Comments on "Bandwidth and spectra of phase-and-frequency-modulated waves"

The problem of the evaluation of RF spectra of waves frequency or phase modulated by random noise is of great importance in the design of trunk radio systems. The system designer is particularly interested in the tail region, from the point of view both of bandwidth requirements and of interference considerations. As a consequence, a considerable body of work has been published, and it is disheartening to the commentor to find that Dr. Abramson, in his above-named contribution [ibid., vol CS-11, Dec 1963, pi3 407-414], ignores virtually all the existing detailed treatments. Especially is this so in so far as one of the papers that might have been cited appeared in the same journal as did his own paper, not so very long ago. Spectrum evaluation in practical cases is liable to run into difficnlties, and Dr. Abramson´s paper gives, perhaps, a misleading impression as to the universal application of his approach.