Приложение 3. Программа расчета отношения сигнал/шум.

  

%   Estimation of the signal-to-noise ratio

 

clear all

 

%   Modelling of sigma(omega)

t00=1.3;

ts=t00/150;

fmax=1/ts;

fchar=1/t00;

fcharmin=2.5*fchar;

fcharpl=2.6*fchar;

%alpfa=2*ts*fchar;

ffilin=[0 2*ts*fcharmin 2*ts*fcharmin 2*ts*fcharpl 2*ts*fcharpl 1];

m=[1 1 1.47 1.47 1 1];

%m=[1 1 1 1 1 1];

b=fir2(550,ffilin,m);

[h,freal]=freqz(b,1,512,fmax);

%freal=w./2./ts./pi;

%plot(freal, abs(h))

%figure

subplot(2,1,1);

plot(freal, abs(h).*abs(h))

zoom xon

grid on

xlabel('Частота, отн.ед.');

ylabel('\sigma (f)');

title('а')

hnorm=abs(h)./max(abs(h));

 

 

%   Signal

shirot=36;

dlitot=4;

mu=zeros(dlitot,shirot);

%mu1=zeros(dlitot,shirot);

norma=zeros(dlitot,shirot);

 

for kt=1:shirot

    t0=2.0-(kt-1)./20;

    fsig(kt)=1/t0;

omtr=2*pi/t0;

for kdlit=1:dlitot

dlitimp=kdlit*t0;

dlit=20*t0;

t=0:ts:dlit;

%y=gauspuls(t-2,1,1);

y=rectpuls(t-dlitimp/2-t0/2,dlitimp).*sin(omtr.*(t-t0/2-dlitimp/2));

%figure

%plot(t,y)

%zoom xon

yfft=abs(fft(y));

yfft2=yfft.*yfft;

yfft1=yfft/max(yfft);

df=1/dlit;

f=0:df:20/t0;

flenpl=length(f);

fmaxpl=max(f);

%figure

%plot(freal,hnorm,f,yfft1(1:flenpl))

%zoom xon

 

%   Reflection of the signal from the target

 

%figure

%freqz(b,1)

sout=filter(b,1,y);

%sout=filtfilt(b,1,y);

%plot(t,sout)

%zoom xon

 

 

%   Signal-to-noise ratio

sout1fft=abs(fft(sout));

sout1fft2=sout1fft.*sout1fft;

%mu(kdlit,kt)=0;

%mu1(kdlit,kt)=0;

    for ks=1:flenpl;

        if f(ks)>1/t0-1/dlitimp & f(ks)<1/t0+1/dlitimp

            mu(kdlit,kt)=mu(kdlit,kt)+sout1fft2(ks).*df;

            norma(kdlit,kt)=norma(kdlit,kt)+yfft2(ks).*df;

        end

%        if f(ks)>1/t0+1/dlitimp & f(ks)<1/t0+2/dlitimp

%            mu1(kdlit,kt)=mu1(kdlit,kt)+sout1fft2(ks).*df;

%        end

    end

 

end

end

mu=mu./norma;

%[mumaxdlit,inddlit]=max(mu,[],1);

%[mumax,ind]=max(mumaxdlit);

%mumax=max(mumaxdlit);

%munorm=mu./mumax;

[mumindlit,indmdlit]=min(mu,[],1);

[mumin,indm]=min(mumindlit);

munorm=mu./mumin;

%mu1norm=mu1./mu1max;

%deltaf=fsig./fsig(ind)-1;

 

%figure

%plot(deltaf,munorm)

subplot(2,1,2);

plot(fsig,munorm)

grid on

 

xlabel('Частота сигнала, отн.ед.');

ylabel('Выигрыш в отношении сигнал/шум');

title('б')

%figure

%plot(fsig,mu1norm)

zoom xon