CRAF Newsletter 2003/1

May 2003

The European Science Foundation is an association of its 70 member research councils and academies in 27 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

The World Radiocommunication Conference 2003 (WRC-03) organized by the International Telecommunication Union (ITU) from 9 June till 4 July in Geneva is a very important event for radio astronomy. This special edition of the CRAF Newsletter is devoted to radio astronomy issues at WRC-03.

CRAF has participated actively within CEPT in the preparation of European Common Proposals, ECPs, for the numerous WRC-03 agenda items of concern to radio astronomy and supports them. The specific interest in these agenda items of radio astronomers in various CEPT countries is listed in section 4 of this Newsletter.

The basic issues at hand of particular interest to the Radio Astronomy Service are similar to those addressed at previous WRCs, e.g. proposals for the allocation of new satellite downlinks adjacent to radio astronomy bands, and placing limits on the levels of unwanted emissions from satellites into bands used for radio astronomy. To protect the fundamental science done by radio astronomers great care has to be taken at the WRC concerning the regulation of these issues.

The worldwide radio astronomy community is working towards the construction of a new generation of giant radio telescopes, with collective surfaces of up to a square kilometre and operating in the frequency domain of 150 MHz to 950 GHz. CRAF supports the ECP on the necessity for studies on the required operational conditions for their successful operation.

Wim van Driel - Paris Observatory

2. Introduction to CRAF

The science of radio astronomy plays a key role in increasing our understanding of the universe in which we live. Radio astronomy is a so-called passive service, in the sense that 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, CRAF, the Committee on Radio Astronomy Frequencies of the European Science Foundation does its best to keep the frequency bands used by radio astronomers free from interference. A brief introduction to the ESF is given at the top of this Newsletter.

CRAF works towards this aim by:

The Committee acts also to help EISCAT - the European Incoherent Scatter Scientific Association - whose important experiments in the polar ionosphere face 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.

3. European radio astronomy

Radio astronomy is a dynamic 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-03 agenda items of interest
Austria1decameter research1.8.2, 1.20
Belgium1<1 GHz1.8.2, 1.20
Czechia10.8 - 5 GHz1.8.2, 1.15, 1.16, 1.31, 1.33, 1.34
Finland1>~20 - ~120 GHz1.8.2, 1.13, 1.25, 1.32
France3all1.8.2, 1.13, 1.15, 1.16, 1.20, 1.25, 1.31, 1.32, 1.33, 1.34
Germany3>0.4 - ~100 GHz1.8.2, 1.11, 1.15, 1.16, 1.20, 1.25, 1.31, 1.32, 1.33, 1.34
Greece1<1 GHz1.8.2, 1.20
Hungary11 - 1.5 GHz1.8.2, 1.15
Italy40.3 - 44 GHz1.8.2, 1.13, 1.15, 1.16, 1.20, 1.25, 1.31, 1.32, 1.33
Latvia10.3 GHz and ~10 GHz1.8.2
Netherlands20.2 - 8 GHz1.8.2, 1.15, 1.16, 1.20, 1.31, 1.33
Poland20.1 - 7 GHz1.8.2, 1.15, 1.16, 1.20, 1.31, 1.33
Portugal10.1 - 0.7 GHz1.8.2, 1.20
Russia141.6 - 23 GHz1.8.2, 1.11, 1.15, 1.16, 1.31, 1.33, 1.34
Spain31.6 - 275 GHz1.8.2, 1.13, 1.15, 1.16, 1.25, 1.31, 1.32, 1.33
Sweden11.3 - 116 GHz1.8.2, 1.13, 1.15, 1.16, 1.25, 1.31, 1.32, 1.33
Switzerland10.1 - 4 GHz1.8.2, 1.20, 1.33
Turkey186 - 116 GHz1.8.2
Ukraine71.8.2, 1.20
United Kingdom60.04 - 44 GHz1.8.2, 1.11, 1.13, 1.15, 1.16, 1.20, 1.25, 1.31, 1.32, 1.33, 1.34

Europe also participates in radio astronomy stations in ITU Region 2, on Hawaii, in Chile and in the USA operating at mm-wave and sub-mm-wave frequencies.

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

4. New generation of radio telescopes: a challenge for the radio environment

Radio Astronomy is continuously working on the improvement of its instruments, in terms of increased sensitivity, spectral-, time- and angular resolution. A variety of technologies are applied for this, such as single dish telescopes with dimensions of up to 300 meters, radio interferometers with baselines extending beyond the dimensions of the earth (space Very Long Baseline Interferometry), receiver backends with up to a million channels, superconducting components and system temperatures only a few degrees above the absolute zero level.

