Codage spatio-temporel multi-rafales pour systèmes à antenne active

REE N°5/2015 55 RADARS A ANTENNES ELECTRONIQUES RADAR 2014 Codage spatio-temporel multi-rafales pour systemes a antenne active Par Guy Desodt1 , Georges-Edouard Michel1 , Jean-Paul Guyvarch1 , Francois Le Chevalier1 , Olivier Rabast2 Thales Air Systems, France1 , Onera, France2 This paper proposes to transmit coloured codes varying from burst to burst, with the same angular coverage, and to fuse the signals they produce over the different bursts. If the ambiguity functions of the coloured codes have high sidelobes in different areas, a fusion process like a “K over N” criterion produces a global ambiguity function with reduced sidelobes while the main lobe keeps its narrow beam width (ratio 1/ 2 on each axis, compared to a non-coloured waveform). As an example, the fused codes can be non-coloured, adjacent sub-bands, circulating codes or optimized phase codes. In this paper, a global ambiguity function is computed in the case of a 2-D active array antenna made of 4x4 transmit sub-arrays, and full Digital Beam Forming at Receive. 5 coloured waveforms (non-coloured, circulating codes, optimized codes) are fused by a criterion “3 over 5”. This case demonstrates that the