 The pulse appears later and later at successive points on 2.2.9 Waveform distortion and the line because it takes time to travel over any distance, i.e. there is a propagation delay. As the line is uniform frequency dispersion throughout its length, the amount of delay at any point is proportional to distance between that point and the 2.2.9.1 Amplitude distortion source of the pulse. These time delays are shown as t1, t2, and t3 in Figure 2.2-11. Another way of describing this is The waveform of the pulse in Figure 2.2-11 alters as it to say that the pulse propagates along the line with travels along the line. This shape alteration is caused by a uniform velocity. the line constants (inductance, capacitance, resistance and conductance of the line) affecting each sinusoidal component of the waveform in a different manner. The 2.2.8.3 Attenuation high frequency components, which predominate on the edges of the pulse waveform, suffer greater attenuation The amplitude of the pulse is attenuated as it propagates because of increased reactive effects; the lower fre- down the line because of resistive losses in the wires. The quency components, which predominate on the flat amount of attenuation per unit length is uniform portion of the waveform, suffer less attenuation. The throughout the line because the line cross-section is variation of attenuation with frequency is described by uniform throughout the line length. Uniform attenuation the frequency response of the line. means that the fractional reduction in pulse amplitude is the same on any line section of a given length. This is more easily understood by referring to Figure 2.2-11, 2.2.9.2 Frequency distortion where the pulse amplitude at plane 1 has been reduced by a factor of 0.8. At plane 2, which is twice as far from In addition to attenuation, there are also time constants the source as plane 1, the pulse height has been reduced associated with the line components (inductance, capaci- by a further factor of 0.8, i.e. a total of 0.82 or 0.64 of its tance, re