1、STD*CEPT ERC REPORT 45-ENGL 1997 U 232b414 0015631 bBB ERC REPORT 45 Enropean Radioconmunications Committee (ERC) within the European Conference of Postai and Telecommunications Administrations (CEP“) .- y L, _.- ., SHARING BETWEEN THE FIXED AND EARTH EXPLORATION-SATELLITE SERVICES IN THE BAND 50.2
2、- 66 GHz (PASSIVE) Sesimbra, January 1W STDmCEPT ERC REPORT 45-ENGL 1777 D 232b414 00L5b32 51Y Copyright 1996 the Enropean Conference of Postal and Telecommunications Administrations (CEFT) ERC REPORT 45 Sharing between the Fixed and Earth Exploration-Satellite (passiw) Services in the band 50.2 . 6
3、6 GHz TABLE OF CONTENTS 1 EXECUTIVE SUMMARY 1 2 INTRODUCTION . 1 3 ALLOCATIONS 2 Use by the EESS . Why the lower slop e. 3 Current plans and insumentation, . 3 Anticipated pedormance imPnvements 5 Rationale behind the choice ofthe band 54.25 - 58.2 GHz for the Fixed Service . 6 4 SHARING PARAMETERS
4、. 6 Parameters for the passive sensors 6 3.1 3.1.1 3.1.2 3.1.3 3.1.4 3.1.5 Why microwave sounding around 60 GHzZ 2 Operations of the microwaw temperature so un de 5 3.2 4.1 4.1.1 4.1.2 4.1.3 4.1.4 Description of the principles of microwave souiiding 6 Comparison between cross-track and Conical pnshb
5、room sensors 7 Ohex sensor parametex s. 8 Interference thresh0 ld. 8 4.2 Parameters for the fixed links 8 4.3 Propagation 9 5 SHARING ANALYSIS 10 5.1 Interference through direct coup ling. 10 Calculation of critical elevation . 10 Link budget calculaia . 12 Interference by indirect propagation mecha
6、nisms . 13 6 OTHER CONSIDERATIONS . 13 Percentages of time and location . 14 pulfilment of the mandata 14 7 CONCLUSIONS . 14 5.1.1 5.1.2 5.2 6.1 6.2 Annex 1 PRELIMINARY ANALYSIS OF INDIRECT PROPAGATION MECHANISMS Interference throughrenectiOns fromroof tops . 17 Interference through scattaing from v
7、ertical surfaces . 20 Interfaence through tropospheric scattering 21 Interference ihmugh tropospheric scattg 21 A.l A.2 A.3 A.4 A.5 Interference ihmugh rain statt . 20 ERC REPORT 5 Page 1 1 EXECUTIVE SUMMARY This report presents the resuits of the study on sharing between the Fixed Service (FS) and
8、passive sensors of the Earth Exploration-Satellite (passive) Service (EESS) in the frequency band 50.2 - 66 GHz. The study has been focused on the bands 50.2 - 50.4 GHz and 54.25 - 58.2 GHz, which are allocated on a CO-primary basis in the Radio Regulations. The report gives the background on why th
9、ese two services require allocations in this part of the spectrum It also investigates the required protection criteria for the EESS and the operating requirements for the FS. The firidin%s are that sharing is possible at frequencies above 55.78 GHz. At frequencies between 54.67 - 55.78 GHz sharing
10、would be possible with varying degrees of restrictions on the PS. Below 54.67 GHz, sharing is totally impracticable within the 15 MHz bandwidth of a push-broom sensor channeL The following should be noted about these conclusions: - the calculations have been based on the need to protect cross-track
11、push-broom sensors, which are expected to be brought into service soon after 2005; the current generation of passive sensors require less skent resictions on the FS. - a number of indirect propagation mechanisms have been identified, but the impact of these could not be firmly established; the concl
12、usions are based on the impact of the direct propagation mechanism, with the preimhary assumption that the interfereace caused by other mechanisms would be accepted by the remote sensors, - fixed links are assumed to be located at an altitude of O km above sea level (asl); for areas more than 500 m
13、asl, the restrictions on the PS axe tightened further, - the protection criteria of Recommendation -R SA.1029 include a provision that the specified interference dueshold could be exceeded for up to 5% of measurement cells; since the inhpretation of this provision is unclear, SE20 could not implemen
14、t it; furthennore, the provision was found unacceptable to the EESS experts in SE20; it is recommended that IT SG 7 study this issue; sharing sides to date have assumed that the interference threshold wiii not be exceeded in any measurement cell. A further study focussing on the band 55.22 - 55.78 G
15、Hz can be found in ERC Report 46. 2 INTRODUCTION This report addresses the feasibility of sharing between the Fixed Service and the Earth Exploration-Satellite (passive) Service in the kquency range 50.2 - 66 GE. The ERC has previously published two reports on this subject ERC Report 17 on the band
16、57.2 - 58.2 GHz and WC Report 19 on the band 54.25 - 57.2 GHz. In snrmnary, the conciusions of these reports are that in the upper band sharing presents no problem, whereas in the lower band interference fmm fixed links to passive sensor satellites may occur, but these can be avoided through coordin
17、ation or restrictions on the fixed links. However, some concerns were expressed that these reports were not complete, and in order to get a Wer undersanding of the sharing conditions, the foilowing topics were identified for further study: * the reasons that these two services have to use shared ban
