CRAF Newsletter 2004/1

June 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.


Contents


1. Chairman's corner

Many old as well as new opportunities are going to challenge an easy start of my chairmanship.

Among the new good ones, for 5 years from mid 2004, CRAF can count on a completely new budget funded by RadioNet (a European Integrated Infrastructure Initiative), under the Network Activity NA8 label. Firstly, it will open novel chances for a better understanding and more fruitful compliance between the radio astronomers needs and our work, and secondly it will provide a solid contribution to those CRAF members having difficulties with their travel expenses.

Under RadioNet and IUCAF sponsorship we are also planning to organize a Summer School on Radio Astronomy and Spectrum Management in 2005. Our major aim there will be to involve new people, well motivated to learn from the “pillars of strength” that at present support all CRAF activities, the unwritten art and the hard rules, governing the Frequency Protection arena.

In the meantime, in late October this year, the ESF is sponsoring our workshop on “Active Protection of Passive Radio Services: towards a concerted strategy”, that we are organizing in Cagliari, Sardinia, 28th-29th October 2004. We expect there to tighten up the connection with all other Passive Users of the radio spectrum, in such a way that we can always present a common position with respect to our counterparts at all the international tables of consultation and decision making. A fragmented policy instead would weak the positions of each of us, but much more than that, it would be the best arm of attack in the hands of our competitors.

At the same time many old troubles will require a lot of resources in trying to preserve our right to explore the natural level of background noise. Among them are the case of the Ultra Wide Band devices, in particular Short Range Radars, Power Line Communication, as well as a few others that will require careful attention.

My congratulations for the work done by Wim van Driel, the previous CRAF chairman, who opened up these new good opportunities. I will put all my effort into advancing them in the best interest of Radio Astronomy and related sciences.

Roberto Ambrosini - Istituto di Radio Astronomia, Bologna


2. Report of the 38th CRAF meeting [15-16 April 2004]

The 38th CRAF meeting was held on 15-16 April in the “Salle de Conseil” of the Paris Observatory.

Key items discussed were:
- An ESF sponsored workshop is to held on October 28-29, 2004, at Cagliari, Sardinia, Italy. The aim of this workshop to create closer ties with other so-called passive services using the radio spectrum for Earth exploration by satellite, atmospheric sensing, etc.). There are many common regulatory aspects relevant to the protection of passive measurements, which are due to similar sources of pollution in the electromagnetic environment;
- Broadcasting-satellite, BSS, developments in the band 620-790 MHz: based on the conclusions in ITU-R WP7D, the CEPT developed a report on the compatibility of this BSS development and radio astronomy;
- Revision of Stockholm 1961 – Regional Radiocommunication Conference 04/05: the protection of radio astronomy in the band 608-614 MHz needs to be properly retained;
- Extension of the frequencies used by the Iridium satellite system: CRAF has brought this issue to the attention of the CEPT, considering the ESF/CRAF-Iridium Agreements concluded in 1998. The ECC responded to CRAF with a recent report with results of monitoring observations done at the Satellite Monitoring station at Leeheim, Germany. The frequency extension confirmed by Leeheim needs further analysis;
- The development of Ultra-Wide Band, UWB, below 10.6 GHz remains a source of great concern for CRAF. In particular, the pressure on the protection of radio astronomy in frequency bands to which footnote 5.340 applies (“all emissions are prohibited”) enhances these concerns. This issue is currently addressed in ITU-R TG1/8 and CEPT ECC TG3;
- The discussions on short range radar at 24 GHz (SRR) are a major concern: CRAF noted significant difficulty within CEPT to come to an agreed position on this matter. CRAF also noted that statements by the European Commission that all services need to be protected from SRR interference are jeopardized by this same EC policy. The passive services contributed actively and with a concerted view to these discussions;
- Power Line Transmissions, PLT: The PLT developments may have crucial consequences for, e.g., the perspectives for LOFAR: according to the PLT radiation limits that are currently considered, LOFAR may well become “PLT-limited”.


3. ESF Review of CRAF 2003

In accordance with its Statute and the Charter of CRAF, ESF conducted at the end of 2003 the quinquennial review of CRAF necessary for the extension of CRAF’s mandate as an ESF Expert Committee.

ESF assembled a Review Panel of international experts under the chairmanship of ESF-PESC Committee member Dr Massimo Martinelli of IPCF-CNR Pisa. The Panel met on 30-31 October, and considered the progress and achievements of CRAF since the last Review in 1996. The Panel received a statement from CRAF, a range of CRAF information and publications and held an interview with the then chair of CRAF, Wim van Driel.

The Review Panel found the work of CRAF and the Frequency Manager to have been exceptionally well conducted and effective.

The major recommendations of the Review, which have been fully accepted by the ESF Executive Board, were that the mandate of CRAF be extended until the end of 2008, that a workshop with other passive RF spectrum users be organised (see elsewhere in this newsletter) and that an Memorandum of Understanding (MoU) be drawn up for organisations participating in CRAF (in preparation).

