Committee on Radio Astronomy Frequencies

The Committee on Radio Astronomy Frequencies (CRAF) is a committee of the European Science Foundation (ESF).

ESF Expert Committee on Radio Astronomy Frequencies (CRAF)

Progress Report for 1992-1995

On behalf of European radio astronomers concerned with interference in the frequency bands used for radio astronomy, the European Science Foundation had formed an ESF Committee on Radio Astronomy Frequencies (CRAF). The task of the Committee is to coordinate activities to keep the frequency bands used by radio astronomers free from interference. It will attempt to fulfil this task by:
- Co-ordinating the radio astronomy case in Europe in discussions with the major public and private telecommunications agencies.
- Acting as the European voice in concert with other groups of radio astronomers in discussions within the international bodies that allocate frequencies.
- Initiating and encouraging scientific studies aimed at reducing interference at source, as well as the effects of interference.

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.

1. CRAF membership

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.

At present the members representing their countries are from the Observatoire Royal de Belgique (Belgium), Ondrejov Astronomical Observatory (Czechia), Nançay Observatory (France), Max-Planck Institut für Radioastronomie (Germany), the Istituto di Radioastronomia C.N.R. (Italy), the Netherlands Foundation for Research in Astronomy (the Netherlands), Toru Radio Astronomy Observatory (Poland), the Observatório AstronĒmico, Prof.Manuel de Barros, Universidade do Porto (Portugal), Scientific Council on Radio Astronomy of the Russian Academy of Sciences (Russia), Centro Astronomico de Yebes (Spain), Onsala Space Observatory (Sweden), Institute of Astronomy, ETH Zentrum (Switzerland), Marmara Research Centre (Turkey) and the Nuffield Radio Astronomy Laboratories (United Kingdom).

Also the following organizations are CRAF members: the European Space Agency (ESA), the European Incoherent Scatter Scientific Association (EISCAT) (Finland, France, Germany, Norway, Sweden, United Kingdom), the Institut de Radio Astronomie Millimétrique (IRAM) (France, Germany, Spain).

The European Science Foundation (ESF) is represented by a liaison officer. The names of the CRAF members during 1992-1995 and their addresses are given in the membership list.

2. Management and operation of the committee

The Committee is self-managed from its Office at the Netherlands Foundation for Research in Astronomy. Dr.R.J.Cohen (NRAL, Jodrell Bank, U.K.) is the Chairman and Dr.T.A.Th.Spoelstra (NFRA, Dwingeloo, the Netherlands) the Secretary.

3. Major activities

The Committee became operational in July 1988. Since that time attention has been paid to current problems in the Radio Regulations as well as technical aspects such as interference reduction techniques.

3.1. Review of the meetings and major items discussed

The Committee had the following meetings during 1992-1995:
meeting 12:22-23 April, 1992Noto (Italy)
meeting 13:20-21 October, 1992Bonn (Germany)
meeting 14:20-21 April, 1993Brussels (Belgium)
meeting 15:18-19 October, 1993Strasbourg (France)
meeting 16:11-12 April, 1994Torun (Poland)
meeting 17:17-18 October, 1994Madrid (Spain)
meeting 18:10-11 April, 1995Grenoble (France)
meeting 19:28-29 September, 1995Porto (Portugal)

The major items discussed were:

  • General: in all meetings the current interference problems in the different European countries were reported and discussed. In addition in each meeting attention was paid to the current status of interference from satellite systems.

  • meeting 12: the two main subjects of the meeting were an evaluation of the results of the WARC 1992 and the status and future perspectives of CRAF. The most important result of the WARC 1992 was the upgrade of the status of the Radio Astronomy Service in the band 1610.6-1613.8 MHz from secondary by footnote to co-primary world-wide in the table of frequency allocations of the Radio Regulations. Another favourable result was that this WARC recommended a CCIR study, as a matter of urgency, on the spurious emissions from space transmissions in all bands, with a view to specifying spurious and out-of-band emission limits in the Radio Regulations, for the protection of the Radio Astronomy Service and other passive services, at the next competent WARC. Two members of CRAF attended the meeting for its full duration, and they contributed in no small measure to the favourable outcome for the Radio Astronomy Service. A similar forceful effort will be necessary at future WARCs.

