Development of Passive Bistatic Radars based on Orthogonal Frequency-Division Multiplexing modulated signals for short and medium range surveillance Facoltà di Ingegneria dell’Informazione, Informatica e Statistica Dottorato di Ricerca in Telerilevamento XXVIII Ciclo Candidato Claudio Palmarini 1151374 Tutor Prof. Pierfrancesco Lombardo 2 INDEX 1 Introduction ................................................................................................................................................................ 5 2 Exploited signals of opportunity ................................................................................................................................. 7 2.1 OFDM Modulation............................................................................................................................................. 7 2.2 DVB-T signal characteristics .............................................................................................................................. 8 2.3 DAB signal characteristics ............................................................................................................................... 12 2.3.1 DAB in Italy .................................................................................................................................................. 14 2.4 OFDM Modulated signals as opportunity signals ............................................................................................ 16 3 DVB-T based PBR ...................................................................................................................................................... 18 3.1 Introduction .................................................................................................................................................... 18 3.2 Receiver architecture and signal processing chain ......................................................................................... 19 3.3 Sidelobe level control ...................................................................................................................................... 21 3.3.1 Selective utilization of the technique ......................................................................................................... 23 3.4 Disturbance cancellation ................................................................................................................................. 24 3.4.1 Introduction ................................................................................................................................................ 24 3.4.2 ECA and ECA-B approaches ......................................................................................................................... 24 3.4.3 Limitations of the ECA-B ............................................................................................................................. 28 3.4.4 ECA-Sliding technique ................................................................................................................................. 33 3.4.5 Performance analysis against real data ...................................................................................................... 37 3.4.6 Considerations on the computational cost ................................................................................................. 43 3.4.7 Conclusions ................................................................................................................................................. 46 3.5 Range-Doppler map evaluation ...................................................................................................................... 47 3.5.1 Problem statement ..................................................................................................................................... 47 3.5.2 State of the art ............................................................................................................................................ 47 3.5.3 Comparative study of existing algorithms .................................................................................................. 51 3.5.4 Block based Channelization Technique ....................................................................................................... 54 3.5.5 Conclusions ................................................................................................................................................. 60 3.6 Target DoA estimation .................................................................................................................................... 61 3.6.1 Introduction ................................................................................................................................................ 61 3.6.2 Data Model and ML estimator .................................................................................................................... 61 3.6.3 Strategy for array sizing .............................................................................................................................. 63 3.6.4 Remainder estimator .................................................................................................................................. 67 3.6.5 Performance Comparison ........................................................................................................................... 68 3.6.6 Unbalanced array ........................................................................................................................................ 70 3 3.6.7 Results from the acquisition campaigns ..................................................................................................... 75 3.6.8 Conclusions ................................................................................................................................................. 79 3.7 Multi-frequency integration ............................................................................................................................ 80 3.7.1 Introduction ................................................................................................................................................ 80 3.7.2 Approaches for multi-frequency integration .............................................................................................. 80 3.7.3 Experimental analysis ................................................................................................................................. 81 3.7.4 Conclusions ................................................................................................................................................. 87 3.8 GPU code implementation .............................................................................................................................. 88 3.8.1 GPU computing ........................................................................................................................................... 88 3.8.2 Effects on the execution time ..................................................................................................................... 89 4 DAB based PBR ......................................................................................................................................................... 90 4.1 Introduction .................................................................................................................................................... 90 4.2 State of the art ................................................................................................................................................ 90 4.3 DAB signal generator ....................................................................................................................................... 90 4.4 Receiver architecture ...................................................................................................................................... 94 4.4.1 Selection of the sampling frequency ........................................................................................................ 100 4.5 Preliminary performance evaluation ............................................................................................................ 102 4.5.1 Acquisition geometries ............................................................................................................................. 102 4.5.2 Acquisition campaigns .............................................................................................................................. 102 4.6 Conclusions ................................................................................................................................................... 105 5 Conclusions ............................................................................................................................................................. 106 References ...................................................................................................................................................................... 108 List of publications .......................................................................................................................................................... 111 4 1 INTRODUCTION In the last years the interest in passive bistatic radar (PBR) for surveillance purposes has significantly grown up for the potential role it could play in both civilian and