CRAF Newsletter 2000/1

CRAF Newsletter 2000/1

April 2000

The European Science Foundation is an association of its 67 member research councils and academies in 23 countries. The ESF brings European scientists together to work on topics of common concern, to co-ordinate the use of expensive facilities, and to discover and define new endeavors that will benefit from a co-operative approach
The scientific work sponsored by ESF includes basic research in the natural sciences, the medical and biosciences, the humanities and the social sciences.
The ESF links scholarship and research supported by its members and adds value by cooperation across national frontiers. Through its function as coordinator, and also by holding workshops and conferences and by enabling researchers to visit and study in laboratories throughout Europe, the ESF works for the advancement of European science.

On behalf of European radio astronomers, the ESF Committee on Radio Astronomy Frequencies, CRAF, coordinates activities to keep the frequency bands used by radio astronomers free from interference.


1. Editorial

WRC-2000 is a major event for radio astronomy. We have interests in many of the agenda items, and the way the voting goes could be crucial for our future. This special edition of the CRAF Newsletter is devoted to radio astronomy issues at WRC-2000.

Arguably the most important issue for radio astronomy as a whole is agenda item 1.16, `to consider allocation of frequency bands above 71 GHz to the earth exploration satellite (passive) and radio astronomy services ... '. The last frequency allocations to radio astronomy at millimetre wavelengths were made in 1979, when mm-wave astronomy was still in its infancy. WRC-2000 gives us an important opportunity to obtain new mm-wave allocations at a time when the mm-wave spectrum is still largely unused for commercial purposes and the airwaves are clear. We need to get the right protection to ensure the success of the next generation instruments such ALMA, the Atacoma Large Millimetre Array, which is under construction in Chile.

Also on the agenda for WRC-2000 are proposals for new frequency allocations for satellite downlinks adjacent to radio astronomy frequency bands. Satellite transmitters can be a big problem for radio astronomy, as there is no way for us to avoid them: we are looking up and they are transmitting down. No matter how carefully we site our radio telescopes, there is no escape from satellites. Just a few satellites can block out cosmic signals so that none of the world's radio telescopes can receive them. The WRC has a responsibility to take great care in allocating frequencies for satellite downlinks as far as possible from radio astronomy frequency bands.

To make matters worse, unwanted signals from satellites can spill into the supposedly quiet frequency bands in which we are trying to operate. This is the radio equivalent of pollution. The WRC-2000 will consider, for the first time, placing internationally agreed limits to the amount of unwanted emissions from satellites. The limits proposed do not guarantee the full protection we need, but they represent the first step towards protecting the scientific use of radio against the ever-growing flotillas of telecommunications satellites.

Let us hope for a good outcome from WRC-2000 on all these issues.

R. J. Cohen
Jodrell Bank Observatory

2. Introduction to the European Science Foundation

The European Science Foundation (ESF) acts as a catalyst for the development of science by bringing together leading scientists and funding agencies to debate, plan and implement pan-European scientific and science policy initiatives.

ESF is the European association of 67 major national funding agencies devoted to scientific research in 23 countries. It represents all scientific disciplines: physical and engineering sciences, life and environmental sciences, medical sciences, humanities and social sciences. The Foundation assists its Member Organisations in two main ways: by bringing scientists together in its scientific programmes, networks, exploratory workshops and European research conferences, to work on topics of common concern; and through the joint study of issues of strategic importance in European science policy.

It maintains close relations with other scientific institutions within and outside Europe. By its activities, the ESF adds value by cooperation and coordination across national frontiers and endeavours, offers expert scientific advice on strategic issues, and provides the European forum for science.

3. Introduction to CRAF

The science of radio astronomy plays a key role in increasing our understanding of the environment and the universe in which we live. Radio astronomy is a passive service, so it never causes interference to other users of radio. Unfortunately it is becoming increasingly difficult to protect radio astronomy observatories from man-made interference, as use of the radio spectrum increases on Earth and in space.

On behalf of European radio astronomers, the Committee on Radio Astronomy Frequencies of the European Science Foundation (CRAF) does its best to keep the frequency bands used by radio astronomers free from interference.

