Hamming Code Encode Error

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

Answer 1

[Walter Roberson]

comm.HammingEncoder is old MATLAB (some point before R2019a).

See https://www.mathworks.com/help/comm/ref/encode.html

[James Manns]

Is there a better way to do error correction?

[Walter Roberson]

@James Manns

Yes. https://www.mathworks.com/help/comm/error-detection-and-correction.html