1、 STD-ITU-R RECMN S-1343-ENGL 2777 H i855212 0530732 AT2 W Rec. ITU-R S.1341 1 RECOMMENDATION ITU-R S. 1341 * SHARING BETWEEN FEEDER LINKS FOR THE MOBILE-SATELLITE SERVICE AND THE AERONAUTICAL RADIONAVIGATION SERVICE IN THE SPACE-TO-EARTH DIRECTION IN THE BAND 15.4-15.7 GHz AND THE PROTECTION OF THE
2、RADIO ASTRONOMY SERVICE IN THE BAND 15.35-15.4 GHz (Question ITU-R 242/4) (1 997) The ITU Radiocommunication Assembly, considering 4 that Resolution 1 16 (WRC-95) of the World Radiocommunication Conference (Geneva, 1995) calls for studies by the ITU-R of the sharing situation between feeder links (s
3、pace-to-Earth) for the mobile-satellite service (MSS) and the aeronautical radionavigation service in the band 15.4-15.7 GHz; b) that the band 15.4-15.7 GHz is allocated to the aeronautical radionavigation service on a primary basis and that No. 953 (S4.10) of the Radio Regulations (RR) applies; c)
4、that the WRC-95 has added an allocation to the fixed-satellite service in this band for feeder links of non-geostationary (non-GSO) networks in the MSS in the space-to-Earth direction; d) that the requirements for feeder links (space-to-Earth) of non-GSO satellite systems need to be accommodated in
5、this band; e) that emissions from satellites can cause harmful interference to stations in the aeronautical radionavigation service; 9 that power flux-density (pfd) limitations have been placed on the emissions from non-geostationary space stations to protect the aeronautical radionavigation service
6、 in accordance with No. S5.5 1 1 A of the RR, which are subject to review by the TU-R; id that the coordination of satellite emissions with aeronautical radionavigation stations is not considered practical; h) that emissions from aeronautical radionavigation stations propagated along the Earths surf
7、ace can cause unacceptable interference to feeder-link earth stations; j that methods are needed to determine the coordination and separation distances required between feeder-link earth stations and aeronautical radionavigation stations in order to protect the feeder-link earth stations; k) that ai
8、rcraft stations are not permitted to transmit in the band 15.45-15.65 GHz in accordance with No. S5.5 1 1 B of the RR; 1) that there is fairly extensive use of this band by the aeronautical radionavigation service for airborne, land and ocean based stations; m) that the technical and operational cha
9、racteristics of the aeronautical radionavigation stations are reasonable well defined; n 0) angles; Pl that the technical and operational characteristics of feeder links are not well defined; that satellite systems in this frequency range usually do not operate with low earth station antenna elevati
10、on that studies have been made with respect to 9 o; * This Recommendation should be brought to the attention of Iiadiocoiumunication Study Groups 7 and 8. STD-ITU-R RECMN S-33qI-ENGL 1997 4855232 0530933 739 H 2 Rec. ITU-R S.1341 s) that the adjacent band 15.35-15.4 GHz is allocated to the radio ast
11、ronomy service and other passive services and that protection from harmful interference due to emissions from space stations is needed (see No. S5.511A of the RR); r) provided for in No. S5.341; that all emissions are prohibited in the band 15.35-15.4 GHz in accordance with No. S5.340 except those s
12、) astronomy service, that Recommendation ITU-R RA.769 provides threshold levels of detrimental interference for the radio recommends I that feeder links for the MSS should be limited to the band 15.43-15.63 GHz (Note i); 2 that provisionally the pfd at the Earths surface produced by emissions from t
