Interrogation Scheduling for the Discrete Address Beacon System

This document is disseminated under the sponsorship of the Department of Transportation in the interest of information exchange. The United States Government assumes no liability for its contents or use thereof. This " report..is. an attempt to define the interrogation scheduling.proble " rn which arises ill the implementation of the discrete address beacon idea. The interfaces of this problem) with other parts of the beacons ystern. design are discussed, and several specifiti algorithms for scheduling are analyzed for both arrays and rotating antennas. Discrete Address Beacon Availability is unlimited. Document maybe Interrogation Scheduling Algorithm released to the National Techaical hformation Sertice, Sprimfield, Virginia 22151, for sale to the pubfic. a. The Effect of Changing and Imperfectly ~o~ Target Range 52 b. The Effect of Changing and ~perfectly Known Target Azimuth 52 c. Tracking Requirements for Interrogation Scheduling 53 111. I. INTRODUCTION The FAA is currently undertaking the development of a new surveillance system, the Discrete Address Beacon System (DABS), which will complement the introduction of automation in air traffic control to form the so-called upgraded third generation system. The basic system concept was spelled out in the ATCAC Report [ 11, whichrecommendedits development, and a detailed discussion of the system and its planned development may be found in the FAA Technical Development Plan [2] for DABS. The basic idea, which gives DABS its name, is to assign to each aircraft a unique code, and to direct all interrogations to a given aircraft by using that aircraft's unique address. Each aircraft is interrogated in turn, and responds only to interrogations containing its address. This scheme provides the mechanism for eliminating overlapping replies from targets close in range, by scheduling interrogations in time so that the replies do not overlap, and at the same time establishes a data-liti between aircraft and the ground which can be used for traffic control purposes. The interrogation scheduling problem itself is the subject of this note, in which we attempt to define the problem, discuss some specific algorithms, and study their capacity in terms of the number of tar gets a DABS can handle. In the following sections we give a brief discussion of the DABS system concept, which provides the background for the interrogation scheduling problem, and then discuss the schedtiling problem in general terms, with emphasis on its interaction with other elements of the DABS system design, such as surveillance and communication requirements , …