CRAF Newsletter 2004/2

December 2004

The European Science Foundation is an association of its 76 member research councils and academies in 29 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. Chairman's corner

These are times of deep restructuring both in house and in our environment: but unfortunately not really expected at the beginning of this year!

Firstly, the request for retirement by our Frequency Manager, Dr. Titus Spoelstra, has opened a gap in the history of CRAF that will not be easily filled. In September we advertised the position vacancy via many different home pages and links: we plan to have the first interviews with candidates in mid-January and shortly after to nominate the successor.

Secondly, the idea of a new European Research Council (ERC) has triggered a lot of discussions within ESF on how to contribute to such a new organization. All the Standing and Expert committee chairs as well as representatives of the various scientific communities have been consulted in a “bottom up” process of generating new ideas.

The CRAF position within ESF has been clarified in very simple terms: since its beginning, CRAF has found under the ESF “hat” the most appropriate institutional entity that guarantees a substantial independence from industrial and commercial interests, with respect to our objectives of fundamental research in the field of Radioastronomy. As a matter of recent fact, for example during the UWB and SRR debates, the attack on even our best protected frequency bands has been so aggressive because of the support that the car industry has found in other European institutions.

As a consequence, the ESF Executive Board has assured us that this independency concept will be continued as one of the fundamental guidelines for the future structure of the ESF.

RadioNet has given us a completely new possibility to increase our impact and visibility toward our radioastronomy colleagues, the “end users” of our work. RadioNet will support participation in CRAF meetings of techical and scientific staff from observatories who are closely related to operational problems, as well as travel costs from CRAF Members who may have financial difficulties. Funds are now available, so suitable individuals are strongly encouraged to apply. For further information on RadioNet: on RadioNet and on RadioNet and spectrum management.

The RFI2004 meeting in Pentincton, Canada, offered both exciting learning opportunities on the latest RFI mitigation, excision and filtering algorithms and techniques, and also an appreciation of the work done and to be done by people involved in the Frequency Regulatory field, as reported in the presentation of, e.g., CRAF's Wim van Driel on the SKA project.

I would also like to compliment all organizers and participants to the ESF and RadioNet sponsored workshop about “Active Protection of Passive Radio Services: toward a concerted strategy”, held in Cagliari last October. I think that in this case we have really reached the solid result of identifying a common view between different scientific communities, living too separated until now. This uniformity of strategies has to be developed in an even more efficient way, but now the first links are well established and ready for common actions in the future.

Finally a warm invitation to all to the Second Summer School in Frequency Management: it will be the best opportunity for our community to share our experiences and our to welcome the younger colleagues who will succeed us. See you in Castel San Pietro (Bologna, Italy) next 6-10th of June!

Roberto Ambrosini - Istituto di Radio Astronomia, Bologna

2. Report from the 39th CRAF meeting [11-12 October 2004]

The 39th CRAF meeting was held on 11-12 October 2004 in hotel “Maison Rouge” in Strasbourg at the kind invitation of the European Science Foundation.

Key items discussed were:
- An ESF sponsored workshop on Passive use of the Radio Spectrum is to be held on October 28-29, 2004, in Cagliari, Sardinia, Italy, The aim of this workshop is to strengthen the ties with other so-called passive services using the radio spectrum (such as the Earth Exploration Satellite Service (EESS), atmospheric sensing, etc.), in view of the many common regulatory aspects relevant to the protection of measurements, which are due to similar sources of pollution in the electromagnetic environment and receiver sensitivity requirements;
- Regional Radiocommunication Conference 04/06 (RRC04/06): The RRC, which is working on a revision of the Stockholm 1961 broadcasting channel plan, completed its first session in May 2004. This first session established the framework, rules and planning processes for the second session of the conference. The protection of radio astronomy in the band 608-614 MHz needs to be properly retained;
- Iridium satellite system: CRAF has brought the issue of the extension of the frequencies used by the Iridium system to the attention of the CEPT and noted that the ESF/CRAF-Iridium Agreements concluded in 1998 and 1999 and the CEPT MRC Recommendations are still in force. At its 5th meeting (July 2004) the ECC decided inter alia that CRAF and Iridium should be encouraged to re-establish dialogue to resolve the issue. The initial meeting is foreseen on November 2nd, 2004 in London. The results of this meeting will be reported to the ECC for its 6th meeting (November 2004) where the ECC intends to finalize this issue;
- Ultra-Wide Band (UWB) issues: TG3 completed a draft ECC Report on the compatibility between UWB technology and radiocommunication services below 10 GHz. The report has been adopted by WG SE for public consultation. After completion of this consultation it will be submitted to the ECC for finalization. Within CEPT, the ECC report will be used to develop a spectrum mask for UWB applications;
- Short Range Radar (SRR) at ~24 GHz and ~79 GHz: At its 5th meeting (July 2004), the CEPT ECC reached a compromise decision on SRR at ~24 GHz with parameters that raised concern among the passive services. In its Radio Spectrum Committee (RSCOM) the European Commission wished to relax the CEPT compromise significantly in support of industry and ignoring the interests of the passive services. The EC, however, did not yet find sufficient support for this and might come back to this issue later in 2004;
- Global Transmission Experiment (at ~1428 MHz): A request from the German Aerospace Center (DLR) to cooperate with CRAF for the completion of an experiment onboard the International Space Station was not accepted because it does not contribute to the protection of radio astronomy and the experiment does not comply with the international Radio Regulations.

