk(1:10*30),'k','linewidth',1.5)
title('PSK Modulation');grid on
xlabel('Time');ylabel('Amplitude')
%AWGN
for snr=0:20
askn=awgn(ask,snr);
pskn=awgn(psk,snr);
fskn=awgn(fsk,snr);
%DETECTION
A=[];F=[];P=[];
for i=1:n
%ASK Detection
if sum(sa1.*askn(1+30*(i-1):30*i))>0.5
A=[A 1];
else
A=[A 0];
end
%FSK Detection
if sum(sf1.*fskn(1+30*(i-1):30*i))>0.5
F=[F 1];
else
F=[F 0];
end
%PSK Detection
if sum(sp1.*pskn(1+30*(i-1):30*i))>0
P=[P 1];
else
P=[P 0];
end
end
%BER
errA=0;errF=0; errP=0;
for i=1:n
if A(i)==b(i)
errA=errA;
else
errA=errA+1;
end
if F(i)==b(i)
errF=errF;
else
errF=errF+1;
end
if P(i)==b(i)
errP=errP;
else
errP=errP+1;
end
end
BER_A(snr+1)=errA/n;
BER_F(snr+1)=errF/n;
BER_P(snr+1)=errP/n;
end
figure(2)
subplot(411)
stairs(0:10,[b(1:10) b(10)],'linewidth',1.5)
axis([0 10 -0.5 1.5]);grid on
title('Received signal after AWGN Channel')
subplot(412)
tb=0:1/30:10-1/30;
plot(tb, askn(1:10*30),'b','linewidth',1.5)
title('Received ASK signal');grid on
subplot(413)
plot(tb, fskn(1:10*30),'r','linewidth',1.5)
title('Received FSK signal');grid on
subplot(414)
plot(tb, pskn(1:10*30),'k','linewidth',1.5)
title('Received PSK signal');grid on
figure(3)
semilogy(0:20,BER_A, 'b','linewidth',2)
title('BER Vs SNR')
grid on;
hold on
semilogy(0:20,BER_F,'r','linewidth',2)
semilogy(0:20,BER_P, 'k','linewidth',2)
xlabel('Eo/No(dB)')
ylabel('BER')
hold off
legend('ASK','FSK','PSK');
⛄ 运行结果
⛄ 参考文献
[1] Bharati S , Rahman M A , Podder P . Implementation of ASK, FSK and PSK with BER vs. SNR comparison over AWGN channel[J]. 2020.
