bpf.m

来自「通信中一些基本实验的程序AM、FM、ASK、FSK、PSK等等」· M 代码 · 共 22 行

function [t,st]=bpf(f,sf,B1,B2)
%This function filter an input at frequency domain by an ideal
%bandpass filter
%input
%      f:frequency samples
%      sf:input data spectrum samples
%      B1:bandpass's lower frequency
%      B2:bandpass's higher frequency
%Outputs:
%      t:frequency samples
%      st:output data's time samples
df=f(2)-f(1);
T=1/df;
hf=zeros(1,length(f));
bf=[floor(B1/df):floor(B2/df)];
bf1=floor(length(f)/2)+bf;
bf2=floor(length(f)/2)-bf;
hf(bf1)=1/sqrt(2*(B2-B1));
hf(bf2)=1/sqrt(2*(B2-B1));

yf=hf.*sf.*exp(-j*2*pi*f*0.1*T);
[t,st]=F2T(f,yf);