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Hamming Code Encode Error

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James Manns
James Manns am 30 Apr. 2024
Kommentiert: Walter Roberson am 30 Apr. 2024
How to correct the following error?
Unable to resolve the name 'comm.HammingEncoder'.
Error in Finalcomputerassignment (line 75)
enc = comm.HammingEncoder;
clc;
clear all;
% Load the 'lenna' image
lenna = imread('lenna.png');
% Convert the image to grayscale
lenna_gray = rgb2gray(lenna);
% Convert pixel values to bits
lenna_bits = reshape(de2bi(lenna_gray, 8, 'left-msb'), [], 1);
% Define Eb/No values for low and high SNR
Eb_No_low = 0;
Eb_No_high = 4;
% Modulate using BPSK
modulated_signal = pskmod(lenna_bits, 2);
% Calculate SNR values for low and high SNR, taking into account the noise power in BPSK
% For BPSK, the bit energy is the same as the symbol energy since there is one bit per symbol
SNR_low = Eb_No_low + 10*log10(1);
SNR_high = Eb_No_high + 10*log10(1);
% Transmit and receive at low SNR
received_low = awgn(modulated_signal, SNR_low, 'measured');
% Demodulate received signal at low SNR
demodulated_low = pskdemod(received_low, 2);
% Transmit and receive at high SNR
received_high = awgn(modulated_signal, SNR_high, 'measured');
% Demodulate received signal at high SNR
demodulated_high = pskdemod(received_high, 2);
% Reshape demodulated bits to original image size
szin = size(lenna_gray,1:2);
decoded_image_low = reshape(demodulated_low, [], 8);
decoded_image_low = uint8(bi2de(decoded_image_low, 'left-msb'));
decoded_image_low = reshape(decoded_image_low, szin);
decoded_image_high = reshape(demodulated_high, [], 8);
decoded_image_high = uint8(bi2de(decoded_image_high, 'left-msb'));
decoded_image_high = reshape(decoded_image_high, szin);
% Employ a linear error detection code (only detection and no correction)
% Calculate and display Bit Error Rate (BER)
ber_low = sum(abs(double(lenna_bits) - double(demodulated_low))) / length(lenna_bits);
ber_high = sum(abs(double(lenna_bits) - double(demodulated_high))) / length(lenna_bits);
fprintf('BER at low SNR (0 dB): %f\n', ber_low);
fprintf('BER at high SNR (4 dB): %f\n', ber_high);
% Plot original, received image at 0 dB SNR, and received image at 4 dB SNR
figure('Position', [100, 100, 1200, 400]);
% Original Image
subplot(1, 3, 1);
imshow(lenna_gray);
title('Original Image');
% Received Image at 0 dB SNR
subplot(1, 3, 2);
imshow(decoded_image_low);
title('Received Image (0 dB SNR)');
% Received Image at 4 dB SNR
subplot(1, 3, 3);
imshow(decoded_image_high);
title('Received Image (4 dB SNR)');
% Task 3: Use an error correction code using syndrome lookup table
% Error correction code
% Let's use a (7, 4) Hamming code
enc = comm.HammingEncoder;
dec = comm.HammingDecoder;
% Corrected images at 0 dB and 4 dB SNR
corrected_img_low = correct_image(received_signal_low, enc, dec);
corrected_img_high = correct_image(received_signal_high, enc, dec);
% Display corrected images
figure;
subplot(1,2,1);
imshow(corrected_img_low, []);
title('Corrected Image (0 dB SNR)');
subplot(1,2,2);
imshow(corrected_img_high, []);
title('Corrected Image (4 dB SNR)');
% Function to correct image using error correction code
function corrected_img = correct_image(received_signal, enc, dec)
% BPSK demodulation
demodulated_bits = sign(received_signal);
% Perform error detection and correction
detected_bits = step(dec, demodulated_bits);
% Convert bits back to image
corrected_img = reshape((detected_bits + 1) / 2, 8, []).';
end

Akzeptierte Antwort

Walter Roberson
Walter Roberson am 30 Apr. 2024
comm.HammingEncoder is old MATLAB (some point before R2019a).
  2 Kommentare
James Manns
James Manns am 30 Apr. 2024
Is there a better way to do error correction?

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