1、 Recommendation ITU-R M.1841-1(02/2013)Compatibility between FM sound-broadcasting systems in the frequency band of about 87-108 MHz and the aeronautical ground-based augmentation system in the frequency band 108-117.975 MHzM SeriesMobile, radiodetermination, amateurand related satellite servicesii
2、Rec. ITU-R M.1841-1 Foreword The role of the Radiocommunication Sector is to ensure the rational, equitable, efficient and economical use of the radio-frequency spectrum by all radiocommunication services, including satellite services, and carry out studies without limit of frequency range on the ba
3、sis of which Recommendations are adopted. The regulatory and policy functions of the Radiocommunication Sector are performed by World and Regional Radiocommunication Conferences and Radiocommunication Assemblies supported by Study Groups. Policy on Intellectual Property Right (IPR) ITU-R policy on I
4、PR is described in the Common Patent Policy for ITU-T/ITU-R/ISO/IEC referenced in Annex 1 of Resolution ITU-R 1. Forms to be used for the submission of patent statements and licensing declarations by patent holders are available from http:/www.itu.int/ITU-R/go/patents/en where the Guidelines for Imp
5、lementation of the Common Patent Policy for ITU-T/ITU-R/ISO/IEC and the ITU-R patent information database can also be found. Series of ITU-R Recommendations (Also available online at http:/www.itu.int/publ/R-REC/en) Series Title BO Satellite delivery BR Recording for production, archival and play-ou
6、t; film for television BS Broadcasting service (sound) BT Broadcasting service (television) F Fixed service M Mobile, radiodetermination, amateur and related satellite services P Radiowave propagation RA Radio astronomy RS Remote sensing systems S Fixed-satellite service SA Space applications and me
7、teorology SF Frequency sharing and coordination between fixed-satellite and fixed service systems SM Spectrum management SNG Satellite news gathering TF Time signals and frequency standards emissions V Vocabulary and related subjects Note: This ITU-R Recommendation was approved in English under the
8、procedure detailed in Resolution ITU-R 1. Electronic Publication Geneva, 2013 ITU 2013 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without written permission of ITU. Rec. ITU-R M.1841-1 1 RECOMMENDATION ITU-R M.1841-1*Compatibility between FM sound-br
9、oadcasting systems in the frequency band of about 87-108 MHz and the aeronautical ground-based augmentation system in the frequency band 108-117.975 MHz (2007-2013) Scope Resolution 413 (WRC-03) invited ITU-R to study any compatibility issues between the broadcasting and aeronautical services operat
10、ing around 108 MHz and to develop new or revised ITU-R Recommendations as appropriate. This Recommendation provides technical and operational requirements that may be used by administrations as a technical guideline for establishing the compatibility of the ICAO ground-based augmentation system (GBA
11、S) above 108 MHz and frequency modulation (FM) broadcasting systems operating up to 108 MHz. The ITU Radiocommunication Assembly, considering a) that, in order to improve the efficiency of spectrum utilization, there is a need to refine the criteria used when assessing compatibility between the FM s
12、ound-broadcasting service and the aeronautical services in the nearby frequency band; b) that there is a need for a compatibility analysis method for identifying potential incompatibilities associated with a large broadcasting assignment plan; c) that there is a need for a detailed, case-by-case com
13、patibility analysis method to investigate potential incompatibility cases identified by a large scale analysis or for individual assessment of proposed broadcasting or aeronautical assignments; d) that there is a need to continue the refinement of the compatibility criteria and assessment methods, r
14、ecommends 1 that the criteria given in Annex 1 may be used for compatibility calculations; 2 that the method given in Annex 2 may be used for predicting potential incompatibilities associated with a large broadcasting assignment plan; 3 that the techniques in Annex 3 may be used for detailed, case-b
15、y-case compatibility calculations concerning potential interference cases identified by the method given in Annex 2 or concerning individual assessment of proposed assignments to broadcasting or aeronautical stations; 4 additionally, that results of practical verification of predicted compatibility
16、situations as well as other relevant information may be used for coordination and to effect further refinement of the compatibility criteria, assessment method and techniques given in Annexes 1, 2 and 3 respectively. *This Recommendation should be brought to the attention of Radiocommunication Study
17、 Group 6. 2 Rec. ITU-R M.1841-1 Annex 1 Interference mechanisms, system parameters and compatibility assessment criteria CONTENTS Page 1 Background and introduction . 3 2 Types of interference mechanisms . 3 3 Compatibility assessment parameters . 4 4 Compatibility assessment criteria . 9 Appendix 1
