1、CCIR RECNN*476-3 72 4855212 0517452 273 Rec. 496-3 215 RECOMMENDATION 496-3* LIMITS OF POWER FLUX-DENSITY OF RADIONAVIGATION TRANSMITTERS TO PROTECT SPACE STATION RECEIVERS IN THE FIXED-SATELLITE SERVICE IN THE 14 GHz BAND (1 974- 1982- 1986- 1992) The CCIR, considering that Earth-to-space transmiss
2、ions of the fixed-satellite service (FSS) share the band 14-14.3 GHz with the that the World Administrative Radio Conference (Geneva, 1979) has asked the CCIR to study the criteria for that Radio Regulation No. 856 requires that the use of this band by the radionavigation service shall be such that,
3、 in the band 14-14.3 GHz, sufficient protection for geostationary satellites in the FSS can be obtained by that some kinds of radionavigation device, such as small ship radars and motor vehicle collision avoidance a) radionavigation service; b) frequency sharing in this band (Recommendation No. 708,
4、O 2.12); Cl as to provide sufficient protection to space stations in the FSS; d) limiting the power flux-density produced at the geostationary-satellite orbit by stations of the radionavigation service; e) devices, although generally of comparatively low power, may be used in very large numbers, rec
5、ommends 1. that in order to provide sufficient protection to space station receivers of the FSS, the following limits for non-pulsed radionavigation transmitters should apply: 1.1 that where the value of D, as defmed below, is less than 2 x 10-4, the maximum value of the peak power flux- density pro
6、duced at any point in the geostationafy-satellite orbit by any radionavigation transmitter in the band 14-14.3 GHz should not exceed -150 dB(W/m2) in any 1 MHz band; 1.2 that where the value of D, as defined below, exceeds 2 x 10-4, the maximum value of peak power flux- density produced at the geost
7、ationary-satellite orbit by any radionavigation transmitter should not exceed: -187 - 10 log D dB(W/m2) (1) in any 1 MHz band, where D is the estimated geographical density of radionavigation transmitters per km2 simultaneously active in any 1 MHz band, taking into account future needs and averaged
8、over the territory of the administration concerned or over an area of 106 km2, whichever is less. Note I - An analysis concerning sharing criteria for the protection of receiving space stations in the 14-14.3 GHz FSS band is given in Annex 1. * This Recommendation should be brought to the attention
9、of Study Group 4. COPYRIGHT International Telecommunications Union/ITU RadiocommunicationsLicensed by Information Handling Services216 CCIR RECMN*496-3 92 4855232 0539453 12T Rec. 496-3 ANNEX 1 Analysis in support of sharing criteria for the protection of receiving space stations in the fixed-satell
10、ite service in the band 14-14.3 GHz 1. Protection criteria for the FSS receiving space station The FSS satellite receiving system noise temperature is assumed to be 1500 K. The level of permissible interference, considered to be 10% of the thermal noise at the satellite receiver input in a 1 MHz ref
11、erence bandwidth, is therefore -147 dBW - 10 log n, where n is the number of simultaneous in-beam interference entries. 1.2 interferencefrom transmitters in the radonavgation service (14-14.3 GHz) This criterion, expressed in power flux-density at the input of the satellite receiving antenna assumed
12、 to have an effective aperture relative to 1 m2 of -3 dB, is -14.4 dB(Wlm2) - 10 log II. Assuming that the radionavigation antennas are randomly oriented in the horizontal plane, the number of simultruieous in-beam interference entries in a 1 MHz band, received by a satellite antenna which is illumi
13、nating the Earth at a low angle of elevation is given by: e n = DA- 360 where: D: average density per km2 of the radionavigation transmitters simultaneously active, within the 1 MHz band A : area of the Earths surface covered by the satellite receiving antenna (ian2) 0 : representative average value
14、 for the beamwidth of the radionavigation transmitting antennas (degrees). Assuming that the average value for 8 is taken as 6O, and the coverage area A is 1.2 x 106 ha, then: n = D x 2 x 104 Thus the maximum value of peak power flux-density which any transmitter may produce at the geosttionary-satellite orbit would be given by: -187 - 1OlogD dB(W/m2) in any 1 MHz band. COPYRIGHT International Telecommunications Union/ITU RadiocommunicationsLicensed by Information Handling Services