  • meeting 13: the main subjects which were discussed at the meeting were the preparation for a world-wide joint experiment to monitor GLONASS satellites in collaboration with the GLONASS administration (20-22 November 1992) and the status of interference problems in Europe. In particular channel 38 (608.0-614.0 MHz) remains a source of serious worry in Italy and the Netherlands. The use of the 92 cm band by active services is increasing. The 21 cm band is severe under pressure in Czechoslovakia and Italy (particularly in Noto). In most of the countries participating in CRAF efforts are made to monitor the interference status.

  • meeting 14: the meeting investigated the new structure of the International Telecommunication Union, ITU, and its implications for the work of CRAF. Furthermore, it analyzed the results of the world-wide GLONASS-Radio Astronomy Joint Experimetn (20-22 November 1992).

  • meeting 15: discussed at the meeting were the CEPT related developments, the World Radio Conferences 1993 (+2y, y=0,1,2,... years) and the activities of the ITU Voluntary Group of Experts (VGE). The CEPT European Radiocommunications Office (ERO) made a Detailed Spectrum Investigation. The input of CRAF to this work had been discussed and defined. Also discussed was the participation of CRAF in the CEPT SE17 project team dealing with "the compatibility between MSS uplink and other radio systems in the 1610-1625.5 MHz band".

  • meeting 16: the meeting evaluated the reslts of the CEPT SE17 PT and started the discussion on the question to which extent radio astronomy needs radio frequency bands which are 100% free of interference.

  • meeting 17: attention was paid to the new developments and methods in spectrum management, changing regulation and new standards. Furthermore, pricing of spectrum use is now a real issue. The VGE views on the harmonization of the Radio Regulations will be addressed during the 1995 World Radio Conference.
    The meeting evaluated the results of the SFCG-14 meeting where aspects of the introduction of radio astronomy on the shielded zone of the moon were discussed. Concerning policy, the meeting took as a fact that a general policy is essential for the future work of CRAF. This has to be integrated in the doctrine that all radio astronomers should speak the same language and tell the same story in discussions with administrations and active spectrum users. Pricing the spectrum is becoming an important question and the developments have to be monitored very carefully. The implementation of this policy may have serious impact on the budgets and operations of observatories
    s. Some "radiation-free oases" in the radio spectrum are mandatory for radio astronomy. However, policy implies the need to bridge the gap between the administrative and physical understanding of "radiation free". To this aim education has to be one of CRAF's goals.

  • meeting 18: the CEPT European Common Proposals to the World Radiocommunications Conference WRC-95 [23 October - 17 November, 1995, in Geneva] with impact on the Radio Astronomy Service were evaluated.
    Secondly, the format for a European database for EMI events had been fixed. The strategy with respect to future WRCs (which occur every 2 years) and to several satellite systems was discussed. Special attention was paid to the extent UNESCO defends scientific use of the radio spectrum at the ITU.

  • meeting 19: the meeting discussed the preparations for the World Radiocommunications Conference WRC-95 which will pay much attention to the report of the ITU Volutary Group of Experts, VGE, implying a simplification/revision of the ITU-R Radio Regulations. The meeting also discussed the increasing threat of interference from MSS Low Earth Orbiting satellites using frequency bands near bands allocated to the Radio Astronomy Service and the protection of mm-astronomy.

