Hello R. R.
It is my understanding that you want to encode a LDPC code with a rate of 1/3 and a length of less than 10,000. Additionally, you prefer not to use the 'dvbs2ldpc' function due to its default length.
To achieve this, you can utilize the 'ldpcQuasiCyclicMatrix' function, which takes two parameters: 'blockSize' and the matrix 'P'. The matrix 'P' is a (N – K)-by-N matrix, where N > K > 0. It is essential that the last N – K rows of the parity-check matrix are invertible in a Galois field of order 2.
Here, N represents the LDPC codeword block length, and K represents the number of information bits in the LDPC codeword.
For a 1/3 rate, N = 3*K and the value of 'blockSize' will depend on the length of the message.
Refer to the following links for detailed information and an example with 3/4 rate.
- https://www.mathworks.com/help/comm/ref/ldpcencoderconfig.html
- https://www.mathworks.com/help/comm/ref/ldpcquasicyclicmatrix.html
Hope this answer helps.
