1、 Rec. ITU-R M.1459 1 RECOMMENDATION ITU-R M.1459* PROTECTION CRITERIA FOR TELEMETRY SYSTEMS IN THE AERONAUTICAL MOBILE SERVICE AND MITIGATION TECHNIQUES TO FACILITATE SHARING WITH GEOSTATIONARY BROADCASTING-SATELLITE AND MOBILE-SATELLITE SERVICES IN THE FREQUENCY BANDS 1 452-1 525 MHz AND 2 310-2 36
2、0 MHz (Question ITU-R 62/8) (2000) Rec. ITU-R M.1459 The ITU Radiocommunication Assembly, considering a) that in Region 2, frequency allocations to the aeronautical mobile service for telemetry have a primary status in the band 1 435-1 525 MHz and have priority over other mobile services under RR No
3、. S5.343; b) that WARC-92 adopted an additional allocation in the band 1 429-1 535 MHz, on a primary basis to the aeronautical mobile service for Belarus, the Russian Federation and Ukraine to be used exclusively for aeronautical telemetry subject to RR No. S5.342; c) that in accordance with the dec
4、ision by WRC-95, in the United States of America, telemetry stations in the aeronautical mobile service have a primary status in the 2 300-2 390 MHz band and have priority over other mobile services under RR No. S5.394; d) that in Canada, telemetry stations in the aeronautical mobile service have a
5、primary status in the 2 300-2 483.5 MHz band and have priority over other mobile services under RR No. S5.394; e) that in France, frequency assignments to telemetry stations in the aeronautical mobile service have a primary status in the 2 310-2 360 MHz band and have priority over other mobile servi
6、ces under RR No. S5.395; f) that in Europe future airborne telemetry equipment should tune primarily to the frequency range 2 300-2 400 MHz; g) that the band 1 492-1 525 MHz has been allocated to the MSS (space-to-Earth) in Region 2 taking account of the provisions of RR Nos. S5.348 and S5.348A; h)
7、that WARC-92 allocated the band 1 452-1 492 MHz on a primary basis to the BSS (digital sound broadcasting (DSB) (see Note 1) and the broadcasting service (DSB) subject to the provisions of RR Nos. S5.345 and S5.347; j) that at WARC-92, an additional allocation in the United States of America, India
8、and Mexico of the 2 310-2 360 MHz band to BSS (DSB) and the broadcasting service (DSB) was made on a primary basis under RR No. S5.393; k) that in the band 1 452-1 525 MHz, WARC-92 adopted an alternative allocation on a primary basis for the fixed and mobile services in the United States of America
9、in accordance with RR No. S5.344; l) that in Japan in the band 1 492-1 525 MHz, a coordination threshold of 150 dB(W/m2) in any 4 kHz band for all angles of arrival was adopted at WRC-95 for the protection of specialized land mobile services in accordance with RR No. S5.348A; m) that coordination is
10、 required under RR No. S9.11A and Resolution 528 (WARC-92); n) that Resolutions 528 (WARC-92) and 213 (Rev.WRC-95) invited the ITU-R to conduct the necessary studies prior to the next competent WRC; o) that additional studies have been introduced in the ITU-R for determining the probability of inter
11、ference to telemetry stations in the aeronautical mobile service which could lead to less stringent protection values, and that these studies are expected to continue; _ *This Recommendation should be brought to the attention of Radiocommunication Study Group 6. 2 Rec. ITU-R M.1459 p) that telemetry
12、 stations in the aeronautical mobile service have a wide range of characteristics and some may have less stringent protection criteria values than those contained in the recommends, recommends 1 that the values needed for protection of the aeronautical mobile service for telemetry systems in the 1 4
13、52-1 525 MHz band shared with geostationary satellites in the BSS (DSB) or the MSS, should be determined by the following (see Note 4): for geostationary satellites visible to any aeronautical telemetry receiving station, the protection value corresponds to a pfd at the telemetry receiving station i
14、n any 4 kHz band for all methods of modulation: 181.0 dB(W/m2) for 0 4 193.0 + 20 log dB(W/m2) for 4 20 213.3 + 35.6 log dB(W/m2) for 20 60 150.0 dB(W/m2) for 60 90 where is the angle of arrival (degrees above the horizontal plane); 2 that the values needed for protection of the aeronautical mobile
15、service for telemetry systems in the 2 310-2 360 MHz band shared with the BSS (DSB) should be determined by the following (see Note 4): for geostationary satellites visible to any aeronautical telemetry receiving station, the protection value corresponds to a pfd at the telemetry receiving station i
16、n any 4 kHz band for all methods of modulation: 180.0 dB(W/m2) for 0 2 187.1 + 23.66 log dB(W/m2) for 2 11,5 162 dB(W/m2) for 11.5 90 where is the angle of arrival (degrees above the horizontal plane); 3 that the calculation methods and mitigation techniques given in Annexes 1 and 2 may be used, as
17、applicable, for determining the probability of interference to telemetry systems in the aeronautical mobile service. NOTE 1 DSB refers to digital audio broadcasting as per RR Nos. S5.345 and S5.393. NOTE 2 The example calculation used to derive the protection values as set out in Annex 1 represent a
18、 worst-case scenario. Mitigation techniques given in Annex 2 may enhance sharing. NOTE 3 As safety of life aspects are to be considered with mobile aeronautical telemetry systems and efficient use of the spectrum allocated by WARC-92 to the BSS (sound) appears not to be possible, attention is drawn
19、to studies being conducted under Question ITU-R 204/10 (see Recommendation ITU-R BO.1383). NOTE 4 Administrations are encouraged to submit information to ITU-R concerning performance and availability targets for the mobile aeronautical telemetry service with a view to developing an appropriate ITU-R
20、 Recommendation. ANNEX 1 Calculation of pfd interference levels to aeronautical mobile telemetry systems from geostationary satellite emissions 1 Introduction The analyses and results given in the following sections of this Annex are for the purpose of calculating interference to aeronautical mobile
21、 telemetry systems. Rec. ITU-R M.1459 3 2 Development of values The following development can be used in general, but the numerical values are for the 1 452-1 525 MHz band. 2.1 Telemetry system characteristics General system characteristics are given in the CPM Report to WARC-92 and are as follows.
