phspec.m

来自「此程序给出了不同情况的雷达距离测量仿真平台」· M 代码 · 共 38 行

% Spectrum for Phase Modulated Sine Wave
% --------------------------------------

clf;clc;clear;

j=sqrt(-1);

% Sample with fs

fs=2048;     % Hz
t=(1:fs)/fs; % sec

% Baseband and 400 Hz noise

f0=0;fm=400; % Hz
dfi=4;       % Degrees

x=exp(j*(2*f0*t+dfi/360*2*pi*sin(2*pi*fm*t)));

% Find spectrum

X=fft(x,fs);
X=fftshift(X);
Pxx=X.*conj(X);

Pxx=Pxx/max(Pxx);
Pxxdb=10*log10(Pxx+1e-10);

% Plot over frequency axis +/- fs/2

f=(-fs/2:fs/2-1);

plot(f,Pxxdb);grid;
xlabel('Frequency - Hz');
ylabel('Power - dB');
title(['Spectrum for 400Hz Phase Modulation']);
axis([-1500, 1500, -80, 0 ]);