Tadashi Koga

Performance evaluation of a WAM system using measured range

Wide Area Multilateration (WAM) is a useful aeronautical surveillance system which is able to achieve high performance. However, WAM has a drawback in which position errors increase rapidly outside a constellation of receiver stations in principle. One of the solutions for the drawback is to apply a measured range between a receiver station and an aircraft to the Time Difference of Arrival (TDOA) localization. This paper describes test results of performance evaluation for a WAM experiment system using the measured range.

Downlink Aircraft Parameter-Based High-Accuracy Tracking System for Air Traffic Surveillance

With the rapid increase in air traffic demands, the more accurate and reliable tracking systems for aircraft surveillance are required to improve the capacity, safety, and efficiency of air traffic control (ATC) services. As a suboptimal hybrid filter, the Interacting Multiple Model (IMM) estimator has been applied in the practical aircraft tracking systems. However, it is difficult for the standard IMM filter to precisely estimate the aircraft state when the target is maneuvering since the detection of maneuvers is often delayed by the response of Kalman filters. On the other hand, in the Mode S radar Enhanced Surveillance (EHS), the downlink aircraft parameters (DAPs) are available for obtaining the updated states of aircraft; however, this information of aircraft parameters has not been used systematically to improve the performance of current tracking systems. In this paper, a DAPs-based tracking system which is able to dynamically revise the mode probabilities of the IMM estimator according to the real-time change in the aircraft motion is proposed. The results of computer simulations and practical experiments show the effectiveness of the proposed system by comparing it with the standard IMM-based tracking system.

Results of an evaluation of a multilateration system using ACAS signals

In 2002, we proposed a new aircraft positioning system. The system uses aircraft collision avoidance system (ACAS) signals to determine aircrafts positions. To evaluate the surveillance performance of the system, we have developed an experimental system for airport surface surveillance and conducted an evaluation. We describe the background of our development and introduce the experimental system and time difference of arrival (TDOA) detection techniques. We present the results of the evaluation conducted in the Sendai Airport in 2003.