Integrated navigation system architecture

The essence of an integrated navigation system is to combine the long-term accuracy of position fixing aids such as GPS, LORAN C, and TRN with the short-term accuracy and continuous availability of the dead-reckoning systems such as INS and Doppler radar. Modern systems use Kalman filter techniques with time-varying gains and which make extensive use of mathematical models of the system dynamics to accomplish this task. An important design feature of an integrated navigation system is the provision of `graceful degradation´, with an indication of the expected level of accuracy to the user. Several conflicting aspects which have to be considered when deciding upon a system architecture are discussed