The CAST-4000 produces GPS RF signals to stimulate either tightly or loosely-coupled GPS/INS navigation systems.

The system algorithms contain mature avionic sensor simulations for aiding. A strapdown Inertial Navigation System, Barometric Altimeter, Attitude Heading Reference System, Radar Altimeter and numerous auxiliary sensors are available over an optional 1553 interface.

The CAST-4000 has the ability to output raw IMU measurements to a receiver under test when equipped with an optional interface. This allows users to test GPS receivers that are tightly or loosely integrated with a strapdown IMU. The form of the optional interface (bus, shared memory, etc) is customized to the user's particular requirements.