    3.2. Actions taken + results

  • Some progress has been made in the development of techniques for frequency monitoring and software to alleviate interference problems. Further work on the definition of a number of technical concepts is required before these techniques can be used at observatories.
  • Special attention has been given to current frequency allocation and management problems in Italy, which have led to a less than desirable electromagnetic environment for radio astronomical work. It is observed that in Italy quite often radio astronomy suffers much interference within the frequency bands allocated to the Radio Astronomy Service. The Committee tries to do its utmost best to improve the situation. The Committee communicated with the appropriate European bodies such as NATO and to the Italian administration in various departments to stimulate activity for proper protection of radio astronomy in Italy.
  • The Committee stimulated already initiated NATO-CCMS activities to investigate the possibilities of a more alert administrative control of frequency allocation matters, including international judicial support. CRAF was informed about good perspectives for the acceptance of the proposed NATO-CCMS studies.
  • The well-prepared and coordinated activities of the CRAF members who participated in the World Administrative Radio Conference 1992, WARC-92, (as members of the IUCAF delegation or a national delegation) contributed in no small measure to the favourable outcome for the Radio Astronomy Service. One favourable result of WARC-92 has been the upgrade of the status of the Radio Astronomy Service in the band 1610.6-1613.8 MHz from secondary by footnote to co-primary world-wide in the table. Another favourable result was that this WARC has recommended a CCIR study, as a matter of urgency, on the spurious emissions from space transmissions in all band, with a view to specifying spurious and out-of-band emission limits in the Radio Regulations, for the protection of the Radio Astronomy Service and other passive services, at the next competent World Radio Conference.
    This same alertness and activity in the preparation for the World Radio Conference 1995, WRC-95, and the work during this conference resulted again in a favourable outcome. One of the results is the footnote protection of the methanol line at 6.7 GHz and footnotes to protect the Radio Astronomy Service from out-of-band emission from Low Earth Orbiting satellites, LEOs, with reference to the levels of harmful interference for radio astronomy as given in ITU-R RA769.
  • CRAF communicated with the CEPT Radiocommunications Office about the Detailed Spectrum Investigation (DSI) performed by this bureau in preparation of a European frequency table by the year 2008. It observes that in the DSI - phases I and II, the CRAF views have been integrated almost completely.
  • CRAF participated in the CEPT SE17 PT on "the compatibility between MSS uplink and other radio systems in the 1610-1625.5 MHz band". Basically the question is how the existing services in this band and INMARSAT are able to operate together in a radio-quiet way. Sharing of MSS with the RAS turned out to be very difficult. For sharing of MSS with radio astronomy coordination distances of the order of 250 km are required.
  • CRAF participates in the CEPT SE28 PT on "MSS technical standards, operational and compatibility issues". Basically the question is how the existing services in this band and Mobile Satellite Systems service are able to operate together in a radio-quiet way in the frequency bands 1610-1626.5 MHz, 1980-2010 MHz, 2170-2200 MHz and 2483.5-2500 MHz. Special attention is paid to the what turned out the most difficult problem: sharing of MSS and radio astronomy. MSS did not agree with the results of CEPT SE17 PT and is putting very strong pressure on the work of this PT to obtain results favourable for MSS.
  • CRAF participated in the organization of the scientific program of the Wroc aw EMC Symposium 1994 (28 June - 1 July 1994). It organized a session on "Interference Effects in Radio Astronomy" which followed the first general lecture on the first day of the meeting given by Sir Francis Graham Smith (Jodrell Bank) om "The Radio Universe". The CRAF session contained the 5 papers. In the future, CRAF will participate regularly in these bi-annual conferences.
  • CRAF communicated with the NATO about interference problems caused by (strategic) radar in Italy (Noto, Sicily) and Spain (Pico Veleta). NATO indicated that actions will be taken to improve the situation for radio astronomy.
  • CRAF communicated with various satellite companies about interference problems and interference threat by broadcast and cloud radar. The response of industry is cooperative so far.
  • In 1995 CRAF published a Handbook for Radio Astronomy (which was initially requested by the CEPT) and a Newsletter. The Handbook was very well received. CRAF got very positive reactions from different countries all over the world. The ITU and CEPT also showed much interest and suggestions were given for improvement in the 2nd edition which may be published early 1997. The Newsletter is available on the WorldWideWeb as is the CRAF homepage. The Newsletter is published twice each year. It is currently only available on the world-wide-web.

