1、ITU-R RECMN*SA* 3OLb 74 = 4855232 0523357 35T Deep-space earth station Deep-space earth station Terrestrial or earth station Near-earth station Rec. ITU-R SA.1016 Terrestrial or earth station Earth orbiting satellite Deep-space station Deep-space station 33 RECOMMENDATION ITU-R SA. 1016 SHARING CONS
2、IDERATIONS RELATING TO DEEP-SPACE RESEARCH (Question ITU-R 210/7) (1 994) The ITU Radiocommunication Assembly, considering that the feasibility of frequency sharing between deep-space research stations and stations of other services is a) presented in Annex 1, recommends 1. stations in other service
3、s except: that, with coordination, deep-space research can share frequency bands in the Earth-to-space direction with receiving aeronautical mobile stations, receiving satellite stations, and microwave sensor satellites, when any of these may come within line-of-sight; receiving mobile stations that
4、 come within the separation distance required for interference protection; transmitting terrestrial stations having an average e.i.r.p. exceeding 81 dBW in the bands near 2 GHz and 84 (IBW in the bands near 7 GHz; that, with coordination, deep-space research can share frequency bands in the space-to
5、-Earth direction with - the radioastronomy service; - - - - 2. stations in other services except: transmitting aeronautical mobile stations, transmitting satellite stations, and active microwave sensor satellites, when any of these may come within line-of-sight; transmitting mobile stations that com
6、e within the separation distance required for interference protection. - ANNEX 1 Sharing considerations relating to deep-space research 1. Sharing considerations: deep-space Earth-to-space bands Table 1 and the following paragraphs consider the possibility of interference in the deep-space research
7、Earth- to-space bands. TABLE 1 Potential interference in Earth-to-space bands I Receiver I Source I ITU-R RECMN*SA= 1016 94 4855232 05123360 071 M 34 Rec. ITU-R SA.1016 1.1 Potential interference to terrestrial or earth station receivers from deep-space earth station transmitters The normal maximum
8、total power for current deep-space earth stations is 50 dBW. For a minimum elevation angle of lo“, the e.i.r.p. directed towards the horizon does not exceed 57 dB(W/4 kHz), assuming the reference earth station antenna radiation pattern of Recommendation ITU-R SA.509. For spacecraft emergencies, the
9、maximum total power may be increased to 56 dBW, giving not more than 63 dB(W/4 kHz) at the horizon. These values of e.i.r.p. meet the requirements of No. 2540 of the Radio Regulations (RR). Aircraft stations within line-of-sight of a deep-space earth station may encounter total power flux-densities
10、as shown in Fig. 1. For an aircraft altitude of 12 km, the maximum line-of-sight distance to an earth station is 391 lun and the total power flux-density at the aircraft can never be lower than -83 dB(W/m2), again assuming the antenna pattern of Recommendation ITU-R SA.509. Depending on distance and
11、 earth station antenna direction, the aircraft station may experience much higher flux densities and interference levels. Coordination with airborne stations is generally not practicable. FIGURE 1 Power flux-density vs. distance from earth station Distance fiom transmitter (km) Transmitter: Deep-spa
12、ce earth station 100 kW, 70 m diameter antenna A: main beam, 34.5 GHz B: main beam, 17 GHz C: D: E: F: G: main beam, 7 170 MHz main beam, 2 115 MHz 5“ off main beam axis (14.5 dBi gain, Recommendation -R SA.509) 48“ off main beam axis (-10 dBi gain, Recommendation ITU-R SA.509) geostationary orbit a
13、ltitude: 35 800 km Super refraction, ducting, and precipitation scatter may couple emissions from deep-space earth station transmitters into terrestrial receivers, and receivers of other earth stations. Except for airborne terrestrial receivers, coordination for these conditions is generally practic
14、able. See 2.3 for discussion of interference from airborne transmitters, and 8 3 for coordination considerations. IT-R RECMN*SA* 1QLb 94 4855212 0523163 TOB Rec. ITU-R SA.1016 35 1.2 Potential interference to satellite receivers from deep-space earth station transmitters Satellites that come within
15、the deep-space earth station beam will encounter power flux-densities as shown in Fig. 1. When the earth station is tracking a spacecraft whose direction is such that the antenna beam passes through the geostationary satellite orbit (GSO), the power flux-density at that point on the orbit will vary
16、with time as shown in Fig. 2. For example, the total power flux-density will be -95 dB(W/m2) or more for 32 min. The figure assumes a transmitter power of 50dBW, a 70 m antenna, and the reference earth station antenna pattern of Recommen- dation ITU-R SA.509. An important observation is that the min
17、imum power flux-density at the GSO within line-of-sight of a deep-space earth station is at least -122 dB(W/m2), regardless of antenna pointing direction. The duration and magnitude of signals from deep-space earth station transmitters which may interfere with satellites in non-geostationary orbits
