仿真时，生成一个10us的脉冲和一个1us的脉冲，对应的带宽为0.1MHz和1MHz
clc;clear all;close all; %% 常量 GHZ = 1e9; MHZ = 1e6; KHZ = 1e3; Hz = 1; S = 1; MS = 1e-3; US = 1e-6; NS = 1e-9; %% 参数设置 FS = 100*MHZ; f = 10*MHZ; NN = 8192; x = (0:NN-1)/NN*FS/MHZ; tau = 10*US; B = 1/tau/MHZ N = floor(tau/(1/FS)); t = (0:N-1)/FS; sig = zeros(1,NN); sig(1,1:N) = sin(2*pi*f*t); figure; y = abs(fft(sig)); plot(x,y); xlabel('频率(MHZ)'); figure; y = 20*log10(abs(fft(sig))); plot(x,y); xlabel('频率(MHZ)'); tau = 1*US; B = 1/tau/MHZ N = floor(tau/(1/FS)); t = (0:N-1)/FS; sig = zeros(1,NN); sig(1,1:N) = sin(2*pi*f*t); figure; y = abs(fft(sig)); plot(x,y); xlabel('频率(MHZ)'); figure; y = 20*log10(abs(fft(sig))); plot(x,y); xlabel('频率(MHZ)');幅度 取对数后，观测3dB带宽
