On the distortion of the rising edge of a carrier-free signal

The 1D problem related to the distortion of the rising edge of a carrier-free signal, which arise abruptly at the starting point, is examined. It is demonstrated that, in propagation through an arbitrary (including, absorbing) medium, the signal's rising edge is not distorted and moves exactly with the speed of light in vacuum. Signals are revealed to attenuate with growing path length. Such attenuation occurs due to shortening of the time interval on which the rising part of the signal continues to hold its initial value without a decrease in its initial amplitude. The given time interval has been estimated.