Abstract: The present invention provides a method and apparatus to detect a missing micro-filter. In embodiments, the detection is performed by measuring the distortion caused by an unfiltered telephone device using a SELT (Single Ended Line Test) technique. According to certain aspects, the signal used to perform the distortion measurement is designed such that it causes minimal impact on vectored lines within the same cable. Embodiments of the invention first determines the estimated loop length, then uses the loop length to select a set of signal parameters that will be used to perform the distortion measurement. The parameters to be selected include transmit frequency band and PSD level. According to further aspects, embodiments of the invention include automatically running a missing filter test immediately following a line drop to determine if the line drop was caused by a missing micro-filter.

Abstract: The present invention provides a method and apparatus to detect a missing micro-filter. In embodiments, the detection is performed by measuring the distortion caused by an unfiltered telephone device using a SELT (Single Ended Line Test) technique. According to certain aspects, the signal used to perform the distortion measurement is designed such that it causes minimal impact on vectored lines within the same cable. Embodiments of the invention first determines the estimated loop length, then uses the loop length to select a set of signal parameters that will be used to perform the distortion measurement. The parameters to be selected include transmit frequency band and PSD level. According to further aspects, embodiments of the invention include automatically running a missing filter test immediately following a line drop to determine if the line drop was caused by a missing micro-filter.