調頻Matlab

Question

我想制作一個連續的sinwave，它將改變他的頻率3次，就像在照片中一樣。 我嘗試了fmmod函數，但是我無法使其正常工作，所以還有其他方法，謝謝。

這是我的代碼

Fs = 44100; % Sampling rate of signal
Fc = 3000; % Carrier frequency
t = [0:Fs-1]'/Fs; % Sampling times
x = sin(2*pi*4000*t)+sin(2*pi*5000*t)+sin(2*pi*8000*t); % my signal

dev = 50; % Frequency deviation in modulated signal
y = fmmod(x,Fc,Fs,dev);
plot(y)

Answer 1

不帶fmmod的頻率調制：

Fs = 44100; % Sampling rate of signal
T=1/Fs; % period

t = 0:T:0.01; % sample times

% amplitude of message signal
vm = 5
% amplitude of carrier signal 
vc =5
% message frequency 
fm =500
% carrier freq
fc = 5e3
% modulation index
m =5

figure

y = vc*sin(2*pi*fc*t+m.*cos(2*pi*fm*t));
plot(t,y);