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BPSK

The document outlines a MATLAB script for BPSK (Binary Phase Shift Keying) modulation and demodulation, including the generation of a carrier signal and the addition of AWGN (Additive White Gaussian Noise) to simulate transmission. It calculates the Bit Error Rate (BER) across various SNR (Signal-to-Noise Ratio) levels and visualizes the results through plots. The script also demonstrates the demodulation process and the effect of noise on the transmitted signal.

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touuot0712
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7 views3 pages

BPSK

The document outlines a MATLAB script for BPSK (Binary Phase Shift Keying) modulation and demodulation, including the generation of a carrier signal and the addition of AWGN (Additive White Gaussian Noise) to simulate transmission. It calculates the Bit Error Rate (BER) across various SNR (Signal-to-Noise Ratio) levels and visualizes the results through plots. The script also demonstrates the demodulation process and the effect of noise on the transmitted signal.

Uploaded by

touuot0712
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Download as PDF, TXT or read online on Scribd
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%DECODING

clc; clear all ;close all ; de=[];


b=[1 1 0 1 0 0 1 1 0 1]; for i =1:length(b)
b1=[b,b(length(b))]; k=sum(demod(1+(i-1)*length(t):i*length(t)));
nc=3; if k>0
Tb=1; de=[de,ones(1,length(t))];
fc=nc/Tb; else
fs=100; de=[de,zeros(1,length(t))];
t=linspace(0,1,fs); end
length(t) end
%carrier signal figure;
c_t=sin(2*pi*fc*t); plot(de,'LineWidth',2)
figure ; title('Demodulated signal');
plot(t,c_t) xlabel('Time (s)');
title('Carrier signal'); ylabel('Amplitude');
xlabel('Time (s)'); grid on;
ylabel('Amplitude'); %% BIT ERROR RATE
grid on; N = 1e6;
SNR_dB = 0:1:15;
BER = zeros(1, length(SNR_dB));
%BPSK data = randi([0 1], 1, N);
s_t=[]; bpsk_signal = 2*data - 1
for i =1:length(b) for snr_idx = 1:length(SNR_dB)
if b(i)==1 % Add AWGN to the BPSK signal for the given SNR
s_t=[s_t,c_t]; snr = SNR_dB(snr_idx);
else noisy_signal = awgn(bpsk_signal, snr, 'measured');
s_t=[s_t,-c_t]; % BPSK Demodulation (Detect positive as 1 and negative
end as 0)
end received_bits = noisy_signal > 0;
length(s_t) % Calculate Bit Error Rate (BER)
figure; num_errors = sum(data ~= received_bits); % Count bit
subplot(2,1,2) errors
t1=linspace(0,10,1000); BER(snr_idx) = num_errors/N; % BER for this SNR
plot(t1,s_t) end
title('BPSK signal');
xlabel('Time (s)'); % Plot BER vs SNR
ylabel('Amplitude'); figure;
grid on; semilogy(SNR_dB, BER, 'b-o', 'LineWidth', 2);
subplot(2,1,1) xlabel('SNR (dB)');
stairs(0:1:10,b1,'LineWidth',2) ylabel('Bit Error Rate (BER)');
title('BINARY DATA'); title('BER vs SNR for BPSK in AWGN Channel');
xlabel('Time (s)'); grid on;
ylabel('Amplitude');
grid on;
%Channel transmission
snr=15;
ch_t=awgn(s_t,snr,"measured");
figure;
plot(t1,ch_t)
title('Transmitted signal');
xlabel('Time (s)');
ylabel('Amplitude');
grid on;
%demodulation
c2_t=sin(2*pi*fc*t1);
demod=ch_t.*c2_t;
figure;
plot(t1,demod)
title('demod')
xlabel('Time (s)');
ylabel('Amplitude');
grid on;

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