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查看完整版本: 美国对付中国最高机密:低频主动声纳(LFA)间谍船

ssdff 2007-6-14 13:05

美国对付中国最高机密:低频主动声纳(LFA)间谍船

美国进驻日本对付中国最高机密:低频主动声纳(LFA)间谍船,常驻那霸基地,至今为止尚未为我方在东海上捕获目标,非常狡滑!
低频主动声纳

美国海军计划配备一种潜艇探测系统,名为低频主动声纳(LFA),覆盖地球海洋的80%。低频主动声纳的研制是基于,甚低频声波[100-1000 Hz] 可以传播很远,能够探测到低噪音潜艇。低频主动声纳系统使用高强度声波,据说高达235分贝这样的水平,甚至更高[海军已经给出了低频动声纳在大约2公里距离160分贝的特性]。高强度声波是由拖拽于TAGOS级舰船后的大规模声波发射机产生的。

目前的被动SURTASS拖拽式列阵声纳,探测低噪音潜艇的能力有限。因此,在低频主动(LFA) 拖拽式列阵声纳领域的研究已经进行了一些时日。TAGOS 级舰船的低频主动声纳具有在更远距离上探测低噪音潜艇的潜力。

由于美国海军在近岸地区冲突中遭遇低速柴油动力潜艇的可能性增加了,浅水声学这一问题就比较突出。由于各种声音混杂传播,声波特征高度混乱,目标多普勒效应低,浅水、低速潜艇声学上的探测和分辨比冷战威胁时期困难了很多。有效的声纳性能要求新的信号处理算法。而由于高速处理的要求,新的信号算法不能在海军舰艇平台上应用。一种数字/光学混合处理器(HyDOP) 将验证使用植入式可升级高性能数字和光学处理方式解决这一难题的可行性。这需要采用高强度算法,不能在实时处理的传统处理器上执行。海军研究实验室 (NRL)正在开发的一种高速声学相关器将作为Intel Paragon XP/S-25计算机的协处理器。

低频声纳开发的时间已经超过10年,1988年以来在某些海域已经试验了25次。海军试验低频声纳超过了7500小时。低频声纳的IOT&E 于1992年10月在阿拉斯加海湾完成,测试安装于经过修改的单体研究船上的低频声纳的工程开发模式(EDM) 。COMOPTEVFOR 发现,SURTASS低频声纳系统在操作的有效性和适应性方面具有潜力。

BBN 已经发展了ARTS列阵船舶计划,专门解决低频主动声纳源的这一难题。列阵可以产生传播大约100英里的高强度、低频、可变波段声波(235分贝,100-1000 Hz)的蝶形声波。拖拽式列阵配置在水下100米,速度3节,以10%的功率周期发射脉冲。在近期试验中,低频主动 (LFA)声纳 系统探测到了远距离的潜艇。第一艘主动声纳船,TAGOS 23号,已经在建造中。四艘专用船已经列入计划,分配给大西洋舰队和太平洋舰队。列装之前的过度时期,一艘租借的船,Cory Chouest号,用于舰队检验和验证低频主动声纳技术。而且,声学资源压缩技术已在开发中,重量和能源需求将减少50%。这些技术的成熟将使低频主动型列阵能配置在目前的AGOS 19级船舶上。

低频主动声纳的批评者,比如自然资源保护协会 [NRDC]指责说,这将使海洋哺乳动物遭受噪声污染,比其受到影响的强度高2000亿倍。数年前,La Jolla斯克里普斯海洋学学院的耗资4000万美元的海洋气候的声学温度测量法(ATOC)项目中,CA计划在Monterey 海湾国家海洋禁猎区开辟一个低频水下声源。虽然,海洋气候的声学温度测量法(ATOC)项目计划产生195分贝水平的噪音,自然资源保护协会(NRDC)成功干预,阻止了这个研究项目就低频声波对海洋哺乳动物的影响这一悬而未决的进一步研究。海军已经同意自然资源保护协会的请求,低频主动声纳项目将进行环境影响评价。低频主动声纳的环境影响评价于1997年8月进行,报告由低频主动声纳系统承包人编写。美国海洋运动组织已经与其他一些环境团体联合工作,监视政府和水下声学产业界。
Low-Frequency Active (LFA)

