Abstract
While there are recent researches on hypersonic vehicle-borne multichannel synthetic aperture radar in ground moving target indication (HSV-MC-SAR/GMTI), this article, which specifically explores a robust GMTI scheme for the highly squinted HSV-MC-SAR in dive mode, is novel. First, an improved equivalent range model (IERM) for stationary targets and GMTs is explored, which enjoys a concise expression and therefore offers the potential to simplify the GMTI process. Then, based on the proposed model, a robust GMTI scheme is derived in detail, paying particular attention to Doppler ambiguity arising from the high-speed and high-resolution wide-swath. Furthermore, it retrieves the accurate two-dimensional speeds of GMTs and realizes the satisfactory performance of clutter rejection and GMT imaging, generating the matched beamforming and enhancing the GMT energy. Finally, it applies the inverse projection to revise the geometry shift induced by the vertical speed. Simulation examples are used to verify the proposed GMTI scheme.
Highlights
Flight-borne synthetic aperture radars (SAR) provide tremendous potentials to generate microwave imageries of ground moving targets (GMT) [1] and stationary targets.due to the flight characteristics of the platforms, traditional SAR processing exhibits some limitations [2]
The data acquisition model is defined as follows: an arbitrary GMT is denoted by T ( x T, R0 ); the nearest distance between the radar carrier and T is represented by Rb ; the speed vector along the X 0 -axis and Y 0 -axis are denoted by v x0 and vy0 ; along-track velocity (ATV) and cross-track velocity (CTV) of a GMT are indicated by v a and vr ; the adjacent channel distance is represented by d; the distance between the first and the n-th channel is denoted by dn = (n − 1) × d
SC,n p JP, q JP = [SC,n ( p − ( Nr − 1)/2, q − ( Na − 1)/2), . . . , SC,n ( p + ( Nr − 1)/2, q + ( Na − 1)/2)] ∈ 1× Nr · Na where the range-cell and azimuth-cell numbers in the pixel window are represented by Na and Nr, the range-cell and azimuth-cell indexes in terms of the joint-pixel are indicated by p JP and q JP, the number of pixels in a pixel window is denoted by NC = Nr · Na ( N − 1) + 1
Summary
Flight-borne synthetic aperture radars (SAR) provide tremendous potentials to generate microwave imageries of ground moving targets (GMT) [1] and stationary targets. When dealing with a high-squint, a highspeed, and a dive orbit, the range model of HSV-SAR/GMTI has non-negligible high-order or coupled phase terms and may induce distortion on the GMT envelopes [6,7,8,14,15]. While the CFT-modified algorithm [15] rejects the DA clutter and performs the small-interval sweep on unknown CTV, it is computationally time-consuming To tackle these problems, this article presents a robust GMTI scheme for the highly squinted HSV-MC-SAR with a dive orbit. This article has the following contributions: While there are recent researches on highly squinted HSV-MC-SAR/GMTI [14,15], this article, which explores a GMTI scheme in dive mode, is novel It presents the IERM of a stationary target and GMTs, performs the accurate clutter rejection with matched beamforming, and achieves the GMT imaging and location.
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