Research On Waveform Design Method For Cognitive SAR

Cognitive synthetic aperture radar(Cognitive SAR)is a new type of radar.It is a new generation of intelligent SAR system that introduces and imitates the characteristics of biological cognition.It has the ability to sense,understand,learn,infer and make deci-sions.Cognitive SAR can make use of the environment and target information,and with its closed-loop feedback characteristics,it can achieve an integrated adaptive mechanism at the receiving end and the transmitting end.Therefore,it can make up for the short-comings of traditional SAR's single working mode and its inability to adaptively adjust its working mode while the environment changes drastically.At the same time,cognitive SAR has the characteristics of adaptively adjusting the transmission waveform parameters,which can improve the radar's performance in complex electromagnetic and geographic environments.However,researches based on cognitive SAR system are just emerging.Waveform design method is a key technology for the design of the cognitive SAR.According to the needs of high-resolution imaging and well detection of cognitive SAR,this paper studies the waveform design method for cognitive SAR.The main tasks are as follows:(1)Researched the architecture of cognitive SAR system based on Haykin frame-work.Analyzed the closed-loop feedback characteristics of its transmitting-receiving structure and analyzed the key technologies involved.Researched the technical charac-teristics of each key technology.The above work has laid a theoretical support for the research of cognitive SAR.(2)Proposed an environmental information sensing method based on machine learn-ing image classification and state prediction for cognitive SAR.Proposed a method to obtain the clutter power spectral density from the echo.Solved the problem of difficult information perception such as environmental terrain and clutter power spectral density.Lay the foundation for building a dynamic and static information base for cognitive SAR.(3)Proposed a method of designing cognitive SAR waveforms based on joint optimal criteria,and constructed a joint optimization model based on output signal-to-noise ratio and resolution.Gave a block diagram of the environment awareness method.Solved the problem of solving optimal transmitting waveform and filter based on joint optimal criteria.Provided a concise and accurate optimal transmitting waveform and filter analysis expression for cognitive SAR.(4)Studied the cognitive SAR imaging technology based on waveform design.Ana-lyzed and compared the difference between the performance of the technology and tradi-tional SAR imaging in the target image signal to noise ratio,imaging resolution and other performance indicators.Provided a foundation for the practical application of cognitive SAR imaging technology.The above research contents have been verified by simulation,and the results show that the proposed design method of cognitive SAR transmitting waveform and filter can improve the detection performance of cognitive SAR under strong clutter environment while ensuring its imaging performance.