[問題] 請問"pulsegen"這各指令該如何用...已回收
function p=pulsegen(fs,T,edge,type,f,opt);
% p=pulsegen(fs,T,edge,type,f,opt);
% a --> signal generation program
% fs --> is the sampling frequency
% T --> is the total signal length
% edge --> is a decay parameter for some waveforms
% it is used in 'gaussian', 'monocycle', 'biexponential', 'mexican hat',
'sinc', 'double sinc', 'sinc squared'
% and windowed sweep
% it is mostly a parameter to describe how much the edge of the pulse is
decayed.
% type --> is the type of the waveform desired
% allowable types are 'gaussian', 'square', 'triangle', 'monocycle',
% 'biexponential', 'mexican hat', 'sinc', 'double sinc', 'sinc
squared','sweep', and 'windowed sweep'
% f is the modulation frequency if left out it is assumed 0.
% opt is an optional argument for pulse waveforms requiring a lower and
higher frequency
% it is used in 'double sinc' ,'sweep' and 'windowed sweep' for the low
and high frequency.
% the pulses are always normalized to a peak amplitude of 1
if nargin<4 % test for optional arguments
error('not enough input arguments');
elseif nargin==4
f=0;
opt=[16*edge/(5*T),64*edge/(5*T)];
elseif nargin==5
opt=[16*edge/(5*T),64*edge/(5*T)];
end
if (edge==0)
edge==1;
end
t=-T/2:1/fs:T/2;
sig=(T/8/edge)^2;
switch type
case {'guassian'} %generate a guassian pulse
y=exp(-(t).^2/sig);
case {'square'} %generate a square pulse
y=ones(size(t));
case {'triangle'} %generate a triangle pulse
y=(t+T/2).*(t<0)-(t-T/2).*(t>=0);
case {'monocycle'} %generate a gaussian monocycle
y=2*t./sig.*exp(-(t).^2/sig);
case {'biexponential'} %generate a biexponential pulse
y=exp(-abs(t)*8*edge/T);
case {'mexican hat'} %generate a gaussian second deriviative
z=t./sqrt(0.75*sig);
y=sqrt(1/2*pi).*(1-z.^2).*exp(-z.^2/2);
case {'sinc'} %generate a sinc function
y=sinc(2*pi*edge*16.*t/(5*T));
case {'double sinc'} %generate a bandlimited function from two sinc functions
y=opt(1)*sinc(2*opt(1).*t)-opt(2)*sinc(2*opt(2).*t);
case {'sinc squared'} %generates sinc squared function
y=sinc(2*pi*edge*16.*t/(5*T)).^2;
case {'sweep'} %generate frequency sweep
theta=(opt(1)+(opt(2)-opt(1))/T).*(t+T/2);
y=real(exp(j*(theta.*(t+T/2)-pi/2)));
case {'windowed sweep'} %generate a windows frequency sweep
theta=(opt(1)+(opt(2)-opt(1))/T).*(t+T/2);
y=real(exp(j*(theta.*(t+T/2)-pi/2)));
c=length(y);
edge=min(1,edge);
edge=max(0,edge);
w=hamming(ceil(c*(1-edge)));
w2=[w(1:ceil(length(w)/2));ones(c-length(w),1);w(ceil(length(w)/2)+1:end)]';
y=w2.*y;
otherwise
error('invalid pulse type');
end
%apply a modulation
if f~=0
y=y.*cos(2*pi*t*f);
end
%normalize the peak of the pulse to 1
p=y./max(abs(y));
ps.要怎麼用才能畫出(得到)一個0~1秒為振幅1，其餘時間皆為零之方波訊號。
謝謝!!
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