共查询到18条相似文献，搜索用时 156 毫秒
1.
2.
详细阐述了网格编码调制(TCM)的原理及其在水下无线通信中的应用。同时用System View对系统进行仿真，仿真结果显示，该方案使水下无线通信系统的性能得到明显改善。 相似文献
3.
为了在恶劣的水声信道中确保数据的可靠传输,采用性能优异的Turbo码,以6711DSP为核心处理单元构建译码系统。系统采用戈泽尔算法进行跳频的软解调,迭代的软输出维特比译码算法(SOVA)进行译码。系统经过实验室水池的试验,证实能保证译码的实时性及其在恶劣信道中数据传输的正确性,具有相当优异的性能。 相似文献
4.
5.
本文针对海上数据采集系统在信号传输方面存在的不足之外，提出采用微机控制下的无线通信方式进行改进。文中介绍了系统设计思想，系统硬件构成，通过对传输数据进行ＤＴＭＦ编码，大大提高了系统的可靠性。 相似文献
6.
在城市的交通、电力、供热、自来水、煤气等行业中，无线监测、监控系统是解决这些待业有关生产自动调度、环境监测与监控的最佳方案之一。本文通过对天津市热网监测系统的介绍，论述了采用超短波无线通信技术实现热网监测、监控系统的方法及系统组成结构，从而为同类系统的开发提供一般设计方法。 相似文献
7.
浅海水声信道的随机时–空–频特性给数据的可靠传输带来了重大挑战,低复杂度和理论上证明能到达香农限的极化码(Polar code)可以增强水声通信系统的鲁棒性。水下传输的图像、语音、文本、海洋监测数据和遥控指令具有不等重要性的特点,宽码率 Polar 码能够适应不同水声信道和不等重要性的信息传输。 目前 Polar 码在水声通信中的实验研究多为仿真分析,设计了宽码率 Polar 码在厦门港海域海试验证,在不同信噪比的实录环境噪声下进行分析。海试结果表明：在良好的信道条件下,宽码率 Polar 码的性能优异,0.25 码率的 BPSK 和 QPSK 在实录环境噪声信噪比为–1 和 4 时实现零误码,其低复杂度信道编译码机制和宽码率与水声信道相匹配,可有效提高水声数据传输的可靠性和有效性,为基于 Polar 码的稳健可靠水声通信系统提供海试实验验证。 相似文献
8.
9.
10.
水下光通信具有高数据速率、低链路延迟等优势，但水体浑浊、对准困难等原因限制了其应用， 声通信则因具有互补性可被用于组成声、光混合通信系统。但考虑到声、光信号不同传播特性，常规上此类声、光混合通信系统均采用声、光用独立调制、解调的方式实现，造成较高的硬件系统开销。因此，提出了近程水下声光一体化高速通信方案，该方案采用 PPM 调制方式，基于同一套调制、解调模块以一体化的方式支持声、光 2 种通信链路，通过声、光 2 种通信模式的一体化实现，以更低的系统硬件实现复杂度提供具有更好的指向特性、水质、环境噪声适应性的近距高速链路。经水池实验验证：该系统在近程通信时，声、光通信链路均可实现 1 Mbps 数据速率的无误码通信。 相似文献
11.
S.G. Sturmey 《Marine Policy》1984,8(3):203-216
The author examines problems which liner conferences are likely to encounter in administering and policing the UN Code of Conduct for liner conferences which entered into force on 6 October 1983. Following an introduction dealing with the nature and structure of the Code itself and the problems which these pose for its interpretation and administration, the author discusses the responsibility for administration in relation to Code provisions, and then turns to the controversial questions of the administration of the cargo sharing system. Further sections deal with policing the Code and the nature of the remedies available in the case of disputes which cannot be settled within the conference system of self-policing. The final sections deal with the question of the role of governments, appropriate authorities and the EEC. 相似文献
12.
The underwater acoustic image transmission system based on the high-speed DSP device TMS320C549 has been studied.We use Goertzel algorithm for source decoding and MFSK for modulation.Turbo code is used for channel coding and decoding.The purpose is to implement underwater video image data transmission. 相似文献
13.
Ademuni Odeke 《Marine Policy》1984,8(1):56-63
This article analyses the UK legislation which will implement the UNCTAD Code of Conduct for Liner Conferences. The historical background to the Merchant Shipping (Liner Conferences) Act, 1982 is outlined and the author points out the relative decline of the UK merchant fleet in the face of competition from developing maritime nations, socialist countries and the USA. Provisions in the UK act curtailing the provisions of the Code are described. UK opposition to the cargo sharing and flag preference provisions of the Code is described and the article concludes by arguing that, although the Code does not satisfy all the UK demands, it remains the best option in a world increasingly dominated by protectionism. 相似文献
14.
《Ocean & Coastal Management》2005,48(2):177-188
A study was conducted in southwest coastal areas of Bangladesh to assess the status and to understand the degree of awareness of the FAO Code of Conduct for Responsible Fisheries among different stakeholders and its application in the area of shrimp culture in Bangladesh. Articles 9.1 and 9.4 of the Code were used for the investigation. Interviews with potential shrimp farmers and key informants at different level were undertaken for the investigation. A checklist was developed using both open and closed ended questions. Although Bangladesh is a signatory to the Code, virtually no significant efforts have been made to date to comprehend and elaborate the provisions of the Code within the context of Bangladesh. General awareness on the existence and significance of the FAO Code of Conduct, its scope, and purpose are yet to be increased for persons and institutions involved in shrimp aquaculture. 相似文献
16.
17.
《Ocean & Coastal Management》2003,46(1-2):77-102
The article offers an analysis of the globalisation debate in the context of international fisheries governance. It argues that there are significant transformations in fisheries policy-making in international economics, international institutions and international law-making which alter state authority in fisheries management. Thus, decision-making at international, regional and national levels is increasing, displaced from the state level. This ‘multi-level’ decision-making is exemplified in the United Nations Food and Agricultural Organisation's Code of Conduct for Responsible Fisheries, 1995. The Code represents a sound instrument of fisheries governance, capable of responding to contemporary global transformations. Changes are illustrated by comparing the Code and the Agreement on Straddling Fish Stocks and Highly Migratory Fish Stocks, 1995, in the areas of international economics, institutions and law-making. Reference is made to interaction between a range of actors and to formal and informal procedures. In conclusion, a process of ‘fisheries governance’ is confirmed, emerging from a new environment of international fisheries relations. 相似文献
18.
《Marine Policy》2015
The paper presents the results of evaluation of compliance of the bag net fishery of Maharashtra coast, India with the relevant clauses of Article 7 (Fisheries management) of the Code of Conduct for Responsible Fisheries (CCRF). Questionnaire-based approach that covered ten categories of stakeholders responsible wholly or partially for the management of the bag net fishery was used in the present study. Evaluation of the Code revealed an overall compliance level of 67.52%. The study identified the critical areas of low compliance levels that require immediate attention. Though the bag net fishery is the most common and traditional fishery of Maharashtra that supports livelihood of several fishers, there is no specific policy to regulate, develop and ensure sustainability of the bag net fish resources. Therefore the Code could be taken as a reference document to facilitate responsible management of the bag net fishery taking the local conditions into account. The findings of the present study could be used as a diagnostic tool to help in suggesting measures to ensure sustainability of the bag net fishery resources achievable by making amendments to the fisheries policies of the State. 相似文献