1、 Recommendation ITU-R SA.1014-2(02/2011)Telecommunication requirementsfor manned and unmanneddeep-space researchSA SeriesSpace applications and meteorologyii Rec. ITU-R SA.1014-2 Foreword The role of the Radiocommunication Sector is to ensure the rational, equitable, efficient and economical use of
2、the radio-frequency spectrum by all radiocommunication services, including satellite services, and carry out studies without limit of frequency range on the basis of which Recommendations are adopted. The regulatory and policy functions of the Radiocommunication Sector are performed by World and Reg
3、ional Radiocommunication Conferences and Radiocommunication Assemblies supported by Study Groups. Policy on Intellectual Property Right (IPR) ITU-R policy on IPR is described in the Common Patent Policy for ITU-T/ITU-R/ISO/IEC referenced in Annex 1 of Resolution ITU-R 1. Forms to be used for the sub
4、mission of patent statements and licensing declarations by patent holders are available from http:/www.itu.int/ITU-R/go/patents/en where the Guidelines for Implementation of the Common Patent Policy for ITU-T/ITU-R/ISO/IEC and the ITU-R patent information database can also be found. Series of ITU-R
5、Recommendations (Also available online at http:/www.itu.int/publ/R-REC/en) Series Title BO Satellite delivery BR Recording for production, archival and play-out; film for television BS Broadcasting service (sound) BT Broadcasting service (television) F Fixed service M Mobile, radiodetermination, ama
6、teur and related satellite services P Radiowave propagation RA Radio astronomy RS Remote sensing systems S Fixed-satellite service SA Space applications and meteorology SF Frequency sharing and coordination between fixed-satellite and fixed service systems SM Spectrum management SNG Satellite news g
7、athering TF Time signals and frequency standards emissions V Vocabulary and related subjects Note: This ITU-R Recommendation was approved in English under the procedure detailed in Resolution ITU-R 1. Electronic Publication Geneva, 2010 ITU 2010 All rights reserved. No part of this publication may b
8、e reproduced, by any means whatsoever, without written permission of ITU. Rec. ITU-R SA.1014-2 1 RECOMMENDATION ITU-R SA.1014-2 Telecommunication requirements for manned and unmanned deep-space research (1994-2006-2011) Scope This Recommendation briefly describes some essential characteristics of de
9、ep-space telecommunications. These characteristics influence or determine the requirements for selection of candidate bands, coordination, band sharing and protection from interference. The ITU Radiocommunication Assembly, considering a) that telecommunications between the Earth and stations in deep
10、 space have unique requirements; b) that these requirements affect the selection of candidate band, band sharing, coordination, protection from interference and other regulatory and frequency management matters, recommends 1 that the requirements and characteristics described in Annex 1 for deep-spa
11、ce telecommunications should be taken into account concerning deep-space research and its interaction with other services. Annex 1 Telecommunication requirements for manned and unmanned deep-space research 1 Introduction This Annex presents some characteristics of deep-space research missions, the f
12、unctional and performance requirements for telecommunications needed to conduct deep-space research by means of spacecraft, and the technical methods and parameters of systems used in connection with such missions. Considerations regarding bandwidth characteristics and requirements are found in Repo
13、rt ITU-R SA.2177. 2 Rec. ITU-R SA.1014-2 2 Telecommunication requirements Deep-space missions require highly reliable radiocommunications over long periods of time and great distances. For example, a spacecraft mission to gather scientific information at the planet Neptune takes eight years and requ
14、ires telecommunication over a distance of 4.65 109km. The need for high e.i.r.p. and very sensitive receivers at earth stations is a result of the large radiocommunication distances involved in deep-space research. Continuous usage of deep-space radiocommunication bands is a consequence of the sever
15、al missions now in existence and others being planned. Because many deep-space missions continue for periods of several years, and because there are usually several missions in progress at the same time, there is a corresponding need for radiocommunication with several spacecraft at any given time.
16、In addition, each mission may include more than one spacecraft, so that simultaneous radiocommunication with several space stations will be necessary. Simultaneous coordinated radiocommunication between a space station and more than one earth station may also be required. 2.1 Telemetering requiremen
17、ts Telemetering is used to transmit both maintenance and scientific information from deep space. Maintenance telemetering information about the condition of the spacecraft must be received whenever needed to ensure the safety of the spacecraft and success of the mission. This requires a weather inde
18、pendent telecommunications link of sufficient capacity. This requirement is a partial determinant of the frequency bands that are preferred for deep-space research (see Report ITU-R SA.2177). Science telemetering involves the sending of data that is collected by the on-board scientific instruments.
