Multichannel operation is not supported.

i tried doing encoding and modulation using

enc = comm.LDPCEncoder;

bpskMod = comm.BPSKModulator('PhaseOffset',pi/2);

data = randi([0 1], 256, 8);

encodedData = enc(data);

shows error as

EError using LDPCEncoder/parenReference Multichannel operation is not supported.

i also tried using encodedData = enc(data.'); and it still show the same error.

please help. thank you.

Answer 1

[Satwik]

Hi Putri,

I understand that your code is giving an error when you try to encode a 256x8 binary matrix with a LDPCEncoder .The error message is "Multichannel operation is not supported."

For an LDPCEncoder the input data must be a single column matrix i.e. K x 1, hence the data should be

data = randi([0 1],K,1);

Unrecognized function or variable 'K'.

Where K is by default initialized as 32400. This default value comes from the of ParityCheckMatrix whose size is by default set to 32400 x 64800 sparse logical.

To change the value of K you need to change the size of ParityCheckMatrix itself.

enc.ParityCheckMatrix = sparse([eye(256) eye(256)]);

The above code will change the size of ParityCheckMatrix to 256 x 512 sparse logical.

Now you can make your data 256 x 1 size matrix.

Please look into the below code for reference:

enc = comm.LDPCEncoder;
% enc.ParityCheckMatrix  % If you want to see the default ParityCheckMatrix
bpskMod = comm.BPSKModulator('PhaseOffset',pi/2);
enc.ParityCheckMatrix = sparse([eye(256) eye(256)]);  % Can be changed to any size depending on your usecase
data = randi([0 1],256,1); % Data matrix should only have a single column
encodedData = enc(data);

Hope this helps!