Abstract: An apparatus for detecting Packet Energy Transfer (PET) in a cable is disclosed herein. The PET detecting apparatus includes an input adapted to generate a current by operative communication of the input with the cable, wherein the cable communicates PET as a pulse train. A spectral analyzer compares frequencies of maxima of the power spectrum of a signal derived from the current with a fundamental frequency of the pulse train and a harmonic frequency of the pulse train to detect PET in the cable. A power maximum of the power spectrum at the fundamental frequency and a second power maximum of the power spectrum at the harmonic frequency indicates PET in the cable. No power maximum of the power spectrum at the fundamental frequency or no second power maximum of the power spectrum at the harmonic frequency indicates no PET in the cable.

Abstract: A characteristic of a local loop is used to estimate the loop's data carrying capacity. The characteristic is measured and applied to a table previously stored in memory which contains values relating the characteristic to downstream data rates. Using interpolation when required, an estimate of the data carrying capacity of the local loop is estimated based on the measured characteristic. The measured characteristic may be, for example, the input impedance or the DC resistance of the local loop.

Abstract: A line isolation device (LID) for use in an ADSL system provides a single low pass filter that filters out the higher band ADSL signals for all of the Plain Old Telephone Services (POTS) terminal devices within a customer's premises. The LID may be easily added to an existing ADSL system by routing signals from a customer bridge through the LID. The LID has a low pass filter for removing the ADSL signals and also has a bypass path for carrying unfiltered ADSL and POTS signals to an ADSL transceiver unit. The filtered POTS signals are supplied back to the customer bridge and to binding posts on the customer bridge where all POTS terminal devices receive their POTS signals. The re-routing of the signals within the NID through the LID can be easily accomplished by disconnecting a testing jack on the customer bridge and routing the signals through the LID. Alternatively, the customer bridge may be completely removed from the NID and replaced with a customer bridge having an integral low pass filter.