Patent ID: 7005862

Claim:
An apparatus for measuring electric characteristics of a cable assembly that is connected to the apparatus via a connecting unit, by outputting a predetermined frequency signal to the cable assembly, measuring an amplitude of reflection coefficient of the predetermined frequency signal, and calculating a propagation delay time of the cable assembly based on a time-dependent variation of the amplitude of reflection coefficient, the apparatus comprising: a reflection-coefficient measuring unit that measures the time-dependent variation of the amplitude of reflection coefficient in each of connection states including a first connection state in which a first connector with both terminals open-circuited is connected to the connecting unit; a second connection state in which one terminal of a second connector with other terminal short-circuited, having same propagation delay time as that of the first connector, is connected to the connecting unit; a third connection state in which one terminal of the cable assembly is connected to the connecting unit, and other terminal of the cable assembly is connected to the first connector; and a fourth connection state in which one terminal of the cable assembly is connected to the connecting unit, and other terminal of the cable assembly is connected to the second connector; and an output processing unit that visually outputs a superposition of the time-dependent variations of the amplitude of reflection coefficient in the first and the second connection states or a superposition of the time-dependent variations of the amplitude of reflection coefficient in the third and the fourth connection states; wherein a half of a time difference between a branch point of the time-dependent variations of the amplitude of reflection coefficient in the first and the second connection states and a branch point of the time-dependent variations of the amplitude of reflection coefficient in the third and the fourth connection states is obtained as the propagation delay time.