Abstract: A local positioning system uses at least one node to track a location of a mobile tag. The system measures flight times of signals communicated between the node and the tag to determine values indicative of the range of the tag from the node. If desired, the values may be filtered in an effort to increase the accuracy of the range estimation. As an example, a Kalman filtering algorithm may be used. Multiple antennas are used at both the node and the tag to provide more accurate range estimates and to determine when the tag is entering a dead zone where signals are blocked or attenuated by obstacles.

Abstract: A local positioning system uses at least one node to track a location of a mobile tag. The system measures flight times of signals communicated between the node and the tag to determine values indicative of the range of the tag from the node. If desired, the values may be filtered in an effort to increase the accuracy of the range estimation. As an example, a Kalman filtering algorithm may be used. Multiple antennas are used at both the node and the tag to provide more accurate range estimates and to determine when the tag is entering a dead zone where signals are blocked or attenuated by obstacles.

Abstract: A differential time domain digital communication bridge module interfaces 100 Mbps Ethernet traffic with a T3 communication link, using a relatively small sized data buffer. To avoid dropping packets, the relatively large sized buffer in the Ethernet switch is used to temporarily store packets, in when an upper threshold of the storage capacity of the buffer is reached. The upper threshold leaves enough storage overhead in the buffer to allow the Ethernet switch to complete its current transmission of a maximum length packet. When a lower threshold is reached a ‘resume transmission’ packet is sent to the switch. The lower threshold provides sufficient buffer space to allow the T3 transmitter to read out the contents of the buffer without underflow.