Design of efficient second-order spectral-null codes

An efficient recursive method has been proposed for the encoding/decoding of second-order spectral-null codes, via concatenation by Tallini and Bose. However, this method requires the appending of one, two, or three extra bits to the information word, in order to make a balanced code, with the length being a multiple of 4; this introduces redundancy. Here, we introduce a new quasi-second-order spectral-null code with the length equiv 2 (mod 4) and extend the recursive method of Tallini and Bose, to achieve a higher code rate