Method of Passive MMW Image Detection and Identification for Close Target
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Method of Passive MMW Image Detection and Identification for Close Target LiangChao Li & JianYu Yang & GuoLong Cui & ZhengMao Jiang & Xin Zheng
Received: 8 September 2008 / Accepted: 18 November 2010 / Published online: 14 December 2010 # Springer Science+Business Media, LLC 2010
Abstract This paper mainly deals with the problem of detecting and identifying target in close range, the performance of which will be effected by the radiometer’s parameters and target’s characteristics. According to the relationship between the range equation of the Passive Millimeter Wave (PMMW) and these parameters, we present a convenient statistical method based on PMMW image detection to solve the inherent problem by statistical radiometer parameters, which can be achieved by the W band radiometer experimental data. Finally, we validate the method by simulation and experiment. The results show that the method is convenient for detecting and identifying target in close range. Keywords PMMW . Radiometer . Range equation . Detection and identification
1 Introduction Passive millimeter-wave (PMMW) imaging system forms images by detecting the millimeter-wave radiation energy from the scene and utilizing the differences of the radiation intensity [1, 2]. It can penetrate clouds, fog, light drizzle, and some clothes, which is widely used in airport security, scene monitoring, concealed weapons detection, et al [3–8]. For most of these applications, a detailed two-dimensional image is adequate. However, there are many other applications where the range to an object is also of interest. At microwave and millimeter wavelengths, the main ranging technique is radar, which is an active method. For active method, a disadvantage is the occurrence of speckle noise. A small number of raindrops may lead to erroneous ranging of clouds with a cloud radar; or in
L. Li (*) : J. Yang : G. Cui : Z. Jiang : X. Zheng School of Electronic Engineering, University of Electronic Science and Technology of China, Chengdu, People’s Republic of China 610054 e-mail: [email protected]
J Infrared Milli Terahz Waves (2011) 32:102–115
103
case of an object with specula surfaces, the return signal critically depends on the object orientation. On the other hand, passive imaging is free of speckle noise. Instead, thermal noise limits the object detect-ability. An important advantage of passive imaging is the fact that object shape and size do not have deteriorating effects [5]. However, the obtained images in PMMW usually have poor resolution due to the weakness of the target’s self-radiation energy, especial far field. Therefore far field target detection is not a likely candidate for PMMW imaging detection. There is insufficient resolution for the small size of the target, and the path loss would be very high at W band for far field detection. Thus, short to medium field target detection of PMMW will be taken more consideration in recent years [9, 10]. As to detection and identification for close target, the performance will be affected by the radiometer’s parameter
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