Efficient double asymmetric error correcting codes

Two constructions for double-asymmetric-error-correcting codes are given. These codes offer some desirable properties for optical communication, where it is important that most codewords have small weights. The first construction gives a subset of a double-error-correcting BCH code. The code offers considerable improvement in the weight distribution at the expense of one extra bit of redundancy (in almost all cases) over the BCH code. The code is semisystematic and has the same degree of encoding/decoding complexity as the BCH code. The second construction is completely systematic and has twice the information rate as the BCH code in several cases. This code is easy to encode and decode and has fewer 1s than 0s