Comments on `Orthogonal convolutional coding for the PPM optical channel´ by G.E. Atkin and H.P. Corrales

In a recent paper by G.E. Atkin and H.P. Corrales (ibid., vol.7, no.4, p.731-4, 1989) Viterbi´s orthogonal convolutional coding scheme is suggested for efficient communication on Pierce´s noiseless PPM optical channel. It is pointed out that the performance curves presented there erroneously correspond to a code rate of unity. If the correct code rate of 1/k is used (assuming 2^k-array PPM), the orthogonal convolutional codes are seen to be inferior for the proposed application. A reply by the authors of the original paper is given in the form of a correction (ibid., vo.8, no.6, p.1007-8)