1、CCIR RECMNr826 92 4855212 0520232 3Lb considering a) the need to provide radio transmissions of digital data for use by ships to automatically update and make corrections to their electronic charts, as expressed by the International Maritime Organization (IMO); b) that these data transmissions must
2、be performed with minimum error in view of possible marine accidents that might arise from a mistake in an automatically-made change to an electronic nautical chart; C) that transmission of digital data at MF and HF is subject to signal distortion and fading which adversely affect error ratios in di
3、gital systems; d) that methods of error correction employed in MF and HF would necessarily slow down rates of signal transmission, thereby resulting in unacceptable time durations for sending the volume of data required for chart corrections; e) that transmission of digital data at the required data
4、 rates is not possible in the narrow bandwidths available at LF; 0 that studies of present and anticipated volumes of data traffic have shown that there will probably be adequate channel capacity available in the MARSAT-A and INMARSAT-C systems for an electronic ch,m updating service; that satellite
5、 transmissions in the INMARSAT-A and INMARSAT-C systems provide wide-area coverage at sea; h) that the use of forward error detecting and correcting coding of the digital data used for chart updating, combined with the favourable signal-to-noise ratios attained in the INMARSAT-A and INMARSAT-C syste
6、ms should result in acceptable error ratios; that many ships are, or will be, equipped with INMARSAT-A ship earth stations (SES)? thereby making it possible to establish a two-way, interactive updating service whereby a ship requests and receives updates for specific charts, and that such ships can
7、receive updating broadcasts on INMARSAT-A; k) that many ships will be equipped with INMARSAT-C SESs, including EGC SafetyNET receivers, that are especially suited for receiving broadcast group cais of digital data including those for the updating of electronic charts, and that INMARSAT-C can also be
8、 used for interactive, selective updating; 1) that there is a need to establish a standardized system of digital VHF broadcasts in the maritime mobile band for the purpose of placing temporay warning symbols automatically on electronic nautical charts on ships within the coverage area, I j) I Rec. 8
9、26 217 RECOMMENDATION 826* TRANSMISSION OF INFORMATION FOR UPDATLNG ELECTRONIC CHART DISPLAY AND INFORMATION SYSTEMS (ECDIS) (Question 98/8) ( 1992) The CCIR, I * The Director, CCIR, is requested to bring this Recomeudatiou to the atteutiou of the Interiiatiorial Maritime Organizatiori (IMO), the Wo
10、rld Meteorological Organization (WMO), the International Hydrographical Organization tIH0) arid the Intemational Maritime Satellite organization (DiMARSAT). COPYRIGHT International Telecommunications Union/ITU RadiocommunicationsLicensed by Information Handling ServicesCCIR RECMN*Bilb 72 4552l12 052
11、0233 252 m 218 Rec. 826 recommends 1, information for updating electronic chart display and information systems: that a suitable forward error detecting ,and correcting code be used in connection with the transmission of 2, ting information to ships to update electronic chtut display and information
12、 systems; that INMARSAT-A and INMARSAT-C, including EGC Safety“, be recognized as a means for transmit- 3. and information systems, a VHF chainel in thc maritime mobile band be designated for that purpose. that where harbours have facilities for transmitting local information for display on electronic chart display COPYRIGHT International Telecommunications Union/ITU RadiocommunicationsLicensed by Information Handling Services
