IMPROVED METHOD FOR DETERMINING SUBSCRIBER LOOP MAKE-UP

摘要

A method and circuitry for comparing simulations (1718) of a subscriber loop (1776) to acquired waveforms (1731). The method consists of analyzing the echo responses (1764) generated by the transmittal of pulses onto the subscriber loop. A slowly decaying signal caused by the inductive effect is removed (1713) from the echo signal. A simulated waveform (1717) is compared to the actual echo signal. By the method a discontinuity is identified in the frequency domain (1731), the time domain signal representing each discontinuity is then obtained via an inverse fast Fourier transform and subtracted (1750) from the acquired data. The remaining data is then processed similarly (1750) as the method moves from the first discontinuity (1714) located nearest to a detector to the last discontinuity located farthest from the dectector. The circuitry consists of an arrangement for calculating the difference between the responses on two branches of the loop. By use of this differential probing circuitry the echo response is captured and used in determining gauge and discontinuities.