13、he feeder links of a space system of non-GSO satellites for all conditions and for all methods of modulation should not exceed the values given in 2.1 under the condition given in 3 2.2 (Note 2); 2.1 plane: in the frequency band 15.43-15.63 GHz, where cp is the angle of arrival (degrees) above the l
14、ocal horizontal - 127 dB(Wm2)inlMHz for O I cp 20 - 127 + 0.56(cp - 20)2 dB(W/rn2)inlMHz for 20 I cp 25 -113 dB(W/m2)inlMHz for 25 I cp 29 -136.9 + 25 10g(q - 20) dB(WIm2) in 1 MHz for 29 I cp 31 -111 dB(W/iii2) in 1 MHz for 31 I cp I 90 2.2 3 aeronautical radionavigation service is not required; th
15、at these limits relate to the pfd which would be obtained under assumed free-space propagation conditions; that with the pfd limits given in recommends 2 coordination of satellite emissions with receiving stations in the 4 that surface based radars as described in Annex 1 should not operate in the b
16、and 15.43-15.63 GHz; 5 that the threshold distance for the coordination of emissions from stations in the aeronautical radionavigation service with respect to feeder-link earth stations for the MSS based on an earth station antenna gain in the local horizontal plane of 1 1.5 dBi are: - . 150 km from
17、 the ground segment for aircraft landing system (ALS); - - 6 least 5“: 600 km from aircraft using general purpose radars; 60 km from the aircraft landing surface for radar sensing and measurement systems; that feeder-link earth stations should limit their operation to angles above the local horizont
18、al plane of at 7 that emissions from the feeder links of a space system of non-GSO satellites for all conditions and all methods of modulation should take into account the threshold levels for the radio astronomy service given in Recommendation ITU-R RA.769 for the band 15.35-15.4 GHz (see Note 3);
19、8 NOTE 1 - The bandwidth given in recommends 1 is smaller than that allocated by WRC-95 for non-GSO MSS feeder links. This difference is recommended to facilitate sharing between the non-GSO MSS feeder links and the aeronautical radionavigation service. Recommends 1 will be reviewed at a later date
20、in accordance with the outcome of a future WRC. NOTE 2 - The feasibility to design and operate feeder links in the space-to-Earth direction with the provisional pfd limits given in recommends 2.1 has not yet been studied. Further, the provisional pfd values given in recommends 2.1 should be reviewed
21、 to ensure protection to the ARNS. NOTE 3 - Additional design and operational constraints may be placed on MSS space-to-Earth feeder links in order to take into account the threshold levels for the radio astronomy service given in ITU-R RA.769 per recommends 7. that additional information is contain
22、ed in Annexes 1,2, and 3. STD-ITU-R RECNN S-LI4L-ENGL 1977 9 4855212 0530714 b75 3 Rec. ITU-R S.1341 G(cp) = ANNEX 1 43 dBi for O I cp 4 43 - 5(cp - 4) dBi for 4 I cp 9 18 dBi for 9 I cp 16 43.2 - 21 10gq dBi for 16 I cp 48 8 dBi for 48 I cp 5 90 Aeronautical radionavigation systems in the 15.4-15.7
23、 GHz band 1 Surface based radars (SBR) The land and ship based SBR are used for the detection, location, and movement of aircraft and other vehicles on the surface of airports and other aircraft landing areas. 1.1 Antenna patterns - Nominal 3 dB beamwidth: 3.5“ vertical, inverted cosecant to -31“ 0.
