Abstract: Determining that a slope of test values resulting from two test conditions being applied to a remote device via a network connection and a reference circuit is within a predetermined range, and applying full power to the remote device if the slope is within the predetermined range. The determination using the slope reduces the effects of voltage drop variation caused by diodes and leakage of current by transistors in the remote device. The determination is performed by first applying a first reference voltage to both the remote device and reference circuit and storing the resulting two voltages. Next, a second reference voltage is applied to both the remote device and reference circuit and the resulting two voltages are stored. A first difference is calculated from the two voltages resulting from the testing of the remote device, and a second difference is calculated from the two voltages resulting from the testing of the reference circuit.

Abstract: Determining that a slope of test values resulting from two test conditions being applied to a remote device via a network connection and a reference circuit is within a predetermined range, and applying full power to the remote device if the slope is within the predetermined range. The determination using the slope reduces the effects of voltage drop variation caused by diodes and leakage of current by transistors in the remote device. The determination is performed by first applying a first reference voltage to both the remote device and reference circuit and storing the resulting two voltages. Next, a second reference voltage is applied to both the remote device and reference circuit and the resulting two voltages are stored. A first difference is calculated from the two voltages resulting from the testing of the remote device, and a second difference is calculated from the two voltages resulting from the testing of the reference circuit.

Abstract: This specification discloses a telephone conferencing arrangement employed with a plurality of conference interface ports in a time division multiplex (TDM), private branch exchange (PBX). Each port receives from the PBX the TDM conference signal of a respectively associated conferee and transmits an analog version of the conference signal to the conferencing system. Conferencing is achieved by combining the analog conference signals into a plurality of composite signals which are subsequently recombined via resistance-value related conductive paths with the uncombined analog conference signals in selectable transmission phases and amplitudes so as to provide at the receiving terminal of each conference interface port a composite signal comprised of the selectably phased conference signals transmitted by the other conference interface ports.

Abstract: A lamp rate generator is disclosed which generates signals for controlling the illumination of key lamps at key telephone sets so that they may be illuminated at wink or flash rates. In addition, a "zero-crossing" signal is generated to determine the onset of conduction in a PNPN switch in the ungrounded side of the lamp power lead to ensure that the rise time of current delivered to the lamp load shall follow the rectified ac waveform of the power source. The circuit is most advantageously employed in time division PBXs which must be rendered secure against transient noise signals that could be induced by current surges having steep wave fronts.