关键词: |
SHIPPING, VESSEL TRAFFIC SYSTEMS, CONTROL SYSTEMS, MODIFICATION, FREQUENCY MODULATION, COST ESTIMATES, CODING, SIDEBANDS, DATA LINKS, DIGITAL COMMUNICATIONS, WATER TRAFFIC, COAST GUARD RESEARCH, TRANSPONDERS, LORAN, AUTOMATIC TRACKING. |
摘要: |
Coast Guard Vessel Traffic Service (VTS) facilities rely heavily on radio communications to acquire the location of vessels and disseminate this information to other interested shipping. As the communication requirements change, the Coast Guard must be knowledgeable of the options available to meet the new requirements. To provide a basis for future system expansion and design, this study explores the commmunication channels available to maritime mobile service and the impact of change from voice to voice/data and data/only communication. Analysis under Task I reviews all frequency bands available for maritime service, identifying for each band all permissable transmission methods. Task II considers three candidate systems. The performance of these systems was analyzed with respect to present and future communications requirements using statistical VTS communication data. The systems are described with respect to hardware requirements and are characterized by the attainable data transmission rate. Cost estimates are furnished for all equipment not normally carried on commercial seagoing vessels, as well as the cost of modifying existing equipment. As a result of this study, the following conclusions are stated: (1) The introduction of a voice-based periodic position reporting scheme will quickly saturate available communication channels; and (2) There are digital communication systems capable of expanding the capacity of existing communication channels. |