It works towards this aim by:

The Committee acts also to help EISCAT - the European Incoherent Scatter Scientific Association - whose expensive radar equipment and important passive experiment in the polar ionosphere faces similar severe interference problems.

The members of CRAF are appointed by the ESF Executive Council for a three year period, after consultation through the appropriate channels. They are drawn among experts active in the field of frequency management at radio-astronomical observatories in Europe complemented by ESF representatives.

4. European radio astronomy

Radio astronomy is an active science in Europe. The following table lists the European countries in which radio astronomy stations are operating and the number of stations involved. All these countries also participate actively in the work of CRAF.

countrynumber of RAS stationskey frequency interestsWRC-2000 impact
Austria1decameter researchagenda item 1.2
Belgium1<1 GHzagenda items 1.2, 1.11
Czechia10.8 - 5 GHzagenda items 1.2, 1.6, 1.11, 1.15.1
Finland1>~20 GHzagenda items 1.2, 1.4, 1.16
France3allagenda items 1.2, 1.4, 1.5, 1.11, 1.15.1, 1.16
Germany3>0.4- ~100 GHzagenda items 1.2, 1.4, 1.5, 1.11, 1.14, 1.15.1, 1.16
Greece1<1 GHzagenda items 1.2, 1.11
Hungary11 - 1.5 GHzagenda items 1.2, 1.15
Italy40.3 - 44 GHzagenda items 1.2, 1.4, 1.5, 1.11, 1.14, 1.15.1
Latvia1agenda item 1.2
Netherlands20.2 - 8 GHzagenda items 1.2, 1.6, 1.11, 1.15.1
Poland20.1 - 7 GHzagenda items 1.2, 1.11, 1.15.1
Portugal10.1 - 0.7 GHzagenda items 1.2, 1.11
Russia141.6 - 23 GHzagenda items 1.2, 1.6, 1.14, 1.15.1
Spain31.6 - 275 GHzagenda items 1.2, 1.4, 1.5, 1.6, 1.15.1, 1.16
Sweden11.3 - 116 GHzagenda items 1.2, 1.4, 1.5, 1.6, 1.14, 1.15.1, 1.16
Switzerland10.1 - 4 GHzagenda items 1.2, 1.6, 1.11
Turkey186 - 116 GHzagenda items 1.2, 1.16
Ukraine7agenda item 1.2
United Kingdom60.04 - 44 GHzagenda items 1.2, 1.4, 1.5, 1.6, 1.11, 1.14, 1.15.1

Europe also participates in radio astronomy stations in Region 2, including on Hawaii, Chile, USA. These stations operate at mm-wave and submmm-wave frequencies.

The European Incoherent Scatter Facility (EISCAT) operates 4 stations in northern Scandinavia at frequencies 0.2 - 0.9 GHz.

5. WRC agenda items relevant for radio astronomy

The agenda for WRC-2000 contains 15 items of concern to radio astronomy. The most important are:

6. ITU-R Working Party 7D

The discussions in Working Party 7D of ITU-R concentrated mainly on the "Preliminary Draft New Recommendation" (PDNR) on x% of permissible data loss, a new 5 GHz allocation for the Radio Navigation-Satellite Service, RNSS, allocations above 71 GHz and the EPFD (Equivalent Power Flux Density) proposal coming in a liaison statement from TG1/5 and in a French contribution.

The work of WP7D was divided into the topics:

  • 1. The x% PDNR
  • 2. TG1/5 issues
  • 3. EPFD methodology for which drafting groups were formed.

    The proposed allocations above 71 GHz were also discussed. The difference between the existing proposals to WRC-2000 from different ITU-R regions are minor and did not cause a strong effort, at that stage, to perfectly align them before the conference. The main difference is the wish of Australia and Korea to protect SiO line frequencies around 130 and 170 GHz a bit better than the CEPT and CITEL proposals.

