An PC-based Airborne SAR Baseband System

This paper presents the development work of a PC-based airborne SAR baseband system that integrates commercial off-the-shelf Arbitrary Waveform Generator (AWG) and high-speed digitizer, and a custom-designed Timing and Control Unit (TCU). The proposed system is general purpose, in which the critical operating parameters such as waveform modulation format, baseband bandwidth, pulse width, pulse repetition frequency, and all the relevant timing and control signals are re-configurable in real-time. As a brief functional summary of the system, it can, i) generates 2-channel (I & Q) of 1.2 GHz (maximum) bandwidth chirp signal with its pulse width ranged from 0.5 us to 100 mu s, ii) able to digitize 2-channel (I & Q) of 1 GHz (maximum) bandwidth chirp echoes with on-board 4 G-Samples of recording buffer, and iii) generate accurate and precise timing and control signals with timing resolution of 10 ns. The system is currently deployed as the baseband and control system for Josaphat Microwave Remote Sensing Laboratory (JMRSL) C band airborne full polarimetric Circularly Polarized Synthetic Aperture Radar (CP-SAR) sensor built for Earth surface, environmental, and disaster monitoring.