Passive ISAR imaging of air targets using DVB-T signals

This paper presents a concept of passive ISAR imaging of air targets using DVB-T transmitters as illuminators of opportunity. The presented concept has been successfully proved using both simulated and real data collected during a measurement campaign carried out by the Warsaw University of Technology in Poland. All stages of the signal processing algorithm for bistatic passive ISAR imaging have also been described. Passive ISAR images created of different air targets as a result of the proposed signal processing method have been included.

I. Introduction

The main application of the modern passive coherent location (PCL) systems is in the detection, tracking and localization of air targets [1]. Nowadays, the functionality of the pCL radars has entered a stage of maturity. Due to this fact, researchers have begun to think about additional modes for a passive radar system. One such mode is air target imaging using the Inverse Synthetic Aperture Radar (ISAR) technique, which is well known from active radar technology [2]. The main problem with such an application is in the obtaining of high range resolution of the target image, which is strictly connected with the bandwidth of the illuminated signal. The most obvious solution is to use other active radars with wide bandwidth sounding signals as illuminators of opportunity. However such illuminators of opportunity are not very common, and it is difficult to get practical coverage of the large operational territory. Typically a large radar coverage is given by ATC and/or EW radars, which are usually narrowband systems (of a few MHz). Due to this fact, using the dense network of commercially available continuous wave transmitters (e.g. FM-radio, DAB, DVB-T, GSM, LTE, WiFi, etc.) as the source of illumination seems to be a viable solution.