    CRAF had prepared an input document on the x% issue, which appeared long to be the only sensible input. The meeting was informed, however, that an agreed text had been developed and adopted in the US also. This text was acceptable to almost all of us, as it was also very similar to the CRAF text. All three recommends started: "that administrations use...", and this had been the formulation, which had made it acceptable to the some administrations, who had wanted to avoid the word "coordination".
    As expected, the x% PDNR was given highest priority and consumed most of the time of WP7D.
    At the end of the week, WP7D approved the PDNR, which now recommends:

    1. That, for evaluation of interference, a criterion of five percent be used for the aggregate data loss to the RAS due to interference from all networks, in any frequency band allocated to the RAS on a primary basis, noting that further studies of the apportionment between different networks are required;
    2. That, for evaluation of interference, a criterion of two percent be used for data loss to the RAS due to interference from any one network, in any frequency band which is allocated to the RAS on a primary basis; and
    3. That the percentage of data loss, in frequency bands allocated to the RAS on a primary basis be determined as the percentage of integration periods of 2000 seconds in which the average spectral power flux density at the radio telescope exceeds the levels defined in Recommendation ITU-R RA.769. The effect of interference that is periodic n time scales of the order of seconds or less, such as radar pulses, requires further study.

    Work on this new recommendation had started on request, from mobile satellite services, to adapt the protection requirements of radio astronomy to the changing environment of moving terrestrial transmitters, which are switched on or off randomly. During the course of the work, the environment changed again, and WP7D was asked, by Task Group 1/5 (Unwanted Emissions), to include moving satellite transmitters, so-called LEOs (low earth orbiting satellites) into our work. These, however, are switched on and transmit, and only under rare circumstances are switched off and deorbited. But they move relative to the observing direction of a radio telescope, and the power they deliver into the receiver varies with the relative gain of the antenna in their direction. To take the dynamic nature of this interference scenario into better account, the EPFD methodology has been developed for the case of big Earth stations pointing at satellites in geo-synchronous orbit. Its applicability to radio telescopes was also studied by WP7D.

    The EPFD concept takes all sources of interference, e.g. all satellites of a LEO constellation above the horizon and calculates the effect as if they all were one source in the main beam of the radio telescope. So, in a statistical manner, this methodology takes the high gain of the antenna main beam into consideration, but in turn wants to take advantage of the low gain between antenna pattern side-lobes. This concept needs careful evaluation, and the text of a working document, which was drafted by WP7D, dealing with the EPFD concept, is very preliminary and still contains some misunderstandings, to say the least.

    Last but not least, the 5 GHz RNSS proposal appeared in a new light. Germany had submitted a paper, which presents the proposal for a 5 GHz GPS-like satellite system. The paper mainly describes a filter, designed to protect radio astronomy in the band 4990-5000 MHz. WP7D (Radio Astronomy) almost unanimously decided not to consider the sensitivity of radio astronomy receivers in the neighbouring band, which is to be filled with strong signals coming from the sky, and the EPFD proponents openly voiced their conviction that their methodology will prove that filtering at the satellite is not at all required! Still, the liaison statement to TG1/5 and WP4A asks for consideration of the filter technique also for other applications. (One other application of such a filter, which has been proposed to us unofficially, is protection of our receiver from the transmitter in the neighbouring band. If this means that we need to provide an internal guard band, and this guard band would need to be as wide as the guard band that RNSS finds necessary, than: Good bye, radio astronomy; the guard band is 10 MHz, just as much as our primary allocation!).

    Given the shortage of time and the priority given to the x% PDNR and EPFD discussions, work on TG1/5 issues was kept for the next meeting of WP7D, which is scheduled for August 2000. TG1/5 meets in October 2000. Only three liaison statements were sent to TG1/5, one of which brings our work on the EPFD concept to their attention.

    Klaus Ruf
    Max-Planck Institut für Radioastronomie

    7. ITU-R Task Group 1/5

    The sixth and penultimate meeting of TG1/5 was held in Bangalore, India, from 6-14th January 2000. This was the first ITU meeting of the new millennium, and it was marked by lavish hospitality more in keeping with a WRC. The meeting began with an address from our host, Chairman K. Kasturirangan of the Indian Space Research Organisation (ISRO), who emphasised the need to use the radio spectrum judiciously and efficiently. "While one recognises the pressure for more spectrum for purely commercial applications, the scientific spectrum requirements are equally important," he said.

