Doppler Parameter Estimation Model Using Onboard Orbit Determination and Inter-satellite Distance Measurement for Spaceborne Bistatic SAR Real-time Imaging

Spaceborne bistatic synthetic aperture radar (SAR) real-time imaging products may provide valuable information in certain applications. The onboard orbit determination data of the spaceborne SAR platform is essential for SAR imaging procedure. For real-time SAR imaging, the onboard orbit determination data is relatively low in accuracy compared with the orbit ephemeris applied in ground SAR processing. This paper proposed a doppler parameter estimation model with onboard satellite orbit determination and inter-satellite distance measurement to reduce estimation errors. Simulation results shows that in most cases the proposed estimation model presents a smaller quadrature phase error (QPE) introduction than the onboard estimation without using inter-satellite distance measurement. This estimation model may be helpful to get spaceborne bistatic SAR real-time imaging products with lower azimuth impulse response width expansion.