18、depends upon those orbits and the direction in which the earth station antenna is pointing. FIGURE 2 Time during which the power flux-density at a point on the geostationary satellite orbit may exceed a minimum power flux-density - 20 - 30 - 40 - h E -50 3 .g -60 c 3 -70 8 1 G -80 a i3 E .g -90 - 10
19、0 - 110 - 120 O 10 20 30 40 so 60 70 80 Time (min) Transmitter: Deep-space earth station, 100 kW, 70 m diameter antenna, 34.5 GHz .m. I. 3 Potential interference to deep-space station receivers from terrestrial or earth station transmitters Terrestrial or earth station transmitters within sight of a
20、 deep-space station are potential sources of interference. Figure 3 shows the space station distance at which the interference power density from such a transmitter equals the receiver noise power density. For example, a trans-horizon station with 93 dB(W/lO kHz) e.i.r.p. in the 2.1 GHz band could i
21、nterfere with a space station receiver at ranges up to 4.1 x lo9 km (600 K noise temperature, 3.7 m ITU-R RECMNxSA- 1Olb 94 4855212 O523162 944 Source Deep-space station Deep-space station Terrestrial or earth station Earth orbiting satellite 36 Rec. ITU-R SA.1016 Receiver Terrestrial or earth stati
22、on Earth orbiting satellite Deep-space earth station Deep-space earth station spacecraft antenna). The possibility of interference at such a great distance poses a threat to space missions to planets as far away as Uranus. Stations with lower e.i.r.p., or with antennas pointing away from the eclipti
23、c plane, have less potential for interference. FIGURE 3 Spacecraft distance from terrestrial transmitter for interference power equal to receiver noise power A trans-horizon transmitter: 2 115 MHz D: radiwrelay transmitter: 7 170 MHz e.i.r.p.: 93 dB(W/lO kHz) receiver noise power:-191 dB(W/20 Hz) e.
24、i.r.p.: 48.8 dB(W/Hz) receiver noise power: -182.6 dB(W120 Hz) e.i.r.p.: 55 dB(W/lO kHz) receiver noise power: -189 dB(W/20 kHz) B: radiolocation transmitter: 34.5 GHz E: 1 AU = 1.5 x lo8 km F inner bunday of deep space: 2 x lo6 km C: radiolocation transmitter: 17 GHz e.i.r.p.: 40.9 dB(W/Hz) receive
25、r noise power: -186 dB(W/20 Hz) 1.4 Potential interference to deep-space station receivers from Earth orbiting satellite transmitters Earth orbiting satellites typically have antennas directed to the Earth or to other satellites. Interference with deep-space station receivers may occur for those bri
26、ef periods when the satellite antenna is directed so as to permit main beam coupling. As received at deep-space stations, signals from satellites will almost always be weaker than those from earth stations. 2. Sharing considerations: space-to-Earth bands Table 2 and the following sections consider t
27、he possibility of interference in the deep-space research space-to- Earth bands. TABLE 2 Potential interference in space-to-Earth bands ITU-R RECMNaSA- 1016 94 m 4855212 0523363 880 m Rec. ITU-R SA.1016 37 2.1 Potential interference to terrestrul or earth station receivers from deep-space station tr
28、ansmitters Figure 4 shows the power flux-density at the surface of the Earth caused by typical deep-space stations. These stations often use low gain, wide beam antennas while near Earth. After a time not exceeding six hours after launch, they are usually at a sufficient distance for the power flux-
29、density at the surface of the Earth to be less than the maximum permitted by the RR for protection of line-of-sight radio-relay systems. FIGURE 4 Power flux-density at the surface of the Earth YS. spacecraft distance - 60 - 80 h N -100 = -120 2 2 -140 -160 h Y .- 1 G a - 180 id id 1 o6 1 o7 Spacecra
30、ft distance (km) A: B: C: D: E: F: 13 dBW transmitter, 37 dBi antenna gain, 2 295 MHz 13 dBW transmitter, 48 dBi antenna gain, 8 425 MHz 13 dBW transmitter, 52 dBi antenna gain, 13 GHz 13 dBW transmitter, 60 dBi antenna gain, 32 GHz 13 dBW transmitter, 0 dBi antenna gain -154 dB(W/m2) power flux-den
31、sity, RR No. 2557 io9 IOO When the transmitting space station is using a higher gain directional antenna, there is the potential for interference with sensitive terrestrial receivers if their antennas are directed so as to permit main beam coupling. A space station operating at 2.3 GHz with an e.i.r
32、.p. of 51 dBW at a distance of 5 x lo8 km could create an input of -168 dBW to a trans-horizon receiver (27 m antenna, main beam). The duration of such interference would be of the order of a few minutes, once a day, because of the rotation of the Earth. 2.2 Potential interference to Earth orbiting
33、satellite receivers from deep-space transmitters Considerations of this interference are similar to those for the space station to terrestrial receiver case, 0 2.1, with the exception of the path geometry. Depending on the changing conditions of that geometry, occasional brief interference is possib