    The meeting was attended by over 80 delegates, representing 10 countries and 13 sector members (including CRAF and IUCAF). Radio astronomy had 5 delegates from India, and one delegate from each of Germany, Japan, Netherlands, UK and USA. The radio astronomy issues were dealt with by Drafting Group 6, chaired by Willem Baan. DG6 also considered other passive services, and the safety services.

    The Preliminary Draft New Recommendation (PDNR) on protection of safety services from unwanted emissions was improved. Unfortunately no representatives of the safety services were able to participate. This has been a recurring difficulty throughout the life of TG1/5.

    The PDNR on protection of passive services from unwanted emissions was greatly improved. The work was done in two ad hoc drafting groups. Adhoc-1 chaired by Jim Cohen (UK and CRAF) worked on the main body of the PDNR and Annexes 1-3, and Adhoc-2 chaired by S. Sayeenathan (ISRO) dealt with the band-by-band studies in Annex 4. Three representatives of the satellite services participated in the work of the drafting groups, ensuring that the discussions were lively and sometimes heated. The friction proved to be fruitful on this occasion, and although we did not produce a pearl, the PDNR was substantially improved by the end of the meeting.

    One of the interesting new issues to emerge at the Bangalore meeting was the question of compliance. Supposing that limits on unwanted emissions from spacecraft were to be set as low as radio astronomers would like them, how would the satellites be tested before launch? It appears that current procedures are totally inadequate to check the out-of-band performance of satellites. Satellite manufacturers are unlikely to embrace emissions checks willingly, so pressure from governments will probably be needed (as for chemical pollution issues).

    Despite the good progress made in Bangalore, I am concerned at the state of the band-by-studies. After nearly five years we (TG1/3 and now TG1/5) are still awaiting information from the relevant ITU-R working parties on the practicable levels of unwanted emissions from satellites into passive bands. In the absence of this information it has been impossible to complete the studies or to agree on strong recommendations. The current PDNR on passive services says only that unwanted emission limits may be used in certain frequency bands. It cannot give numbers if none have been supplied by the working groups. One might question how such a weak recommendation could protect passive service from unwanted emissions. Some of these concerns were shared by several administrations, who asked for a short statement to be inserted to the Chairman's Report on the Sixth Meeting.

    The seventh and final meeting of TG1/5 is scheduled to be held in Geneva on 23rd-31st October 2000.

    R. J. Cohen
    Jodrell Bank Observatory

    8. Radio Astronomy and space systems

    The most serious interference to radio astronomy comes from the increasing number of satellite networks encircling the Earth. Satellite systems are global (or at least regional) in their coverage, hence no terrestrial radio telescope is safe from them, however remotely and carefully sited. The signals from satellites completely overpower cosmic signals, not only in the frequency band used intentionally by the satellite, but often in nearby frequency bands. The Russian global navigation satellite system GLONASS served as a prime warning of these dangers.

    A single GLONASS satellite has a flux density of about 107 Jy, so strong that it interferes with radio astronomy measurements of the OH 1612 MHz line whenever the satellite is above the horizon. In fact not only the navigation signal but also the unwanted sideband emission causes interference. The problem is still in the process of being cured, by a shift of the GLONASS frequencies away from the radio astronomy allocation, and by outfitting new generation satellites with filters.

    IRIDIUM was the first to come and the first to go of a new generation of mobile communication satellite networks, employing a flotilla of 66 satellites in low-Earth orbit to provide mobile communications between any two points on the planet. Unfortunately, the frequency band used for the downlink transmissions is close to the same OH 1612 MHz line that until recently has been obliterated by GLONASS. Furthermore, the power flux density on the Earth's surface from Iridium satellites was thousand times stronger than that from GLONASS. It was early recognized that unwanted emissions from the satellites would be a problem. In fact, because of non-linearities in the output amplifier of an Iridium satellite, the level of the unwanted emissions rose according to the number of callers the satellite was serving. Fortunately, Iridium never made it to critical traffic densities.