3. ESF sponsored Workshop on Active Protection of Passive Radio Services

A workshop on "Active Protection of Passive Radio Services: towards a concerted strategy" was held in Cagliari, Sardinia, Italy, on 28th and 29th October 2004. The workshop was sponsored by the European Science Foundation, with additional support from RadioNet. The meeting brought together for the first time the radio astronomical and remote sensing communities in a relaxed informal venue. There were 26 delegates from 9 countries, who between them represented 5 national and international space agencies, the meteorology community, the aeronomy community, the geodetic community, and 6 major radio astronomy observatories.

The workshop addressed the threats to scientific use of passive radio frequency bands from rapidly increasing levels of radio pollution, and from commercial pressures to relax regulatory control.

The presentations covered the current and future use of frequencies for radio astronomy, for passive remote sensing for climate monitoring, meteorology and environmental studies, and for passive remote sensing of the middle atmosphere from the ground. Current radio interference problems and future threats such as ultra-wide band (UWB) technology were discussed. Structural and political issues were treated, and forthcoming WRC agenda items of common interest were reviewed.

The heart of the workshop was an open discussion on the second day. The need for good liaison and better communication between the groups was reiterated by many speakers. A long-term formal structural solution could come from enlarging the mandate and constitution of IUCAF. The need to make decision makers aware of our frequency needs was emphasised, along with the need to provide real figures on the economic value of keeping passive frequency bands passive. We also need to lobby for pre-launch testing of unwanted emissions from satellites, for improved monitoring of frequency usage, and for respect of ITU rules. Regarding future WRCs, we have already established good coordination and common positions on unwanted emissions and on 1.4 GHz. We now need to develop equally good coordination on other items of common interest, including the possible alloaction of frequencies above 275 GHz.

The Workshop recognized the common interests of our groups as one. We use passive bands for astronomy, for remote sensing from satellites and for remote sensing from the ground, but we all rely for the integrity of our work on the passive bands being truly passive. We identified a big problem of perception of the needs of passive band activities and their socio-economic importance. We identified a need to gather our arguments for the preservation of each individual passive frequency band (what would be lost?) and to make this information more widely known. A list of action items was drawn up and it was agreed that we should aim to have a follow-up workshop in 2006.

The workshop concluded with a visit to the site of the Sardinia Radio Telescope (SRT), which is under construction 35 km North of Cagliari. The SRT will be a 64-m diameter dish with an active secondary mirror, enabling it to cover a very wide frequency range from 0.3 to 100.0 GHz.

The Workshop programme and powerpoint presentations are available on the workshop website.

4. Short Range Radar, SRR, at ~24 GHz - conclusion?

In its 8th meeting (Gothenburg, 5-9 July 2004) the CEPT ECC concluded on the issue of Short Range Radar at ~24 GHz:

  • The maximum penetration levels for SRR is fixed to be 7% (as a compromise between 5.9 and 8.3%);
  • The reference date is fixed at 1 January 2013;
  • An automatic deactivation function shall be introduced for all vehicles equipped with SRR, with a transition period of 2 years for its introduction, during which manual deactivation of SRR devices would be required;
  • A review should be carried out by the EC Radio Spectrum Committee (RSCOM) in 2009 to assess the level and trends in the penetration of 24 GHz SRR and to consider whether the reference date should be set earlier.

