Complete GPS/INS Engineering Test System
This engineering test system, CAST-4000 GPS/INS, generates GPS RF signals to simulate loosely or tightly coupled navigation systems. It uses avionic sensor simulations, which include gimbaled or strapdown Inertial Navigation System, Attitude Heading Reference System, Barometric Altimeter, Radar Atimeter, Doppler, and numerous auxiliary sensors. These sensors are accessed over an optional 1533 interface.
How the CAST-4000 Works
An IMU normally calculates specific force in gyros and ∆V’s, which then provide angular velocity. An INS uses these metrics to compute the attitude, position, and velocity of the user. GPS receivers that use inertial systems usually do not receive the IMU metrics, but receive INS outputs instead. Some receivers, however, are integrated with an IMU and use the ∆θ and ∆V measurements directly.
CAST Navigation’s GPS GNSS 4000 engineering test system, CAST-4000, can output raw inertial measurement unit (IMU) measurements to a receiver when equipped with an optional interface (shared memory, bus, etc.) directly. The user can customize this interface to specific requirements.
Advantages of the CAST-4000
Because the CAST-4000 continuously monitors the position, acceleration, and position of a vehicle, it provides navigational data without requiring communication with a base station. The measurements are simply provided by accelerometers and gyroscopes, which track the position according to a known starting point.
In addition, the original application of INS technology used only stable or gimbaled platform techniques. The inertial sensors are strapped to a stable platform, separated from the rotational motion of the aircraft or vehicle. The CAST-4000 GPS/INS engineering test system, on the other hand, supports strapdown INS/GPS, where the accelerometers are rigidly mounted parallel to the body axes of the aircraft. This means the strap-down inertial navigation system can help testers sense the turning rate of the vehicle.