Abstract: Method and apparatus for generating a bandlimited square waveform for use as a ringing voltage in a telephone network is described. One embodiment comprises a method of generating a ringing voltage signal for transmission to a telephone device. The method comprises calculating a truncated Fourier series representation of a square wave using only low order harmonic frequencies thereof; determining a sampling rate; generating digital sample data using the truncated Fourier series representation and the sampling rate; and converting the digital sample data to an analog signal.

Abstract: In one embodiment, an overvoltage protection circuit is disclosed for decoupling a voltage source available at a Subscriber Line Interface circuit (SLIC) from a subscriber loop line conductor when the voltage source is shorted to the conductor in a non-ringing condition. In another embodiment, a multi-point protection apparatus is provided for protecting a SLIC against transients having different levels.

Abstract: A system for holding small objects such as flashlights, containers of liquids for intravenous dispensing, tools, clamps, containers, receptacles, fishing rods, cooking utensils and the like. A bracket that attaches to an elongated prop such as an electrical conduit, pipe, railing, i.v. stand, wheel chair frame, stake, hospital bed guards, or post is disclosed. Bracket attachment is accomplished by placing the bracket perpendicularly over the prop and twisting the bracket ¼ turn. A variety of holders may be detachably attached to the bracket to enable a variety of objects to be held in a desired position. An interlocking, linked, positionable extension may be disposed between the bracket and the holder to enable the holder to be positioned as desired.

Abstract: Spiral inductors are provided on multiple internal layers of a printed circuit (PC) board and configured to form a filter. An external end of each of the spiral inductors can be coupled by a via to opening in ground planes provided on external surfaces of the PC board. Using such vias, the external end of each of the spiral inductors can be coupled by lumped elements, such as a capacitor, an inductor, or combination of capacitors and inductors to the ground planes to enable tuning of the filter after the PC board has been manufactured. Such lumped element components can further interconnect the external ends of two spiral inductors to provide alternate filter configurations which are easily tunable. Internal ends of the spiral inductors can also be connected together by a via to the ground planes to provide superb grounding due to limited line lengths between filter components and ground.

Abstract: A wireless data communications network utilizes a frequency synthesizer to achieve a systematic frequency hopping arrangement wherein frequency is incremented by two times the channel spacing from lowest frequency to highest frequency. When adjusting the frequency from highest frequency to lowest frequency a one times the channel spacing frequency hop is utilized for the first and half and last hop and two times the frequency spacing is utilized otherwise. In this manner, alternating frequencies are selected so that the same frequency is only utilized once during any complete cycle and the size of frequency transitions is held to a minimum allowing a narrow bandwidth filter and inexpensive implementation of the phase locked loop portion of the synthesizer.