The Journal of Engineering
IET International Radar Conference (IRC 2018)
Wind speed estimation of low-altitude wind
shear based on combined space–time main
channel adaptive processing
eISSN 2051-3305
Received on 25th February 2019
Accepted on 8th May 2019
E-First on 31st October 2019
doi: 10.1049/joe.2019.0662
www.ietdl.org
Hai Li
1
, Jie Wang
1
, Qing H. Guo
2
, Yi J. Li
1
1
Tianjin Key Lab for Advanced Signal Processing, Civil Aviation University of China, Tianjin, People's Republic of China
2
School of Electrical, Computer and Telecommunication Engineering, University of Wollongong, Wollongong, Australia
E-mail: haili@cauc.edu.cn
Abstract: This study presents a low-altitude wind shear speed estimation method based on combined space–time main
channel adaptive processing. The method first reduces the dimension of the radar echo data of the measured range unit by
constructing a dimension-reduced joint space–time transform matrix, and then constructs the optimal weight vector of the
dimension-reducing processor to adaptively filter the reduced-dimensional data. Furthermore, accurate estimation of the speed
of the wind field is achieved in the presence of the amplitude–phase error. Simulation results demonstrate the effectiveness of
the proposed method.
1 Introduction
Airborne weather radar is the eye of civil aircraft [1], it can warn in
case of catastrophic weather such as low-altitude wind shear. When
the airborne weather radar detects the wind shear in the look-down
mode, the echoes of wind shear signal are usually covered by
strong clutter. Therefore, the effectiveness of clutter suppression
will directly affect the accuracy of wind speed estimation for low-
altitude wind shear. The conventional methods of clutter
suppressing [2–4] are to find an appropriate notch in the clutter
suppression while preserving the wind shear signal. However,
when there is an amplitude–phase error in the array, the clutter
spectrum will be broadened in the space, which reduces the degree
of freedom of the processor, seriously affects the performance of
clutter suppression, and therefore affects the accuracy of the wind
speed estimation.
Phased array radar has superior performance in target detection
and parameter estimation in strong clutter background [5]. Space–
time adaptive processing (STAP) [6] is the key technique of clutter
suppression and target detection for airborne phased array radar. It
can realise clutter suppression and signal matching using the
space–time coupling characteristics of radar echoes [7, 8].
Traditional STAP has been applied to target detection and
parameter estimation, but it is mostly aimed at point targets and
relatively few works are available for distributed targets, e.g. low-
altitude wind shear. In particular, the research on low-altitude wind
shear detection of airborne weather radar under the condition of
amplitude–phase error has not been reported in the literature.
In this work, a low-altitude wind shear wind speed estimation
method based on combined space–time main channel adaptive
processing is proposed. This method constructs a dimensionality-
reducing processor by calculating the reduced-dimensional joint
space–time transformation matrix, and uses the optimal weight
vector of the dimensionality-reduction processor to achieve clutter
suppression and match of wind shear, thereby achieving effective
estimation of wind speed.
2 Signal model
Fig. 1 illustrates the geometry of the airborne forward-looking
radar. The platform is at altitude H and moving at a constant speed
V. A uniform linear array with N elements is employed, and the
element spacing is d = 0.5λ, where λ is the wavelength of the radar
signal. In Fig. 1,
θ and φ are the horizontal azimuth and pitch
angles of the ground scattering bins, θ
0
and φ
l
are the horizontal
azimuth and pitch angles of low-altitude wind shear. Assume that
the clutter is non-fluctuating and the noise is additive white
Gaussian [6].
The number of coherent processing pulses in a coherent
processing interval is denoted by K and the pulse repetition
Fig. 1 Geometry of the airborne forward-looking radar
J. Eng., 2019, Vol. 2019 Iss. 21, pp. 8125-8128
This is an open access article published by the IET under the Creative Commons Attribution-NonCommercial-NoDerivs License
(http://creativecommons.org/licenses/by-nc-nd/3.0/)
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