Publication: Magyar Közlöny
Issue: MK-2007-70 (Year: 2007, Number: 70)
Era: 2004-2010
Section: Melléklet a 2007. évi XLVI. törvényhez
Paragraph Index: 4994

c) 8.33 kHz channels spaced 25 kHz away from an assigned frequency of a 25 kHz channel should be planned in accordance with 2.2. 3. Criteria to be employed in establishing adjacent channel frequency deployment of VHF facilities that have a service range beyond the radio horizon For the most economical use of frequencies and to ensure freedom from interference, planning must be based on an accurate knowledge of equipment used. When the equipment characteristics and field strength (or attenuation) curves are on hand for the troposcatter regions, it is relatively easy to determine the required geographical separation. When these are not known, the maximum permitted antenna gain stipulated in 4.1.6.1 will be assumed. There are several conditions that must be calculated and compared to determine the appropriate separation to be used. The conditions to be compared are: 1) ground facility-to-aircraft; 2) aircraft-to-ground facility; 2007/70/II. szám Attachment A Annex 10 — Aeronautical Telecommunications ATT A-5 1/11/01 3) aircraft-to-aircraft; and 4) ground facility-to-ground facility. Case 1.— For the case of protection of aircraft A from a ground facility (see Figure A-4): A. Determine the signal level S (dB rel. 1 µV/m) received from the desired station at the limit of the service radius at the protection altitude. B. Assign the desired protection ratio P (dB) required at the aircraft receiver. C. Let receiver adjacent channel rejection be represented by A (dB). Then the level L (dB rel. 1 µV/m) that can be tolerated at the receiver antenna can be determined by: L = S – P + A D. Distance d (km) from protection point to undesired facility to provide protection established by “C”, is found by application of L to the appropriate curves. Note 1.— Figures A-8 to A-15 are field strength curves appropriate for the average temperate climate over land or sea, which may be used to determine geographical separation for situations where these field strengths will not normally be exceeded more than 5 per cent of the time. These curves were established by the Institute for Telecommunications Sciences and Aeronomy of the Environmental Science Services Administration of the United States. Note 2.— For power levels other than 1 kW the necessary corrections under “C” would have to be made. For example, 5 kW ERP requires a minus 7 dB correction. E. The facility-to-facility separation D is d (km) plus service radius (km). Case 2.— Aircraft (A)-to-ground facility (see Figure A-4): A. Determine signal level Sg at the ground facility receiving antenna for proper system operation. B. Proceed as in Case 1, where L = Sg – P + A C. Ground facility-to-ground facility separation will also be determined as in Case 1 (D = d + service radius (km)). Note.— Where ground facility receivers have sensitivities of less than 1 microvolt across 50 ohms, Case 2 is most likely to yield the separation to be used. Figure A-4. Air-to-ground (facility from A) and ground-to-air (A from facility) A Service area Front or main beam area Back and side radiation Facility-to-facility separation Service radius Protection height Facility site 2007/70/II. szám Annex 10 — Aeronautical Telecommunications Volume V 1/11/01 ATT A-6 Figure A-5. Facility-to-facility separation based on air-to-air (A from B) and ground-to-ground (C and D) Figure A-6. VOLMET planning (illustrating co-channel protection) Figure A-7. VOLMET planning (illustrating adjacent channel protection) Main beam protection area Service radius Aircraft A Aircraft separation Facility-to-facility separation D Facility site Aircraft B 55.6 km 30 NM Aircraft Wanted transmitter 100 watts ERP Unwanted transmitter 100 watts ERP Radio horizon Radio horizon d1 d2 Aircraft Wanted transmitter Unwanted transmitter 2007/70/II. szám Attachment A Annex 10 — Aeronautical Telecommunications ATT A-7 1/11/01 Case 3.— Aircraft (A)-to-aircraft (B) (see Figure A-5): A. Establish service radius and protection altitude for facility to be protected (see aircraft A in Figure A-5). B. Determine closest point to aircraft A that aircraft B will be transmitting to the ground facility site and the altitude where this will take place. C. Proceed as in Case 1, using the aircraft (B) contacting ground facilities as the undesired signal. D. Then L = S – P + A E. The distance d to aircraft B (undesired) obtained from the curves, plus the service radius of the facility to be protected, will determine the separation between aircraft B and the ground facility protected. F. Facility-to-facility separation may then be determined graphically or by trigonometric means. Case 4.— Ground facility-to-ground facility (see Figure A-5). A. Determine signal level that can be tolerated at the receiver antenna at one facility by L = Sg – P + A (see Case 1). B. Then facility-to-facility separation for these conditions is read directly from the curves (after correcting for transmitter power of other facilities if different from 1 kW). C. Should equipment at the two facilities have different characteristics, repeat procedure in “A” and “B” for the other combinations of equipment. D. Of the two distances derived, use the greater to compare with other cases (see below). Note.— In most instances, it will be found that the facility-to-facility consideration will not be the controlling factor in determining geographical separation. Facility separation will then be the greatest distance derived for Cases 1 to 4. 4. Criteria to be employed in establishing geographical separation between ground stations and between aircraft and ground stations for co-channel operation of VHF facilities that have a service area beyond the radio horizon Geographical separation of co-channel facilities can be calculated by using the method given in 2 above except that the adjacent channel rejection A is omitted from consideration. 5. Criteria employed in establishing co-channel frequency deployment of VHF VOLMET facilities In the case of VHF VOLMET services, the geographical separation between co-channel stations should be 55.6 km (30 NM) plus twice the distance to the radio horizon from an aircraft at the highest altitude flown by aircraft in the area concerned. (See Figure A-6.) Note.