bandwidth1.m

关于超宽带的一系列仿真包括高斯波形各阶导函数波形频谱以及采用高斯导函数的跳时超宽带仿真程序

%
%FUNTION 1.2:"cp0101_bandwidth"
%
%evaluates the bandwidth of the input 'signal' with sample period 'dt'
%
%bandwidth is evaluated according to the given 'threshold'(in dB)
%'BW'is the bandeidth
%'f_high'is the higher limit
%'f_low'is the lower limit
%
threshold=-3;
width=1e-1;
points=1000;
f0=1e3;
dt=width/points;
signal=zeros(1,5*points);
signal(2*points:3*points-1)=ones(1,points);
mod=cos(2.*pi.*f0.*linspace(1,5*width,5*points));
signal=signal.*mod;
fs=1/dt;
N=length(signal);
T=N*dt;
df=1/T;
X=fft(signal);
X=X/N;
ds_E=abs(X).^2/(df^2);
ss_E=2.*ds_E(1:floor(N/2));
[Epeak,index]=max(ss_E);
f_peak=index*df;
Eth=Epeak*10^(threshold/10);
imax=index;
E0h=ss_E(index);
while (E0h>Eth)&(imax<=(N/2))
    imax=imax+1;
    E0h==ss_E(imax);
end
f_high=(imax-1)*df;
imin=index;
E0l=ss_E(index);
while (E0l>Eth)&(imin>1)&(index>1)
    imin=imin-1;
    E0l=ss_E(imin);
end
f_low=(min(index,imin)-1)*df;
BW=f_high-f_low;
fprintf('\nFrequency Bandwidth= %f [HZ]\nHigh Frequency= %f [HZ]\nLow Frequency= %f [HZ]\n',BW,f_high,f_low);
figure(2)
frequency=linspace(0,fs/2,length(ss_E));
PF=plot(frequency,ss_E);
set(PF,'LineWidth',[2]);
L1=line([f_high f_high],[min(ss_E) max(ss_E)]);
set(L1,'Color',[0 0 0],'LineStyle',':')
L1=line([f_low f_low],[min(ss_E) max(ss_E)]);
set(L1,'Color',[0 0 0],'LineStyle',':')
L1=line([f_low f_high],[Eth Eth]);
set(L1,'LineWidth',[2],'Color','red','LineStyle',':')
axis([0.8*f_low 1.2*f_high -0.1*Epeak 1.2*Epeak]);
AX=gca;
set(AX,'FontSize',12);
T=title('Frequency domain');
set(T,'FontSize',14);
X=xlabel('Frequency [HZ]');
set(X,'FontSize',14);
Y=ylabel('Single-Sided ESD [V^2s/HZ]]');
set(Y,'FontSize',14);