Considerable technical innovation in the design of radio astronomy antennas will enable the building, in the timeframe of 2003-2015, of a new generation of instruments with very large collecting areas, having a sensitivity about a hundred times better than the largest instruments presently in operation. An additional objective for these new instruments is observation capabilities in various frequency bands not allocated to the Radio Astronomy Service. These (international) instruments will be built in very remote areas, where the radio environment may offer better opportunities for protection of the observations and enhanced protection of the radio environment is sought at their locations only. It should be noted that most of the large radio telescopes presently in operation will continue to be used for scientific research once these new instruments become operational.

Since investments for these instruments will be in the order of more than 2 Billion Euros or US Dollars only a few of them will be built. Three specific telescopes are presently under development, each of which constitutes a large step forward in observational abilities.

The Atacama Large Millimetre Array (ALMA), will operate in all atmospheric windows in the frequency range 31 to 950 GHz. This observatory, comprising 64 telescopes each with a 12 metre aperture will be located on a virtually rainless plateau at an altitude of 5000 meters in the Plain of Chajnantor in the Atacama desert in Northern Chile, in close proximity to the borders with Argentina and Bolivia. The total collecting area of this telescope will be a factor of 40 larger than the currently available largest telescope at the upper end of the covered frequency range and at least a factor 8 at the lower frequencies. This telescope will be built using the extensive experience of radio astronomers with observational systems operating at frequencies up to 1200 GHz.

The second instrument, the Low Frequency Array (LOFAR), is designed to operate in the 10-240 MHz frequency range, with a total collecting area of one square kilometre. The telescope will consist of dozens of stations, each with numerous antennas (in total about 25000, each the size of a common TV antenna). There will be one core location of 320 hectares and about 100 smaller locations ranging from two to four hectares each within an area with about 200 km radius. The stations concentrated in the core location and all other elements of the instrument will be linked through a high-bandwidth optical cable network. The location for the LOFAR is currently under investigation and will be decided in 2003.

The third instrument, the Square Kilometre Array (SKA), will be designed to operate in the whole frequency range of about 150 MHz to 22 GHz, with a total collecting area of one square kilometer. Design studies currently underway are aimed at specifying the operating frequencies and determining the technology to be used for the telescope. The telescope may actually consist of two arrays based on two different technologies and covering two complementary frequency ranges. There will be up to one hundred stations of about 100 by 100 m in size, each comprising many antennas. The SKA will have a compact core with 25 percent of the stations, simulating sensitive single-dish operations, combined with VLBI techniques applied on the longer baselines towards the more distant stations as far out as 4000 km. The location for the SKA is currently under investigation and will be decided in 2006 based on technological, economic, and environmental factors.

The characteristics of the electromagnetic environment in the operating bands of the three telescopes are totally different. The spectrum below 22 GHz is already used intensely by a large number of terrestrial and satellite services, and potentially very harmful Power Line Transmissions (PLT) are planned in the LOFAR frequency range (see item 7 of this Newsletter). Whereas the spectrum between 30 and 60 GHz is currently being considered for future large-scale implementation by these services, the active spectrum allocations above 60 GHz are used only sporadically at present and the implementation of systems emitting in many of these bands is still many years off.

Nevertheless, it may be necessary to have available in the Radio Regulations some specific technical and regulatory provisions to ensure the required radio environment at these observatories. The challenges that need to be faced to enable their successful and efficient operation include the development of:

  • innovative, RFI-resistant systems by radio astronomers;
  • appropriate regulatory instruments for Administrations, which also avoid degrading impact on active services.

    Within the ITU-R Questions need to be defined and studied by all services concerned (and not only the science services) to make an inventory of possible technical, operational and regulatory measures, as well as of mitigation techniques, for the creation of the required radio environment, in order to allow a future WRC to take the required decisions.

    5. Short Range Radar at ~77 GHz

    In Europe, the issue of Short Range Radar, SRR, is the subject of intensive discussion at the highest Administrative level, with industry and with organisations representing the interests of the potentially affected services, i.e. the Earth Exploration Satellite Service, EESS, the Fixed Service, FS, the Radio AmateurService, RAm and the Radio Astronomy Service, RAS.

    Following developments outside Europe, the automobile industry with support of the European Commission aimed for SRR using a frequency band of 5 GHz centred on 24.15 GHz, i.e. from 21.65 to 26.65 GHz.

    The deployment of SRR at ~24 GHz would generate several regulatory and technical problems that are difficult to resolve. An important regulatory problem is that footnote 5.340 applies to the frequency band 23.6-24.0 GHz and prohibits all emissions in this band. Technical studies show that SRR at 24 GHz is not compatible with any of the services operating in the frequency range considered for SRR. Radio astronomy operating in frequency bands near 24 GHz can be protected only if the e.i.r.p. per SRR device is at least 80-100 dB lower than the value of -30 dBm/MHz hitherto considered. The scenario for the FS and the EESS operating in this frequency range is, however, more favourable, but there are still discrepancies of a few tens of dB between SRR emission levels and protection criteria for FS and EESS.

