MIMO-SAR GROUND MOVING TARGET IMAGING IN HRWS MODE
Chao Xie
a
, Libao Wang
a
*
, Dangwei Wang
a
, Ling Wang
b
, Yanfeng He
a
Air Force Early Warning Academy, Wuhan 430019, P. R. China a
National University of Defense Technology, Changsha 410073, P. R. China b
*Corresponding Author: mimosar_wlb@163.com (L. B. Wang)
ABSTRACT
This paper proposes a novel method for MIMO-SAR ground
moving target imaging in HRWS Mode. In order to
compensate the periodically modulated error signal in
Doppler history due to the radial velocity of moving target,
the compressed sensing theory is used to estimate radial
velocity in undersampled signal firstly. Then, the
compensation signal is formed with radical velocity to
remove error signal in the whole Doppler signal. Finally,
ground moving target imaging is achieved by using focusing
function of moving target. The numerical experiments are
provided to demonstrate the effectiveness of the proposed
method.
Index Terms—MIMO-SAR, moving target, HRWS,
compressed sensing
1. INTRODUCTION
Synthetic aperture radar (SAR) has been widely used in the
fields of civil and military
[1, 2]
. As the rising demand on
multifunctional capability in different SAR applications, the
advanced SAR system needs high system degrees of
freedom (DOF), which can be obtained by MIMO-SAR
[3, 4]
.
This paper aims at imaging ground moving target in high
resolution wide swath(HRWS) mode of MIMO-SAR.
To improve the performance of wide-swath and high-
resolution imaging for static scenes, as well as SAR GMTI,
simultaneously, we have proposed a novel signal processing
method for MIMO-SAR in [5].The research have shown
that a periodically modulated error signal due to the radial
velocity of moving target will be introduced in the azimuth
signal, which can lead to a series of unwanted “spurious
peaks” in azimuth image of moving target. In order to
compensating the error signal, auto-focusing method was
used to search the ambiguous Doppler centroid in [6]. In this
paper, a novel method is proposed to image ground moving
target in HRWS mode. The proposed method aims at radial
velocity estimation in undersampling environment by
compressed sensing technique firstly, and then the error
signal is compensated for the whole Doppler signal
2. SIGNAL MODEL IN HRWS MODE
2.1. Problem Description
As we know, MIMO-SAR can obtain an MN-element filled
virtual array with real M+N T/R elements in a single
snapshot. Each virtual element represents a virtual spatial
sampling, and we can use all virtual elements elaborately for
different SAR applications. Similar to the conventional
multi-channel SAR, MN virtual channels can also be
reconstructed, but MIMO-SAR can provide better moving
target detection performance by exploiting the maximum
virtual channels with a limited number of real elements. Of
course, we can reconstruct a single equivalent channel,
which is similar to the conventional MPC-SAR, but it can
provide more wider swath because much lower system PRF
can be used. In this paper, the proposed tradeoff scheme in
[5,6] is also considered to realize MIMO-SAR ground
moving target imaging in HRWS Mode. For example, we
can reconstruct virtual dual-channel as shown in Fig.1 to
realize clutter suppression and moving target processing.
Meanwhile, each virtual channel assigned three virtual
spatial samplings can be used to solve the tradeoff between
wide-swath and azimuth high-resolution for static scene
imaging.
m
t
0
t
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t
2
t
3
t
5
t
6
t
0
1
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t
Fig. 1. Reconstruction of spatial samplings
2.2. Signal Model
978-1-4799-2186-7/14/$31.00 ©2014 IEEE