    The GDL-6/ASTRA-1D satellite operating at a frequency of 10.714 GHz make radioastronomical observations impossible in the geographical area, which is served by the ASTRA TV satellite system, because of out-of-band emissions into the radio astronomy band 10.6-10.7 GHz, the upper part of which, 10.68-10.7 GHz, is passive exclusively ("all emissions are prohibited"). The operator, SES of Luxembourg was informed about this harmful interference, which is shown to be up to 30 dB above the levels of detrimental interference to radio astronomy. ASTRA being commercially successful, there is no perspective that the problem will be solved before the (geostationary) satellite will be replaced.

    At present, ITU does not set any limit on the unwanted emissions from satellites. The first such limits are now proposed for incorporation into the Radio Regulations at WRC-2000. The limits which are proposed do not give radio astronomy the full protection which we would like, but they are a step in the right direction and far better than no limits at all. All users of the radio spectrum ultimately benefit from reduction in radio pollution.

    Also on the agenda for WRC-2000 are proposals for new frequency allocations for satellite downlinks close to radio astronomy bands. Radioastronomers have been lobbying their national administrations to vote against these. Ironically, the examples of GLONASS and Iridium make our case more persuasive. New frequency allocations will also be considered for services using high-altitude platforms. These stratospheric balloons could give radio astronomy similar problems to satellites, unless care is taken in the allocation of frequencies.

    9. Use of microwave techniques for passive remote sensing of the terrestrial atmosphere

    Monitoring terrestrial chemical constituents is essential in the upper part of the atmosphere corresponding to the stratosphere and the mesosphere. At these altitudes higher than 20 km, ozone molecules play an important role by absorbing the ultraviolet (UV) radiation of the sun which is harmful to mankind, flora and fauna, and in general to any terrestrial life if the intensity of the radiation reaching the ground is strong. For more than 50 years, man has imprudently used chloro-fluoro-carbons (freons) which go up into the stratosphere where they are destroyed by UV radiation, freeing large quantities of chlorine monoxide, the most dangerous destroyer of ozone molecules.

    Ground-based microwave sensors have been operational for a long time to survey some key components of the atmosphere. The rapid evolution of technology allows us to improve their performances by the development of new instrumentation. Microwave receivers use heterodyne techniques and are cooled down to 20 K or 4 K in order to reduce receiver temperature and improve the detectability of the stratospheric signal.

    The microwave remote sensing technique involves making high spectral resolution measurements of optically thin pure rotational lines in atmospheric emission. The lines are generally pressure-broadened in the middle atmosphere, allowing information about the vertical profile to be deduced from measurements of the shape of the spectral line. Because the measurements are made in emission, observations can be carried out both day and night, and diurnal time evolution can thus be retrieved.

    In 1989, under the aegis of the World Meteorological Organisation, a Network for the Detection of Stratospheric Change (NDSC) was set up in Geneva. NDSC has 6 primary stations located in the Arctic, at European middle latitudes, at tropical north and south, middle south latitudes and in the Antarctica, and as a large number of complementary stations dispersed around the world. In the primary stations and in some complementary ones, ground-based microwave radiometers are permanently operational to measure ozone, chlorine monoxide, water vapour, nitric acid, carbon monoxide and some other minor constituents.

    The main used frequencies used for these ground-based microwave instruments are 22.235 GHz for water vapour, 111, 142 and 208 GHz for ozone, 204 and 278 GHz for chlorine monoxide, and 115 and 230 GHz for carbon monoxide.

    The retrieval of the constituent profile requires to use a " forward model " code which computes synthetic theoretical spectra based on an a priori profile of the considered molecule, followed by an " inversion " code which uses in most cases the Optimal Estimation Method proposed by C. Rodgers.

    Obtained data are also validated by using measurements obtained by different techniques at the same site or satellite data measured in time coincidence over the ground-based site. Then validated data are stored in two databases located, one at NASA, the second one at NILU (Norwegian Institute for Air Research) at Kjeller, Norway.

    Consequently, researchers using microwave techniques for passive remote sensing of the middle atmosphere share the same concerns as astronomers for the protection of the frequencies they are using.