18、 to Annex 1 GBAS coverage and minimum field strengths (Extracted from Annex 10 to the Convention on International Civil Aviation) . 13 Rec. ITU-R M.1841-1 3 1 Background and introduction FM broadcasting service interference to aeronautical mobile systems used for navigation and surveillance purposes
19、 is a widely recognized problem among users of aviation facilities. In airborne GBAS receivers, the interference problem causes errors in navigation correction information. The interference to these receivers is a serious problem, especially during the critical approach and landing phase, as it is n
20、ot readily evident to the pilot. The effects of interference to aircraft receivers vary with the aircraft location, altitude and intermodulation and spurious emission conditions. The way in which the presence of such interference is flagged varies with the make and model of the receiver. There is an
21、 increasing probability of harmful interference due to the growing need for additional aeronautical and broadcasting frequency assignments. This Annex describes: interference mechanisms; system parameters of the aeronautical mobile systems affected; system parameters of the FM broadcasting stations;
22、 compatibility assessment criteria for GBAS receivers. 2 Types of interference mechanisms In general, from a GBAS receiver point of view, FM broadcasting transmission modulation can be regarded as noise. 2.1 Type A interference 2.1.1 Introduction Type A interference is caused by unwanted emissions i
23、nto the aeronautical band from one or more broadcasting transmitters. 2.1.2 Type A1 interference A single transmitter may generate spurious emissions or several broadcasting transmitters may intermodulate to produce components in the aeronautical frequency bands; this is termed Type A1 interference.
24、 2.1.3 Type A2 interference A broadcasting signal may include non-negligible components in the aeronautical bands; this interference mechanism, which is termed Type A2 interference, will in practice arise only from broadcasting transmitters having frequencies near 108 MHz and will only interfere wit
25、h aeronautical mobile services with frequencies near 108 MHz. 2.2 Type B interference 2.2.1 Introduction Type B interference is that generated in an aeronautical receiver resulting from broadcasting transmissions on frequencies outside the aeronautical band. 4 Rec. ITU-R M.1841-1 2.2.2 Type B1 inter
26、ference Intermodulation may be generated in an aeronautical receiver as a result of the receiver being driven into non-linearity by broadcasting signals outside the aeronautical band; this is termed Type B1 interference. In order for this type of interference to occur, at least two broadcasting sign
27、als need to be present and they must have a frequency relationship which, in a non-linear process, can produce an intermodulation product within the wanted RF channel in use by the aeronautical receiver. One of the broadcasting signals must be of sufficient amplitude to drive the receiver into regio
28、ns of non-linearity but interference may then be produced even though the other signal(s) may be of significantly lower amplitude. Only third-order intermodulation products are considered; they take the form of: fintermod= 2f1 f2 two-signal case or fintermod= f1+ f2 f3 three-signal case where: finte
29、rmod: intermodulation product frequency (MHz) f1, f2, f3: broadcasting frequencies (MHz) with f1 f2 f3. 2.2.3 Type B2 interference Desensitization may occur when the RF section of an aeronautical receiver is subjected to overload by one or more broadcasting transmissions; this is termed Type B2 inte
30、rference. 3 Compatibility assessment parameters 3.1 Introduction This section identifies the parameters of GBAS aeronautical transmitters and receivers relevant for a compatibility assessment. 3.2 Characteristics of aeronautical systems 3.2.1 Designated operational coverage GBAS can be operated in t
31、he following two modes: a) a precision approach service; or b) a positioning service. ICAO requires that GBAS offers at least the precision approach service. Moreover, optionally a positioning service may be provided. 3.2.1.1 Precision approach service Figure 1A illustrates the horizontal extension
32、of a typical designated operational coverage (DOC) for GBAS precision approach service based on the requirements described in Annex 10 to the Convention on International Civil Aviation. It covers a keyhole-shaped area composed of a sector with a width of 35 extending 28 km (15 NM) from the runway st
33、op-end and a second sector with a width of 10 extending additional 9 km (5 NM). Further details are depicted in Fig. 1B. Rec. ITU-R M.1841-1 5 The lower coverage boundary (H) at the maximum distance from the landing threshold point (LTP) for a given glide path angle () shall be computed as follows:
