fmmod

Frequency modulation

Syntax

y = fmmod(x,Fc,Fs,freqdev)

y = fmmod(x,Fc,Fs,freqdev,ini_phase)

Description

y = fmmod(x,Fc,Fs,freqdev) returns a frequency modulated (FM) signal y, given the input message signal x, where the carrier signal has frequency Fc and sampling rate Fs. freqdev is the frequency deviation of the modulated signal.

Note

The value of Fs must satisfy Fs ≥ 2Fc.
The value of freqdev must satisfy freqdev < Fc.

y = fmmod(x,Fc,Fs,freqdev,ini_phase) specifies the initial phase of the modulated signal.

Examples

collapse all

FM Modulate a Sinusoidal Signal

Open Live Script

Set the sampling frequency to 1kHz and carrier frequency to 200 Hz. Generate a time vector having a duration of 0.2 s.

fs = 1000; 
fc = 200;  
t = (0:1/fs:0.2)';

Create two tone sinusoidal signal with frequencies 30 and 60 Hz.

x = sin(2*pi*30*t)+2*sin(2*pi*60*t);

Set the frequency deviation to 50 Hz.

fDev = 50;

Frequency modulate x.

y = fmmod(x,fc,fs,fDev);

Plot the original and modulated signals.

plot(t,x,'c',t,y,'b--')
xlabel('Time (s)')
ylabel('Amplitude')
legend('Original Signal','Modulated Signal')

Figure contains an axes. The axes contains 2 objects of type line. These objects represent Original Signal, Modulated Signal.

Input Arguments

collapse all

`x` — Input message signal
scalar | vector | matrix | 3-D array

Input message signal, specified as a scalar, vector, matrix, or a 3-D array. Each element of x must be real.