    These conclusions were key elements in a Report from the ECC to the European Commission on SRR adopted at the 8th ECC meeting.

    The first two aspects are important for EESS and the third one for radio astronomy.

    A table of Radioastronomy stations was included in the Report from the ECC to the EC on this issue.

    The scientific and meteorological communities, noting the compromise reached, expressed their concerns that the agreed solution, even if strictly applied, will not guarantee the protection of passive services in the frequency range 22.21-24 GHz and in particular in the 23.6-24 GHz band covered by RR No. 5.340.

    They also urged CEPT administrations and the European Commission to make sure that any such temporary authorization of 24 GHz SRR systems is exceptional and can not be used as a precedent for possible introduction of other transmitter devices in bands where RR No. 5.340 is applicable, for temporary or permanent use.

    The passive services were informed that the European Commission at a meeting of its Radio Spectrum Committee (RSCOM) on 29 September 2004 favoured a relaxation of the CEPT decisions in favour of the automobile industry. Such a relaxation will add to the harm on the passive services already expected from SRR. The EC, in its explanatory considerations, showed no appreciation of the requirements for the protection of victim services (even though it is stated in related EC publications that SRR must protect existing services). This view was not supported by CEPT Administrations.

    In its 9th meeting (Brugge, 8-12 November 2004) the ECC adopted its Decision on 24 GHz SRR issues.

    5. Ultra-Wide band (UWB) transmissions and radio astronomy

    Ultra Wide band technology (see also Newsletter 2000-3)is expected to generate emissions that have significant negative impact on various radiocommunication services. UWB applications can be generally grouped into the following categories: Medical applications, Consumer communications applications, Automotive applications, Consumer and industrial construction applications, Ground penetrating radar (GPR) systems (which are used to trace land-mines, for example), Industrial liquid level gauges, and High performance data communications systems.

    The USA has developed regulation that specifies the spectrum mask for UWB applications. With this mask, the GPS system is protected at frequencies below 3 GHz. Compatibility studies for UWB transmissions frequencies below 10.6 GHz done within CEPT show that UWB transmissions are incompatible with most radiocommunication services. For radio astronomy it was noted that the maximum tolerable e.i.r.p. per UWB device must be below about -100 to -130 dBm/MHz for a density of 100 UWB devices per km2 depending on the frequency. This differs significantly from the value of -41.3 dBm/MHz as given in applicable FCC Part 15 regulations.

    In October 2004 CEPT Working Group SE adopted a draft ECC Report on the compatibility between UWB and radiocommunication services operating below 10.6 GHz for public consultation. Its ECC Task Group 3 has been established to work on this issue and also to prepare CEPT input to ITU-R Task Group 1/8 which is working at ITU-R level "on Compatibility between ultra-wideband devices (UWB) and radiocommunication services". Various issues require attention, including:

  • the application of the Radio Regulations, specifically its article No. 5.340 which states for several frequency bands that "all emissions are prohibited" in these bands.
  • the implications of activity factors and deployment scenarios (e.g. indoor or outdoor) for the compatbility studies.

    Both ECC TG3 and ITU-R TG1/8 are expected to complete their work in 2005. In the end a spectrum mask needs to be developed that protects all radiocommunication services concerned, including radio astronomy.

    6. Iridium satellite system and radio astronomy

    The Iridium satellite system operated by Iridium Satellite LLC is using frequencies in the range 1613.8 - 1626.5 MHz where the Mobile-Satellite Service, MSS, under which it operates, has a primary allocation for Earth-to-space transmissions and a secondary allocation for space-to-Earth transmissions. Footnote No.5.372 applies to MSS transmissions to protect radio astronomy to which the band 1610.6-1613.8 MHz is allocated on a primary basis.

