Abstract: Systems and methods are disclosed for determining characteristics of a communications medium, such as a subscriber loop. In one embodiment, a system is disclosed to determine at least one characteristic associated with a subscriber loop. The system includes memory that stores data indicative of signal responses and loop characteristics for a plurality of loop configurations. A processor is programmed to ascertain at least one loop characteristic associated with the subscriber loop based on evaluation of data associated with a signal response received via the subscriber loop relative to at least a portion of the data indicative of signal responses stored in the memory.

Abstract: A multi-point communications system that is set forth herein. The communication system comprises a head end unit disposed at a primary site and a plurality of receivers disposed at remote sites. The head end unit includes a transmitter for transmitting OFDM/DMT symbols over a predetermined number of bins across a transmission medium. The OFDM/DMT symbols are transmitted in periodically occurring formatted symbol frames. The cyclic prefix includes a predetermined periodic signal superimposed thereon. The receivers receive the OFDM/DMT symbols over a subset of the predetermined number of bins from the transmission medium and use the superimposed signals to attain symbol alignment.