Analysis of Collided Signal Waveform on the Long Transmission Line of UART-CSMA/CD Control Network

In this paper, waveforms of collided digital signal bits are analyzed by superposition of step responses of a distributed constant circuit for a transmission line. Our analysis indicates narrow voltage spike on the leading edge of bit pulses in collided waveforms. The width and peak of the spike calculated by our analysis were matched with those of experiments. Since the spike might cause signal collision detection failure and cause deterioration of communication performance, our analysis is effective to estimate the allowable maximum length and/or bit rate of a transmission line for control communication network.