34、le. 2.3 Potential interference to deep-space earth station receivers from terrestrial or earth station transmitters Interference to deep-space earth station receivers may come from terrestrial or earth stations over line-of-sight paths, by tropospheric phenomena, or by rain scatter. For coordination
35、 considerations see 0 3. ITU-R RECMN*SA= 1016 94 4855212 0523164 717 W Maximum allowable interference power spectral density (dB(W/Hz) 38 Rec. ITU-R SA.1016 Amount by which aircraft signal exceeds maximum allowable interference power() (dB) Terrestrial services utilizing high power transmitters and
36、high gain antennas are potential interference sources. Earth station transmitters are less likely sources of interference, depending on e.i.r.p. in the direction of the deep-space earth station. Coordination should enable adequate protection from radio-relay stations to be provided. 13.0 Aircraft tr
37、ansmitters within sight of a deep-space earth station may cause serious interference. At maximum line-of-sight distance in any direction (391 km for an aircraft at 12 km altitude), an e.i.r.p. of -26 dB(W/Hz) (for example, 10 dB(W/4 kHz) and O dBi antenna gain) will exceed the earth station interfer
38、ence limit by at least the amount shown in Table 3, assuming the reference earth station antenna pattern. I TABLE 3 Interference from assumed aircraft transmitter 2.3 8.4 -222.5 -220.9 -220.5 35.0 22.1 17.9 I 32.0 I -2 17.3 I 6.9 I (I) Aircraft signal minus the deep-space earth station interference
39、limit. Airborne radionavigation transmitters that may operate in the 32 GHz region of the spectrum are a particular example of potential sources of harmful interference to deep-space earth station receivers. This class of transmitter includes a wide variety of characteristics: output power; CW, puls
40、e, or chirp modulation; fixed or scanning antennas with narrow or wide beam patterns. The probability and degree of interference from a particular transmitter can be determined on a case-by-case basis that is beyond the scope of this Annex. Nevertheless, it is generally true that if an airborne radi
41、onavigation transmitter is within line-of-sight of the earth station receiver, the maximum allowable level of interference can be exceeded for a time sufficient to cause degradation to, or interruption of, service. Coordination with airborne stations is generally not practicable. 2.4 Potential inter
42、ference to deep-space earth station receivers from Earth orbiting satellite transmitters An analysis of the potential for interference in the 2 290-2 300 MHz band from satellites in highly eccentric orbits may be found in ex-CCIR Report 688 (Geneva, 1982). It is concluded that sharing is not feasibl
43、e. This conclusion is also valid for satellites in circular and moderately eccentric orbits. 2.5 Potential interference to deep-space earth station receivers from Earth orbiting satellites that are transmitting to a geostatiunary relay satellite Table 4 presents an analysis of a situation where a li
44、nk between a user spacecraft and a geostationary data relay satellite (DRS) grazes the surface of the Earth near the location of a deep-space earth station. It is assumed that the main beam of the earth station antenna is directed at the user satellite. The negative interference margin means that th
45、e protection criterion for the earth station receiver has been violated. Rec. ITU-R SA.1016 TABLE 4 Interference from relay satellite link to deep-space earth station (32 GHz) DRS user-satellite altitude (km) Transmitter power (dBW) Bandwidth convervion (300 Mbis, QPSK) (dB/Hz) Transmitting antenna
46、gain (dBi) Off-axis gain reduction (dB) Path loss (32.1 GHz) (dB) Earth-station antenna gain (dBi) Received interference (dB(W/Hz) Harmful interference criterion (dB(W/Hz) Interference margin (dB) 500.0 10.0 -84.8 52 -39.3 -184.7 83.6 -1 63.2 -217.3 -54.1 39 1000.0 10.0 -84.8 52.0 -32.3 -190.2 83.6
47、-161.7 -217.3 -55.6 To reduce the negative interference margin shown in the table to O dB, the DRS user satellite must remain at least 1.7“ away from the main beam axis of the earth station antenna. If the earth station is tracking a particular spacecraft in deep-space each day, and if the DRS user
48、satellite passes through the earth station antenna beam at some time during a given day, then the satellite will pass through the beam at less than 1.7“ from the beam axis with a frequency ranging between once every 12 days to once each day. The frequency depends upon the satellite orbit period. For
49、 example, a satellite with an orbit period of 84 min can produce a negative interference margin of up to 0.8 min duration every seventh day. Although an interference interval of less than 1 min is relatively unimportant for some radio services, in the space research service it can result in irreplaceable loss of scientific data for several minutes (see 5 1.1). The analysis presented above considers only a single user-satellite and one deep-space earth station. A greater number of satellites would increase the probability of interference. It is concluded that band sharing by de