34、()()+= 3.0tantanTCHDistHmaxwhere: Distmax: maximum distance in metres from LTP; TCH/tan() : distance in metres from LTP to the glide path intercept point (GPIP i.e. the point where the final approach path intercepts the local level plane); : glide path angle (nominal value is 3 degrees); TCH : thres
35、hold crossing height (height of the approach path above LTP), nominal value is 15 m. This is further illustrated in Fig. 1B. For nominal values of the glide path angle 3 degrees and a threshold crossing height of 15 m at a typical maximum distance of 37 km (20 NM) the following lower coverage bounda
36、ry is obtained: ()() ( )ftmH 190058633.0tan3tan1500037 =+= This DOC is defined on a per runway basis. As a single GBAS ground station may serve multiple aerodromes with multiple runways in its vicinity, the overall DOC may be considered as the sum of the DOCs. Some administrations may also use the G
37、BAS in a way such that the DOC may not be aligned with a runway. FIGURE 1A Typical GBAS precision approach DOC M.1841-01ARunwaystop end28 km (15 NM)9 km (5 NM)35351010NOTE Not drawn to scale. 6 Rec. ITU-R M.1841-1 FIGURE 1B More detailed specification of typical DOC for GBAS precision approach M.184
38、1-1BPlan view135 m (450 ft)LTPFinal approach path35 degrees10 degrees28 km (15 NM)-from runway stop-end37 km (20 NM)from runway stop-end3 000 m (10 000 ft)min. 585 m(1 900 ft)for = 3greater of 7 degreesor 1.75: glidepathangle0.3 . 0.45 curved earthGPIPNOTE Not drawn to scale. Editorial Note The DOC
39、is derived from the requirements for GBAS in Annex 10 to the Convention on International Civil Aviation. The depicted elevation diagram for GBAS is not the same as for ILS in Fig. 1 of Recommendation ITU-R SM.1009-1. 3.2.1.2 Positioning service The DOC of a GBAS for positioning can vary from one ins
40、tallation to another: a typical DOC for GBAS for positioning may be circular and have a radius of 43 km (23 NM) from the GBAS transmitter. Some installations may have a greater radius depending on the operational requirements and frequency planning constraints. Details can be obtained from the appro
41、priate national Aeronautical Information Publication (see definitions in Annex 4) (AIP). 3.2.2 Field strength The minimum field strength to be protected throughout the DOC (see 3.5.4.4.2.2 of Appendix 1) is 215 V/m (46.6 dB(V/m). 3.2.3 Frequencies GBAS frequencies lie in the band near to the FM broa
42、dcasting band, and can operate on ILS/VOR frequencies as well as those in between. GBAS frequencies occupy channels at 25 kHz intervals and may be as follows: 108.025, 108.050 . 117.950 MHz. 3.2.4 Polarization There are two types of polarization that can be used by GBAS; horizontal and an optional a
43、dditional vertical polarization. It is only the horizontal polarization that is intended for international civil aviation use and therefore only aircraft with horizontally polarized antennas are considered in this Recommendation. The use of the optional vertical polarization is only intended for nat
44、ional use. Rec. ITU-R M.1841-1 7 3.3 Characteristics of FM broadcasting stations 3.3.1 Maximum effective radiated power The most accurate available value of maximum e.r.p. should be used for compatibility calculations. 3.3.2 Horizontal radiation pattern The most accurate available information for ho
45、rizontal radiation pattern (h.r.p.) should be used for compatibility calculations. 3.3.3 Vertical radiation pattern The most accurate available information for vertical radiation pattern (v.r.p.) should be used for compatibility calculations. 3.3.4 Spurious emission suppression In the North American
46、 experience, it has not generally been necessary to require the suppression of spurious emissions by more than 80 dB. Considering special circumstances within some areas of Region 1 and some areas of Region 3, the values given in Table 1, for spurious emission suppression in the aeronautical band 10
47、8-137 MHz, may be recommended for the case of radiated intermodulation products from co-sited broadcasting transmitters. TABLE 1 Maximum e.r.p. (dBW) Suppression relative to maximum e.r.p. (dB) 48 85 30 76+SLKfNfNc(4) where: N1, N2: broadcasting signal levels (dBm) at the input to the aeronautical r
48、eceiver for broadcasting frequencies f1and f2respectively; f1, f2: broadcasting frequencies (MHz) f1 f2; K = 78 for GBAS; Lc: correction factor (dB) to account for changes in wanted signal levels (see 4.3.3.3); S : 3 dB margin to take into account of the fact that the receiver immunity criteria equa
49、tions given in Annex 10 to the Convention on International Civil Aviation do not provide comprehensive compatibility assessment formulae. b) Three-signal case ()()()064.01.108;4.0maxlog204.01.108;4.0maxlog204.01.108;4.0maxlog20332211+SLKfNfNfNc(5) where: f1, f2, f3: broadcasting frequencies (MHz) f1 f2 f3; N1, N2, N3: broadcasting signal levels (dBm) at the input to the aeronautical receiver for broadcasting frequencies f1, f2and f3respectively; K = 78 for
