High-resolution ISAR imaging of fast rotating targets based on pattern-coupled Bayesian strategy for multiple measurement vectors

Very high resolution inverse synthetic aperture radar (ISAR) imaging of fast rotating targets is a complicated task. There may be insufficient pulses or may introduce migration through range cells (MTRC) during the coherent processing interval (CPI) when we use the conventional range Doppler (RD) ISAR technique. With compressed sensing (CS) technique, we can achieve the high-resolution ISAR imaging of a target with limited number of pulses. Sparse representation based method can achieve the super resolution ISAR imaging of a target with a short CPI, during which the target rotates only a small angle and the range migration of the scatterers is small. However, traditional CS-based ISAR imaging method generally faced with the problem of basis mismatch, which may degrade the ISAR image. To achieve the high resolution ISAR imaging of fast rotating targets, this paper proposed a pattern-coupled sparse Bayesian learning method for multiple measurement vectors, i.e. the PC-MSBL algorithm. A multi-channel pattern-coupled hierarchical Gaussian prior is proposed to model the pattern dependencies among neighboring range cells and correct the MTRC problem. The expectation-maximization (EM) algorithm is used to infer the maximum a posterior (MAP) estimate of the hyperparameters. Simulation results validate the effectiveness and superiority of the proposed algorithm.     

机载光电雷达它机试飞技术研究

机载光电雷达受平台及大气环境影响较大,而它机试飞能有效规避研制风险,是产品研制的必经阶段。本文介绍了机载光电雷达它机试飞试验系统组成、试验流程和数据处理等内容。经工程验证,实施过程满足任务需求,对其他光电系统的它机及本机试飞具有参考价值。     

Change detection in synthetic aperture radar images based on unsupervised artificial immune systems

In this paper, we propose a novel change detection method for synthetic aperture radar images based on unsupervised artificial immune systems. After generating the difference image from the multitemporal images, we take each pixel as an antigen and build an immune model to deal with the antigens. By continuously stimulating the immune model, the antigens are classified into two groups, changed and unchanged. Firstly, the proposed method incorporates the local information in order to restrain the impact of speckle noise. Secondly, the proposed method simulates the immune response process in a fuzzy way to get an accurate result by retaining more image details. We introduce a fuzzy membership of the antigen and then update the antibodies and memory cells according to the membership. Compared with the clustering algorithms we have proposed in our previous works, the new method inherits immunological properties from immune systems and is robust to speckle noise due to the use of local information as well as fuzzy strategy. Experiments on real synthetic aperture radar images show that the proposed method performs well on several kinds of difference images and engenders more robust result than the other compared methods.     

Performance evaluation of noise reduction method during on-line monitoring of MV switchgear for PD measurements by non-intrusive sensors

Partial Discharge (PD) measurement is a globally accepted method for insulation diagnosis of electrical assets. The consequences of insulation breakdown are well known. The trend is to move from conventional offline testing to online monitoring for insulation life prediction, which results in the inclusion of high frequency noise in the captured signals. Therefore de-noising is of paramount importance in online monitoring to obtain useful information from the signal.In this research, a 20 kV switchgear panel has been subjected to PD faults in the laboratory and measurements have been carried out by using different non-intrusive sensors including a novel sensor, the D-dot sensor and recorded by a high frequency oscilloscope. The measured results show the effective applicability of sensors for switchgear. The Discrete Wavelet Transform (DWT) has been used to de-noise PD signals in this paper. Time domain and frequency domain comparison of original and de-noised PD signals reveals the significance of this technique for online monitoring of Medium Voltage (MV) switchgear. Finally, an adaptive online de-noising concept, based on automatic de-noising is also proposed in this paper.     

对空监视雷达探测威力检飞的几个问题

以新的观点论证了对空监视雷达探测威力检验飞行中所需的采样点数和飞行架次，讨论了预警机雷达威力检飞的特殊问题，包括地区选择、航线设计和目标机标定等。     

伪码连续波交会对接雷达信号处理机设计

介绍了某伪码连续波交会对接雷达信号处理机设计.在测距中,提出用噪声较小的载波相位△伪距测量值对伪距进行处理,得到高精度测距值.在测角中,提出了一种干涉仪天线阵结构和干涉仪解模糊算法,针对通道载波相位误差可能引起的解模糊错误,又提出了一种纠正方法,仿真显示,在发生解模糊错误的概率高达0.42的情况下,该方法仍然可以识别并纠正所有解模糊错误.实验表明,该信号处理机可以满足空间航天器交会对接的要求.     

探地雷达在地下管线探测中的应用

探地雷达技术是如今适应快速、准确、无损地探测地下障碍物而迅速发展的电磁技术。文中介绍了探地雷达的工作原理及工作方式，并通过结合工程实例来探讨探地雷达在地下管线探测中的广泛应用。     

某雷达数据处理有关问题分析

对某雷达数据处理应用中存在的一些特殊问题进行讨论分析,并就具体问题提出了解决的方法.     

一种PD雷达动目标模拟与微波测控系统

介绍了一种基于PC／104总线，具有GPIB程控功能，采用无内部微波源体制，通过在雷达载频上调制多普勒频率模型目标速度信息，延迟雷达发射机触发脉冲模拟目标距离信息并具有微波功率精确定标与衰减功能的PD雷达动目标模拟与微波测控系统。     

光纤通信在天波超视距雷达中的应用

天波超视距雷达是低空防御系统中一种有效的预警手段。通过采用光纤传输技术，利用其信息传输容量大，速度快，频带宽，抗干扰能力强，线路损耗低。易于施工等特点，实现全相参雷达的信息传输和系统控制，具有优良的保密性，稳定性、抗干扰性和抗摧毁能力。