矩形窓の振幅スペクトル

clear; close all; clc;

N=2^5;
wave = boxcar(N);
amp  =2.0*fft(wave, 2048)/N;
freq = linspace(-0.5,0.5,length(amp));
mag = 20*log10(abs(fftshift(amp/max(abs(amp)))));

plot(freq,mag);