Detection of Branch Points by Modified FFT

This paper illustrates the existence of branch points in transients on lossy transmission lines and presents a technique of detecting branch points. By applying modified FFT to the transient signal and from the resulting amplitude and phase spectra, it is possible to detect and distinguish banch points from poles. Numerous examples are given to demonstrate the effectiveness of the modified FFT and the use of windowing in improving the detectability of a small branch point under the influence of a nearby strong pole.