    Between 1998 and 1999 negotiations between ESF/CRAF and Iridium LLC (the predecessor of Iridium Satellite LLC) under the auspices of the CEPT Milestone Review Committee, MRC, reached agreement on the protection of radio astronomy stations by the Iridium system, stating "From 1 January 2006, European radioastronomers shall be able to collect measurement data consistent with the recommendation ITU-R RA769-1". These agreements were taken by the CEPT as the basis for regulatory guidance to its member states in MRC Recommendations on this issue (for reading, see Iridium and Radio Astronomy in the band 1610.6-1613.8 MHz, Newsletter 1998-3 and Newsletter 1999-2).

    In February 2003 the FCC agreed to an expansion of the frequencies used by the Iridium satellite system from 1621.35-1626.5 MHz downward to 1618.25 MHz. In June 2004, the FCC issued a Further Notice of Proposed Rulemaking "to explore whether CDMA and TDMA MSS operators could share an additional 2.25 MHz of spectrum at 1616.0-1618.25 MHz".
    This significant change constitutes a change in the conditions for the Agreements completed between Iridium and ESF/CRAF and the related CEPT MRC Recommendations regulating the protection of radio astronomy in Europe from interference from the Iridium system. This frequency extension was motivated by the frequency need of the Iridium system during the war in Iraq.

    For its operation in CEPT countries, the operations of the Iridium satellite system are subject to the obligations in the abovementioned Agreements and relevant CEPT MRC Recommendations which are still in force. These documents include the need for the Iridium satellite system to comply with the spfd -238 dB(Wm-2Hz-1) limit on unwanted emissions into the 1610.6-1613.8 MHz radio astronomy band from January 1st, 2006, in the absence of an alternative solution.

    Monitoring observations at the Nancay observatory confirm that Iridium is using frequencies below 1621.35 MHz as is seen from the figure (courtesy Nançay Observatory).

    A recent report on monitoring measurements of Iridium satellites made at the German Leeheim Satellite Monitoring Station convincingly shows the occurrence of unwanted emissions in the 1610.6-1613.8 MHz RAS band. The strongest unwanted emission seen corresponds to a level 25 dB above the threshold level for detrimental interference in astronomical spectral line observations, as given in Recommendation ITU-R RA.769 (January 2004).

    On 2 November 2004 a meeting between CRAF and Iridium Satellite LLC took place, hosted by the UK Office of Communications (OFCOM) at their London headquarters.

    In this meeting, Iridium Satellite LLC, Iridium, explained in its introduction that the new company, formed following the bankruptcy of the former Iridium LLC, was refocused on supplying voice and data services to remote areas, including the seas and oceans. The satellites are expected to last until 2014. Iridium said it regretted that interested parties had not contacted Iridium Satellite earlier concerning the issues with radio astronomy.

    CRAF explained the history of the Iridium case in Europe and the role of the CEPT in bringing about the current agreements. CRAF also explained the nature of the Framework Agreement and the Interim Agreement. Iridium was also informed that the concerned ERC MRC Recommendations are still in force.

    CRAF pointed out that interested parties in Europe have tried to maintain contact with Iridium over the years: CRAF contacted Iridium after the Interim Agreement was signed in 1999, in accordance with the milestones of the Workplan annexed to this Agreement, but it never received any reply from Iridium. Due to the total lack of response from Iridium, CRAF ceased sending them correspondence regarding the Agreements in 2000.

    OFCOM asked which improvements have been made by Iridium on the satellites to protect radio astronomy. Iridium explained that the satellites launched so far are all of the same design as the initial satellites, probably from the initial stock. Iridium said it had done some work on reducing the intermods in their system to reduce the unwanted emissions.

    The Leeheim measurements were discussed and Iridium raised a number of questions that they consider have not yet been fully answered. The basic issue is whether the Leeheim measurements show that observations according to Rec 769 could be made. It was agreed to forward a new series of questions, as agreed upon by CRAF and Iridium during the meeting, to Leeheim through the ECC.

    A further meeting is planned in early February, hosted by OFCOM, at which it is hoped someone from Leeheim can attend.

    7. Second Summer School in Spectrum Management and Radio Astronomy

    The second Summer School in Spectrum Management and Radio Astronomy will be held at Castel San Pietro, near Bologna, Italy, on 6-10 June, 2005.

    The purpose of the Summer School is to offer a comprehensive view of both regulatory and technical issues related to radio astronomers' use of the spectrum. The intended audience are members of the radio astronomy and related radio engineering community, who are becoming active in this area at the local, national or international level.

