% Hamming窗加权非线性调频脉压
clc; clear ; close all ;
B =0.5e6 ;
T = 500e-6 ;
fs = 1e6;
N = fs * T ;
fd =0e3 ;
f = linspace( -B/2 , B/2 , N ) ;
t = linspace( -T/2 , T/2 , N ) ;
wf = inline( '0.54+0.46*cos( 2*pi*x/0.5e6)' , 'x' ) ;
k = T / quad(wf , -B/2 , B/2 ) ;
tf = k * ( 0.54 * f + 0.23 * B / pi * sin( 2 * pi * f / B )) ;
ft = interp1( tf , f , t , 'linear','extrap' )
figure
plot( ft )
title( '调频斜率' )
grid on ;
pha = zeros( 1 , N -1 ) ;
for i = 1:N-1;
pha( i + 1) = pha( i ) + ( ft( i ) + ft( i +1 ) ) * pi / fs ;
end
Nlfmsig=exp(j*pha);
conjnlfmsig=conj(Nlfmsig(end:-1:1));
Nlfmmag=conv(Nlfmsig,conjnlfmsig);
Magdb=20*log10(abs(Nlfmmag)/(max(abs(Nlfmmag))));
figure
plot( real(Nlfmsig) )
title('非线性调频信号')
figure
plot( Magdb );
grid on
