Probability of Positive Identification with an IFF E-scan System

Abstract: Both military and civil aircrafts depend on a built-in identification system called SSR on a daily basis. IFF is the military adaption of the system for use by fighter jets in order to separate friendly aircrafts from foes but also to coexist with commercial aircrafts. The system is built around two devices, an interrogator on the own aircraft and a transponder on the target. The aim is to be able to perform an interrogation with as high probability of correct identification as possible. There are several factors that can compromise or prohibit a friendly aircraft from answering to an interrogation and it should therefore not be classified as a foe. In this master thesis work, the ability of identification for Saab AB’s new fighter jet Gripen E has been investigated. A system model has been created using Simulink and Matlab, mirroring a full link connection between the IFF E-scan system on Gripen E and a target aircraft. The model includes six subsystems, covering the fighter jet’s antenna array system in both transmitter and receiver mode, the transponder equipment, link budgets and signal propagation. Different data sets with main and control beam antenna patterns for the Gripen E IFF system are loaded into the model via user selected beam steering.. It has been found that the model simulates the environmental effects on the transmitted patetrns at different distances well. It can be used to investigate how the antenna coverage changes when applying beam steering to the E-scan system and at which distances identification is possible for a chosen steering angle.