IEEE Geoscience and Remote Sensing Magazine - March 2020 - 45

for glacier monitoring, the continuous collection interval is
too long for some parts of the glacier, and the complex atmospheric conditions of the glacier area also affect the accuracy
of the system [28]-[30]. GB-DInSAR technology remains a
hot spot in international research. With the application domain expanding and gradually deepening, many problems
have appeared in the practical application of GB-DInSAR.
This puts higher requirements on the model method, radar
system, and data processing algorithm and calls for further
research and exploration.
This article provides a comprehensive and systematic summary of the research and application of GB-DInSAR technology over the past 20 years, which is helpful for researchers
engaged in GB-DInSAR to fully understand the development
process, research status, and challenges associated with this
technology. We also hope that this article plays a positive role
in the promotion of GB-DInSAR applications.
GB-DInSAR SYSTEM THEORY
As shown in Figure 1, the GB-DInSAR system first obtains
time-series echo data and then generates the complex image corresponding to each sequence of data through the
imaging algorithm. Next, deformation maps can be generated using differential interference processing. Finally, after
geocoding the deformation maps and images, the final results are obtained.
A GB-DInSAR system can be divided into two modes, linear scanning and arc scanning, according to the formation
methods of its synthetic aperture. The following sections introduce these two modes as well as related theories. Then,
the signal setup in the system is given, and the geometric and
signal models of the GB-DInSAR system are described.
WORKING MODES OF GB-DInSAR
LINEAR SCANNING MODE
In the linear scanning mode, the radar antenna is placed on
a straight-track platform to form a rectilinear synthetic aperture [31]. This mode is simple and practical; however, due to
the limited length of the rail, the monitoring range is easily
limited by the angular width of the antenna beam. Figure 2
depicts a schematic diagram of the linear scanning mode.
The range resolution in the linear scanning mode is determined by the bandwidth of the transmitted signal. The
expression of the range resolution is

MARCH 2020

ARC SCANNING MODE
In the arc scanning mode, the radar antenna is fixed at one
end of the rotating arm on the radar platform. With this
rotational motion, the antenna forms an angular synthetic
aperture on the horizontal plane. Compared with the linear
scanning mode, the arc scanning mode can obtain a larger
monitoring range in the same scanning time. Meanwhile,
the system structure easily meets the requirement for being
small and portable, which is typical of current practical engineering applications. Figure 3 shows a schematic diagram of
the arc scanning mode. The range resolution in arc scanning
mode is the same as that in (1). Its azimuth resolution is

d arc =

mR(t)
, (3)
(2r $ i s)

where i s is the sweep angle, r is the length of the rotating arm
(which is usually 1-2 m in actual systems), and R(t) is the target slant range [32]. The azimuth resolution in the arc scanning

GB-DInSAR
System

Time-Series
Echo Data

DIn

Imaging

Deformation
Image

Complex
Images

Geocoding

mR(t)
d a = (2L ) , (2)
s
IEEE GEOSCIENCE AND REMOTE SENSING MAGAZINE

Final
Results

FIGURE 1. The whole processing flowchart of a GB-DInSAR system.

δa

c
d r = 2B , (1)
w

where c is the speed of light and B w is the bandwidth of the
transmitted signal.
The synthetic aperture length in the linear scanning
mode is determined by the length of the rail. As a result,
the azimuth resolution expression is

where L s is the length of linear rail (which is usually 1-2 m
in the actual system), m is the wavelength of the transmitted signal, m /(2 L s) represents the angular resolution, and
R(t) is the slant range. The azimuth resolution decreases as
the slant range increases. Meanwhile, a larger L s and smaller m will obtain a higher azimuth resolution.

δr

R (t )

FIGURE 2. A schematic diagram of the linear scanning mode.

IEEE Geoscience and Remote Sensing Magazine - March 2020

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