The U.S. Navy plans to deploy a new submarine detection system, known as Low Frequency Active Sonar (LFA), throughout 80% of the world's oceans. LFA is based on the fact that very low frequency sound [100-1000 Hz] can travel great distances and detect quiet submarines. The LFA system uses intense sound, reportedly at levels in the range of 235 decibels or greater [the Navy has given a figure of 160 dB at about 2 km from the LFA] generated by massive sound transmitters towed behind TAGOS-class ships.

Current passive SURTASS towed array sonars are limited in their capability to detect quiet submarines. Thus research has been going on for some time in the area of low frequency active (LFA) towed array sonar. LFA offers the potential for TAGOS ships to make longer range detections of quiet submarines.

The shallow-water acoustics problem has risen in importance due to the increased salience of regional conflicts where the US Navy may to encounter slow, diesel submarines close to shore. The shallow-water, slow submarine is significantly more difficult to detect and classify acoustically than the cold war threat, due to the complex propagation, high clutter, and low target Doppler. Effective sonar performance requires new processing algorithms which cannot be implemented on current Naval platforms due the high processing requirements. A Hybrid Digital/Optical Processor (HyDOP) is to demonstrate the feasibility of using embedded scalable high performance digital and optical processing to solve this problem. This requires application of computationally intensive algorithms which cannot be implemented in real time using conventional processors. A high-speed optical correlator being developed by the Naval Research Laboratory (NRL) will act as a coprocessor to an Intel Paragon XP/S-25 computer.

LFA has been under development for more than a decade, and has been tested perhaps 25 times in several oceans since 1988. The Navy has already tested LFA for over 7,500 hours. IOT&E of LFA was completed in October 1992, in the Gulf of Alaska, testing an engineering development model (EDM) of the LFA system installed in a converted, monohull research vessel. COMOPTEVFOR found the SURTASS LFA system potentially operationally effective and potentially operationally suitable.

BBN has developed the ARTS array vehicle concept specifically to address the formidable problems of low-frequency active sonar sources. The array creates a dish shaped pattern of very loud, low frequency, variable broadband sound (235 dB re 1 礟a @ 100-1000 Hz) that reaches out roughly 100 miles. The towed array is deployed about 100 meters deep at three knots, pulsing on a 10% duty cycle. In recent experiments, Low-Frequency Active (LFA) system has detected submarines at long ranges. The first LFA ship, TAGOS 23, is under construction. Four dedicated vessels are planned, divided between the Atlantic and Pacific Fleets In the interim, a leased ship, Cory Chouest, is being used as a fleet asset to test and validate LFA technologies. In addition, compact acoustic source technologies are under development that will provide a 50% reduction in weight and power requirements. Successful maturing of these technologies will allow LFA-type arrays to be deployed from existing TAGOS 19-class vessels.

Critics of LFA, such as the Natural Resources Defense Council [NRDC], charge that it will expose marine mammals to noise pollution at a level 200 billion times greater than that which is known to disturb them. Several years ago the $40 million acoustic thermometry of ocean climate (ATOC) program of the Scripps Institution of Oceanography in La Jolla, CA proposed to operate a low frequency underwater sound source in the heart of the Monterey Bay National Marine Sanctuary. Although ATOC proposed to generate noise at a level of only 195 decibels, NRDC successfully intervened to stop this research program pending further study of the effects of low-frequency sound on marine mammals. The Navy has agreed to NRDC's request that an EIS be prepared for the LFA program. The LFA Draft Environmental Impact Statement is due in August 1997, and is being written by the contractor for the system. The American Oceans Campaign has been working in coalition with a number of other environmental groups to keep tabs on government and industry underwater sound generation.
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查看完整版本: 美国对付中国最高机密:低频主动声纳(LFA)间谍船