ammod

Amplitude modulation

Syntax

y = ammod(x,Fc,Fs)

y = ammod(x,Fc,Fs,ini_phase)

y = ammod(x,Fc,Fs,ini_phase,carramp)

Description

y = ammod(x,Fc,Fs) returns an amplitude modulated (AM) signal y, given the input message signal x, where the carrier signal has frequency Fc. The carrier signal and x have a sampling frequency Fs. The modulated signal has zero initial phase and zero carrier amplitude, so the result is suppressed-carrier modulation.

Note

The value of Fs must satisfy Fs ≥ 2Fc.

example

y = ammod(x,Fc,Fs,ini_phase) specifies the initial phase in the modulated signal y in radians.

y = ammod(x,Fc,Fs,ini_phase,carramp) performs transmitted-carrier modulation instead of suppressed-carrier modulation where carramp is the carrier amplitude of the modulated signal.

Examples

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Compare Double-Sideband and Single-Sideband Amplitude Modulation

Open Live Script

Set the sample rate to 100 Hz. Create a time vector 100 seconds long.

fs = 100;
t = (0:1/fs:100)';

Set the carrier frequency to 10 Hz. Generate a sinusoidal signal.

fc = 10; 
x = sin(2*pi*t);

Modulate x using single- and double-sideband AM.

doubleY = ammod(x,fc,fs);
singleY = ssbmod(x,fc,fs);

Create a spectrum analyzer object to plot the spectrum of the signals.

sadsb = spectrumAnalyzer( ...
    SampleRate=fs, ...
    PlotAsTwoSidedSpectrum=false, ...
    YLimits=[-60 30]);
sadsb(doubleY,singleY)

Plot of the spectrum of signals on a spectrum analyzer. The X-axis is the frequency in hertz and the Y-axis is the power in decibels per meter.

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.