Abstract: Method and apparatus for alternately providing positive and negative direct current voltages to a single twisted pair includes a power source configured to provide a first signal and a second signal, the first and second signals having different polarities, a controller configured to provide a control signal in accordance with a predetermined timing signal, and a voltage alternating switch circuit having first and second output terminals, the voltage alternating switch circuit coupled to the power source configured to receive the first and second signals, the voltage alternating switch circuit further coupled to the controller configured to receive the control signal, and in accordance thereto, providing first and second signals alternately to first and second output terminals, such that the adverse corrosive effect of positive voltage line powering is minimized.

Abstract: High-speed digital transmission can be achieved with existing phone lines and HDSL chipsets while retaining plain old telephone service (POTS) with full failsafe capability. One original digital data signal ?4! at a rate of at least 352 kbps and typical 384 kbps and one POTS channel ?10! digitized at 64 kbps are multiplexed by a HPCS card ?6! of a signal provider ?1!. The resulting digital signal is transported over a twisted based on the current technology. At a receiving end, the signal is demultiplexed and regenerated by a subscriber's HPCS card ?7!. The subscriber's HPCS card is line-powered via the cable ?2! to avoid dependence upon local power. The regenerated signals are transmitted over one POTS line ?42! and one data line ?8! to or within a remote premise. Both HPCS cards have bypass relays for the POTS line to ensure the subscriber's POTS access in the event of a local power outage or electronic failure.