NAVSIM is a comprehensive Monte Carlo simulation of a Global Positioning System (GPS) and Inertial Measurement Unit (IMU) integrated navigation system. It is an analytical tool for use as an aid to system configuration selection, system tuning, sensor tradeoff studies, scenario preparation and performance analysis.

The software enables evaluation of the total system performance under simulated conditions using robust modeling for user vehicle motion, satellite constellation, GPS receivers, inertial platforms, other navigation sensors (Doppler, radar beacons, altimeters, etc.) and multi-mode Kalman filters.

NAVSIM was designed and documented using the DeMarco structured methodology. Modular libraries are used to adapt NAVSIM to individual computers and operating systems. These design features make NAVSIM easy to support and modify for specific needs.