Frequency-modulation distortion in linear networks. With special application to minimum-phase-type networks

The problem of distortion of frequency-modulated waves by 4-terminal linear passive networks has become of increasing importance with the development of multi-channel f.m. communication systems. The paper surveys the somewhat confusing historical background of this subject and after discussion of some essential basic concepts presents a detailed analysis of the problem of small-order distortion. An attempt has been made, using the work of Medhurst,1 to present the results in a form suitable for computer programming. Special attention is given to networks which satisfy the minimum-phase condition, because thereby distortion becomes expressible in terms of the amplitude response alone. The results show in a visual yet quantitative manner the error involved in the use of the quasistationary solution.