1、 Rec. ITU-R S.524-9 1 RECOMMENDATION ITU-R S.524-9 Maximum permissible levels of off-axis e.i.r.p. density from earth stations in geostationary-satellite orbit networks operating in the fixed-satellite service transmitting in the 6 GHz, 13 GHz, 14 GHz and 30 GHz frequency bands (Questions ITU-R 70/4
2、 and ITU-R 259/4) (1978-1982-1986-1990-1992-1994-2000-2001-2003-2006) Scope This Recommendation provides maximum off-axis e.i.r.p. levels not to be exceeded by earth stations associated with geostationary-satellite networks operating in the fixed-satellite service and transmitting in the 6 GHz, the
3、13 GHz, the 14 GHz and the 30 GHz frequency bands. A number of notes provides additional guidelines on the application of the off-axis e.i.r.p. levels. The ITU Radiocommunication Assembly, considering a) that geostationary satellite networks in the fixed-satellite service (FSS) operate in the same f
4、requency bands; b) that some non-geostationary satellite networks in the FSS may operate in the same frequency bands as some geostationary satellite networks in accordance with the Radio Regulations (RR); c) that interference between networks in the FSS contributes to noise in the network; d) that i
5、t is necessary to protect a network in the FSS from interference by other such networks; e) that it is necessary to specify the maximum permissible levels of off-axis e.i.r.p. density from earth stations, to promote harmonization between geostationary satellite networks, and also where applicable to
6、 limit interference power from GSO FSS earth stations to uplinks of non-GSO systems; f) that the contribution of interference from an earth station of an adjacent satellite network into a space station receiver is a function of the earth station off-axis e.i.r.p. density; g) that the use of antennas
7、 with the best off-axis performance will lead to the most efficient use of radio-frequency spectrum and the GSO; h) that off-axis e.i.r.p. density levels are determined by the side-lobe gain, the transmitter output power level and spectral distribution of that power, noting a) that Annex 1 and Annex
8、 2 describe the basis on which certain of the levels in this Recommendation were derived, 2 Rec. ITU-R S.524-9 recommends 1 that earth stations operating in GSO networks in the FSS transmitting in the 5 725-7 075 MHz frequency band should be designed in such a manner that at any angle, , which is 2.
9、5 or more off the main lobe axis of the earth station antenna, the e.i.r.p. density in any direction within 3 of the GSO does not exceed the following values: 1.1 for emissions in systems other than those considered in 1.2 and 1.3 below: Angle off-axis Maximum e.i.r.p. per 4 kHz 2.5 48 In case of cl
10、ear-sky condition, the maximum permissible levels of off-axis e.i.r.p. density that do not constrain the operation of the GSO/FSS systems mentioned in the previous section are as follows: 27 25 log () dB(W/40 kHz) for 2.0 7.0 16 dB(W/40 kHz) for 7.0 48 However, further studies are needed to select a
11、ppropriate margin to the excess, because various types of antennas should be taken into account. 4.2.4 Conclusion This Annex showed several GSO/FSS system parameters, an example of a measured antenna radiation pattern, and the maximum permissible levels of off-axis e.i.r.p. density that do not const
12、rain the operation of these GSO/FSS systems. The maximum permissible levels of off-axis e.i.r.p. density should be selected so as not to restrict the variety of services provided by existing and future satellite systems. Furthermore, off-axis e.i.r.p. densities must include appropriate margin to the
13、 excess of the actual antenna side-lobe gain from antenna side-lobe design objectives described in Recommendation ITU-R S.580. 20 Rec. ITU-R S.524-9 Therefore, when defining the permissible levels of off-axis e.i.r.p. density from GSO/FSS earth stations operating in the 29.5-30.0 GHz band in any dir
14、ection within 3 of the GSO, these GSO/FSS system parameters and the side-lobe envelope should be taken as the minimum conditions which could be adopted. This has been done in Note 7 of the Recommendation. Where new networks must meet more stringent limits, provision must be made for ensuring that mo
15、re strigent limits are not imposed to existing networks. This has been done in Notes 8 and 9 of the Recommendation. Annex 2 1 Introduction Using the formula given in Note 10 to establish the increase, for low elevation angle terminals, above the maximum off-axis e.i.r.p. level transmitting in the 27
16、.5-30.0 GHz band (see Note 1), the range between the maximum and the minimum pfd received at the GSO (from any point on the Earths surface from which the elevation angle to the GSO is greater than 5), would not be more than about 1 dB. Given the proposed model for off-axis e.i.r.p. limits for transm
17、itting earth station terminals having elevation angles 30 or less, the variation in pfd at the GSO, over the range of atmospheric parameters examined, is less than the difference in free space loss alone (1.32 dB), which occurs over the entire range of elevation. In the 6 GHz or the 14 GHz bands, th
18、e off-axis e.i.r.p limits in recommends 1 to 3 are independent of elevation angle. Atmospheric absorption even at low elevation angles in these bands is small when compared with the variation in the pfd at the GSO due to free space loss alone. Using the model proposed in Note 10, the variation of pf
19、d received at the GSO will be less than that which occurs due to free space loss alone. Thus, the impact of permitting low elevation angle earth station terminals at 30 GHz to transmit with the additional off-axis e.i.r.p proposed, over the range of atmospheres studied will have very minimal risk to
20、 the coordination of co-frequency uplinks to GSO satellite networks. In atmospheres where water vapour density, , is greater than about 7.5 g/m3, the peak pfd at the GSO, due to low elevation angle earth station terminals implementing the proposed uplink power compensation, will be less than that at
21、 angles above 30 where no uplink power compensation is used. Figures 6, 7 and 8 show, using Recommendation ITU-R P.676, the relative levels of pfd received at the GSO as a function of elevation angle. In all three cases examined, a ground elevation of 0 m (amsl) and an atmospheric pressure of 1 013 hPa were assumed. Rec. ITU-R S.524-9 21 22 Rec. ITU-R S.524-9