24、35“ horizontal; - Frequency range: 15.65-16.7 GHz; - Polarization: circular; - Typical gain: 43 dBi; - - Maximum side-lobe level: 25 dB below peak gain; Maximum back-lobe level: 35 dB below peak gain; - Vertical tilt range: f 1.5“; I - Maximum horizontal scan range: 360“ 1.1.1 Antenna elevation enve
25、lope pattern Based on measured data and side-lobe level specifications and with the peak gain directed at +IS“, an elevation envelope gain pattern is defined as follows where cp is the elevation angle (degrees): 1.1.2 Antenna azimuth envelope pattern Based on measured data and side-lobe level specif
26、ications, the azimuth gain pattern is defined as follows where cp is the relative azimuth angle (degrees): 143 - 11ocp2 dBi for 0 I cp 0.4767 dBi for 0.4767 I cp 0.72 17.07 - 6.5 log p dBi for 0.72 I cp 48 = dBi for 48 I cp I 180 1.2 Other characteristics 1.2.1 Transmitting - Peak e.i.r.p.: 86 dBW -
27、 - Pulse duration: 0.04 ps - Pulse repetition frequency: 8 192 Hz Pulse 3.5 dB bandwidth: 25 MHz. 4 Rec. ITU-R S.1341 1.2.2 Receiving - - Typical antenna gain: 43 dBi Typical noise figure: 6.2-6.9 dB. 2 Aircraft landing systems (ALS) These ALS are general purpose systems and are used on ships, as po
28、rtable or permanent land based systems and for shuttle landings. The microwave scanning beam landing system (MSBLS) is one such system. Some of the characteristics vary with the particular applications. 2.1 The antenna patterns are similar for all applications including the MSBLS. The scanning range
29、s vary with application. The scanning ranges given below cover all applications. Surface based station antenna patterns The antenna complement of the ALS consists of an elevation antenna and an azimuth antenna. The elevation antenna portion of the ALS is used to transmit vertical angle data to the a
30、ircraft. - Nominal 3 dB beamwidths: i .3“ vertical 40“ horizontal - frequency range: 15.4-15.7 GHz - polarization: horizontal and vertical - typical gain: 28 dBi - - maximum side-lobe level: 17 dB below peak gain in both planes maximum vertical scan range: O“ to 30“. The azimuth antenna portion of t
31、he ALS is used to transmit azimuth information to the aircraft: - Nominal 3 dB beamwidths: 2.0“ horizontal 6.5“ vertical - - - polarization: horizontal and vertical - typical gain: 33 dBi - - the vertical pattern is spoiled to achieve at least a 20 dBi gain at 20 degrees above the horizon frequency
32、range: 1 5.4- i 5.7 GHz maximum side-lobe level: 17 dB below peak gain in both planes maximum horizontal scan range: k 35“. 2.1.1 Combined antenna elevation envelope pattern A combined vertical envelope gain pattern based on measured data is defined as follows where cp is the elevation angle (degree
33、s): dBi for O I cp 8 dBi for 8 I cp 14 r3 33 - 0.833(9 - 8) dBi for 14 I cp 32 dBi for 32 I cp 34 dBi for 34 I cp 40 dBi for 40 I (p I 90 1: - 0.2(cp - 40) STD-ITU-R RECMN S-Ll4L-ENGL 3777 4855212 0530736 448 Rec. ITU-R S.1341 5 2.1.2 Azimuth antenna patterns The azimuth envelope pattern of the elev
34、ation antenna is defined as follows where p is the relative azimuth angle (degrees): 28 - 0.0062p2 dBi for O I cp 70 - 2.37 dBi for 70 I cp I 180 G(cp) = The azimuth envelope pattern of the azimuth antenna is defined as follows where cp is the relative azimuth angle (degrees): 133 - 2q2 dBi for O I
35、cp 3 dBi for 3 5 p 5 dBi for 5 I cp 48 Iii.5 - 25 logcp Wcp) = I- 9.53 dBi for 48 I cp I 180 2.2 Other characteristics 2.2.1 Transmitting - Peak e.i.r.p.: 71 dBW - - Pulse duration: 0.333 ps - Pulse repetition frequency: 3 334 Hz Pulse 3.5 dB bandwidth: 3 MHz. 2.2.2 Receiving - - Typical antenna gai
36、n: 8 dBi Typical noise figure: 8 dB. 3 Aircraft multipurpose radars (MPR) The aircraft MPR is a radionavigation, radiolocation and weather radar. 3.1 Antenna patterns The antenna is a parabola of approximately 0.3 m diameter which is scanned vertically and horizontally with respect to the heading an
