INTERNATIONAL STANDARDS AND RECOMMENDED PRACTICES Annex 10, Volume V Second Edition Corrigendum EnglishIFrenchlS panish 291 1 102 AERONAUTICAL TELECOMMUNICATIONS ANNEX 10 TO THE CONVENTION ON INTERNATIONAL CIVIL AVIATION VOLUME V Aeronautical Radio Frequency Spectrum Utilization SECOND EDITION - JULY 2001 CORRIGENDUM 1. Please replace existing page ATT B-1 dated 111 1/01 by the attached new page bearing the notation "Corr". 2. Record the entry of this corrigendum on page ii.
ATTACHMENT B. CONSIDERATIONS AFFECTING THE DEPLOYMENT OF LF/MF FREQUENCIES AND THE AVOIDANCE OF HARMFUL INTERFERENCE 1. Particularly in areas of high density of NDBs, it is recognized that efficient planning is essential in order to a ensure satisfactory operation of ADF equipment, and b provide the most efficient usage of the limited frequency spectrum available for the NDB service. It is axiomatic that regional meetings will so plan facilities as to ensure that all facilities will receive the best possible protection from harmful interference. Nevertheless, in certain regions, congestion of facilities has been such that regional meetings have had to plan in terms of a minimum protection ratio. Regional meetings include in their planning consideration of such factors as a the possibility of reducing the number of NDBs required, by coordination of system plans b the possibility of reducing the coverage where a lesser grade of service than that obtainable within the rated coverage is acceptable c the characteristics of ADF equipment in use d the atmospheric noise grades, appropriate to the area concerned e ground conductivity and f interference protection required at the edge of the rated coverage. Of the foregoing factors, that which is most susceptible to improvement of a technical kind is c. 2. The 1979 World Administrative Radio Conference adopted regulations concerning the assignment of frequencies for aeronautical radio beacons operating in the LF/MF frequency bands. A minimum protection ratio wanted/ unwanted signal ratio of 15 dB is to be used as the basis for frequency assignment planning RR Appendix S12. The following data concerning the attenuation characteristics of ADF equipment was used in the EUR region to aid in the frequency assignment process Frequency Attenuation difference kHz dB The above figures or distance separation criteria derived from them have also been applied in other regions in determining the minimum protection ratio. Where a bearing accuracy of 25 degrees is required at the edge of cover, a minimum protection of 15 dB by day should be used as the basis for LF/MF channel assignment planning. 3. In view of the fact that in many regions there is a need to improve the planning criteria it is considered that the main source from which improvement can be derived is recognition of higher attenuation figures than those given above. Regional meetings are accordingly advised that, when the congestion is such that the use of the above figures no longer permits efficient planning of the LFIMF frequency spectrum available, the following figures represent from a technical point of view the best that can be accepted in determining distance separation criteria Frequency Attenuation difference kHz is When using these figures, it should be noted that the RF selectivity of modem ADF equipment is in general better ANNEX 10 - VOLUME V ATT B-1 Corr. 29/1/02
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