FMCW SAR Imaging Based on Software Defined Radio Architecture

FMCW (Frequency Modulated Continuous Wave) Radar systems could be implemented using less complexity and low-cost Software-Defined Radio (SDR) architecture. This paper presents a full study and implementation of FMCW radars based on NI LabVIEW® for Synthetic Aperture Radar (SAR) operation mode. Besides that, a real-time implementation for target detection is achieved based on the SDR platform. The used platform is the Universal Software Radio Peripheral (USRP-2932) and NI LabVIEW® software development environment has been used to interface between the USRP to the Host PC. After target detection, the received target’s echoes are stored in a complex form for SAR image formation. The well-known Range Doppler Algorithm shows promising performance to focus the extracted complex data. SDR approach gives researchers the ability to control the transmitted waveform characteristics, which has high flexibility due to the usage of both software data processing and software waveform generation. The transmitted waveform is a linear frequency modulated (LFM) signal generated from the transmitter USRP. The transmitted signal hits a target located at a certain distance from the source. A second USRP is used as a receiver to collect the returned target echoes. Storing the received echoes at a matrix that presents the complex raw data of the imaged target. The de-chirping or de-ramping pulse compression technique is used for range resolution enhancement.