A Signal Cyclic Shifting Method Based on Frank Code for Range Ambiguity Suppression in SAR System

A Signal Cyclic Shifting Method Based on Frank Code for Range Ambiguity Suppression in SAR System

연구 분야: Infrastructure

학회: International Conference on Wireless and Satellite Systems

High-resolution and wide-band (HRWS) are the performance pursued by SAR systems, which cannot be improved at the same time due to the limitation of the minimum antenna area. How to suppress the range ambiguity is the key factor that achieve HRWS imaging. There are mainly three ways to achieve it, such as using multi-channel technology, transmitting signals with specific nature and build different physical models. But there are some problems with these methods, like increasing the system complexity or being unable to completely suppress the range ambiguity of each order. In this letter, a signal cyclic shifting method based on Frank code is proposed to suppress the range ambiguity problem of SAR system. By applying this method, a single antenna is used to sequentially transmit and receive Frank code subsequences in the flight direction of the platform without increasing the system complexity. Then process the echo signal with a matching filter constructed by the cyclic shift method. The post-processing is completed by traditional SAR imaging algorithms. Finally, the range unambiguity and low sidelobes images will be obtained, which may cause ambiguity in the azimuth spectrum. Through the simulation of wide-swath scenes and comparing imaging results of different transmitted signals, it has verified the effectiveness of the method based on Frank code.