| 摘要 |
701,492. Cross-talk measurements. COMPAGNIE GENERALE D'ELECTRICITE. July 14, 1952 [July 20, 1951], No. 17703/52. Class 37 In order to measure the cross-talk between two circuits, an alternating voltage is applied to one of the circuits and a cathode-ray oscillograph is arranged so that it can be connected either to the input of this circuit, through a calibrated adjustable attenuator, or to either end of the other circuit. An adjustable frequency generator 1 supplies a sinusoidal voltage to a limiter 2, the output of which is applied through an amplifier 3 to the near end A of the disturbing circuit 4, which is terminated at it far end B by a balancing device 12. The output of the amplifier 3 is also connected to a calibrated network 5, giving an adjustable attenuation, which can be connected through a two-way switch 8 and an amplifier 7 to the deflecting plates of a cathode ray oscillograph 9. The disturbed circuit 6 is closed at its ends A, B by balancing devices 14, 13 adjusted to its characteristic impedance. A time-base 11 supplied by a fraction of the voltage of the generator 1 provides the horizontal sweeps of the oscillograph. A device 10 connected to the Wehmelt cylinder of the oscillograph 9 eliminates the negative half-cycles of the voltage. For measuring far-end cross-talk the end B of the disturbed circuit 6 is connected through the balancing device 14, switch 8, and amplifier 7 to the oscillograph 9 and the peak voltage observed on the screen. The switch 8 is then changed over to connect the attenuator 5 to the amplifier 7 and the attenuator is adjusted until the same peak voltage is produced, the cross-talk being obtained from the reading of the attenuator. To measure near-end crosstalk the near end A of the circuit 6 is connected to the balancing device 14 and a similar measurement is made. The position of voltage peaks on the screen enables the distance from the end A of fault couplings between the circuits 4, 6 to be obtained. |
