Patent ID: 6795538
Filing Date: 2004-09-21
Classification: H04L,H04M

Abstract:
A bidirectional telephone delivery system for supporting a multiplicity of telephone subscriber lines at a downstream distribution terminal using only two of a multiplicity of pre-existing transmission line pairs connected between an upstream distribution terminal and said downstream distribution terminal and having automatic initialization and monitoring capabilities, comprising:two transmission line pairs extending between said upstream distribution terminal and said downstream terminal; said downstream distribution terminal comprising: DC power distribution circuitry for receiving power from said upstream distribution terminal on said pair of transmission line pairs and providing a DC power source in said downstream distribution terminal; downstream formatting circuitry for mapping a multiplicity of PCM formatted data packets into a standard communication format different than said standard PCM format for transmitting to said upstream distribution terminal on said two transmission line pairs; and a downstream pair of isolation transformers, each having downstream coils connected to said downstream formatting circuitry and upstream coils connected one each across one of said transmission line pairs; said upstream distribution terminal comprising: power circuitry for generating a source of regulated and current limited DC power and having a power output terminal and a return terminal; upstream formatting circuitry for receiving said PCM data packets from said downstream distribution terminal formatted in said different format and for reformatting in standard PCM format, said upstream formatting circuitry further for mapping a multiplicity of PCM formatted data packets into a standard communication format different than said PCM format, for transmitting to said downstream distribution terminal on two transmission line pairs; an upstream pair of isolation transformers, each of said pair having an upstream coil connected to said formatting circuitry and each having a downstream coil connected across one of said transmission line pairs, each of said downstream coils of said pair of transformers further being connected one each to said power output terminal and said return terminal of said power circuitry for providing DC power to said downstream distribution terminal; and initializing and monitoring circuitry for providing a predetermined sequence of steps for powering up and monitoring selected parameters of said system to assure proper operation before receiving and transmitting telephone communication data between said upstream terminal and said downstream terminal, said predetermined sequence of steps comprising transitioning to a waiting state after a first time duration of signal loss, said waiting state defining a second time duration greater than said first time duration, said second time duration selected to minimize noise cross-talk caused by power switching in said transmission line pairs.