18、ds * the parameters assumed for the sensors * the range of parameters possible for the FS * the extent of the problem area within the band * coordination methods * the expected interference fkomin-direct propagation mechanisms * cost implications of changing the frequency for PS and EESS * satellite
19、 visibility statistics. Further detailed study of the band 55.22 - 55.78 GHz can be found in ERC Report46. STD.CEPT ERC REPORT q5-ENGL 1997 = 232b414 0015b35 223 m ERC REPORT 5 Page 2 3 3.1 3.1.1 ALLOCATIONS in the frequency range 50.2 - 66 GHz there are two sub-bands where the PS and the EESS have
20、co-primary docations in the Radio Regulations. These are: * 50.2 - 50.4 GHz * 54.25 - 58.2 GHZ CEFT Recommendation T/R 22-03 divides the band 54.25 - 58.2 GHz into two parts: 54.25 - 57.2 GHz is to be used for local connections and supporting inhsiructure for largescale mobile networks and 57.2 - 58
21、.2 GHz is intended for low-power, short-range systems. Use by the EESS Why microwave sounding around 60 GHz? 500.00 1oo.w 10.00 0 t o Q L O I 5 1.w W N 0.1c 0.01 11 II 1 1 I I II I1 I 1 III - CH. 3-14 i, CH.l I VAPOR 1 CH. 17 G OXYGEN CH: 2 40 80 120 160 200 240 280 320 FREQUENCY GHzl -/, I I I I 11
22、 I I 11 Figure 1: Zenith atmospheric opacity due to oxygen and water vapour Atmospheric temperature profiles are amongst the essential parameters which are routinely used by meteorological services for operational weather forecasting, and by the scientific communiy involved inclimate and environment
23、al monitoring studies. These appiications do not generate direct commercial return. However, they have an important impact on all economic activities, and Contribute heavily to human weh and life conservation. Atmospheric temperatwe profiles are currently obiained from spaceborne sounding instnunent
24、s working in the inhred spectrum andin themicrowave spectrum (including oxygen absorption around 60 GHz) As compared to IR techniques, theall-weather capability (the ability for a spaceborne sensor to “see“ through most clouds) is probably the most important feature that is offered by microwave tech
25、niques. STDOCEPT ERC REPORT 45-ENGL 1777 m 2326414 0015b3b 1bT m ERC REPORT 45 Page 3 This is fundamental for operational weather forecasiing and atmospheric science applications, because more than 60% of the Earths surface, on average, is totally obscured by clouds, and only 5% of any 20x20 km spot
26、 (corresponding to the typical spatial resohition of the IR sounders) is completely cloud-free. This situation severely hampers operations of IR sounders, which have very littie or no access to large, meteorologically active regions. The next 9 absorption spectrum around 118 GHz has a lower potentia
27、l due to its partinilar structure (monochromatic, as compared to the rich multi-line stmcture mund 60 GHz) and is more heavily affected by the attenuation caused by atmospheric humidity, as it is shown on Figure 1. It appears thathe 50/70 GHz band offers a unique possibility to perform aii-weather m
28、easurements of the vertical atmospheric tempture profiles from a satellites orbit 3.1.2 3.13 Why the lower slope The lower slope of the 60 GHz absorption peak is preferred over the upper slope, since the water vaponr absorption is greater on the upper slope. This results in sharper weighting functio
29、ns at the lower slope, and thus better all weather capabilities. Current plans and insrumenaion Since 1978, the Earth Exploration-Satellite Service has used sections of the 50.2 - 58.2 GHz band for passive microwave sounding of the atmosphm. These measurements are provided by thMicrowave Sounding Un
30、ir (MSU) instrument which is flown on the operational series of polar-orbiting weather satellites operated by NOAA. MSU is a 4 channel radiometer (see Table 1 for channel charactenstics) with two channels m the frequency band under discussion (at 54.76 - 55.16 GHz and 57.75 - 58.15 GHz). On the basi
31、s of experience gained with the MSU data, NOAA is going to upgrade the microwave sounding capability on its operational polar-orbiting satellites, expected in 19%. This capability wili be provided by two new instruments: the Advanced Microwave Sounding Unit - A (AMSU-A), for detexminhg atmospheric t
32、emperahire profiles, and the Advanced Microwave Sounding Unit - B (AMSU-B), for determining atmospheric water vapom profiles. Together, these two instniments have 20 microwave channels, of which 9 AMSU-A channels fall within the 54.25 - 58.2 GHz band and one in the 50.2 - 50.4 GHz band. Table 1: MSU
33、 channel characteristics The channel characteristics of these instruments are given in Tables 2 and 3 respectively. Figure 1 shows the atmospheric attenuation at microwave frequencies due to oxygen and water vapour together with the 20 AMSU channel positions Further upgrading of the microwave soundi
