1、 Rec. ITU-R S.1714 1 RECOMMENDATION ITU-R S.1714 Static methodology for calculating epfdto facilitate coordination of very large antennas under Nos. 9.7A and 9.7B of the Radio Regulations (2005) The ITU Radiocommunication Assembly, considering a) that WRC-2000 adopted, in Article 22 of the Radio Reg
2、ulations (RR) , equivalent power flux-density (epfd) limits to be met by non-GSO FSS systems in order to protect GSO FSS and GSO broadcasting-satellite service networks in parts of the frequency range 10.7-30 GHz; b) that WRC-2000 agreed that additional protection above that provided by the epfd lim
3、its in considering a) is required for certain GSO FSS networks with specific receive earth stations having all of the following characteristics: i) earth station antenna maximum isotropic gain greater than or equal to 64 dBi for the frequency band 10.7-12.75 GHz or 68 dBi for the frequency bands 17.
4、8-18.6 GHz and 19.7-20.2 GHz; ii) G/T of 44 dB/K or higher; iii) emission bandwidth of 250 MHz or more for the frequency bands below 12.75 GHz or 800 MHz or more for the frequency bands above 17.8 GHz; c) that, in order to provide this additional protection, WRC-2000 adopted RR Nos. 9.7A and 9.7B, e
5、stablishing a procedure for effecting coordination between specific earth stations in a geostationary network in the FSS and systems in the FSS using satellites in non-GSO in certain frequency bands; d) that the technical conditions for triggering coordination under RR Nos. 9.7A and 9.7B are defined
6、 in RR Appendix 5 and include the thresholds in considering b) and the following epfdradiated by the non-GSO FSS satellite system into the earth station employing the very large antenna when this antenna is pointed towards the wanted GSO satellite: i) in the frequency band 10.7-12.75 GHz: a) 174.5 d
7、B(W/(m2 40 kHz) for any percentage of time for non-GSO satellite systems with all satellites only operating at or below 2 500 km altitude; or b) 202 dB(W/(m2 40 kHz) for any percentage of the time for non-GSO satellite systems with any satellites operating above 2 500 km altitude; ii) in the frequen
8、cy bands 17.8-18.6 GHz or 19.7-20.2 GHz: a) 157 dB(W/(m2 MHz) for any percentage of time for non-GSO satellite systems with all satellites only operating at or below 2 500 km altitude; or b) 185 dB(W/(m2 MHz) for any percentage of the time for non-GSO satellite systems with any satellites operating
9、above 2 500 km altitude; e) that the calculation of epfdproduced by a non-GSO satellite system as a function of time requires the use of a suitable simulation software tool; 2 Rec. ITU-R S.1714 f) that Recommendation ITU-R S.1503 provides a specification for a software simulation tool for calculatin
10、g epfdas a function of time, however it does not take into account the inclination of a GSO satellite; g) that as a consequence of the high gain of the very large GSO earth station antennas and the nature of the epfd equation, non-GSO satellites in the side lobes of the very large GSO earth station
11、antennas do not significantly contribute to the epfdvalue; h) that WRC-03 adopted Resolution 85 (WRC-03) which allows, on a provisional basis until appropriate software is available, for coordination under RR Nos. 9.7A and 9.7B to be effected using only the characteristics of the GSO FSS network; j)
12、 that there is limited guidance for conducting coordination under RR Nos. 9.7A and 9.7B, recommends 1 that the methodology in Annex 1 to this Recommendation could be used by administrations effecting coordination under RR Nos. 9.7A and 9.7B to calculate the worst case static epfd value from a non-GS
13、O system at a specific GSO earth station antenna when this antenna is pointed towards the wanted GSO satellite; 2 that the results from recommends 1 should be compared to the epfdprotection criterion of the GSO network and the criterion referred to in considering d) to determine if there is potentia
14、l for the non-GSO system to not meet this protection criterion; 3 that if the non-GSO system meets the GSO epfdprotection criterion and the criterion referred to in considering d) then coordination should be considered complete; 4 that if the non-GSO system does not meet the GSO epfdprotection crite
15、rion or the criterion referred to in considering d) then a more detailed analysis will be required. Annex 1 1 Description of the methodology In Circular Letter CR/176, the Radiocommunication Bureau requested that administrations responsible for non-GSO satellite systems in certain frequency bands su
16、bject to epfdlimits submit supplementary information to the ITU within six months of 26 March 2002 pursuant to resolves 2 of Resolution 59 (WRC-2000). This supplementary information contains the details about the satellite network operations and the pfd masks that are required to calculate the epfd
17、levels produced by the non-GSO systems. The methodology proposed in this Recommendation makes use of this supplementary information and does not require any other additional information regarding the non-GSO satellite systems. In order to meet the epfdlimits, non-GSO satellite systems will need to e
