1、 Rec. ITU-R S.1716 1 RECOMMENDATION ITU-R S.1716* Performance and availability objectives for fixed-satellite service telemetry, tracking and command systems (Question ITU-R 262/4) (2005) Scope This Recommendation resulted from multi-year studies within Radiocommunication Working Party 4B and provid
2、es guidance to the designers of fixed-satellite service systems on the technical and operational aspects of telemetry, tracking and command systems. The ITU Radiocommunication Assembly, considering a) that all FSS satellites have telemetry, tracking and command (TT b) that TT c) that TT d) that TT e
3、) that loss of the uplink command carriers to the satellite and downlink telemetry and ranging carriers during orbital maneuvers or during solar eclipse periods could result in the loss of a satellite; f) that some satellites with service links in bands above 17 GHz may also operate service links in
4、 bands below 17 GHz; g) that some GSO FSS operators may co-locate their satellites operating above 17 GHz with satellites operating below 17 GHz; h) that GSO FSS operators should be given some flexibility to operate TT j) that the spectrum requirements for TT and, accordingly the operator has contro
5、l over the period(s) and number of times in which the command can be sent. One can then expect the average telemetry, command and ranging link signal reliability to be, in practice, much greater than the availability values listed in Tables 6 and 7. Comparing the performance and availabilities of TT
6、C systems operating in the 30/20 GHz and 50/40 GHz bands when similar TT&C link design parameters as those in the 14/11-12 GHz bands are utilized, it was shown that a number of factors limit the performance of TT&C links above 17 GHz. 18 Rec. ITU-R S.1716 In addition, Radiocommunication Bureau (BR)
7、 Circular Letter CA/99 requested adminis-trations and Sector Members to provide technical and operational characteristics of their FSS TT&C systems. A database has been created by BR at the ITU website: http:/web.itu.ch/brsg/srg4/info/wp4b/index.html. Table 13 provides a summarized analysis of the d
8、ata gathered in response to BR Circular Letter CA/99. TABLE 13 Summary of the availability and link margins from BR Circular Letter CA/99 Link availability (%) 6/4 GHz 14/11 GHz 20 GHz Minimum Maximum Average Minimum Maximum Average Minimum Maximum Average Ranging 99.7 99.998 99.76859 94.9981 99.992
9、3 99.14992 99.42525 99.97716 99.70121Telemetry 99.7 99.999 99.80755 99.9 99.999 99.96253 Not applicable Not applicable Not applicableCommand 99.7 99.999 99.83424 99.3403 99.99874 99.89163 99.9 99.99511 99.94756Link margin (dB) 6/4 GHz 14/11 GHz 20 GHz Minimum Maximum Average Minimum Maximum Average Minimum Maximum Average Ranging 0.7 42.31633 13.07245 0.48482 30.9111 16.26529 1.306482 7.30482 4.305651Telemetry 0.5 39.45 24.40857 6 30.8 19.41385 Not applicable Not applicableNot applicableCommand 0.5 24.5 7.307692 2.38 22.2 10.97929 13.7 19.6 16.65