22、Aeronautical telemetry and telecommand operations are used for flight testing of manned and unmanned aerospace vehicles. Vehicles are tested to their design limits, thus making safety of flight dependent on the reliability of information received on a real-time basis. When being tested to design lim
23、its, signal strength loss can exceed 30 dB due to nulls in the aircraft antenna pattern caused by aircraft attitude changes. Required C/N: 9-15 dB Transmitter power: 2-25 W Modulation type: PCM/FM Transmission path length: up to 320 km Receiving system noise temperature: 200-500 K Receiving antenna
24、gain: 20-41 dB Receive antenna first side-lobe levels for two antennas: 10 m (diameter): 20 dBi (antenna gain) 2.4 (from centre) 2.44 m (diameter): 7-14 dBi (antenna gain) 10 (from centre) A number of antenna diameters are employed between the 20-41 dB limits. Left-hand and right-hand circular, as w
25、ell as linear polarizations, are used. Channel assignments are made in 1 MHz increments. Typical emissions are 1, 3 and 5 MHz in bandwidth with wider assignments made for video and other complex measurements. The maximum air space for a telemetry receiving site is defined as a cylinder with a horizo
26、ntal radius of 320 km around the site, with the lower bound determined by visibility and the upper bound determined by an altitude of 20 km. The minimum air space for a particular mission is defined as a vertical cylinder with a radius of 20 km within the maximum air space with the same lower and up
27、per bounds as for the maximum air space. Continuous RF tracking is employed using both monopulse and conical scan techniques. Two antenna diameters are given a 2.44 m and a 10 m diameter. Figure 1 shows measured gain values for three 2.44 m antennas. Since these antennas track a moving vehicle so th
28、at the antenna gain toward a geostationary satellite is variable, there is a side lobe and backlobe gain which is exceeded or not exceeded 50% of the time. The following composite pattern is developed on this basis for antenna gains from 29 dB to 41.2 dB. Gf7Gf7Gf8Gf6Ge7Ge7Ge8Ge6+=1.9521.952sinlog20
29、2.41)(G dBi for 0 0.94 (1a) = log201.35)(G dBi for 0.94 3.82 (1b) Gf7Gf7Gf8Gf6Ge7Ge7Ge8Ge6+=0.4790.479sinlog2029)(G dBi for 3.82 5.61 (1c) = log75.1827.27)(G dBi for 5.61 12.16 (1d) = log2505.34)(G dBi for 12.16 48 (1e) 8)( =G dBi for 48 180 (1f) 4 Rec. ITU-R M.1459 The values of 1.952 and 0.479 ass
30、ociated with angle are in radians. The telemetry transmitting antennas are mounted on airborne vehicles and, ideally, would be isotropic radiators to cover all possible radiation angles toward the telemetry receiving station. However, in practice, multiple reflections and blockage from the airborne
31、vehicles cause large variations in the gain pattern. Multiple reflections generally result in a Raleigh fading distribution, and measured gain functions have shown that this is approximately the case as shown in Fig. 2. Using Fig. 2 for a near-worst case, including propagation effects, the probabili
32、ty (portion of time), P1, that a given gain, G1, is not exceeded can be expressed as: P1(G G1) = (1 e3.46 G1)1.25(numerical) (2) Distributions corresponding to an exponent of (5G1) are observed. The received C/N and carrier power, C, at output of the telemetry receiving antenna are proportional to t
33、his function. 1459-01302010010200 5 10 15 20 25 30 35 407FIGURE 1Measured data on 2.44 m diameter antennasDegrees off-axis ()Gain(dBi)Site 1Site 2Site 350% sidelobe34.05 25 log 29 + 20 logsin 0.479 0.479 FIGURE 1 1459-01 Rec. ITU-R M.1459 5 1459-02G1(dBi)10 0 10 20 30 40 5010525104252510310210125251
34、ProbabilitythatG1isnotexceededFIGURE 2Airborne telemetry transmitting antenna gains, G1Antenna type No. 1Antenna type No. 2Antenna type No. 3(1 e3.46G )1.251FIGURE 2 - 1459-02 2.2 Interference from geostationary satellites 2.2.1 Time-gain function of interference If it is assumed that the telemetry
35、antenna may be pointed at any point on its hemisphere of visibility, the cumulative probability, P2, that a satellite at geostationary altitude is within a radius of , as viewed from the telemetry receiving station, is: P2= (1 cos ) for 0 /2 (3) 6 Rec. ITU-R M.1459 The in equation (1) is the same as