    Jerome de La Noe
    Observatoire de Bordeaux

    10. In memoriam Jean-Claude Sémiond

    Jean-Claude Sémiond started his carreer at the Paris Observatory in 1965 within the framework of a campaign to investigate possible observatory sites, which in particular led to the selection of the CFH telescope site on Hawaii and the development of the Calern observatory. Until 1972 he performed numerous observing missions at the high-altitde sites that were installed following this site-research. He started the station of Gondrand near Briancon and subsequently he participated in observing programes at the Corsican station of Tozzarella, in that of the sierra de Gador in southern Spain and in the Californian-Mexican area. We owe him the creation of the infrared observatory of Saint Veran.

    From 1973, Jean-Claude Sémiond participated in the project group of the first research airplane for atmospheric research in which he was in charge of the development of on-board instrumentation. We owe him much for the success of this first airplane, the precursor of what have become the French national research planes.

    Jean-Claude Sémiond participated in numerous measurement on-board campaigns in France and Europe.

    In 1977, Jean-Claude Semiond took the task to develop an outer atmosphere research site built near the village of Villeau in Beauce. This reference site became a supporting facility for numerous experiments in the field of atmospheric physics until 1988 for the benefit of a large number of laboratories and research programs.

    It was also in 1977 that Jean-Claude Semiond took charge of the construction of the Division Technique and from then, for more than 20 years, he was involved with Gerard Calvet in all real estate programs of the INAG and subsequently of the Institut National des Sciences de l'Univers, INSU. Among their most important realisations must one count the constructions of the Calvern observatory, the cable car system of the plateau Bure and the construction of the observatory of Toulouse.

    In the very difficult real estate dossier of the solar telescope THEMIS on Tenerife, it was undeniably thanks to the combination of the complementary competencies of Jean-Claude Sémiond and of Gerard Calvet that the operation could be realised with success.

    As another complex of operations, it was again Jean-Claude Sémiond who from 1995 to 1997 directed the renovation of the cryogenic rooms of the LGGE of Grenoble which he brought to a good end. During the same period his great organisational experience contributed largely to the construction of the two showcase research vessels of the INSU, the TETHYS II and the COTES DE LA MANCHE.

    Very recently, circumstances provided an opportunity for Jean-Claude Sémiond to take the task of defending the interests of radio astronomy for the protection of frequency bands for observations. He represented the Minister for Scientific Research at the Agence Nationale des Fréquences where it is activities were greatly appreciated.

    Jean-Claude partcipated very actively in the negotiations of CRAF with Iridium LLC and Motorola Inc to achieve adequate protection of radio astronomy at 1.6 GHz by means of the best possible agreements (Newsletter 1999-2). His presence and contributions were essential to bringing this arduous task to a successful completion.

    Finally after the accident with the cable car of Bure in July 1999, he and Gerard Calvet were asked to take again the very complex dossier to bring the installation back into operation again. In the framework of this new responsibility and during the technical work that started to become organised, he found his death on Wednesday, December 15, together with Gerard Calvet, a technician of IRAM, a cable car specialist and the pilot of the helicopter.

    11. CRAF meeting 29 (20-21 March 2000)

    The 29th CRAF meeting was hosted by IRAM in Granada, Spain, on March 20-21, 2000. The main items discussed during the meeting concerned the Mobile-Satellite Service at 1.6 GHz, i.e. the coordination of mobile earth stations, MES, and aeronautical earth stations, AES, of GLOBALSTAR and Inmarsat, respectively; the evaluation of the studies in ITU-R Working Party 7D and ITU-R Task Group 1/5; the CRAF position on the WRC-2000 agenda items which are relevant for radio astronomy; the establishment of radio quiet zones around radio astronomy stations; and CRAF participation in various project teams and meetings of the CEPT ERC family.

    The meeting started with an in memoriam of Jean-Claude Sémiond, who died at Plateau de Bure by a helicopter accident in December 1999.

  • CRAF work in CEPT context: CRAF participated actively in the European preparations for the WRC-2000 within the CEPT (i.e. its Conference Preparatory Group, CPG, and several of the CEPT project teams). Also, the conclusions of the CEPT Detailed Spectrum Investigation Phase III (862-3400 MHz) reflects the CRAF contributions and recommended that 'detailed consideration be given to the future protection of the radio astronomy service in connection with the expected increased use of the frequency range 862-3400 MHz, in particular in the bands mentioned in S5.149 and their adjacent bands, noting the serious cause of interference from airborne and space stations'. The issue of coordinating the EISCAT facilities within northern Scandinavia found a clear place in the DSI-III conclusions.