34、ng capability will be achieved (in the 2005 timefiame) by the addition of “stratosphexic“ channels in the frequency range 60.4 - 61.2 GHz. Such channels will increase the maximum height at which the atmosphexic temperature is retrieved from approximately 45 km to approximately 70 un This technique r
35、elies on a special interaction between the Earths magnetic field and particular Qabsqtion lines (Zeeman splitting). STDBCEPT ERC REPORT 45-ENGL 1997 232L414 0035637 OT6 m ERC REPORT 45 Page 4 Table 2: AMSU-A channel characteristics The service provided by the MSU instrument is iikely to continue unt
36、il the end of 1997. The first flight of the AMSU-A and AMSU-B instruments, on NOAA-K., is cmentiy scheduled for 1995. They will be operated continuously und about 2005. before being replaced with new impved instmments on a converged sdes of US polar satellites. Table 3: AMSU-B channel characteristic
37、s The foliowing other microwave sounding instruments must also be mentioned: - The SSMfl (Special Sensor Minowavflemperahue) has 7 channels (50.5 to 58.4 GHz), and is currently operated on the US defense meteorologicai polar satelites DMSP. - The SSMZS is a new sensor under development for the DMSP
38、series. It integrates into one unique instrument microwave channels previously distributed amongst three distinct SensorSSML (surface sensing), SSMfl (atmospheric temperature profiles), andSSML4 (atmospheric humidity profiles). in t Where: * Ts(K) is the radiometer system noise temperature, which in
39、cludes the receiver temperahm and the antenna conibutioa The antenna contribution itself is essentially th it ishigher if all pixels in a line are sampled simutaneonsly (case of a “push-broom“ type instrument). Note 2: The design of the instrument must realize a difficult trade-off behveemdiometric
40、resolution (reqniring a wide channel bandwidth), andverticai resolution (requiring a narrow channel bandwidth). On AMSU-A, this difliculty is overcome at the expense of hardware complexity in the following way: Some cheis are built with the sum of up to4 narrow-band sub-channelscarefully selected at
41、, ideallyewt identical absorption levels of the 4 spectrum., on the slopes of neighbohg absorption peaks. 4.1.2 Comparison between cross-track and conical push-broom sensors For the push-broom instrument, two configurations can be envisaged: - cross-track viewing in a piane normal to the satellite s
42、ub-track, extending I58 on each side of the nadir direction; - conical wiewing around the nadir direction, providing a constant incidence angle of about St the level of the ground, corresponding to about 4F with respect to the nadir direction at the level of the sateliite. The conical viewing instru
43、ment has advantages in the domain of data processing. However, it provides unifody degraded data due to the high (constarit) incidence angle. In addition, the swath width is limited by the geometry. The cross-track viewing instrument provides on average beter soundings and has a wider swath, thus ac
44、hieving global coverage. Therefore a cross-track viewing push-broom instrument is preferred. It is expected to develop such an instrument within about 10 years. STD*CEPT ERC REPORT 45-ENGL 1777 W 2326414 001i5b41 527 m ERC REPORT 45 Page 8 4.1.3 Interference threshold Recommendation ITU-R SA.1029 gi
45、ves interference criteria for passive remote sensing. It defines the harmful interference level at the input of the radiometer, (W), as ph = 0.2kATe B Based on the performance Criteria given in Recommendation ITU-R SA.1028 this gives the interference threshold, in the reference bandwidth 100 MHz: *
46、-161 dBW for a scanning sensor * -166 dBW for a push-broom sensor 4.1.4 Other sensor parameters A number of other parameten are needed for the sharing analysis. Typical values are given below for present and future sounders. Mechanical scanning Push-broom Interference threshold Bandwidth Integration
47、 time Antenna diameter IFOV 3dB points Cross-track width Antenna gain Side lobes Beam efficiency Radiometric resolution Swath width Pixel size (nadir) Number of pixelshe Orbit altitude (circular) Orbit inclination (sun-synchronism) Year in service -161 dBW1100 MHz 4ooMHz 0.2 c 15 cm 3.3O +I- 50“ 36
48、dBi - 1OdBi 95% 0.3 K 2300 km 49 km 30 850 km 98.8 O 1995 -166 dBW/100 MHZ 15 MHz 2.45 s 45 m l.1 +I- 50“ 45 dBi -10 dBi 95 % 0.1 K 2300 km 16 km 90 850 km 98.8 2005 It should be noted that the push-broom sensor desaibed above is not yet developed and thus the parameters described wili be subject to
49、 review and possible alteration, taking advantage in particular of the experience gained through the exploitation of AMSU-A data. 4.2 Parameters for the fixed links The important parameters for the sharing analysis are output power, antenna pattern, elevation angle, altitude and density of links. prETS 300 407 for the band 54.25 - 57.2 GHz specifies a maximum output power of 1 W and two aliemative antenna patterns: a standard pattern with 3 c) The satellite looks at every point of the earths surface at a low vertical angle fomore Ulan one