37、d attitude of the aircraft: - - - polarization: vertical - typical gain: 30 dBi - - The envelope pattern of the antenna is defined as follows where cp is the relative azimuth angle (degrees): nominal 3 dB beamwidth: 4.5“ frequency range: 15.4- 15.7 GHz maximum horizontal scan range I45“ maximum vert
38、ical scan range f 20“. - STD*ITU-R RECMN S-13LiL-ENGL 3777 W Li855212 0530737 38Li W 6 Rec. ITU-R S.1341 3.2 Other characteristics 3.2.1 Transmitting - Peak e.i.r.p.: 70 dBW - Pulse repetition frequency: 800 Hz - Pulse duration: 2 ps - Pulse 3.5 dB bandwidth: 0.5 MHz. 3.2.2 Receiving - - Typical ant
39、enna gain: 30 dB Typical noise figure: 8 dB. 4 Radar sensing and measurement system (RSMS) Measurement techniques using radar technology at 15 GHz are particularly suited to smaller aircraft, including helicopters, offering the benefits of compact, light, equipment with good antenna directivity and
40、more than adequate performance for many operational radionavigation applications which are not practicable at lower frequencies due to propagation or other reasons. For use in a height measurement mode this higher frequency band confers system design benefits, such as lower cross coupling and absenc
41、e of triangulation effects, which are particularly important for accurate measurement at very low (metric) separations. For some operational applications they present the only viable technical solution. Systems using these techniques are widely used in certain parts of the world where they make an i
42、mportant contribution to the safety of aircraft operation. Measurement of height, and ground clearance, is one of the most critical parameters in the operation of aircraft when used to assist the final stages in a landing. High accuracy and interference free operation are vital to success and the en
43、hancement of safety. RSMS are essentially used in low level operations up to a nominal height of around 1 500 in. An antenna mounting which transmits and receives vertically downwards would be used in the great majority of applications. Power reduction proportional to height above terrain is employe
44、d to reduce scatter, and other undesirable effects. 4.1 RSMS characteristics 4.1.1 Transmitter - Frequency range: 15.63-15.65 GHz - Peak power: 30 dBmw - Antenna gain: 13 dBi, back lobes 4 dBi - PRF158kHz - - Duty cycle (max.): 3% - Pulse length (max.): 500 ns Pulse 3.5 dB bandwidth: 2 MHz. 4.1.2 Re
45、ceiver - Antenna gain: 13 dBi, back lobes 5 dBi - Noise figure: 6 dB. STD.ITU-R RECMN S-L3LiL-ENGL 3777 Li855212 0530738 230 M Rec. ITU-R S.1341 7 ANNEX 2 Protection criteria for the aeronautical radionavigation service and sharing feasibility with feeder links for the MSS (space-to-Earth) in the 15
46、.4-15.7 GHz band and protection of the radio astronomy service in the band 15.35-15.4 GHz (Surface based radars (SBR), used on land and ships for the detecting, location and movement of aircraft and other vehicles on aircraft landing areas) 1 Characteristics of aeronautical radionavigation systems S
47、everal systems are identified that operate in this band. These include land and ship based surface detection radars (SBR), ALS, MPR, and RSMS. The antenna patterns of these systems are an important element in determining the pfd as a function of elevation angle. Antenna envelope gain patterns and th
48、e other pertinent characteristics are given in Annex i. 2 Analyses 2.1 Worst case pfd limits The general expression for the calculation of a pfd limit for this case is: pfd 5-217.6 + 10l0gB - 2Ol0gL - GIT + IIN dB(W/in2) in B where: B: bandwidth (Hz) h : wave length (in) GIT: antenna gain/noise temp
49、erature (dB) IlN: allowable interferencehoke (dB) Since these systems operate in the ARNS and are considered as Safety Service systems, the protection requirements may be more severe than for other services. Assuming an IIN limit of -10 dB, the solution of equation (1) for the SBR parameters given in Annex 1 results in a pfd limit of -146 dB(W/m2) in 1 MHz. Solution of equation (I) for the systems parameters given in Annex 1 results in a pfd limit of -i 11 dB(W/m2) in i MHz for the ALS and RSMS, and -133 dB(W/m2) in I MHz for the MPR. These values are based on the maximum antenna gain
