2.2.1 VHF data exchange system channel usage for channel plan A 2.2.1.1 VHF data exchange system between terrestrial stations – Automatic identification System (AIS) use channels AIS 1 (161.975 MHz) and AIS 2 (162.025 MHz), in accordance with Recommendation ; – Application Specific Messages (ASM) use channels ASM 1 (channel 2027) and ASM 2 (channel 2028) are non-navigation ASMs; – VDE1 lower legs (channels 1024, 1084, 1025 and 1085) are ship-to-shore VHF data exchange (VDE); – VDE1 upper legs (channels 2024, 2084, 2025 and 2085) are shore-to-ship and ship-to-ship VDE. 2.2.1.2 VHF data exchange system between satellites and terrestrial stations – AIS 1 (161.975 MHz) and AIS 2 (162.025 MHz) are used as uplinks for receiving AIS messages by satellite; – SAT up1 (channel 2027) and SAT up2 (channel 2028) are used for receiving ASM by satellite; – SAT up3 (channels 1024, 1084, 1025, 1085, 1026 and 1086) is a ship-to-satellite VDE uplink; – SAT Downlink (channels 2024, 2084, 2025, 2085, 2026 and 2086) is the satellite-to-ship VDE downlink. 2.2.2 Technical characteristics 2.2.2.1 ShipborneVHF date exchange system receivers are protected As in AIS, shipborne VDES receivers are on the upper legs of RR Appendix 18, 4.6 MHz above the lower legs, which facilitates protection by filtering from receiver blocking by ships VHF radios. 2.2.2.2 Satellite downlink is optimized The satellite downlink power is spread over 6 channels to minimize interference to terrestrial services and to maximize reception by ship VDES stations. 2.2.2.3 VDE1 uses both legs of the duplex channels Full channel capacity is utilized for the duplex channels in VDE1 by using the lower legs for ship-to-shore and the upper legs for shore-to-ship and ship-to-ship digital messaging. 2.3 Channel plan B
Channel plan A ship-ship A) Affected by own ships AIS transmissions, but may be protected from ships own voice communication through filtering. Good B) Affected by own ships AIS transmissions, but may be protected from ships own voice communication through filtering. Good Channel plan B A) Affected by own AIS transmissions, but may be protected from ships own voice communication through filtering. Good B) Affected by own ships AIS transmissions, and may be blocked by ships own voice communication Poor Channel plan C A) Affected by own ships AIS transmissions, but may be protected from ships own voice communication through filtering. Good B) Affected by own AIS transmissions, and may be blocked by ships own voice communication Poor Channel plan D A) Affected by own ships AIS transmissions, but may be protected from ships own voice communication through filtering. Good B) Affected by own ships AIS transmissions, but may be protected from ships own voice communication through filtering. Good Annex 2 Study from China for channel plan D 1 Task goal The goals of the task are as follows: – Compatibility analysis between VDE and ASM, between VDE and voice, and between different VDE systems. – Calculation and simulation of needed isolation space between antennas of VDE and ASM or voice applications subject to implement of compatibility. 2 Task condition The main condition and input parameter of the task is as following: 1) VDE channel: be consistent with Recommendation Annex 3, or Annex 4: – The class of emission: 50K0F1DDN (Annex 3), or 100K0F1DDN (Annex 4). – Modulation: 16 × 16-QAM (Annex 3), or 32 × 16-QAM (Annex 4). – The carrier power: 50 W (coast station transmitters), 25 W (ship station transmitters). – The adjacent channel selectivity: at least dB. – The spurious response rejection ratio: at least 70 dB. – The radio-frequency intermodulation rejection ratio: at least 70 dB.
of data transmitting and receiving. This is crucial to a safety and security-related system. – To reduce the requirement for the adjacent channel ratio down to 65 dB or 60 dB (see Table 6.14 in provision 6.4.9.2.1 of ETSI 300 392-2 V3.4.1). This option costs the quality of data transmission and reception to ensure the ideal system data rate, and obviously stronger coding and error correction are needed. This might be proper for applications for commercial purposes. 3) Further studies and tests are needed for the physical systems and prototypes in the real world. 6 Antenna spacing The antenna isolation IReq (dB) be calculated with the formula: Pt: transmitting power (W) S: receiver sensitivity level (dBµV); or S = Pmin(dB) + 113 In: receiver interference rejection index (dB). According to the standard of China, In should be more than 100 dB. The vertical isolation IAV (dB) of two VHF antennas be calculated with the formula: H: vertical distance from the top of the lower antenna to the bottom of the upper antenna (m). The horizontal isolation IAH (dB) of two VHF antennas could be calculated with the formula: d: horizontal distance between two VHF antennas (m). The following conditions should be implemented for ensuring the isolation of VHF antennas: The model and gain simulating scheme of an omnidirectional antenna for a coastal station is shown as Figs. A2-11 and A2-12. Figures A2-13 and A2-14 give the horizontal gain scheme and the vertical gain scheme respectively. A2-11 The model of an omni-directional antenna for a coastal station A2-12 The gain simulating of an omni-directional antenna for a coastal station
A2-13 The horizontal gain simulating scheme A2-14 The vertical gain simulating scheme Table A2-2 gives the antenna isolation space for VHF applications. TABLE A2-2 Radiant power (W) Receiving sensitivity (dBm) Interference rejection index (dB) Isolation (dB) Horizontal space (m) Vertical space (m) 25 −98 100 51 79.18 5.30 −107 100 42 28.09 3.14 50 −103 100 49 62.97 4.72 −107 100 45 39.73 3.74 Annex 3 Study from Canada for channel plan A, B and C The attachment is a study on impacts relating to plans A, B and C for VDE and AIS systems as well as the differences between each plan. Channel plan D was not developed when this study was completed; therefore plan D was not considered. This study discusses options on various technologies to mitigate interference and provides scenarios on specific communications under the proposed plans A, B and C. It provides recommendations in the attempt to optimize frequency allocation for maritime communications in the VHF band. It was determined that, for each channel plan, compromises are required in terms of, but not limited to, integration of VDES and AIS communications, antenna separation and filtering and site selection.