高频面波雷达干扰抑制：斜投影偏振滤波新方法

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"斜投影偏振滤波在高频面波雷达中的干扰抑制" 本文主要探讨了在高频表面波雷达（High-Frequency Surface Wave Radar, HFSWR）系统中，如何利用斜投影偏振滤波（Oblique Projection Polarisation Filtering, OPPF）技术来有效地抑制干扰。HFSWR因其长监测距离和高分辨率的特性，在海洋监测、海岸防御等领域有着广泛的应用，但同时也面临着各种干扰问题。传统的滤波方法可能不足以应对这些挑战，因此，研究新型的滤波策略显得至关重要。首先，文章介绍了偏振滤波的基本原理，这是一种利用信号偏振特性进行处理的方法，可以区分不同偏振状态的信号，从而筛选出目标信号。而斜投影偏振滤波则是将这一概念与斜投影理论相结合，创建了一种新的滤波器设计。OPPF可以通过构建目标信号的偏振子空间和干扰的偏振子空间，或者直接使用实验数据来实现。接着，文章提出了两种构建OPPF算子的方法：理论OPPF和改进的OPPF。理论OPPF基于理想化的模型和先验知识，而改进的OPPF则适用于干扰未知或难以精确估计的情况，具有更强的适应性。同时，作者还分析了估计误差对滤波器性能的影响，指出准确的偏振子空间估计对于优化滤波效果至关重要。通过数值模拟和实验数据的分析，OPPF被证明在干扰抑制方面表现出色，能有效提升HFSWR系统的信噪比和目标检测能力。特别是在干扰特性不明确的情况下，改进的OPPF滤波器表现出了优于传统偏振滤波器的性能，这为实际应用提供了有力的支持。此外，文章引用了《IET Radar, Sonar and Navigation》期刊，表明这是一个经过同行评审的研究成果，具有较高的学术价值。发布日期为2011年，表明该研究是在HFSWR技术发展早期阶段进行的，对后续的相关工作产生了深远影响。这项研究揭示了斜投影偏振滤波在解决HFSWR系统干扰问题中的潜力，为未来开发更高效、适应性强的滤波算法提供了理论基础和技术参考。同时，对于理解偏振滤波在雷达系统中的作用以及如何优化滤波器设计，也提供了深入的见解。

Published in IET Radar, Sonar and Navigation

Received on 19th May 2011

Revised on 20th August 2011

doi: 10.1049/iet-rsn.2011.0175

ISSN 1751-8784

Oblique projection polarisation ﬁltering for

interference suppression in high-frequency

surface wave radar

X.-P. Mao A.-J. Liu H.-J. Hou H. Hong R. Guo W.-B. Deng

Harbin Institute of Engineering, 150001, People’s Republic of China

E-mail: mxp999@hotmail.com

Abstract: Polarisation ﬁltering is a valid approach for interference suppression in high-frequency surface wave radar (HFSWR)

and other systems. Based on the fundamental principle of the oblique projection and polarised ﬁltering, an oblique projection

polarisation ﬁlter (OPPF), which can be constructed from the polarisation subspaces of the target signal and those of the

interference or directly from experimental data, is proposed in this study. Generalised methods for constructing the OPPF

operators (theoretical OPPF and improved OPPF) are provided and the impact on the performance caused by the estimation

errors is also discussed. Numerical results from simulation and experimental data demonstrate that the proposed ﬁlter is an

effective means of interference cancellation. It is proved that OPPF is an extension of the conventional polarised ﬁlter,

whereas the improved OPPF is more suitable for the situation where the interference is unknown.

1 Introduction

As a s upplement of the signal processing technique in time,

frequency and spatial domain, polarisation signal processing

has been widely applied in the ﬁelds of signal extraction

and interference suppression [1–5], whereas polarisation

ﬁltering is an important branch of it for interference

suppression. Based on the orthogonal projection, the

optimal performance of a conventional polarisation ﬁlter

can only be achieved when the polarised state of the target

signal is orthogonal to that of the interference. However,

this condition cannot always be met and distortion of the

phase and amplitude of the target signal will be introduced

because of non-orthogonality. The amplitude distortion that

depends on the spherical distance between the target signal

and the interference on the Poincare

sphere, is commonly

named polarisation loss.

To separate the non-orthogonal polarisation signals and

suppress the interferences more efﬁciently, Poelman and

Guy [6, 7] proposed a linear polarisation-vector transformer

(LPVT) to convert the non-orthogonal polarisation signals

to orthogonal signals. Similarly, in [8] an oblique

polarisation ﬁlter is proposed to separate two completely

polarised seismic waves by phase-shift, rotation and

ampliﬁcation operations on them. These researchers have

made positive contributions in view of the non-orthogonal

polarisation signal processing technique. However, few

methods involve avoiding the distortion of the desired

signal’s phase and amplitude introduced by polarisation

ﬁltering.

In a coherent system, a conventional polarisation ﬁlter must

be time-varying to adapt to the time-varying property of the

polarisation parameters of the interference, and a time-

varying distortion of the amplitude and phase of the target

signal is introduced. Owing to the time-varying

characteristic of the polarisation parameters, the correlation

of the target signals will be lost. As a result, the target

signals may be strong enough after interference suppression,

but disappear after correlation accumulation. This

disadvantage limits the application of the polarisation ﬁlter

technique.

To solve this problem, a null phase-shift polarisation

(NPSP) ﬁlter is proposed in [2]. NPSP ﬁlter consists of a

LPVT, a single notch polarisation (SNP) ﬁlter and an

amplitude/phase compensation device. The amplitude/phase

compensation device performs the compensation for the

distortion of the amplitude and phase caused by the time-

varying polarisation ﬁltering.

Without exception, all methods mentioned above convert

the non-orthogonal polarisation signals to orthogonal

signals so as to mitigate the interference. Obviously, it is

more convenient and efﬁcient to process the non-orthogonal

polarised signal directly without any polarisation

transformation. As an extension of the orthogonal

projection and a powerful tool for signal processing, the

oblique projection operator has many advantages to process

the non-orthogonal signal. Therefore, in this paper, the

oblique projection operator is introduced to the polarisation

ﬁelds and a more effective polarisation ﬁlter, called oblique

projection polarisation ﬁlter (OPPF) [9, 10], is proposed by

combining the oblique projection [11–16] and the

conventional polarisation ﬁltering technique. Theoretical

analysis and simulation results demonstrate that the

proposed OPPFs, including the theoretical OPPF and the

IET Radar Sonar Navig., pp. 1–10 1

doi: 10.1049/iet-rsn.2011.0175

The Institution of Engineering and Technology 2012

www.ietdl.org

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高频面波雷达干扰抑制：斜投影偏振滤波新方法

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