36、 in equation (3). Thus, by combining equations (1) with (3), functions can be developed which relate the probability (portion of time) that the telemetry receiving antenna gain, G, toward the satellite is equal to or greater than a given value, G2, as shown in Fig. 3. The received I/N and the interf
37、erence power, I, are proportional to the functions shown in Fig. 3. In the case of geostationary satellite, the angle-of-arrival of interference at a telemetry receiving station is fixed. The only randomness involved is the telemetry receiving antenna pointing variations. Testing of airborne vehicle
38、s is often restricted to areas over water or uninhabited land in order to preclude danger to life or property in case of catastrophic failure of the vehicle being tested, thereby limiting the azimuth angles for these tests. There are also minimum limits on the azimuth and elevation pointing angle va
39、riations of the telemetry receiving antenna that are defined by the minimum air space in 2.1. FIGURE 3 - 1459-03 1459-031032525 2510125 2511021041055001040302010G1(dBi)Probability that G2is exceededFIGURE 3Telemetry receiving antenna gain probability, G22.2.2 C/I analysis Since equation (2) is propo
40、rtional to C and the functions in Fig. 3 are proportional to I, the probability of C/I can be determined and is proportional to: )()/()/()/(2211GG“PGGPICICPc (4) where (C/I)cis a chosen value. The square brackets indicate the joint, cumulative probability function. The C and I functions are independ
41、ent since they result from independent sources. The indicated integrations were performed for various limited ranges of P2which, in turn, corresponds to limited steradian areas, S, when the satellite is within the minimum airspace defined in 2.1. These integrations may be expressed as: )()/()/(11221
42、23GGPGG“PGGGP = (5) The (C/I) in equation (4) is normally expressed in relation to (C/N), and since loss of availability is the prime concern, it is expressed in relation to the threshold (C/N)Tas follows: (C/I) (C/N)T(P4/P3) (6) Rec. ITU-R M.1459 7 where P4 : probability associated with (C/N)Tand i
43、s set equal to P(G) P3 : probability associated with (C/I). The ratio (P4/P3) is analogous and numerically equal to (I/N) criteria. The allowable non-availability, P, is based on C/(N + I) so that P(G) = P P3which results in: P(G) = P/(I/N + 1) (7) It is now necessary to relate G to pfd. First, a pf
44、d is determined when the telemetry antenna is directed toward the satellite: )W/(m)/4()/(202BGNIBTkpfd (8) where: k: Boltzmanns constant T: noise temperature (K) B: bandwidth (Hz) G0 = 13 183 (41.2 dB). This pfd is associated with a (G)mat a P(G). At G0, only C is variable and thus, C/I is given by
45、equation (2). The (G)mfunction is closely approximated by: (G)m= 45 000/P(G)1.25(9) The pfd from equation (8) can be increased by (G)m/(G). Thus: )W/(m)()()()()/4()/(220BGPGPGGGNIBTkpfdmm= (10) 2.2.3 Impact on telemetry link design Analyses show that the value of P, the telemetry link non-availabili
46、ty, does not significantly affect the pfd values. The pfd values are primarily determined by the value of (I/N). The impact on the telemetry link measured in terms of the decrease in usable range, R, for a given P, as a function of (I/N) can be determined from equation (7), since R2 1/(N + I) for a
47、fixed transmitter power. The decreased usable range as a function of (I/N) is shown in Fig. 4. The impact on telemetry link design becomes severe for (I/N) values greater than one (0 dB) because the link must be designed to overcome interference rather than internal noise. The maximum practical valu
48、e is considered to be approximately 0.5 (3 dB) with smaller values desired. 2.2.4 Interference allowances Based on the factors given in 2.2.3, the following aggregate allowances appear appropriate for this case. The total noise is the sum of internal noise, NI, plus interference from satellites, IS, plus interference from terrestrial sources, IT. The aggregate permissible interference from satellites and terrestrial sources are: IS= 0.25 (NI+ IS+ IT) (11)IT= 0.10 (NI+ IS+ IT) 12) From this, the aggregate allowable I/N from satellites is 0.3846 or 4.
