Power-limited remote termination converter with wetting current and emergency power operation for digital data transmission equipment

A method of operating digital terminal equipment, which is coupled to a communication link, and is operative to conduct digital communications over said communication link, said communication link being powered by way of a telecommunication facility that is remote with respect to said digital terminal equipment, said method comprising the steps of:

• (a) for a first, normal mode of operation of a local power source, deriving power for operating said digital terminal equipment from said local power source, so that said digital terminal equipment may conduct digital communications over said communication link;
• (b) for a second, abnormal mode of operation of said local power source in which power from said local power source is insufficient to operate said digital terminal equipment, maintaining operation of said digital terminal equipment, so that said digital terminal equipment may continue to conduct digital communications over said communication link, by deriving power for operating said digital terminal equipment from said communication link, and limiting said power derived from said communication link to no more than a prescribed limited amount of power.

An apparatus for operating digital terminal equipment, which is coupled to and is operative to conduct digital communications over a communication link, said communication link being powered by way of a telecommunication facility that is remote with respect to said digital communication terminal equipment, said apparatus comprising:

• a first power coupling circuit, which is operative, for a first, normal mode of operation of a local power source, to derive power for operating said digital terminal equipment, from said local power source, so that said digital terminal equipment may conduct digital communications over said communication link;
• and
• a second power coupling circuit, which is operative, for a second, abnormal mode of operation of said local power source in which power from said local power source is insufficient to operate said digital terminal equipment, to maintain operation of said digital terminal equipment, so that said digital terminal equipment may continue to conduct digital communications over said communication link, by deriving power for said digital terminal equipment from said communication link, and limiting said power derived from said communication link to no more than a prescribed limited amount of power.