The paper focuses on a navigation facility, relying on commercial-off-the-shelf (COTS) technology, developed to generate high-accuracy attitude and trajectory measurements in postprocessing. Target performance is cm-level positioning with tenth of degree attitude accuracy. The facility is based on the concept of GPS-aided inertial navigation but comprises carrier-phase differential GPS (CDGPS) processing and attitude estimation based on multiantenna GPS configurations. Expected applications of the system include: (a) performance assessment of integrated navigation systems, developed for general aviation aircraft and medium size unmanned aircraft systems (UAS); (b) generation of reference measurements to evaluate the flight performance of airborne sensors (e.g., radar or laser); and (c) generation of reference trajectory and attitude for improving imaging quality of airborne remote sensing data. The paper describes system architecture, selected algorithms for data processing and integration, and theoretical performance evaluation. Experimental results are also presented confirming the effectiveness of the implemented approach. 1. Introduction Field test refers to the testing of a device or sensor in the conditions under which it will be actually used. Field testing becomes necessary when numerical and indoor testing may fail, that is, in all the cases in which the operative conditions are difficult to be reproduced with high fidelity by software or laboratory simulations. A typical example is the performance assessment of integrated navigation systems for airborne applications. In this case several factors must be taken into account, including but not limited to: (a) the intrinsic dynamical and statistical models of sensor and systems, (b) the selected data fusion strategy, and (c) the typical and the worst case manoeuvres that must be considered to determine a trustworthy dynamical model of the aircraft where the system is installed. Indeed, high performance heading and attitude determination units are needed both in general aviation and in unmanned aircraft systems (UAS) applications to attain an adequate control performance. UAS are more demanding in terms of attitude determination performance than manned aircraft for a series of issues. First, the absence of a human pilot onboard prevents the aircraft from using the human senses such as vision and coordination to integrate onboard systems. Furthermore, UAS are required to perform autonomous flight in case of loss of data link with the ground control station where the remote pilot is located [1, 2].
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