# Frequency Modulation using Matlab

*From*: "Nitin" <indianitin@xxxxxxxxx>*Date*: 16 Mar 2006 18:21:44 -0800

HEllo All,

I am having one querry regarding MATLAB.

What I would be doing is that I will give the signal from a microphone

and I have to use MATLAB so that the signal gets frequency modulated

and then I will be taking the output from the headphone jack and mix it

with a carrier frequency [Local Oscillator] and send it to the spectrum

analyzer.I am doing a project named (Software Radio) where you have to

do the signal modulation using Software

So could some one help with the code I have written below

it is giving the error.

??? Error using ==> +

Matrix dimensions must agree..

Regards

Nitin

The Code is :

AI = analoginput('winsound');

addchannel(AI, 1);

Fs = 8000;% Sample Rate is 22050 Hz

set (AI, 'SampleRate', Fs)

d = 10; % 10 second acquisition

set(AI, 'SamplesPerTrigger', d*Fs);

start (AI);

data = getdata(AI);

n = Fs* d;

pause(5);

%plot (data);

%sound(data, Fs);

% set carrier characteristics

Fc = 1000; % carrier frequency (Hz)

c = (1:n) / Fs; % carrier data preparation

c = 2 * pi * Fc * c;

% set modulator

Fm = data; % modulator frequency (Hz)

mi = 0.5; % modulator index

m = (1:n) / Fs; % modulator data preparation

m = mi * cos(2 * pi * Fm * m); % sinusoidal modulation

% frequency modulation

s = sin(c + m); % frequency modulation

%sound presentation

sound(s, Fs); % sound presentation

%pause(d + 0.5); % wating for sound end

.

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