9 - Air Target Tracking

Abstract

When a target is detected, it is useful to correlate consecutive target detections and merge scan-to-scan measurements to track the target. This tracking ranges from simple tracking to track-while-scan (TWS) or single-target tracking (STT)—in which the radar continuously monitors a single target. Tracking also improves the quality of certain target measurements, such as range, velocity, and elevation and azimuth angles. This chapter discusses about TWS and STT. The main coordinate systems used to determine target trajectory independently of platform attitude and motion are as follows: the terrestrial coordinate system carried by the aircraft, the aircraft-related terrestrial coordinate system, the aircraft coordinate system, and the radar antenna-axis coordinate system. STT is characterized by lock-on to a single target. The various phases of this tracking include acquisition, lock-on of range and then velocity loops, and lock-on of angular loops. The aim of Doppler velocity tracking is to slave the central position of velocity filter bank to the Doppler frequency of the target. In antenna tracking, the antenna beam remains pointed at the target. As the antenna pointing direction is defined by two independent parameters (elevation and azimuth angles), this tracking is generally composed of two independent and identical loops. .