Abstract: A method for determining that a GPS receiver is located within a predetermined geofence volume. An embodiment of the invention includes the steps of receiving global positioning system signals from a plurality of GPS satellites; calculating a solution set of possible receiver positions from the global positioning signals; determining whether any portion of the solution set of receiver positions is within the geofence volume; and determining that the receiver is outside the geofence volume if no portion of the solution set of receiver positions is within the geofence volume. The concept of exclusion space is introduced and used in methods for determining the probability that a receiver is within a geofence volume.

Abstract: A method for supplying power from a battery pack includes monitoring an output voltage of a battery pack, where the battery pack comprises a number of fractions and determining whether the output voltage is below a predetermined threshold. The method further includes adding at least one fraction of the number of fractions to the output voltage, when the output voltage is below the predetermined threshold and removing the at least one fraction, if previously added, when the output voltage is no longer below the predetermined threshold.

Abstract: Particular implementations are particularly useful in providing a system in which the hardware is more easily upgradable and new hardware functionality may be added without adding any new physical hardware. Through placement of an FPGA closely associated with the CPU of a personal computer, the FPGA may be reconfigured to act as new hardware. A system for installing new virtual hardware involves loading firmware into memory associated with the FPGA and reconfiguring the FPGA through a microcontroller. Particular implementations include universal ports associated with the FPGA into which adapter plugs can be placed to quickly adapt to any device that may be added through the virtual hardware use of the FPGA. Other implementations include high density connectors into which a plurality of ports of varying configurations may be plugged for connection of external electronic equipment through the FPGA.

Abstract: A method of acquiring signals from satellites in a Global Positioning System (GPS) is disclosed.

Abstract: A detector for detecting cargo in a container has a controller block, a transmitter for transmitting light into the field of view, a receiver for receiving reflected light, and a threshold comparator for determining whether the received light meets a threshold for cargo detection. The receiver includes a DC block for removing effects of ambient light. The detector performs detection multiple times and averages the results, which can be compared with a previously stored condition of cargo presence or absence to increase the detection accuracy further.

Abstract: A method for improving long-term blockage recovery of a communications signal is disclosed. The method includes monitoring a blockage source using at least one application specific-sensor. Time spent in the blockage source is ascertained. Information obtained from the application-specific sensor may be combined with the ascertained time spent in the blockage source to predict a likely blockage recovery time interval.

Abstract: A two-way satellite communications system includes an Earth station communicating with a plurality of remote terminals using a network access protocol that facilitates low power consumption by the terminals. The earth station generates forward link TDM packet data transmissions on one or-more satellite channels, and detects, despreads and decodes multiple concurrent return link slotted CDMA packet transmissions on one or more satellite channels. It communicates through a wired connection with a packet processing center which ultimately both delivers return link packet data to end-customers and receives forward link packet data from end-customers. The remote terminals receive, process and act upon forward link TDM transmissions on one or more satellite channels, and generate slotted spread spectrum CDMA transmissions on the return link on one or more satellite channels.

Abstract: A method is disclosed for tracking the phase of a received phase-modulated carrier carrying a sequence of symbols represented by phase jumps in a low signal-to-noise ratio environment. An input sequence of symbols stored in a delay line. The phase of a current symbol in a phase locked loop, and the phase error detected in the phase locked loop is updated to take into account phase error estimates of future symbols.

Abstract: A circularly polarized patch antenna for wireless communication devices is disclosed. The circularly polarized patch antenna includes a conductive ground plane positioned parallel to a multi-layer resonator with both disposed in a dielectric substrate. The multi-layer resonator may include top and middle conductive layers with meandering between layers. A plurality of slots may be interposed intermittently spanning the top and middle conductive layers. The meandering may be integrated with the slots. The circularly polarized patch antenna may be realized as a multi-layer printed circuit board.

Abstract: A packet data communication system includes a control station and a plurality of mobile terminals that communicate on demand with the control station over a wireless link. The control station has a data port for receiving data packtets destined for the terminals, an arrangement for generating a plurality of data channels for carrying the data packets, and an arrangement for assigning the data packets destined for a particular terminal to one or more of the data channels. A control channel carries control information pertaining to the data channels. The channels are trasmitted to the mobile terminals as an r.f. signal. The terminals have a receiver for receiving the r.f. signal, an analog-to-digital converter for digitizing the received signal, and a buffer for storing the digitized received signal. The terminals continually monitor the control channel to extract control information.