Sea Technology

JUL 2018

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Page 25 of 44 July 2018 | ST 25 At the World Radiocommunication Con- ference – 2012 (WRC-12), it was resolved to consider regulatory provisions and spec- trum allocations to enable possible new AIS terrestrial and satellite technology and new applications to improve maritime radiocom- munication in general. It was recognized that advanced maritime communication systems, such as the VDES, may support the imple- mentation of the GMDSS modernization and e-navigation, requiring a review of the Ra- dio Regulations to accommodate advanced maritime communication systems. The ITU developed the technical characteristics of the VDES, which were partly adopted at WRC- 15. Revision of Radio Regulations' Appendix 18 At WRC-15, the table of transmitting fre- quencies in the VHF maritime mobile band, Appendix 18 of the ITU's Radio Regulations, was revised. As a result, from January 1, 2017, the adjacent two-frequency channels 80, 21, 81, 22 were identified for use by the digital systems described in ITU's Recommenda- tion ITU-R M.1842-1, which are operating on multiple 25-kHz contiguous channels (100-kHz bandwidth). In addition, the adja- cent two-frequency channels 23 and 83 are identified for use by the same digital systems that use two 25-kHz contiguous channels (50-kHz bandwidth), and the two-frequency channel 82 is split on two single-frequency channels for utilization by the same systems. Furthermore, from January 1, 2017, the adjacent two-frequency channels 24, 84, 25, 85, 26 and 86 were identified for the utilization of the VDES. From January 1, 2019, the channels 24, 84, 25 and 85, which are in- tended for the VDES, may be merged to form one duplex channel with a bandwidth of 100 kHz to operate the ter- restrial component of the VDES. Adjacent channels 27, 87, 28 and 88 may be used for possible testing of future AIS applications until Janu- ary 1, 2019. The two-frequency channels 27 and 28 may be used as single-frequency channels: 1027 and 1028 for lower frequencies, and 2027 and 2028 for upper fre- quencies. From January 1, 2019, these channels will be divided into two simplex channels, because channels 2027 and 2028 are designated as ASM 1 and ASM 2 channels, which are used for VDES application specific messages (ASM). Maritime VHF Data Exchange System While the VDES technology concept was developed to solve AIS channel congestion, it also allows a wide variety of information envisaged by the strategy imple- mentation plan for e-navigation, which also potentially supports the modernization of the GMDSS. The VDES could have a significant positive impact on the provision of maritime information services, such as maritime safety information (MSI), general data communications at high data rates, locating, vessel traffic management, satellite communications, etc. The VDES uses a two-way data exchange on channels from the VHF maritime mobile band in: ship-to-ship; ship-to-shore and shore-to-ship; and ship-to-satellite and satellite-to-ship directions. The data exchange using the VDES is as follows: AIS – standard AIS report; ASM (navigational, meteorological and hydrographical infor- mation); VDE (VHF data exchange) – general exchange of information; and SAT – data exchange between ships and satellites. The AIS 1 and AIS 2 are the AIS channels used for the terrestrial link in accordance with ITU's Recommenda- tion ITU-R M.1371-5. These channels are also used as the uplinks for receiving AIS messages by satellite. The long-range AIS channels 75 and 76 are also channels used as uplinks for receiving AIS messages by satellite. The ASM 1 (channel 2027) and ASM 2 (channel 2028) are the channels used for application specific messag- es; the VDE1-A (single or merged channels 1024, 1084, 1025, 1085) is ship-to-shore VDE channels, and the VDE1-B (single or merged channels 2024, 2084, 2025, 2085) is shore-to-ship and ship-to-ship VDE channels. The SAT Up1 (channel 2027) and the SAT Up2 (channel 2028) are used for receiving ASM by satellite, while the SAT Up3 (single or merged channels 1024, 1084, 1025, 1085, 1026 and 1086) is used for ship-to-satellite VDE Channel Frequencies for ship and coast stations (MHz) Ship stations (ship-to-shore) Coast stations Ship stations (long-range AIS) Ship stations (ship-to-ship) Ship stations (ship-to-satellite) Satellite-to-ship 100/150-kHz channel 100/150-kHz channel 1024/1084/1025/1085, lower 2024/2084/2025/2085, frequencies merged, VDE1- upper frequencies merged, A, ship-to-shore VDE1-B, ship-to-ship, shore-to-ship 1024/1084/1025/1085/1026/ 2024/2084/2025/2085/2026/ 1086, ship-to-satellite, SAT up 3 2086, satellite-to-ship, SAT downlink 24/84/25/ 24/84/25/85/26/ 85 86 (SAT) (VDE1) 24 24 157.200 (1024) 161.800 (2024) (VDE1) (SAT) 84 84 157.225 (1084) 161.825 (2084) (VDE1) (SAT) 25 25 157.250 (1025) 161.850 (2025) (VDE1) (SAT) 85 85 157.275 (1085) 161.875 (2085) (VDE1) (SAT) 26 157.300 (1026) 161.900 (2026) (SAT) 86 157.325 (1086) 161.925 (2086) (SAT) 2027 (ASM 1) 161.950 (2027), SAT up 1 161.950 (2027) 2028 (ASM 2) 162.000 (2028), SAT up 2 162.000 (2028) AIS 1 161.975 161.975 AIS 2 162.025 162.025 75 (long-range AIS) 156.775 (ships transmitting only) 76 (long-range AIS) 156.825 (ships transmitting only) Maritime VHF channels and frequencies used for the VDES.

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