Development of airborne distributed analog data acquisition system

Flight testing is a necessary procession which gathers information and data from the airplane when flying. The airborne distributed analog data acquisition system is used to collect, store and display the analog data of the airplane in the flight test, which provide data support for further aircraft state estimating, performance test and fault diagnosis. The essence of it is a wild-distributed data acquisition system which gathers large numbers of analog parameters with high time synchronization accuracy Traditional airborne data acquisition system is based on PCM architecture which has advantages in system time synchronization stability, however, as planes become more sophisticated, a large number of parameters with a wild spatial distribution needs to be collected, the routing needs to be more concise as long as the time synchronization accuracy is highly demanded. As a result, the existing PCM architecture may not fully meets the requirements of the latest flight test. In this paper a hierarchical distributed airborne analog data acquisition system is designed and developed. In order to enhance the system expansibility and achieve high bandwidth, an easy-routing distributed architecture which combines Ethernet with the RS-485 bus was proposed. A RS-485 frame based time synchronization is applied to achieve high time synchronization accuracy. It is verifiable that the developed prototype can synchronously collect analog signals under high time synchronization accuracy, which fully meet the requirements of China self-developed large airplane and boost the development of China aviation industry.