18、mploy some sort of mitigation technique. One of the most common techniques is GSO arc avoidance. GSO arc avoidance can be employed by means of establishing an exclusion zone in three different ways: The exclusion zone is defined from the GSO earth station to X to the GSO arc and the non-GSO satellit
19、e can transmit to a non-GSO earth station located at least a predefined distance from the GSO earth station while inside the exclusion zone; Rec. ITU-R S.1714 3 The exclusion zone is as defined in Fig. 1 however, the non-GSO satellite cannot transmit while inside the exclusion zone; The exclusion zo
20、ne is defined by latitude, and the non-GSO satellite cannot transmit when its sub-satellite latitude is between a certain X latitude range. A diagram of each of these three types of GSO arc avoidance techniques is provided in Figs. 1 through 3. FIGURE 1 Case 1 Exclusion zone FIGURE 2 Case 2 Exclusio
21、n zone 4 Rec. ITU-R S.1714 FIGURE 3 Case 3 Exclusion zone Cases 1 and 2 describe the forms of GSO arc avoidance that would most likely be used by a low earth orbit (LEO) constellation; whereas Case 3 would most likely be used with a HEO type constellation, while all three types of arc avoidance coul
22、d be used with a MEO constellation. Because it is unlikely for a HEO to use the arc avoidance described in Cases 1 and 2, the calculations in these methodologies are limited to circular orbits. The methodology for Case 3 can be utilized for a HEO constellation as long as the radius to the HEO satell
23、ite when it crosses the cut on/off latitude is known. The epfdthresholds in RR Appendix 5 used to determine the technical conditions for triggering coordination between non-GSO FSS systems and specific earth stations in a GSO FSS network are defined on the basis of altitude, with one trigger for non
24、-GSO systems with all satellites operating at or below 2 500 km altitude and another trigger value for non-GSO FSS systems with any satellites operating above 2 500 km altitude. Table 1 shows the relationship between non-GSO orbit type, RR Appendix 5 coordination trigger, and the cases considered fo
25、r mitigation techniques. TABLE 1 Relationship between orbit type, RR Appendix 5 trigger, and mitigation technique Orbit type Appendix 5 Coordination trigger (km) Mitigation techniques LEO 2 500 Cases 1 and 2 MEO 2 500 Cases 1, 2 and 3 HEO 2 500 Case 3 Rec. ITU-R S.1714 5 2 Case 1 Case 1 depicts the
26、scenario when an exclusion zone is defined from the GSO earth station to X to the GSO arc. When the non-GSO is within this exclusion zone it can transmit but not in the direction of the GSO earth station. The distance away from the GSO earth station that the non-GSO can transmit to is determined by
27、the non-GSO operations. The worst-case geometry for this case is depicted in Fig. 1 where the non-GSO is directly in line between the GSO satellite and the GSO earth station but the non-GSO is transmitting to an earth station away from the GSO earth station. This geometry produces a non-GSO side lob
28、e into GSO main beam interference scenario. This mitigation technique would typically be used with a LEO constellation but would also work with a MEO constellation. The algorithm to calculate the epfdvalue requires the following Steps: Step 1: Inputs: Radius of the Earth, non-GSO radius, non-GSO inc
29、lination, GSO radius, GSO satellite longitude, GSO satellite inclination, GSO earth station latitude, GSO earth station longitude. Step 2: Calculate the azimuth and elevation angles from the GSO earth station to the GSO satellite. Step 3: Calculate the sub-satellite latitude and longitude of the non
30、-GSO for the same azimuth and elevation as the GSO satellite. Step 4: If the non-GSO pfd masks are presented in alpha vs. delta longitude form (see Recommendation ITU-R S.1503 for alpha and delta longitude definitions). a) From the pfd masks choose the pfd for the latitude nearest the sub-satellite
31、latitude of the non-GSO for Alpha = 0 or X = 0 and the longitude difference between the GSO and the non-GSO satellites. b) Since this is an in-line event the G(theta)/G(max) portion of the epfd calculation is equal to 1 or 0 dB. c) Because the GSO satellite has a very large bandwidth, there may be s
32、everal sets of pfd masks with overlapping frequencies; all of these should be included. d) Calculate the epfd as defined in RR No. 22.5C. Step 5: If the non-GSO pfd masks are presented in azimuth vs. elevation form (see Recommendation ITU-R S.1503 for azimuth and elevation definitions). a) Calculate
33、 the Earth centred fixed (ECF) coordinates of the GSO satellite, earth station and non-GSO satellite. b) Translate and rotate vector between non-GSO satellite and GSO earth station from ECF coordinates to satellite centred coordinates. c) Calculate azimuth and elevation from the non-GSO satellite to
