A Study on the Range Equation Modeling for Multichannel Medium-Earth-Orbit SAR-GMTI Systems

Abstract

This paper studies the range equation modeling of a ground moving target for multichannel medium-Earth-orbit (MEO) synthetic aperture radar (SAR) ground moving target indication (GMTI), an issue which is challenging to tackle due to the non-linear motion of the radar platform and the Earth rotation. In the paper, the coordinates of the multichannel MEO SAR and the target, as well as the target’s range equation with respect to each channel, are developed. Moreover, an expression of concise form is derived for the target’s quadratic-approximated range equation, which will benefit the design of GMTI methods. Furthermore, theoretical analyses are conducted to reveal the dependency between the accuracy of the quadratic-approximated range equation and the parameters of the radar and the target. Numerical simulations are carried out to investigate the influence of the quadratic approximation of the range equation on the GMTI performance and to figure out the quadratic-approximated range equation’s scope of application.

An Efficient Imaging Method for Medium-Earth-Orbit Multichannel SAR-GMTI Systems

“…In addition, the radar's beam centerline is assumed to cross the target at t a = 0. Based on the kinematics, the coordinates of the satellite in the ECR coordinate system can be expressed as [20] …”

“…The dotted line in the figure represents the motion track of the satellite, and the azimuth axis of the antenna is parallel to the satellite's velocity vector vs(ta) because of the zero-Doppler steering. Therefore, the position vector of the effective phase center of the nth (n = 1, 2, …, N) channel can be represented by rs,n(ta) = rs(ta) − (n − 1)d‧vs(ta)/vs(ta), and the range from the target to the nth channel can be expressed as Based on the kinematics, the coordinates of the satellite in the ECR coordinate system can be expressed as [20] x…”

“…where ω means the argument of perigee, f (t a ) represents the satellite's true anomaly, a indicates the orbit's semi-major axis, and e represents the eccentricity, Ω is the right ascension of ascending node, θ i defines the orbit's inclination, and Ω G (t a ) = Ω G0 + ω e t a presents the Greenwich Hour Angle (GHA), where ω e refers to Earth's rotational angular velocity, and Ω G0 indicates the GHA at t a = 0. The detailed derivation of (1) can be found in [20].…”

“…Many studies on MEO SAR have been conducted in recent years [15][16][17][18][19][20]. The observation performance of MEO SAR and the signal characteristics of static targets had been studied in [15].…”

High Resolution Ranging with Small Sample Number under Low SNR Utilizing RIP-OMCS Strategy and AHRC l1 Minimization for Laser Radar

“…To enhance the ranging performance of laser radar, two distinct methods have been proposed: (1) utilizing improved spectrum-estimation methods [14][15][16][17][18]; and (2) employing techniques like compressive sensing [19][20][21][22][23][24][25][26][27][28], multi-channel technology [29][30][31][32][33][34][35], or deep learning [36][37][38].…”