IEEE Geoscience and Remote Sensing Magazine - March 2020 - 61

Receiving Antenna
Transmitting Antenna

FIGURE 27. The monitoring scene [85].
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FIGURE 28. The imaging results of (a) a MIMO-SAR and (b) the

GB-SAR [85].

Azimuth (°)

contrast using the MIMO-SAR system, a GB-SAR system is
also utilized to conduct experiments. A photo of the MIMOSAR system is presented in Figure 26.
Figure 27 shows a photo of the experimental scene.
The open-pit mine is a typical side slope with diameter of
600 m. During the experimental period, the MIMO-SAR
and GB-SAR systems were put at different positions and
continued monitoring at the same time. Although the
MIMO-SAR images could be acquired quickly using an
image interval of 11 min, the image acquisition intervals
of both systems were set to be the same 3 min. Experimental data sets of 1.5 h from 15 July 2017 13:00 to 14:30
were selected to conduct the analyses. The number of SAR
images acquired using the two systems during the period
was 30 for both.
Figure 28(a) and (b) displays the MIMO-SAR and GBSAR imaging results in the polar coordinates, respectively.
Different pixel colors represent the scattering properties of
corresponding regions of the open-pit mine. Because the
beamwidths of the transmitted signal in the vertical direction are both r/4 and the radar systems were located right
above the pit and directly opposite the monitoring area,
the bottom of the pit could not be illuminated. Considering that the synthesized aperture lengths and the bandwidths of both systems are nearly the same, the resolutions and amplitudes of the imaging results are intuitively
similar. The imaging ability of the MIMO-SAR system is
rather good.
When applying deformation analysis to the MIMOSAR images, the detailed processing steps included phase
unwrapping, atmospheric compensation, and deformation
measurement, in addition to the previously mentioned
steps of SAR imaging, PS selection, and DIn. Considering that the MIMO-SAR and GB-SAR systems were put at
different positions, the deformations were along different
LOS directions. Therefore, no effective comparisons could
be made using the deformation measurement results of
the MIMO-SAR. The atmospheric compensation result is
presented in Figure 29. Note that most of the pixels' unwrapped phase is roughly zero radian, and the atmospheric
phase has been well compensated for.
Figure 30(a) depicts the cumulative deformation map
during the monitoring period. The unit of the color bar is
millimeters. The maximum deformation value is −2 mm,
which is located in the upper part of the open-pit mine

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FIGURE 29. The atmospheric compensation result of a MIMOFIGURE 26. The MIMO-SAR system [85].
MARCH 2020

IEEE GEOSCIENCE AND REMOTE SENSING MAGAZINE

SAR [85].
61

IEEE Geoscience and Remote Sensing Magazine - March 2020

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