Research On Imaging Processing Method Of Single-bit Quantized Synthetic Aperture Radar

Synthetic aperture radar(SAR)is a two-dimensional imaging radar with high resolution.Because of its excellent resolution performance,SAR is widely used in terrain mapping,battlefield reconnaissance,target recognition and other fields.With the increasing requirement of imaging resolution in military and civil fields,the transmitted signal bandwidth of SAR is getting larger and larger,and the echo data volume is increasing significantly,which increases the burden of data acquisition,storage and transmission system.In view of this situation,1-bit quantization SAR is proposed.1-bit quantization SAR adopts an extreme quantization scheme for radar echo—1-bit quantization,that is,only the symbol information of echo data is remained.The scheme reduces the total number of bits of echo data to relieve the pressure of the data acquisition,storage and transmission system.This paper will focus on the research of 1-bit quantization SAR imaging method,and the main work is as follows:1.A 1-bit quadrature compressive sampling SAR imaging technology is studied.Quadrature compressive sampling is an effective compressive sampling method for bandpass analog signals,which can realize low-speed sampling of radar intermediate-frequency echo.In this paper,a 1-bit compressive sampling system of bandpass signal is constructed based on quadrature compressive sampling to further reduce the sampling data rate of SAR echo.In this system,quadrature compressive sampling is used for preprocessing to generate compressive measurement,and then the compressive measurement is quantized to obtain 1-bit compressive sampling data.Through frequency domain analysis,the matrix-vector product of the equivalent measurement matrix is decomposed into a series of fast operations.Finally,this paper describes SAR imaging as a 1-bit sparse reconstruction problem,and based on the structural characteristics of equivalent measurement matrix,a fast SAR imaging method of 1-bit quadrature compressive sampling is proposed.2.A 1-bit bandpass sampling SAR imaging technology is studied.At present,most of 1-bit quantization operations are carried out on the baseband sampling data.There are few researches on the direct 1-bit sampling of bandpass signals which are widely used in radar and communication fields.Based on the bandpass sampling theorem,this paper constructs a 1-bit bandpass sampling system to realize the 1-bit sampling of intermediate-frequency received signals.In this system,after the bandpass sampling of the intermediate-frequency signal,1-bit quantization is directly carried out to obtain 1-bit sampling data.Compared with the 1-bit quadrature compressive sampling system,this system does not need analog preprocessing of the received signal,its structure is simple and easy to implement.Subsequently,by analyzing the process of digital quadrature demodulation,this paper establishes the conventional relationship between the bandpass sampling data and the baseband complex data,so as to describe the 1-bit bandpass sampling SAR imaging as a 1-bit sparse reconstruction problem,and realizes the 1-bit bandpass sampling SAR imaging based on the binary iterative hard threshold algorithm.