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BFSK Exp-1

The document outlines an experiment to implement and analyze Binary Frequency Shift Keying (BFSK) modulation and demodulation using MATLAB/Simulink. It includes the aim, required apparatus, theoretical background, algorithm, MATLAB code, and results, indicating successful implementation with matching original and demodulated bits. The procedure involves generating a random binary sequence, modulating it with two frequencies, and demodulating it to recover the original data.

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singhanisha073
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81 views5 pages

BFSK Exp-1

The document outlines an experiment to implement and analyze Binary Frequency Shift Keying (BFSK) modulation and demodulation using MATLAB/Simulink. It includes the aim, required apparatus, theoretical background, algorithm, MATLAB code, and results, indicating successful implementation with matching original and demodulated bits. The procedure involves generating a random binary sequence, modulating it with two frequencies, and demodulating it to recover the original data.

Uploaded by

singhanisha073
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as PDF, TXT or read online on Scribd
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Experiment 3

1.Aim:

To implement and analyze Binary Frequency Shift Keying (BFSK) modulation and demodulation
using MATLAB/Simulink or any simulation tool.

2.Apparatus Required:
S.No Equipment/Software
1 MATLAB/Simulink
2 PC/Laptop

3.Theory:
Binary Frequency Shift Keying (BFSK) is a digital modulation scheme where two different carrier
frequencies represent binary '0' and '1'. The general BFSK signal is:

s(t)={Acos(2πf1t), for binary 1} S(t)={Acos(2πf2t),

for binary 0}

Where:

• A: Amplitude of the signal


• f1, f2: Frequencies representing binary 1 and 0
• t: Time

Demodulation is done using a bandpass filter or a correlator to detect the frequency


corresponding to each bit.

4.Algorithm / Procedure (MATLAB-based): Modulation:

• Generate a random binary sequence.


• Define carrier frequencies f1 and f2 for bits '1' and '0'.
• Create time vectors for bit duration.
• Modulate each bit using the respective frequency

Demodulation:
1. Multiply the received signal with both f1 and f2 carriers.
2. Use low-pass filters to extract the amplitude.
3. Compare both outputs to decide if bit is 0 or 1.

5.MATLAB Code:
clc;

clear; closeall;

%parameter

bit_rate = 10; % bits per second Tb =

1 / bit_rate; % bit duration fs = 1000;

% sampling frequency t_bit = 0:1/fs:Tb -

1/fs; % time vector for one bit f1 = 100;

% Frequency for binary 0 f2 = 200Lllll

% Frequency for binary 1

% Generate random binary data

data = randi([0, 1], 1, 10); disp('Original Data:');

disp(data); % Modulation modulated_signal = []; for


i = 1:length(data) if data(i) == 0 y = cos(2pif1t_bit);

else y = cos(2pif2t_bit); end modulated_signal =

[modulated_signal y]; end

% Time vector for entire signal t =

0:1/fs:(length(data)*Tb - 1/fs); %

Plot modulated signal figure;

plot(t, modulated_signal);

title('BFSK Modulated Signal');

xlabel('Time (s)');

ylabel('Amplitude'); grid on;

% === Coherent Demodulation === demodulated_data = zeros(1, length(data)); for i

= 1:length(data) segment = modulated_signal((i-1)length(t_bit)+1:ilength(t_bit));

t_local = t_bit;

% Correlation with both carriers corr_f1 =


sum(segment .* cos(2*pi*f1*t_local)); corr_f2 =
sum(segment .* cos(2*pi*f2*t_local));

% Decision based on maximum correlation


if corr_f1 > corr_f2
demodulated_data(i) = 0; else
demodulated_data(i) = 1; end

% Display demodulated data

disp('Demodulated Data:');

disp(demodulated_data); % Plot

comparison figure; stem(data, 'filled');

hold on; stem(demodulated_data, 'r');


legend('Original Data','Demodulated Data');

title('Original vs Demodulated Data');

xlabel('Bit Index'); ylabel('Bit Value'); grid

on;

6.Output:

8.Result:
8. Result:

The BFSK modulation and demodulation were successfully implemented. The


original and demodulated bits were compared and found to match, confirming
correct functionality.

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