    The CRAF position is that SRR deployment at ~24 GHz as anticipated by the automobile industry violates footnote 5.340 in the band 23.6 - 24.0 GHz and SRR must therefore avoid this band completely. This view is shared by others as well.

    The World Radiocommunication Conference of 1997 allocated the band 76 - 77.5 GHz to the Radiolocation Service. This decision was specifically driven by the need for a frequency band for vehicular radar applications. Currently, the automobile industry is looking for a frequency band in the 77 GHz range for SRR. Studies are underway to address the compatibility between SRR and the potentially affected services, i.e. RAm and RAS.

    6. Power Line Communications and LOFAR

    Power Line Communications stands for a complex of applications that include
    - Power Line Telecommunications (PLT or PLC), a means of transmitting high data rates on the mains electricity network;
    - Digital Subscriber Line (DSL), a means of transmitting high data rates on existing copper wire telecommunication networks, for example plain ordinary telephone systems;
    - cable communications, comprising a family of distribution networks that utilise dedicated coaxial cables, to provide traditional Cable TV and increasingly new Interactive services, including Internet access;
    - Local Area Networks (LANs).

    It is currently considered that PLC will be deployed at frequencies below 30 MHz. This application is strongly supported by electricity providers. The impact of the use of power lines for communication on other users of radio frequencies is considered an issue of electromagnetic compatibility, EMC, rather than radiocommunications, and it will be resolved by the appropriate organisations. The CEPT has also addressed this matter and reported pfd levels that will not be sufficient to protect the most sensitive potential victim services, such as radio astronomy.

    Europe is extensively involved in leading edge research in radio astronomy frequencies below 2 GHz. This frequency range is also of great interest for future radio astronomy because of the development of a new generation of giant radio telescopes such as the Low Frequency Array Network, LOFAR, which will have a diameter of 350 km (see section 5) and for which there is a serious chance it will be located in The Netherlands, with several outlying antenna stations in Germany.

    The European standardization institutes working on EMC issues have not yet finalized their work. But considering their progress so far, CRAF has serious concerns that LOFAR will become PLC limited since the presently considered pfd limits exceed the protection criteria for radio astronomy by more than an order of magnitude.

    CRAF's view is that non-radio telecommunications should preferably use fibre optics cables, in order to prevent radio interference to radiocommunication services.

    7. Views on WRC-03 agenda items

    The World Radiocommunication Conference 2003, WRC-03, will be held in Geneva from June 9 - July 4, 2003. The agenda of this conference contains several items which have relevance for radio astronomy. CRAF has participated actively within CEPT in the preparation of European Common Proposals, ECPs, for WRC-03 on these agenda items and supports them.

    CRAF offers some additional comments on a number of agenda items:

  • 1.8.2: The regulation of unwanted emissions to protect the passive services has been on the ITU-R agenda for almost a decade. The CEPT proposes a regulatory solution for implementing pfd limits for GSO systems and epfd limits for non-GSO systems based on the epfd concept as defined in RR Article 22 in the relevant bands.
    The results obtained from the band-by-band studies shall be the basis for bands where limits will apply. Some radio astronomy (RAS) bands are already protected in the Radio Regulations from unwanted emissions (see Nos. 5.208A, 5.443B, 5.511A and 5.551G): it is proposed to address the protection of these RAS bands in the same way. Depending on the outputs of the discussions on Agenda Item 1.15 dealing with footnote 5.443B and Agenda Item 1.32 dealing with footnote 5.551G, there would be a need to review these footnotes and to ensure consistency between all proposals addressing the protection of RAS bands with regard to unwanted emissions from space services.
  • 1.16: During the WRC-03 preparation no evidence for the need of feeder links around 1.4 GHz was demonstrated. Furthermore, ITU-R studies have shown that the introduction of feeder links around 1.4 GHz would imply great difficulties for the protection of both the active and passive services having an allocation in the frequency bands between 1 350 MHz and 1 452 MHz, and that it is very unlikely that these can be solved. Therefore, CRAF supports fully the position of active NOC on this agenda item.
  • 1.31: Particularly the consideration in some proposals to allocate the band 1668-1670 MHz to MSS (Earth-to-space) needs careful consideration. The Conference Preparatory Meeting for WRC-03, CPM-03, (Geneva, 18-29 November 2002) concluded that separation distance of the order of 500 km from a radio astronomy station operating in that band are needed to guarantee protection of that station. This implies that the deployment of MSS stations in that band within CEPT countries is basically not possible, considering the geographical density of radio astronomy stations in Europe. In other regions, this CPM-03 conclusion may imply restrictions on MSS as well.