    3.3. Outstanding problems

    3.3.1. Acute problems

    Very important are two items:
    [a] the bi-annual ITU World Radio Conferences (WRCs), which started in 1993. The agendas are usually known 2-4 years in advance. However, this new set of meetings related with the new ITU structure implies a continuous alterness to the developments which may have implications for the future of the Radio Astronomy Service.
    [b] threat by satellite services. The threat of spurious and out-of-band emissions generated by satellite transmissions is steadily increasing. These emission do significant harm to radio astronomy and CRAF (in close cooperation with IUCAF) works at all possible gremia to protect radio astronomy. This does not imply that CRAF does not like the kind of frequency use satellite based applications are offering, but that the waste of spectrum which is technically not necessary and can technically well be prevented. CRAF's action is against these unwanted emissions within the radio astronomy frequency bands.

    Other important items the Committee had discussed are:

    - the frequency allocation and spectrum management problems in Italy between the Italian private TV network (TV-5) and the "Istituto di Radioastronomia" in Bologna about the use of channel 38 (608 - 614 MHz). In spite of actions taken by CRAF and the Italian radio astronomers, the Italian radio astronomers had to abandon the attempts together with the hope to ever observe the sky in this frequency band. Furthermore, Italian radio astronomers suffer by interference within protected bands at 1.4 and 1.6 GHz from different military and civil sources.
    - the increased interference and threat in the 18 cm band (OH emission) by Mobile Satellite System transmissions, i.e. the Iridium system. CRAF works in CEPT SE28 PT on the protection of radio astronomy.
    - the Belgian MLMS satellite for space-to-Earth transmissions between 400.15 MHz and 401 MHz using spread spectrum spectrum, direct sequence. CRAF fears that harmful interference will be experienced in the radio astronomy bands 322-328.6 MHz and 406-410 MHz. Via a couple of national administrations CRAF expressed its worries to the Belgian administration and the ITU Radiocommunications Bureau, Space Service Department.
    - a major threat to the Radio Astronomy Service comes from the Low Earth Orbiting Satellites of which an increasing number is operational and planned (many hundreds!). They often operated in frequency bands adjacent to radio astronomy bands and generate harmful out-of-band emission.

    3.3.2. Long term problems

    Long term problems are in particular those problems which today and very probably in the near future have not been fully studied by the ITU Radiocommunications Bureau and which will cause severely harmful interference when they come into effect. The indication "long term" indicates that certainly the next few years an adequate solution is very unlikely and methods and techniques have to be found in the radio astronomical community to cope with them.

    Urgent problems are:

    - introduction and application of new transmission techniques: in particular systems using band-spreading are a potential source of harmful interference. In this band-spreading technique bandwidths of several hundreds MHz are used, while the transmitted power is widely spread over this band and may be just under the current ITU-R recommendations. For security reasons generally encryption codes are added to the transmitted signal. For radio astronomy this means that when the wide band spectrum covers a radio astronomy band - let it be at a very low level - the "sky background" increases and it will no longer be possible to study weak features (even after long integration times).
    - time-sharing: proposal are made that the radio astronomy service should accept frequency allocations with the condition that only that fraction of each second Universal Time can be used for passive frequency use (i.e. radio astronomical observations) which is left over after an active application has already taken its part. This procedure may hold for some coordination distance around an observatory. So far many different problems related to sharing have not been considered by the ITU-R, but nevertheless radio astronomy has already to investigat methods to cope with any potential solution.
    - pricing the spectrum is becoming an important question and the developments have to be monitored very carefully. The implementation of this policy may have serious impact on the budgets and operations of observatories. The lacking coordination between the different national administrations within Europe makes this topic rather confuse at present.