    Subjects covered will include the basic technical framework, the regulatory framework (national, regional and worldwide), case studies in coordination, new interfering technologies, interference mitigation techniques, Radio Quiet Zones and the operational requirements of future large instruments. Steps towards improved synergy in spectrum management with other passive radio services, such as Earth exploration by satellite, meteorology and atmospheric research, will also be discussed.

    The Summer School will be sponsored by RadioNet and IUCAF. Young(ish) persons are specifically encouraged to attend. Applications for financial support should be addressed to the CRAF secretariat.

    For information, the report of the first Summer School, which was held in 2002 at NRAO, Green Bank, USA, is available at the IUCAF website.

    8. Coordination with 94 GHz CloudSat radar transmissions

    At WRC97, after much discussion, a primary allocation was made to the Earth exploration-satellite (active) service for spaceborne cloud radars in the band 94-94.1 GHz, where the radio astronomy service has a secondary allocation. Radio astronomy also has primary allocations in the adjacent bands 92-94 GHz and 94.1-95 GHz.

    Since cloud radar transmissions in the band 94-94.1 GHz that are directed into the main beam of a radio telescope could damage its receivers, space agencies operating these radars and the radio observatories concerned should mutually plan their operations so as to avoid such occurrences to the maximum extent possible, according to Footnote 5.562A of the ITU Radio Regulations.

    In July 2004, radio astronomers were informed by NASA of the planned launch in April 2005 of the 22 months’ duration CloudSat cloud-mapping experiment, which will carry a pulsed, 1.8 kW narrow-band, 94.05 GHz nadir-pointing (downward-looking) radar. Power levels of the CloudSat radar are such that they could burn out an SIS-type junction deployed on a typical radio telescope if it is observing at zenith in the 94-94.1 GHz band during an overflight. Moreover, an SIS receiver operating in this band will probably be saturated during a (near) overflight, wherever the telescope is pointed.

    Acting on behalf of the worldwide radio astronomy community, IUCAF, in consultation with CRAF, brought its concerns to the attention of the Space Frequency Coordination Group (SFCG), which subsequently adopted SFCG Resolution 24-2 on this issue at its meeting in September 2004.

    Since it is not possible to turn off the CloudSat radar transmissions as the satellite passes over a radio astronomy site, observatories will need to know when exactly to avoid observing. Further practical information can be found on the IUCAF website on Cloudsat.

    The European sites concerned are Bordeaux (France), Effelsburg (Germany), Metsähovi (Finland), Onsala (Sweden), Pico Valeta (Spain), Plateau de Bure (France), Sardinia (Italy) and Yebes (Spain.)

    9. Abbreviations used in this Newsletter

    CEPT = Conference of European Post and Telecommunication administrations
    CRAF = Committee on Radio Astronomy Frequencies (ESF)
    DLR = Deutsches Zentrum für Luft- und Raumfahrt (Germany)
    EC = European Commission
    ECC = Electronics Communications Committee (CEPT)
    EESS = Earth Exploraration-Satellite Service
    ESF = European Science Foundation
    FCC = Federal Communications Committee (USA)
    GPR = Ground Penetrating Radar
    ITU = International Telecommication Union
    ITU-R = International Telecommunication Union - Radiocommunication Sector
    IUCAF = Scientific Committee on the Allocation of Frequencies for Radio Astronomy and Space Science (UNESCO)
    MRC = Milestone Review Committee (CEPT)
    MSS = Mobile-Satellite Service
    NASA = National Aeronautical and Space Administration (USA)
    OFCOM = Office of Communications (UK)
    RAS = Radio Astronomy Service
    RFI = Radio Frequency Interference
    RR = Radio Regulations (ITU)
    RRC = Regional Radiocommunication Conference (ITU-R)
    RRC(04/06) = RRC 2004/2006
    RSCOM = Radio Spectrum Committee (EC)
    SE = Spectrum Engineering (CEPT)
    SFCG = Space Frequency Coordination Group
    SIS = Superconductor-Insulator-Superconductor (mixer device)
    SRR = Short Range Radar
    TG = Task Group
    UWB = Ultra Wide Band
    WG = Working Group
    WRC = World Radiocommunication Conference (ITU)


    Editorial Group: R. Ambrosini, R.J. Cohen, P. Scott

    Last modified: 28 April, 2005