Loop fault locator

Claim 2

Apparatus for locating telephone cable faults detectable as one or more impedance irregularities in a cable pair, said pair having input terminals, comprising: a return loss bridge haVing as a first leg thereof an impedance element approximating the characteristic impedance of said pair, and as a second leg thereof the impedance of said loop as seen across said terminals, means for generating a steady state cosine wave and for applying said wave to said bridge, means for periodically swept frequency modulating said steady state wave over a predetermined set of frequency ranges, thereby generating periodic time functions, means for determining the power spectra of said periodic functions, and means for identifying the frequencies of the maxima of said power spectra, said identified frequencies corresponding to distances along said pair of faults from said input terminals.

Claim 3

Apparatus for developing indicia of the distance of a telephone cable pair fault from a measuring point comprising: means for applying a sinusoidal test signal concurrently to said faulted pair and to a standard circuit having a preselected impedance characteristic the approximate equivalent of the faulted pair under test; means for repeatedly and substantially linearly varying the frequency of said test signal within a first predetermined frequency range, said range corresponding to the distances from said measuring point of the two ends of a first section of said faulted pair to be tested; means for receiving the return signal resulting from said applied test signal, and for generating a spectral analysis of said return signal to determine its power spectrum, the power spectrum maxima each connoting an impedance irregularity on said faulted pair occurring at a distance from said measuring point determined by the value of the corresponding said frequency.

Claim 4

Apparatus for developing indicia of the distance of a telephone cable pair fault from a measuring point comprising: means for applying a sinusoidal test signal concurrently to said faulted pair and to a standard circuit having a preselected impedance characteristic the approximate equivalent of the faulted pair under test; means for repeatedly and substantially linearly varying the frequency of said test signal within a first predetermined frequency range, said range corresponding to the distances from said measuring point of the two ends of a first section of said faulted pair to be tested; means for receiving the return signal resulting from said applied test signal, and for generating a spectral analysis of said return signal to determine its power spectrum, the power spectrum maxima each connoting an impedance irregularity on said faulted pair occurring at a distance from said measuring point determined by the value of the corresponding said frequency.

Claim 5

Apparatus pursuant to claim 2, further comprising means for repeatedly and substantially linearly varying the frequency of said sinusoidal test signal within each of a plurality of further predetermined frequency ranges, each of said further ranges corresponding to the distances from said measuring point of the ends of further sections of said faulted pair.

Claim 6

Apparatus pursuant to claim 3, wherein said predetermined frequency ranges overlap sufficiently to yield at least two indicia of the same impedance irregularity when said test signal is varied within said predetermined frequency ranges.

Claim 7

Apparatus pursuant to claim 4, further comprising means for multiplying said power spectrum by a monotonically increasing frequency function to compensate for the decrease in reflected amplitude of said return signal with increasing frequency of said frequency ranges.

Claim 8

Apparatus pursuant to claim 3, wherein all said frequency ranges have lower limits of not less than 10 kHz.