Identification of BDS Registers

Abstract

The SSR Mode S technology is currently one of the major means of surveillance in ATM. Addressed surveillance enables the elicitation of replies from Mode S transponder on board of an aircraft containing different flight information in the so-called BDS registers. The type of BDS register as well as its content is characterised by a number of the BDS registers which is determined according to SSR interrogation by default. The study deals with the development of a heuristic algorithm for identification of a particular BDS register with the assumption that the radar query is unknown. A BDS number is assigned to the appropriate message on the basis of the unique bit sequences and other criteria. The algorithm provides the opportunity to obtain various flight data from the aircraft by only receiving addressed surveillance replies on 1090 MHz frequency.