19、The required data rate and acceptable error rate may be quite different as a function of the particular instrument and measurement. Table 1 includes typical ranges of data transmission rates for scientific and maintenance telemetering. TABLE 1 Required bit rates for deep-space research Direction and
20、 function Link characteristic Weather independent Normal High data rate Earth-to-space Telecommand (bit/s) Computer programming (kbit/s) Voice (kbit/s) Television (Mbit/s) Ranging (Mbit/s) 1-1 000 1-50 45 1-4 1 1-1 000 1-100 45 0.2-12 10 1-2 000 1-200 45 6-100 100 Space-to-Earth Maintenance telemete
21、ring (bit/s) Scientific data (kbit/s) Voice (kbit/s) Television (Mbit/s) Ranging (Mbit/s) 8-500 0.008-115 45 0.2-0.8 1 8-500 1-500 45 0.2-8 10 8-2 10540-3 10545 6-1 000 100 Rec. ITU-R SA.1014-2 3 Telemetering link capacity has steadily increased with the development of new equipment and techniques.
22、This increase can be used in two ways: to gather larger amounts of scientific data at a given planet or distance; and to permit useful missions to more distant planets. For a particular telemetering system, the maximum possible data rate is proportional to the inverse square of the radiocommunicatio
23、n distance. The same link capacity that provides for a data rate of 134 kbit/s from the vicinity of the planet Jupiter (9.3 108 km) would also provide for a data rate of 1.74 Mbit/s from the vicinity of the planet Venus (2.58 108km). Because higher data rates require wider transmission bandwidths, t
24、he ability to effectively utilize the maximum telemetering capability depends on the width of allocated bands, and the number of simultaneous mission spacecraft that are within the earth station beamwidth and are operating in the same band. An important contribution to telemetering has been the deve
25、lopment of coding methods that permit operation with a lower signal-to-noise ratio. The coded signal requires a wider transmission bandwidth. The use of coded telemetering at very high data rates may be limited by allocation width. 2.2 Telecommand requirements Reliability is the principal requiremen
26、t of a telecommand link. Commands must be received accurately and when needed. The telecommand link is typically required to have a bit error rate not greater than 1 106. Commands must be received successfully, without regard to spacecraft orientation, even when the primary high gain antenna may not
27、 be pointed to Earth. For such circumstances, reception using a nearly omnidirectional spacecraft antenna is required. Very high e.i.r.p. is needed at earth stations because of low spacecraft antenna gain, and to provide high reliability. With computers on the spacecraft, automatic sequencing and op
28、eration of spacecraft systems is largely predetermined and stored on-board for later execution. For some complicated sequences, automatic operation is a requirement. Telecommand capability is required for in-flight alteration of stored instructions, which may be needed to correct for observed variat
29、ions or malfunctions of spacecraft behaviour. This is particularly true for missions of long duration, and for those circumstances where sequencing is dependent on the results of earlier spacecraft events. For example, the commands for spacecraft trajectory correction are based on tracking measureme
30、nts and cannot be predetermined. The range of required command data rates is given in Table 1. Reliable telecommand includes the need for reliable maintenance telemetering that is used to verify that commands are correctly received and loaded into command memory. 2.3 Tracking requirements Tracking p
31、rovides information used for spacecraft navigation and for radio science studies. 2.3.1 Navigation The tracking measurements for navigation include radio-frequency Doppler shift, the round-trip propagation time of a ranging signal, and the reception of signals suitable for long baseline interferomet
32、ry. The measurements must be made with a degree of precision that satisfies navigation requirements. Measurement accuracy is affected by variations in velocity of propagation, knowledge of station location, timing precision, and electronic circuit delay in earth and space station equipment. Table 2
33、lists a current example of the requirements for navigation accuracy and the associated measurements. 4 Rec. ITU-R SA.1014-2 TABLE 2 Navigation and tracking accuracy requirements Parameter Value Navigation accuracy (m) 300 (at Jupiter) Doppler measurement accuracy (Hz) 0.0005 Range measurement accura
34、cy (m) 0.15 Accuracy of earth station location (m) 1 2.3.2 Radio science Spacecraft telecommunication links can also be important to studies of propagation, relativity, celestial mechanics and gravity. Amplitude, phase, frequency, polarization and delay measurements provide the needed information. T