34、 the GSO earth station. d) From the pfd masks choose the pfd for the latitude nearest the sub-satellite latitude of the non-GSO satellite for the azimuth and elevation from the non-GSO satellite to the GSO earth station. e) Since this is an in-line event the G(theta)/G(max) portion of the epfd calcu
35、lation is equal to 1 (numerical) or 0 dB. f) Because the GSO has a very large bandwidth, there may be several sets of pfd masks with overlapping frequencies; all of these should be included. g) Calculate the epfd as defined in RR No. 22.5C. An Excel worksheet with the appropriate equations and calcu
36、lations preprogrammed has been developed. A picture of the Case 1 calculation page is shown in Table 2. The input values for the non-GSO satellite system are fictional and do not represent any particular system. 6 Rec. ITU-R S.1714 TABLE 2 Case 1 Excel spreadsheet calculations Case 1: Exclusion zone
37、 defined from the GSO Earth station to X to the GSO arc Non-GSO satellite CAN transmit inside exclusion zone but not toward GSO earth station Worst case: non-GSO satellite is inline with the GSO satellite and Alpha = 0 or X = 0 Note: This algorithm is only valid for circular non Inputs Radius of the
38、 Earth (km) Re 6 378.15 Non-GSO radius (km) Rn 7 878 Non-GSO satellite inclination (degrees) i 55 GSO radius (km) Rg 42 164 GSO satellite Longitude (degrees) GSO Long. 30 GSO satellite Inclination (degrees) ig 5 Earth station latitude (degrees) 38 Earth station longitude (degrees) earth Long. 77 Cal
39、culations GSO satellite latitude (degrees) g 5 Difference between earth station and GSO satellite longitude (degrees) g 47 GSO Long. earth Long. Calculate gamma angle from earth station to GSO satellite (degrees) g 53.91141 acossin() * sin(g) + cos() * cos(g) * cos(g) Calculate slant range from eart
40、h station to GSO satellite (km) dg 3 8751.35 sqrt(Re2 + Rg2 2*Re*Rg*cos(g) Calculate elevation angle from earth station to GSO satellite (degrees) el 28.44516 acos(Rg/dg) * sin(g) Calculate azimuth angle from the earth station to GSO satellite (degrees) az 115.6339 if (g0 and 0 Then 90 acoscos(90-)
41、* cos(n) + sin(90-) * sin(n) * cos(az) else 90 acoscos(90+) * cos(n) + sin(90-) * sin(n) * cos(az+180) Calculate long difference between non-GSO satellite and earth station (degrees) n 16.80892 if g0 then acos(cos(n) sin() * sin() / (cos() * cos() else 1*acos(cos(n) sin() * sin() / (cos() * cos() Ca
42、lculate the sub-satellite longitude of the non-GSO satellite at this Az and El (degrees) nGSO Long. 60.1911 earth Long.+ n Rec. ITU-R S.1714 7 TABLE 2 (continued) If satellite pfd masks are presented in Alpha vs Delta Longitude form Calculate the Delta longitude between GSO and non-GSO satellites (d
43、egrees) delta 30.19108 GSO Long nGSO Long Choose pfd from mask for latitude nearest to sub-satellite latitude of non-GSO satellite, because the GSO satellite VLA frequency bandwith is very large there may be several sets of masks with overlapping frequencies, all of these should be added in since th
44、is is an in-line event the Gr(theta)/Gr(max) portion of epfd calculation is equal to 1 (numerical) or 0 dB. Freq 1: pfd of non-GSO satellite with Alpha = 0 or X = 0 and Delta pfd1 140 example Freq 2: pfd of non-GSO satellite with Alpha = 0 or X = 0 and Delta(input NA if not applicable) pfd2 131 exam
45、ple . freq n: pfd of non-GSO satellite with Alpha = 0 or X = 0 and Delta (input NA if not applicable) pfdn 140 example Calculate worst-case epfd (dB(W/(m2 MHz) epfd 130.025 10 log(10(pfd1/10)+10(pfd2/10)+.+10(pfdn/10) If satellite pfd masks are presented in azimuth vs elevation form Calculate the x,
46、 y, z components of the earth station in ECF Earth station x value (km) Xe 1 130.615 Re * cos() * cos(earth Long.) Earth station y value (km) Ye 4 897.23 Re * cos() * sin(earth Long.) Earth station z value (km) Ze 3 926.781 Re * sin() Calculate the x, y, z components of the non-GSO satellite in ECF
47、Non-GSO x value (km) Xn 3 399.674 Rn * cos() * cos(nGSO Long.) Non-GSO y value (km) Yn 5 934.02 Rn * cos() * sin(nGSO Long.) Non-GSO z value (km) Zn 3 910.561 Rn * sin() Calculate vector between non-GSO satellite and earth station Vector X (km) X 2 269.06 Xe Xn Vector Y (km) Y 1 036.788 Ye Yn Vector
48、 Z (km) Z 16.21997 Ze Zn Calculate longitude of ascending node Difference between satellite longitude and ascending node (degrees) del 23.6024 asin(tan() / tan(i) Longitude of ascending node (degrees) an 83.7935 nGSO Long. del 8 Rec. ITU-R S.1714 TABLE 2 (end) Calculate argument of perigee plus true
49、 anomaly Argument of perigee plus true anomaly (degrees) arg 37.29943 asin(sin() / sin(i) Calculate some values for the transformation matrix of the earth station XYZ ECF coordinates to xyz sat (satellite centred) coordinates Cosine of longitude of ascending node cos_an 0.108113 cos(an) Sine of longitude of ascending node sin_an 0.99414 sin(an) Cosine of non-GSO satellite inclination cos_inc 0.573576 cos(i) Sine of non-GSO satellite inclina
