| 摘要 |
<p>Method and apparatus for determining the location of a break in a pair of wires of a multi-wire cable (101) are disclosed. The apparatus comprises means for shorting one wire (K) of a given pair (J&K) and all other wires (M) in a cable (101) to ground; an AC current source (201) for connection across the wires of such a given pair (J&K) to produce an AC voltage across such a given pair (J&K); a multiplier (203) for multiplying the voltage produced across such a given pair (J&K) by a second AC signal, which is in a quadrature phase relationship to the AC current source to form a product signal; and means (204, 205 and 206) for comparing the DC component of the product signal to a reference signal, said reference signal having a value which is inversely proportional to the capacitance of an unbroken pair. The comparison means preferably comprises a filter (204) for extracting from the product signal the DC component; an analog-to-digital converter (205) for digitizing the DC component of the product signal; and an arithmetic logic unit (206) for comparing the digitized DC component of the product signal to the reference signal.</p> |
