Motion Compensation for Radar Terrain Imaging Based on INS/GPS System.

Area of Science:

• Remote Sensing
• Geophysics
• Signal Processing

Background:

• High-quality aerial synthetic aperture radar (SAR) terrain imaging requires precise motion compensation.
• Real-time operation of motion compensation is critical for efficient data analysis by human operators.
• Integrating navigation systems is key to achieving accurate aircraft positioning and velocity data for SAR processing.

Purpose of the Study:

• To evaluate the effectiveness of an Inertial Measurement System (INS)/Global Positioning System (GPS) integrated navigation system for real-time motion compensation in aerial SAR.
• To develop and adapt a Kalman filter algorithm capable of handling asynchronous and multi-frequency navigation data.
• To compare the performance of INS/GPS-based motion compensation against INS-only and no-navigation correction methods.

Main Methods:

• Implementation of a Kalman filter algorithm tailored for INS/GPS data fusion.
• Modification of the Kalman filter to accommodate time-misaligned and differently-frequenced navigation inputs.
• Testing the developed motion compensation system using measured data from an aerial SAR platform.
• Comparative analysis of SAR images processed with INS/GPS, INS-only, and no motion compensation.

Main Results:

• The INS/GPS-based motion compensation system demonstrated superior performance in reducing geometric distortions in SAR images.
• Images processed using INS/GPS showed significant quality improvements compared to INS-only compensation.
• The system effectively utilized navigation data even when not perfectly aligned in time or captured at varying frequencies.

Conclusions:

• The integration of INS/GPS navigation systems provides a robust solution for real-time motion compensation in aerial SAR.
• The proposed Kalman filter modifications enhance the system's adaptability to real-world navigation data characteristics.
• INS/GPS-based motion compensation is highly suitable for practical SAR imaging applications requiring high geometric accuracy.