Abstract: Approximate answers to queries are provided by executing queries against a representation of a data source in addition to, or in lieu of accessing the source data itself. A representation of a data source, referred to herein as an Information Reservoir, is constructed and maintained using probabilistic methodologies based upon a Poisson sampling approach. The Information Reservoir provides approximate answers to ad hoc queries, potentially in a small fraction of the time required to calculate an exact answer. Associated variances are also provided that may additionally be used to calculate confidence intervals bounding the exact answer. An Information Reservoir may be biased toward a subset of the information in the original data source and/or tailored to the anticipated query workload. Queries expressed as if directed to the original data source may be automatically translated to run against the Information Reservoir with little or no additional burden placed on the Information Reservoir user.

Abstract: A geographic pointing device that includes a GPS receiver, a digital compass and informational databases. When a user activates the device, the user's position and direction are displayed on a displayed map, as the user travels, the map and direction are continually updated to reflect the movement. Geographically encoded information concerning points of interest is displayed on the map in response to user preferences.

Abstract: A line protector for a communications circuit provides at least overvoltage protection. The overvoltage protection is effected through a solid state arrester such as a diode. As the solid state arrester is not as long as the carbon electrode type or gas tube arrester which it replaces, the line protector includes a conductive pedestal. The end of the pedestal adjacent to the solid state arrester is shaped to receive one electrode of the arrester, while the other end of the pedestal is shaped to provide a good contact to the grounding circuit of the protector.

Abstract: A line protector for a communications circuit. The line protector has an overvoltage arrestor such as a three electrode gas tube, two of whose electrodes are connected to the line input terminals of the protector by associated conductive elements projecting from the protector base. The third electrode is connected to the ground terminal. The line protector also has two positive temperature coefficient resistors (PTCRs) which protect against marginal overcurrents. Conductive elements connected to the line protector's equipment terminals also project from the base in the same direction as the line input terminal conductive elements project. Each PTCR is in contact with an associated one of the two line input terminal conductive elements and an associated one of the two equipment terminal conductive elements.

Abstract: An overvoltage protector for use with data cables. The protector is connected between the data cable and the piece of equipment to which the data cable is ordinarily connected. The equipment has a chassis ground. The protector includes first and second connectors for connection to the equipment and data cable, respectively as well as a protection circuit and a ground plane. The protection circuit is connected between the data cable connector, the equipment connector and the ground plane. The ground plane is in electrical connection with the conductive shell of the equipment connector. The protector is designed such that the ground plane is brought into electrical connection with the chassis ground when the protector is connected between the data cable and the equipment.