【作者】 徐复；

【导师】 惠俊英；

【作者基本信息】 哈尔滨工程大学 ， 水声工程， 2011， 博士

【摘要】 被动声呐是现代水声对抗最重要的探测装备。早期的被动声呐只能测目标的方位,不能测目标的距离。上世纪70年代出现了被动测距声纳是水声定位技术的一个重大突破。90年代出现的舷侧阵声呐代表了被动声呐的最新体制,是目前舰壳声呐中作用距离最远的被动声呐。但是迄今为止,被动声呐仍然局限于检测宽带目标,对于脉冲目标没有跟踪定位的能力。因此,脉冲信号被动定位成为当前水声定位技术研究的热点,并期待在该领域取得新的突破。侦察脉冲信号是一种窄带信号。它的持续时间短,参数未知且随机出现,因此常规的互相关被动定位技术不适用,只能依靠传统的过门限技术估计信号时延,本论文称之为“直接法”。直接法时延估计的精度依赖于信号的波形,由于脉冲信号在海洋多途信道中传播,波形不可避免地会发生畸变,所以直接法时延估计达不到被动定位的精度要求。本论文从三点定位的基本原理出发,通过分析时延差估计误差与时延估计误差的关联性,采用信道均衡技术提高脉冲信号时延差估计的精度和稳定性。利用信号时延与相移的内在联系,结合自适应处理技术,提出时延差估计误差的整数倍周期修正方法,提高低信噪比信号时延差估计的精度。在此基础上,研究开发了联合多门限脉冲信号被动定位方法。应用该方法处理海试实验数据,其处理结果与雷达测量数据在各方位点的平均相对测距误差小于15%,是本论文的创新性研究成果。常规舷侧阵被动声呐在跟踪低信噪比宽带目标或交叉运动宽带多目标时,经常会发生丢失目标的现象。众所周知,宽带目标跟踪过程中干扰是随机发生的,而信号相对平稳；目标不同,其线谱特征也不相同。本论文综合利用目标的线谱特征和能量信息跟踪目标,改善了对目标的跟踪能力；通过增加目标累积的历史信息显示,将原系统的A式显示模式改造成伪三维显示(B式显示),提高了低信噪比目标的检测概率,使原系统的技术性能有所提高。研究成果具有创新意义。近场噪声分布声图技术在水声对抗技术领域有潜在的应用价值。在海洋信道中,由于多途干扰的影响,它对于噪声目标近场定位的性能会下降。本论文采用虚阵技术抗多途干扰,提出了乘积声图的方法改善分辨率,取得较好的结果。此外,还应用方位引导方法对聚焦波束形成技术进行了改进,得到了方位引导聚焦波束形成方法。它可使运算量大幅减小,降低了对系统资源的要求。本论文的研究成果均在理论分析的基础上,进行了实验验证。更多还原

【Abstract】 Passive sonar is the most important detecting equipment in modern underwater acoustical countermeasure. Earlier passive sonar could only estimate the azimuth of a target, but not to range for any targets. It was a major breakthrough that a new kind of sonar being developed, which could estimate the azimuths as well as distances of targets, in the 70s of the last contrary. Being a representative of the newest design architecture, frank passive sonar, which was presented in the 90s, had possessed the furthest ranging capability compared with the rest of onboard passive sonars. However, all of the passive sonars are constrained to range broadband targets only, remaining useless in ranging for impulse targets up till now. Therefore, passive locating for signal impulses becomes a research hot point recently, expecting to have a new breakthrough in the field it belongs.Surveillance signal impulses, which are brought out randomly, are narrow band signals with short durations and unknown parameters so that conventional correlation techniques are not applicable in passive locating for signal impulses, which has to be relied on the traditional amplitude gated time delay estimation called "Direct method" in this dissertation. Precision of direct time delay estimation relies on signal waveforms. Since waveforms of signal impulses will be distorted unavoidably while propagating in multi sea channels, direct estimation fails to meet the precision requirement for passive locating. The technique of channel equalization was applied to improve the precision and stability of time delay difference estimation in this dissertation from the point of view of principles of three points locating based on the analysis of the relativity between time delay difference and time delay estimation errors. Exploiting the inherent relationship between time delay and phase shift together with adaptive processing techniques, multi period compensation method for time delay difference estimation error was developed leading to the reduction of estimation errors. On the basis of aforementioned techniques, the cooperative multi amplitude gated passive locating technique, which is considered as the creative research achievement of this dissertation, was proposed. Applying this technique to process sea trial data, the average relative ranging error at different azimuths is less than 15%, using the test data obtained by radar as references.It is easy to happen, that one or more of the targets while being tracked by conventional frank passive sonar will be lost under the condition that some of the targets were of lower SNR or moving cross over. It is well known that interferences are created randomly while broadband signals radiated by targets are kept stable during the tracking process. The line components of broadband signals radiated by targets will be different if the targets are different from each other. The information of both line component and signal energy of a target was utilized comprehensively by this dissertation to improve the tracking ability. Display mode of type A of an existing system was transformed into pseudo 3D display (type B) by adding historical information of targets accumulated during operation to the screen, resulting in higher detecting probability for lower SNR targets. Therefore, performance of the existing system is enhanced, which is regarded as a contributive research achievement of this dissertation.The technique of sound distribution map of near field noises is of great potential importance in underwater acoustical countermeasure. Because of the interferences of multi sea channels, its performance of near field locating for noise targets will be degraded. By applying virtual array technique to suppress the interferences of multi sea channels, and developing the technique of product sound map, which was proposed by this dissertation, to improve the resolution, satisfactory results were obtained. Besides, direction guided focused beam forming technique had been developed as well, which could not only locate near field target with high precision but also reduce the computation burden by a big margin.Experimental measurements were carried out in this dissertation to verify theoretical predictions.更多还原