The input pulse to a cable usually appears as in this model. There are three components to this pulse: Amplitude (or pulse height) refers to the voltage magnitude of the pulse. It is measured in volts in the vertical axis denoted ‘A’. Rise time (or pulse ‘turn-on’ time) refers to the length of time it takes the pulse to make the transition from the low or ‘off’ state to the high or ‘on’ state. Rise time (TR) is measured in the horizontal direction and expressed in nanoseconds. Width (w) (or duration) refers to the length of time a pulse remains in the high or on position. It is also measured in the horizontal direction and expressed in nanoseconds. As this input pulse travels down a length of cable, the three components will change.