Decode and recover message from RS codeword
This example shows how to use RS Decoder block to decode and recover a message from a Reed-Solomon (RS) codeword. In this example, a set of random inputs are generated and provided to the comm.RSEncoder function and its output is provided to the RS Decoder block. The output of the RS Decoder block is compared with the input of the comm.RSEncoder function to check whether any errors are encountered. The example model supports HDL code generation for the RS Decoder subsystem.
Set up input data parameters
n = 255; k = 239; primPoly = [1 0 0 0 1 1 1 0 1]; B = 1; nMessages = 4; data = zeros(k,nMessages); inputMsg = (zeros(n,nMessages)); startSig = []; endSig = [];
Generate random input samples
Generate random samples based on n,k, and m values and provide them as input to the comm.RSEncoder function. Here, n is the codeword length, k is the message length, and m is the gap between the frames.
hRSEnc = comm.RSEncoder; hRSEnc.CodewordLength = n; hRSEnc.MessageLength = k; m=0; for ii = 1:nMessages data(:,ii) = randi([0 n],k,1); [inputMsg(1:n,ii)] = hRSEnc(data(:,ii)); inputMsg1(1:n,ii) = inputMsg(1:n,ii); [inputMsg(n+1:n+m,ii)] = zeros(m,1); validIn(1:n,ii) = true; validIn(n+1:n+m) = false; endSig = [endSig [false(n-1,1); true;false(m,1);]]; startSig = [startSig [true;false(n+m-1,1)]]; end refOutput = data(:);
Import the encoded random input samples to the Simulink® model
The output of the comm.RSEncoder function is provided as input to the Simulink block.
simDataIn = inputMsg(:); simStartIn = startSig(:); simEndIn = endSig(:); simValidIn = validIn(:);
Run the Simulink model
modelname = 'RSDecoder';
open_system(modelname);
out = sim(modelname);
Export the decodes samples of the Simulink block to the MATLAB® workspace.
simOutput = out.dataOut(out.validOut);
Compare the output of the Simulink block with the inputs provided to the comm.RSEncoder function
fprintf('\nHDL RS Decoder\n'); difference = double(simOutput) - double(refOutput); fprintf('\nTotal number of samples differed between Simulink block output and MATLAB function output is: %d \n',sum(difference));
HDL RS Decoder Total number of samples differed between Simulink block output and MATLAB function output is: 0