  • MES coordination: CRAF studied the coordination of GLOBALSTAR MESs with radio astronomy stations. In this study the separation distances for a distribution of MESs to a radio astronomy station as a function of transmission channel was determined by using both the deterministic method as given in ERC Report 26 and the Monte Carlo methodology as given in ITU-R Recommendation M.1316 were used. Although the results of both methods are similar, it is noted that the results of the Monte Carlo methodology are very sensitive for several input parameters and at this moment no clear procedure exists to determine the correctness of the estimated separation distances. At this moment, CRAF's view is that in the coordination process the deterministic method should be used. The issue of the Monte Carlo methodology has been put high on the agenda of CRAF: it is subject of study in the 3rd CRAF workshop which is scheduled for June 15-16, 2000, in Bonn.

  • AES coordination: With Inmarsat, CRAF studied the coordination of aeronautical earth stations, AESs, with radio astronomy stations. The conclusions from this study are used in the new ETSI standard for AESs.

  • Preparations for WRC-2000: CRAF concluded the development of its positions on the WRC-2000 agenda items relevant for radio astronomy. About half a dozen CRAF members will participate in the WRC meeting in Istanbul (8 May - 2 June, 2000). IUCAF will also participate with a delegation. The visibility of CRAF in the WRC-2000 will be enhanced by some publications at the conference.

  • ITU-R Working Party 7D and Task Group 1/5: The studies of WP7D and TG1/5 were evaluated in the light of the WRC-2000. CRAF's view is that TG1/5 did not yet complete its studies and its work should be continued after the WRC-2000.
    CRAF had great concerns about the progress of the studies in WP7D. Some issues still under study in WP7D are already used in the report of the ITU-R Conference Preparatory Meeting, CPM, to the WRC-2000 and in European Common Proposals. CRAF is also concerned that a new WP7D draft recommendation on acceptable data loss due to interference is misunderstood and incorrectly used. CRAF will monitor the WP7D developments and communicate its considerations to WP7D.

  • radio quiet zones: CRAF evaluated the characteristics of the radio quiet zones around different European radio astronomy stations. In some countries studies and discussions are still going on the establishment of such protection measures for radio astronomy.

    Titus A.Th.Spoelstra
    CRAF - Dwingeloo Observatory

    12. Abbreviations used in this Newsletter

    AES = Aeronautical Earth Stations
    ALMA = Atacoma Large Millimetre Array
    CEPT = Conference of European Post and Telecommunication administrations
    CFH = Canada-France-Hawaii Telescope Corp.
    CPG = Conference Preparatory Group (CEPT)
    CRAF = Committee on Radio Astronomy Frequencies (ESF)
    DG = Drafting Group
    DSI = Detailed Spectrum Investigation (CEPT)
    EESS = Earth Exploration-Satellite Service
    EISCAT = European Incoherent Scatter Scientific Association
    ERC = European Radiocommunications Committee (CEPT)
    ESF = European Science Foundation
    HAPs = High Altitude Platforms
    INAG = Institut National de Astronomie et Géophysique
    INSU = Institut National des Sciences de l'Univers
    ITU = International Telecommunication Union
    ITU-R = ITU Radiocommunication Sector
    IUCAF = Scientific Committee on the Allocation of Frquencies for Radio Astronomy and Space Science (UNESCO)
    MES = Mobile Earth Station
    MSS = Mobile-Satellite Service
    NDSC = Network for the Detection of Stratospherc Change
    PNDR = Preliminary Draft New Recommendation (ITU-R)
    SG = Study Group (ITU-R)
    SR = Space Research
    TG = Task Group (ITU)
    UNESCO = United Nations Education, Scientific and Cultural Organization
    WP = Working Party (ITU-R)
    WRC = World Radiocommunication Conference (ITU-R)


    Last modified: April 4, 2000