Precision Position, Navigation, and Timing without the Global Positioning System.

摘要

The NAVSTAR Global Positioning System (GPS) has revolutionized modern warfare. Since 2005 almost all US precision-guided munitions have used GPS targeting data. Consequently, weapons delivery systems are able to strike enemy targets with precision, often resulting in little or no collateral damage. Furthermore, nearly all military assets, including aircraft, tanks, ships, missiles, mortar rounds, cargo boxes, and dismounted Soldiers rely on the accurate position determination that GPS provides. For military users of this system, two main limitations emerge. First, the system relies on line of sight that is, the satellites must be in view of the receiver s antenna so that it can acquire the signals. This limitation is most pronounced indoors (including underground) and in urban areas, presenting significant navigational challenges for ground forces, remotely piloted aircraft, and precision munitions. Tall buildings in urban areas block satellites from view and create reflected or multipath signals, confusing GPS receivers. Indoors, GPS signals are present but greatly attenuated; as a result, ground forces operating under protective cover have difficulty obtaining a reliable GPS position.