Decimetre Level Range Resolution for Beidou B3I Signal-Based Passive SAR Imaging—Proof-of-Concept Experimental Demonstrations

Abstract

The construction of the Beidou B3 satellite system, a new-generation global navigation satellite system, has been completed worldwide, however the respective implementation studies remain in the start-up stage. Accordingly, studies of passive Beidou B3I signal-based synthetic aperture radar (Beidou B3I-SAR) are very meaningful in terms of promoting the rapid development of the Beidou technique. This paper proposes methods for Beidou B3I SAR imaging of decimetre level range resolution. To separate aliased reflected B3I signals at range domain, we presented cascaded secondary order differentiation operator (Diff2) and cascaded Teager-Kaiser (TK) operator, applied them to the regions where exists range compressed pulses, respectively. Thereafter to eliminate the obvious side-lobes which brought by the proposed operators and with the values less than zero, zero thresholding scheme is employed. To obtain the final range compressed signals with decimetre range resolution, phase recovery component is performed to the respective zero thresholded pulses. To validate the proposed methods, both proof of concept simulation and the experiment with field Beidou B3I signal raw data are carried out for comparison. The results show that indeed main-lobe width of range compressed pulse can reach the level 0.4 m. This reveals that decimetre level range resolution can be achieved for Beidou B3I-SAR on the basis of proposed methods, in contrast to the current best result of meters level in passive GNSS-based SAR related studies. Meanwhile, in a comparison of the proposed methods on the basis of cascaded Diff2 operator and cascaded TK operator, the later is outer-performed, since the respective brought interference level in background region is less.