Frequency modulation
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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
Fsmust satisfyFs≥ 2Fc.The value of
freqdevmust satisfyfreqdev<Fc.
y = fmmod(x,Fc,Fs,freqdev,ini_phase) specifies the initial phase of the modulated signal.
Examples
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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')
Input Arguments
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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.
Data Types: single | double
Fc — Carrier frequency
positive real scalar
Carrier frequency in hertz (Hz), specified as a positive real scalar.
Data Types: single | double
Fs — Sampling rate
positive real scalar
Sampling rate in hertz (Hz), specified as a positive real scalar.
Data Types: single | double
freqdev — Frequency deviation
positive real scalar
Frequency deviation of the modulated signal in hertz (Hz), specified as a positive real scalar.
Data Types: single | double
ini_phase — Initial phase
real scalar
Initial phase of the modulated signal in radians, specified as a real scalar.
Data Types: single | double
Output Arguments
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y — Frequency modulated output signal
scalar | vector | matrix | 3-D array
Frequency modulated signal, returned as a scalar, vector, matrix, or 3-D array.
Version History
Introduced before R2006a
See Also
Functions
Objects
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