GNSS Wristwatch Device for Networked Operations Supporting Location Based Services

摘要

The TIDGET/ZigBee wristwatch device was designed specifically to provide an ultra low-power, miniaturized wireless GPS tracking device. It includes a low-power GPS sensor, a flash memory, and a ZigBee wireless data link. The design of the device was selected to minimize the power drain to allow operation for extended periods of time. The power savings is accomplished by remoting the GPS signal processing from the sensor to the LocatorNet server. This has the advantage of minimizing the power drain within the TIDGET/ZigBee device while allowing sophisticated signal processing to be performed at the server to maximize the sensitivity of the GPS signal processing solution. The networked system architecture for relaying data between the tracking devices and the LocatorNet Server is illustrated in Figure 1. The ZigBee devices are programmed to search for a ZigBee Gateway that provides a connection to the Internet. Once a Gateway is found, the devices upload their GPS sensor data through the Gateway to the LocatorNet Portal for processing. This paper describes the LocatorNet system architecture and the design of the ZigBee Gateways. The ZigBee Gateways have been developed to be an add-on to a standard PC providing a low-cost, secure method of connecting ZigBee to the Portal through a variety of physical network connections including wired Ethernet for fixed connections or WLAN, cellular, or SATCOM services for mobile units.