Direct-sampling radar receiver based on photonic channelization and spectral stitching

A novel photonic technique to achieve a direct-sampling radar receiver for high-resolution detection based on the conception of channelization and spectral stitching is proposed and experimentally demonstrated. The proposed system exploits multiple incoherent lasers as optical local oscillators to perform wideband spectral segmentation and thus reduce the requirement of sampling rate and bandwidth for the electronic analog-to-digital converters (ADCs). The precise signal reconstruction is achieved using digital signal processing to eliminate the intra-channel and inter-channel signal impairments. The proposed scheme is demonstrated through an inverse synthetic aperture radar (ISAR) imaging experiment using an NLFM signal with low-sidelobe characteristics.