    4. Relations with other bodies

  • CEPT: The Committee has been accepted by the Conference Européenne des Postes et des Télecommunications (CEPT) as a body to discuss with and is invited to its meetings, while it also gets all documentation and it can communicate directly to CEPT (see also ERO).
  • CORF: The Commission on Radio Frequencies (CORF) of the US National Research Council coordinates in the USA activities to keep the frequency bands used by radio astronomers free from interference. CRAF and CORF cooperate intensively. Dr.T.A.Th.Spoelstra, CRAF secretary, is the liaison of CRAF to CORF.
  • EC: The European Community (EC) becomes increasingly active in the field of frequency allocation/management matters. Since its interest is primarily not scientific, it may support proposals which imply (potential) harmful interference for passive services such as radio astronomy. Communicating with this organization CRAF attempts to serve the radio astronomy service to make the its views known, to make suggestions for improvement and to reduce the support to proposals which imply harmful interference to radio astronomy.
  • ERO: CRAF has good contacts with the CEPT European Radio Communications Office (ERO), in Copenhagen. Recently it communicated with this office concerning the radio frequencies used by the different radio astronomical observatories in Europe.
  • ITU-R: Through its members CRAF has intensive contacts with the technical committee of the International Telecommunication Union (ITU), the ITU Radiocommunications Bureau.
  • IUCAF: The Inter-Union-Commission on the Allocation of Freqencies (IUCAF) is a commission of the International Council of Scientific Unions (ICSU). Its parent organisations are the International Union of Radio Science (URSI), the International Astronomical Union (IAU) and the Committee on Space Research (COSPAR). IUCAF deals with matters of frequency allocation, interference and protection on behalf of the radio astronomy service on a world-wide basis. CRAF acts in support of IUCAF and provides IUCAF with all relevant regional European information. The CRAF chairman is an IUCAF member.
  • NATO: CRAF participates actively in a NATO study in the context of the Commission on the Challenges of Modern Society (CCMS) as already described above (section 3.2).

    5. Outlook

    CRAF experiences that the new developments after the WARC 1992 imply that it is more than ever mandatory that within the radio astronomical community there is uniformity and coherence in argumentation in interference and frequency management problems in the communication with the administrations and other relevant bodies. In addition this is urgent facing the European integration.

    5.1. CRAF's needs

    In its work CRAF noted that taking into account the characteristics of the work in preparation of the WARC 1992, which deals with many discussion at administration- and frequency-management-level, and also that after this meeting due to the nature of the problems, it is highly desirable that a professional spectrum-manager is available for this work. A position like this exists already for several years in the United States (a spectrum manager as an employee of the National Science Foundation). Also bodies like space agencies have their spectrum management offices. The experience is that this professionalization is urgently needed in CRAF context as well.
    At present within e.g. the CEPT context many process-forming meetings take place in which decisions are made with far reaching consequences for the protection of radio astronomy frequencies. CRAF is not able to participate in all these meetings. However, this situation has very much a negative impact on the work of CRAF, since in these working groups the real work is done at the very basis where CRAF would be able to influence the outcome. A full-time frequency manager is urgently needed to fill this gap. It is estimated that for this position a budget is needed including a salary for a senior scientist and travel money of comparable quantity. The EVN directors have also indicated the urgency for a CRAF frequency manager by a letter to the ESF Secretary General (see annex).
    Secondly, a 2nd edition of the CRAF Handbook for Radio Astronomy is needed, since the 1st edition is gone and many new items have come up for inclusion. CRAF aims to have the manuscript of the 2nd edition available by the end of 1996.
    Thirdly, a hardcopy of the CRAF Newsletter is needed so that CRAF's views reach a wirder audience.

    To have the radio astronomy voice heard, CRAF needs to continue with an active policy to try to make contact and to communicate with bodies involved in matters of frequency-management.

    6. Conclusions

    The need to coordinate the European efforts being recognized by the astronomical community the CRAF concept was established under the auspices of the European Science Foundation. The results demonstrate that a "structured" discussion on a European level is of great practical value.

    Last modified: June 29, 2001