GPS user equipment has matured and is now available to support the use of live players in networked live/constructive/virtual wargaming simulations. GPS provides true WGS-84 based coordinate information anywhere in the world at any time and to accuracies at the 5 ft (1s) level (demonstrated in high dynamic aircraft using differential GPS).

In supporting DIS-based hybrid live/constructive/virtual networked team training, GPS is directly applicable to the dead reckoning requirements of DIS. The on-board state vector for an integrated GPS/Inertial Reference Unit provides accurate position, velocity and acceleration as well as attitude and attitude rate information so that dead reckoning thresholds can be both position and attitude driven. A simplified analysis is presented in the paper to derive dead reckoning update rates from the G loading levels of various player dynamics. Also, information is provided which results in word length requirements for GPS-based state vector information for transmission over minimum word length DIS Field Instrumentation Protocol Data Units (PDUs, which are the data block formats). The coordinate frame problem in use of GPS-based state vector information from fixed ranges is also addressed, showing that the use of a local geodetic frame is preferable to the use of an earth centered earth fixed frame, in that it is more efficient of network PDU word length. Weapon scoring requirements using GPS-based state vectors are addressed in terms of GPS state vector accuracy required to score various weapons and provide "positive training". These requirements are all applicable to the JTCTS and NGTCS programs which are in the formative stages and will use GPS-based information in DIS Field Instrumentation PDUs.

Results are presented of a combined Northrop/IEC demonstration using the China Lake RAJPO GPS assets linked into a DIS demo for I/ITSEC in November 1993.

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R. Jarrell