Tổng quan hệ thống GMDSS phục vụ TKCN. Năm 1979,Tổ chức Hàng Hải quốc tế (International Maritime Organization IMO) đã tổ chức hội nghị về vấn đề tìm kiếm và cứu nạn trên biển. ... Hệ thống mới được tự động hóa và sử dụng sóng vô tuyến trái đất và vệ tinh cho báo động cấp cứu và các thông tin theo sa
Cau hoi A B C D Dap an Cau hoi A B C D Dap an Cau hoi A B C D Dap an Cau hoi A B C D Dap an Cau hoi A B C D Dap an Cau hoi A B C D Dap an Cau hoi A B C D Dap an Cau hoi One of the guidelines when choosing an High Frequency (HF) band for a specific range, is the greater the distance, the lower the required band use a lower band by day to have the antenna as high as possible use a higher band by day A Line-of-sight propagation would mainly involve communications on HF communications on MF Navtex communications SART, EPIRB, Inmarsat communications A Ground wave propagation is an important feature of communications on 1.6 GHz Ch.16 VHF 8291 kHz 2182 kHz A The main path of propagation for an MHz radio frequency is sky wave direct wave (line of sight) ground wave troposcatter A The propagation path used by HF signals, from the SSB radio, to achieve long-range communications, is direct wave (line of sight) relay wave sky wave ground wave A The main propagation path for an MF radio frequency is space wave sky wave ground wave direct wave (line of sight) A The propagation path for signals from a VHF radio, under normal atmospheric conditions, would be relay wave ground wave sky wave direct wave (line of sight) A Communications through the Inmarsat system are by A B C D Dap an Cau hoi A B C D Dap an Cau hoi A B C D Dap an Cau hoi A B C D Dap an Cau hoi A B C D Dap an Cau hoi A B C D Dap an Cau hoi A B C D Dap an Cau hoi A B C D combination of ground wave and sky wave sky wave space wave ground wave A The communications most affected by antenna height are VHF HF satellite MF A Sky wave propagation is an important feature of H24 communication on 2187.5 kHz Ch 70 VHF 8414.5 kHz 121.5 MHz A When choosing an HF band for a specific communication, one of the guidelines is that ducting can increase the range to use a higher frequency band by day that the range of MHz transmission is greater by day the greater the distance required, use a lower frequency band A The propagation path taken by a radio signal on VHF Ch.16 is inverted wave ground wave sky wave direct wave (line of sight) A The propagation path used by Inmarsat equipment is relay wave ground wave sky wave direct wave (line of sight) A The propagation path for MF NAVTEX signals during daylight is relay wave sky wave ground wave direct wave (line of sight) A The propagation path used by satellite EPIRB equipment is direct wave (line of sight) ground wave sky wave relay wave Dap an A ... most affected by antenna height are VHF HF satellite MF A Sky wave propagation is an important feature of H24 communication on 2187.5 kHz Ch 70 VHF 8414.5 kHz 121.5 MHz A When choosing an HF band