Match Filter and Sampling problem

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Durgaprasad Srinivasa
评论： Subhadeep Koley 2019-11-5
clc;
clear all;
close all;
tp=2.2676*10^-3;
Ts=22.6757*10^-6;
fc=4000;
Tc=(1/fc);
fs=44100;
n=0:Ts:1000;
fp=(1/tp);
w=2*pi*fp;
p=sin(w*n*Ts);
p(find(p<0))=0;
figure(1)
subplot(3,1,1);
plot(n,p);
data = randi([0,1],1,1000);
a=[];
for k=1:2:1000
if data(k)==0 && data(k+1)==0
a=[a 1];
elseif data(k)==0 && data(k+1)==1
a=[a i];
elseif data(k)==1 && data(k+1)==0
a=[a -1];
elseif data(k)==1 && data(k+1)==1
a=[a -i];
end
end
figure(2)
subplot(3,1,2);
y_s=conv(a,p);
Trm=min(numel(n),numel(y_s))
n=n(1:Trm);
y_s=y_s(1:Trm);
plot (n,real(y_s), '-',n,imag(y_s), '--');
%% modulation of 2 signals
figure(3)
subplot(3,1,3);
in_phase_carrier=cos(2*pi*fc*n*Ts);
q_phase_carrier=sin(2*pi*fc*n*Ts);
y_m=real(y_s).*in_phase_carrier+imag(y_s).*q_phase_carrier;
plot (n,real(y_m), '-');
subplot(3,2,3);
plot(n,imag(y_m), '--');
pav=sum(y_m.^2)/length(y_m);
et=sum(y_m.^2)/fs;
snrdb=20;
snrlin=10.^(snrdb./10);
eb=sum(y_m.^2)/length(y_m);
u=0.00022676;
g=5/60;
n1=(u-n);
in_phase_carrier_rec=cos(2*pi*fc*n1*Ts);
q_phase_carrier_rec=sin(2*pi*fc*n1*Ts);
y_mn1=(real(y_s).*in_phase_carrier_rec)+(imag(y_s).*q_phase_carrier_rec);
figure(4)
subplot(4,1,4);
r = (sqrt((1-g)^2))*y_m+y_mn1*g;
plot(n,r);
snrdb=20;
snrlin=10.^(snrdb/10);
n0 = eb/snrlin;
sigma=(n0.*fs)/2;
noise = sqrt(sigma).*randn(1,length(y_m));
recieved=noise+r;
%% demodulation of signal
subplot(4,2,4);
r_dm_in=real(recieved).*in_phase_carrier;
plot(n,r_dm_in,'-');
r_dm_out=imag(recieved).*q_phase_carrier;
plot(n,r_dm_out,'--');
Hello I am trying to demodulate using match filter and sampling it wwith 44100Hz. can anyone help with match filter and sampling of this code.
  1 个评论
Subhadeep Koley
Subhadeep Koley 2019-11-5
Your code is running without an error. Can you elaborate what problem exactly you are facing? What is you expecting as the output?

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