— At 27.8 km (15 NM) beyond the radio horizon, the field strength at 13 500 m (45 000 ft), from a transmitter of 100 W ERP, will be approximately at the receiver muting level of 5 microvolts per metre. 6. Criteria employed in establishing adjacent channel frequency deployment of VHF VOLMET facilities 6.1 For aircraft receivers designed for operation in a 25 kHz channel spacing environment, an effective adjacent channel rejection characteristic of 60 dB or better is assumed. This assumption will result in a geographical separation distance D between VHF VOLMET ground transmitters derived as follows (nautical miles may be substituted for kilometres): D = (d1 + d2) km where d1 = distance between aircraft and wanted ground station = radio horizon + 27.8 km (15 NM) and d2 = distance between aircraft and unwanted ground station = 24.1 km (13 NM). (See Figure A-7.) 6.2 Where it is necessary to take account, on a regional basis, of receivers not specifically designed for 25 kHz channel spacing and used in a 25 kHz channel spacing environment, an effective adjacent channel rejection characteristic of the receiver of the order of 40 dB is assumed. This assumption will result in a minimum geographical separation distance D between VHF VOLMET ground transmitters derived as follows: 2007/70/II. szám Annex 10 — Aeronautical Telecommunications Volume V 1/11/01 ATT A-8 D = (d1 + d2) km where d1 = distance between aircraft and wanted ground station = radio horizon + 27.8 km (15 NM) d2 = distance between aircraft and unwanted ground station = 240.9 km (130 NM). 6.3 Application of the above criteria in the case of aircraft altitudes of 13 500 m (45 000 ft) and 20 000 m (66 000 ft) results in the following separation distances: 6.4 The above criteria are based on the following additional assumptions: 1) Effective radiated power: an ERP of 100 W for the ground stations. Note.— If an ERP of 20 W is assumed, this would result in separation distances for 13 500 m (45 000 ft) of 472 km (255 NM) for 60 dB receiver adjacent channel rejection and 572 km (309 NM) for 40 dB receiver adjacent channel rejection. 2) Interfering signal strength: if the received signal strength is in excess of the free space propagation value, then the maximum value will not exceed the free space value by more than 5 dB over average earth. This condition is satisfied when transmitters of 20 W ERP or more are used in conjunction with a receiver adjacent channel rejection of not less than 35 dB. Thus, the minimum distance for d2 can be derived from a consideration of receiver muting level, receiver adjacent channel rejection and transmitter ERP. 7. RF — Characteristics for digital VHF systems, interference immunity performance 7.1 Receiving function — interference immunity performance. The standard measurement technique for digital systems provides that the desired signal field strength be doubled, and that the undesired signal be applied in increasing levels until the channel performance, that is the specified error rate, degrades to a value equal to the value found at the specified receiver sensitivity. For the VDL, the effect of the measurement technique is that the desired signal strength is increased from 20 microvolts per metre to 40 microvolts per metre. Then the undesired signal on the adjacent or any other assignable channel is raised to the specified level higher than the desired signal until the specified error rate is exceeded. Care should be taken to ensure that on-channel noise power is not included in the measurement of the undesired signal. 7.2 Assignment criteria. Assignment of frequencies for VHF digital link should take into account the VDL RF system characteristics in order to avoid harmful interference to or from co-channel and adjacent channel assignments, in keeping with regionally and nationally agreed spectrum management policies. Altitude Receiver rejection characteristic d1 km (NM) d2 km (NM) D km (NM) 13 500 m (45 000 ft) 60 dB 491 (265) 24.1 (13) 515 (278) 13 500 m (45 000 ft) 40 dB 491 (265) 241 (130) 732 (395) 20 000 m (66 000 ft) 60 dB 619 (334) 24.1 (13) 643 (347) 20 000 m (66 000 ft) 40 dB 619 (334) 241 (130) 860 (464) 2007/70/II. szám Attachment A Annex 10 — Aeronautical Telecommunications ATT A-9 1/11/01 Figures A-8 to A-15. Propagation curves for standard atmosphere (301) for frequency of 127 MHz ESSA/I.T.S.A.—1966 Propagation Model These curves labelled “5 per cent time availability” represent only a statistically expected value; i.e., a probability of 0.05 that a particular situation will result in the specified field strength or greater during 5 per cent of the time. The parameters used to develop these curves include: 1) frequency of 127 MHz; 2) horizontal or vertical polarization; 3) smooth earth with land or sea surface; 4) reflection coefficient of unity magnitude; 5) standard atmosphere with a 301 surface refractivity; 6) continental temperate climate; 7) Nakagami-Rice statistics for within-the-horizon fading; 8) an effective radiated power (ERP) corresponding to 1 kilowatt input power into a lossless half-wave dipole. 2007/70/II. szám Annex 10 — Aeronautical Telecommunications Volume V 1/11/01 ATT A-10 Figure A-8 2007/70/II. szám Attachment A Annex 10 — Aeronautical Telecommunications ATT A-11 1/11/01 Figure A-9 2007/70/II. szám Annex 10 — Aeronautical Telecommunications Volume V 1/11/01 ATT A-12 Figure A-10 2007/70/II. szám Attachment A Annex 10 — Aeronautical Telecommunications ATT A-13 1/11/01 Figure A-11 2007/70/II. szám Annex 10 — Aeronautical Telecommunications Volume V 1/11/01 ATT A-14 Figure A-12 2007/70/II. szám Attachment A Annex 10 — Aeronautical Telecommunications ATT A-15 1/11/01 Figure A-13 2007/70/II. szám Annex 10 — Aeronautical Telecommunications Volume V 1/11/01 ATT A-16 Figure A-14 2007/70/II. szám Attachment A Annex 10 — Aeronautical Telecommunications ATT A-17 1/11/01 Figure A-15 2007/70/II. szám ANNEX 10 — VOLUME V ATT B-1 1/11/01 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:

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