    8. Report of 36th CRAF meeting [27-28 March 2003]

    The 36th CRAF meeting was held on 27-28 March 2003 at the EISCAT Headquarters in Kiruna, Sweden.

    Key items discussed were:
    - Notification of radio astronomy stations with the ITU-R, or their update, is urgently needed, since without proper notification with ITU-R radio astronomy stations may not have the right to claim protection against interference from various sources, specifically space stations. Consultation with the national Administrations is required, since only they are mandated to file these notifications with the ITU-R.
    - Broadcasting-Satellite in the band 620-790 MHz: France (Astrium) proposed a project for satellite broadcasting (BSS) in the band 620 to 790 MHz which led to concern in other CEPT Administrations. CRAF and France are studying the compatibility between BSS and radio astronomy in the bands 608-614 MHz and 1330-1427 MHz in the CEPT project team SE27.
    - Revision of broadcasting channel plan in ITU-R Region 1 (Stockholm 1961): The ITU-R will convene a Regional Radiocommunication Conference in 2004/05 (RRC-04/05) on the planning of terrestrial broadcasting in the VHF/UHF bands, for the combined planning area covering the European Broadcasting Area, the African Broadcasting Area, and the countries outside the African Broadcasting Area which are parties to the Regional Broadcasting Agreement Geneva-1989. The interests of radio astronomy in the band 608-614 MHz were explained to CEPT project team FM24. It was recommended that the administrations take the radio astronomy interests into account when developing their proposals for the conference.
    - Power Line Transmissions, PLT or PLC: The PLC developments may have crucial consequences for, i.e., the perspectives for LOFAR: according to the PLC radiation limits that are currently considered, LOFAR may well become `PLC-limited'. In a Joint Working Group ETSI, CENELEC and CISPR are currently working on the definition of the radiation- and product norm for PLC. CRAF is concerned that in this Joint Working Group the concerns of radio astronomy will not be considered properly.
    - Global Transmission System experiment on the International Space Station, GTS: the Russian GTS administration recognized that the frequency choice of 1428 MHz is wrong and stated that this band will not be used by the system, which is currently on board of the International Space Station.
    - The progress of SE24 compatibility studies on the Ultra Wide Band transmissions and Short Range Radar at 24 GHz and 77 GHz are being monitored with great attention and concern by CRAF. CRAF participates actively in the studies within CEPT on these issues.
    - It is foreseen that a major revision of the CRAF Handbook for Radio Astronomy will be published early in 2004.
    - CRAF participates actively in CEPT discussions on common European positions on WRC-03 agenda items relevant for radio astronomy. CRAF supports the European Common Proposals for this conference. Several CRAF members will participate in the WRC-03 conference.

    9. Abbreviations used in this Newsletter

    ALMA = Atacama Large Millimetre Array
    BSS = Broadcasting-Satellite Service
    CENELEC = European Committee for Electrotechnical Standardisation
    CEPT = Conference of European Post and Telecommunication administrations
    CISPR = International Special Commitee on Radio Interference
    CPM = Conference Preparatory Meeting (ITU)
    CPM-03 = CPM for WRC-03
    CRAF = Committee on Radio Astronomy Frequencies (ESF)
    DSL = Digital Subscriber Line
    ECP = European Common Proposal (WRC)
    EESS = Earth Exploration-Satellite Service
    EISCAT = European Incoherent Scatter Scientific Association
    EMC = Electro-Magnetic Compatibility
    ESF = European Science Foundation
    ETSI = European Telecommunication Standardisation Institute
    FS = Fixed Service
    GSO = Geostationary Orbit
    GTS = Global Transmission System Experiment
    ITU = International Telecommunication Union
    ITU-R = International Telecommunication Union - Radiocommunication Sector
    LAN = Local Area Network
    LOFAR = Low Frequency Array
    MSS = Mobile-Satellite Service
    NGSO = Non-GSO
    NOC = No-Change
    PLC = Power Line Communication
    PLT = Power Line Transmission
    RAm = Radio Amateur Service
    RAS = Radio Astronomy Service
    RFI = Radio Frequency Interference
    RR = Radio Regulations (ITU-R)
    RRC = Regional Radiocommunication Conference (ITU-R)
    SKA = Square Kilometre Array
    SRR = Short Range Radar
    UHF = Ultra High Frequency (300 to 3000 MHz)
    VHF = Very High Frequency (30 to 300 MHz)
    VLBI = Very Long Baseline Interferometry
    WRC = World Radiocommunication Conference (ITU-R)
    WRC-03 = WRC 2003


    Editorial Group: R.J. Cohen, P. Scott, W. van Driel

    Last modified: 7 February, 2005