35、he opportunity to make these measurements depends upon the availability of appropriate allocations. Above 1 GHz, transmission delay and Faraday rotation (charged particle and magnetic field effects) decrease rapidly with increasing frequency, and thus are best studied with the lower frequencies. The
36、 higher frequencies provide relative freedom from these effects and are more suitable for studies of relativity, gravity and celestial mechanics. For these studies, calibration of charged particle effects at the lower frequencies is also needed. Range measurements with an absolute accuracy of 1 or 2
37、 cm are required for this fundamental scientific work. This accuracy depends upon wideband codes and the simultaneous use of multiple frequencies for charged-particle calibration. 2.4 Special requirements for manned deep-space missions The functional requirements for such missions will be similar in
38、 kind to those for unmanned missions. The presence of human occupants in spacecraft will, however, place additional requirements for reliability on the telemetering, telecommand and tracking functions. Given the necessary level of reliability, the significant difference between manned and unmanned m
39、issions will be the use of voice and television links for both Earth-to-space and space-to-Earth radiocommunication. Data rates for these functions are shown in Table 1. From a telecommunication standpoint, the effect of these additional functions will be a required expansion of transmission bandwid
40、th in order to accommodate the video signals. Given the necessary link reliability and performance needed to support the required data transfer rates, telecommunications for manned and unmanned deep-space research are similar. 3 Technical characteristics 3.1 Locations and characteristics of deep-spa
41、ce earth stations Table 3 gives the locations of earth stations with the capability of operating within bands allocated for deep-space research. Rec. ITU-R SA.1014-2 5 TABLE 3 Location of deep-space earth stations Administration Location Latitude Longitude China Kashi Jiamusi 38 55 N 46 28 N 75 52 E
42、 130 26 E European Space Agency Cebreros (Spain) Malarge (Argentina) 40 27 N 35 46 S 4 22 W 69 22 W New Norcia (Australia) 31 20 S 116 11 E Germany Weilheim 47 53 N 11 04 E Ukraine Evpatoriya 45 11 N 33 11 E Russia Medvezhi ozera 55 52 N 37 57 E Ussuriisk 44 01 N 131 45 E Japan Usuda, Nagano 36 08 N
43、 138 22 E United States Canberra (Australia) 35 28 S 148 59 E Goldstone, California (United States) 35 22 N 115 51 W Madrid (Spain) 40 26 N 04 17 W At each of these locations there are one or more antennas, receivers and transmitters that can be utilized for deep-space links in one or more of the al
44、located bands. The principal parameters that characterize the maximum performance of one or more of these stations are listed in Table 4. Although these characteristics do not apply to all stations, it is nevertheless essential that band allocations and criteria for protection from interference be b
45、ased on the maximum performance available. This is required in order to provide for international operation and protection of deep-space missions. TABLE 4 Characteristics of deep-space earth stations with 70 m antennas Frequency (GHz) Antenna gain (dBi) Antenna beamwidth(degrees) Transmitterpower (d
46、BW) e.i.r.p. (dBW) Receiving system noise temperature (K) Receiving system noise power spectral density (dB(W/Hz) 2.110-2.120 Earth-to-space 62 0.14 50 56(1)112 118(1)- - 2.290-2.300 Space-to-Earth 63 0.13 - - 25(2)21(3)214(2)215(3)7.145-7.190 Earth-to-space 72 0.04 43 115 - -8.400-8.450 Space-to-Ea
47、rth 74 0.03 - - 37(2)27(3)213(2)214(3)31.832.3 Space-to-Earth 83.6(4)0.01(4)- - 83(2) (4)61(3) (4)209(2) (4)211(3) (4)34.2-34.7 Earth-to-space 84(4)0.01(4)To be determined To be determined - -(1)56 dBW transmitter power used only during spacecraft emergencies. (2)Clear weather, 30 elevation angle, d
48、uplex mode for simultaneous transmission and reception. (3)Clear weather, 30 elevation angle, receive only. (4)Estimate. 6 Rec. ITU-R SA.1014-2 The receiving performance of deep-space earth stations is usually specified in terms of the ratio of signal energy per bit-to-noise spectral density require
49、d to give a particular bit error rate. Another way to show the high performance and sensitivity of these stations is to express the ratio of antenna gain-to-noise temperature. This quotient, commonly referred to as G/T, is approximately 50 dB/(K) at 2.3 GHz, and 59.5 dB/(K) at 8.4 GHz. These values may be compared with the lower and typical 41 dB/(K) of some fixed satellite earth stations. 3.2 Space stations Spacecraft size and weight is limited by the payload capability of the launch vehicle.
