| Bi-static/multi-station radars exploiting external illuminators (opportunity illuminators such as television/broadcasting stations etc), take full advantages of conventional radars, as well as have quite strong viability. Employing this radar system for moving object image has abroad applications in many aspects such as classify, recognition of object, and so on. The passive radar imaging technology based on external illuminators is essentially attributed to a technology of bi-static/multi-station synthetic aperture radar imaging. The signals of television and frequency-modulation broadcasting which can be seen as Continues-Wave (CW) signals are discussed in the paper. Subsequently, the characteristic of the bi-static synthetic aperture radar is produced. And then, the methods of motion compensation of passive radar imaging based on external illuminators are discussed. According to the point scattered model of target, use the strong correlation of contiguous echo—signal envelope to estimate the maximal value of the correlation function to estimate the compensation factor. But with the increase of aspect change the drift error will be caused, we propose a method based on norm 1 to solve the problem. Finally, several key techniques about passive radar imaging based on external illuminators like TV signal are discussed. |
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