. The Bell System technical journal . ranges A/ are subject to the phase distortion discussed in thepreceding paragraphs, that is, the original forms of the resultants aredelayed by times dB/doo, and then undergo a distortion that dependsupon the terms Bo or the intercepts of the straight lines with thevertical axis. As mentioned above it is convenient to regard these operations astaking place in sequence, the first introducing definite delays and nodistortion in portions of the original signal corresponding to frequencyranges A/, the second introducing a constant amount of phase shift in 554
. The Bell System technical journal . ranges A/ are subject to the phase distortion discussed in thepreceding paragraphs, that is, the original forms of the resultants aredelayed by times dB/doo, and then undergo a distortion that dependsupon the terms Bo or the intercepts of the straight lines with thevertical axis. As mentioned above it is convenient to regard these operations astaking place in sequence, the first introducing definite delays and nodistortion in portions of the original signal corresponding to frequencyranges A/, the second introducing a constant amount of phase shift in 554 BELL SYSTEM TECHNICAL JOURNAL the component waves of each delayed portion. Thus the first opera-tion spreads the wave out on a time scale, the part of the original wavecorresponding to the frequency range having the minimum slope ar-riving first and followed successively by portions corresponding to theremaining frequency ranges. The relative delay for a range A/ isgiven by the difference between the slope of the phase characteristic. -2Tr Fig. 2—A curved phase characteristic. in the range A/and the minimum slope. This difference or the expres-sion [{dB/doo)f — (dB/do))min\ is spoken of as the delay distortion. Thedelay distortion characteristic is simply a graph of the above expressionplotted against frequency. The second operation distorts the waveforms of the delayed portions corresponding to the frequency rangesA/, thus making it impossible to speak of the delay of the final or re-ceived portions or of the received wave as a whole. This may be described in other terms by saying that a network hav-ing a characteristic of the type shown in Fig. 2 may be thought of as if EFFECTS OF PHASE DISTORTION 555 it were made up of two sets of networks, the two sets being connected inseries. The first set consists of a number of networks in parallel, eachnetwork passing a frequency range A/ and having a phase characteristicof the form Bxw, where J5i is the slope of the straight line
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Keywords: ., bookcentury1900, bookdecade1920, booksubjecttechnology, bookyear1
