| 摘要 |
PURPOSE:To determine the value of circuit impedance relatively easil by measuring transmission loss of a transmission line consisting of balanced two lines inserted and connected between two lines by an oscillator and a level meter used for ordinary measurement. CONSTITUTION:To measure transmission loss in the circuit shown in the figure, a switching unit 9 is placed at position shown by solid lines, and an oscillator 6 is oscillated to measure the level by a level meter 7 provided at another end of a transmission line. Then, the switching unit 9 is switched to the position shown by dotted lines, and output of the oscillator 6 is sent to the level meter 7 through a base attenuator 8 to adjust the amount of attenuation to obtain the same level. Resultant reading of the attenuator 8 represents the transmission loss. When R0 represents impedance of the oscillator 6 and the level meter 7, and Z denotes equivalent impedance of subscriber's circuit 10 to be measured, transmission loss L is represented by L=¦R0/(2XZ)+1¦ to evaluate impedance Z by the L value. |
