Real-Time Imaging With a 140 GHz Inverse Synthetic Aperture Radar

A summary of a 140 GHz inverse synthetic aperture radar (ISAR) is presented. High resolution and real time imaging are two key points in the design. Using the frequency-modulated continuous-wave (FMCW) radar technique with a 5 GHz bandwidth, 3 cm range resolution is achieved with assistance of software calibration compensating for nonlinearities of the LFM waveform. In cross-range region, synthetic aperture technique is adopted to improve imaging resolution. Real time imaging capability is enabled by using a hardware structure constructed with
${\rm FPGA}+{\rm CPU}+{\rm GPU}$
in signal processing unit. The final system was used to get ISAR image of a rotating target at 5 m. The 2-D (range and cross-range) imaging resolution is 3 cm
$\,\times\,$
3 cm with a real time image frame rate of 5 Hz.