Hirohisa Tajima

Measurement-Based Evaluation on Detection Probability of Extended Squitter for Air-to-Ground Surveillance

Deployment of Automatic Dependent Surveillance—Broadcast (ADS-B) has commenced worldwide for aeronautical surveillance. In ADS-B, an aircraft broadcasts extended squitters, which include its position measured by the Global Navigation Satellite System. These squitters are received by ground stations. ADS-B has the potential to achieve higher accuracy and higher update rates than conventional radar, however, they are vulnerable to co-channel interference. Therefore, evaluating the performance of extended squitters in real interference environments is crucial for successful deployment of ADS-B, the goal of this work. Our approach is to gather and analyze measurement data from four experimental ground stations in the Kanto airspace, Japan. The measurement data are practical as the sites include two major airports and an antenna tower supporting air-ground communication. Analysis of the data yields a measurement-based model that can estimate the probability of detection of the extended squitter for given link-margin and interfering signal rate. To the best of the our knowledge, this is the first work to derive an expression for the probability of detection based on large-scale measurements. Two applications of the model are demonstrated. First, the improvement on performance made possible by using a sector antenna instead of an omni-directional antenna is predicted; the contributions of improved link-margin and reduced interference are given. Second, the ADS-B coverage is predicted along an experimental flight route.

Evaluating Path Loss by Extended Squitter Signals for Aeronautical Surveillance

For the successful deployment of the aeronautical surveillance systems, it is important to select the appropriate path loss model that is used in the coverage design. While the flight experiment is a traditional approach to evaluate the path loss models, the passive measurement of the 1090-MHz extended squitters (1090 ESs) broadcast by target of opportunity is a new complementary approach. This letter examines the feasibility of the 1090 ES measurement for evaluating the aeronautical path loss models. First, the effect of the alternate transmission using two transponder antennas is removed to extract the effect of the propagation channel. Then, the measurement result during the flight experiment is compared to the reference values given by free-space path loss in order to show the relevance of using the 1090 ES.

ADS-B security consideration in Japanese airspace from a technical perspective

ADS-B is a new means of aeronautical surveillance. Aircraft periodically airborne position, velocity, and identification squitters.

Detection probability estimation model for Wide Area Multilateration

Wide Area Multilateration (WAM) has commenced worldwide for aeronautical surveillance. WAM has potential to achieve better accuracy, probability of detection, and update interval than the conventional radars. However, the probability of detection and update interval have been barely investigated theoretically. Consequently, no guarantee exists that WAM is advantageous against the radars in the probability of detection and update interval. Also, receiver constellation has been designed by considering only the accuracy, which could be a too optimistic approach. Therefore, this paper presents probability-of-detection modeling. Because the probability of detection and update interval in WAM are interrelated, the proposed probability-of-detection modeling is also effective as update-interval modeling. The proposed modeling framework is obtained by connecting sub-models corresponding to the factors affecting the probability of detection, namely radio propagation, interference or FRUIT (False Replies from Unsynchronized Interrogator Transmissions in time), receiver, grouping, localization, signal rate, and filtering. Initial implementation and evaluation validate the modeling framework and derive the insights on future improvement.

Influences of ILS Localizer Signal over Complicated Terrain

This paper is concerned with a numerical simulation of Instrument Landing System (ILS) Localizer (LOC). LOC provides the guidance in the horizontal position of an aircraft for the runway center line. The radiation from LOC antenna generates the composite field which is amplitude modulated by a 90 Hz and a 150 Hz tone. The performance of the LOC is given by the difference in the depth of the modulation (DDM) along the runway centerline. However, their signals are influenced by the scattered waves if the LOC antenna is located over the complicated ground condition. In this paper, we consider the influences of the scattered waves caused by the complicated terrain, from a view point of the numerical simulation by the ray-tracing method (RTM). Firstly the basic principle of the LOC is introduced. Next, the simplified RTM is discussed. Finally, we show some numerical examples for field intensity distribution and DDM. We discuss how the scattered waves influence the performance of LOC.

Influences of 3D Aircraft Model to ILS Localizer

This paper is concerned with a numerical simulation of ILS subsystem Localizer (LOC) which provides the guidance in the horizontal position of an aircraft for the runway center line. The LOC emits two types of signals, that is, carrier wave and sideband waves modulated by a 90 Hz and a 150 Hz tone. The performance of the LOC is given by the difference in the depth of the modulation (DDM). However, their signals are influenced by obstacles, such as large hanger, terminal buildings and aircraft. They result in the DDM errors. In this paper, the authors analyze the multipath interferences caused by aircraft to LOC whose type is one frequency LOC (1fLOC). A simplified ray tracing method is introduced, and 3D aircraft model is used for numerical simulation. It is discussed how scattered waves from aircraft influence to the LOC specifications.