The Report of the Review Panel was adopted by the ESF Executive Board in November 2003.


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

An ESF sponsored workshop on "Active Protection of Passive Radio Services: towards a concerted strategy" will be held on 28-29 October 2004 at Cagliari, Sardinia, Italy.

The aim of the present workshop is to bring together members of the different passive services (radio astronomy and remote sensing), with responsibilities for frequency managment, in order to develop a concerted strategy to deal with issues of common concern. Such a strategy is urgently needed to defend our common resource, the passive frequency bands, particularly in policy-making discussions at national and international levels.

The provisional list of speakers includes Prof. Willem Baan (Astron), Dr. Jim Cohen (JBO), Dr. Bernard Lazareff (IRAM), Dr. Edoardo Marelli (ESA), Dr. Jerome de la Noe (Observatoire de Bordeaux), Jean Pla (CNES), Prof. Hans Richner (WMO), Dr. Klaus Ruf (DLR), Dr. Titus Spoelstra (CRAF), Dr. Wim van Driel (IUCAF), and Robert Wolf (EUMETSAT). Between them they represent space-based and ground-based remote sensing, the meteorology community, and radio astronomy. The workshop will conclude with a visit to the site of the 64-m Sardinia Radio Telescope, currently under construction near Cagliari.

For further information about the Workshop please contact the SOC Chair, Jim Cohen (University of Manchester, Jodrell Bank Observatory, Macclesfield, Cheshire SK11 9DL, England, tel.:(+44)1477-571321, telefax (+44)1477-571618, Email: rjc@jb.man.ac.uk).


5. LOFAR - a collection of challenges

The Low Frequency Array LOFAR (Low Frequency Array) is a new-generation radio telescope that will operate in the frequency range 10 - 240 MHz. LOFAR will use phased-array techniques to achieve far higher sensitivity, frequency and spatial resolution, than any existing low-frequency radio telescope. Besides being a facility for radio astronomy, it can also be used for research in geophysics and agriculture.

LOFAR was originally conceived as a multi-national project, but due to significant national and local government funding ASTRON was able to start the project on its own in the Netherlands. ASTRON has already pioneered small scale phased array systems consisting of many elements for possible use in next generation telescope systems like the SKA, the Square Kilometre Array which is expected to be built in the next decade. Therefore, the idea of constructing LOFAR from a large number of antennas which are spread over a large area, together forming a sensor array with exquisite properties, was a logical step.

The LOFAR system design includes an optimal combination of imaging and calibration properties together with system partitioning based on feasible building blocks. About a quarter of the antennas are concentrated in a central core 320 hectares in area. "Arms" on which some 50 stations are placed stretch out from this core. There are about 100 ‘low’ and ‘high’ band antennas per station (each station covers 4 hectares), with increasing distances between stations. The maximum distance between stations is about 300 kilometres.

The individual antennas having a height of up to 2 meters are omnidirectional, but the combination of all antennas in a station allows the formation of a beam that can be electronically steered anywhere on the sky, by using phase control of the antenna signals. It is even possible to make multiple beams (say 8 beams) that can be placed independently anywhere on the sky. No mechanically moving parts are involved. The antennas are followed by as many low noise amplifiers. The received signals are collected, digitized and combined at the antenna station where they are also inserted in a data stream that channels all data along an "arm" to a central processing facility with an overall data rate of 20 Terabits per second. Further data reduction reduces this rate at the input of the central processing facility to about 200 Gigabits per second which are further processed using a real-time supercomputer.

LOFAR will be the first operational radio telescope of a new group of new technology radio astronomy instruments. It leads the way in developing novel ways to operate large scale facilities. One such aspect is the multiple beam capability. This effectively means that LOFAR will behave as 8 independent telescopes, each with its own observing schedule. LOFAR will be controlled and data collected and made available through the internet for use all over the world. Radio astronomers in the Southern Hemisphere should be able to use their assigned beam to access parts of the sky that remain invisible from their part of the world.

In the spring of 2004 a test station was erected consisting of 64 antenna elements and put into operation at the site where the central core is planned. The test station has delivered all-sky imaging capability and has provided a stream of data allowing the evaluation of instrumental and calibration concepts. Very encouraging results have been obtained within a brief period.

LOFAR is a challenge in various aspects: in imaging, calibration and other key technologies, in data communication scenarios, in the development of radio quiet environments for the individual sites (considering also that the considered communication routes routes run past schools, business parks, residential areas, etc.).

Any radio telescope aims to observe the Universe at the highest possible sensitivity. This is a specific challenge in the frequency range of interest for LOFAR. The radio spectrum is crowded by the emissions from broadcasting, amateur radio, mobile telecommunication and aeronautical transmitters. Advancements in understanding how to mitigate the interference has bolstered the confidence that LOFAR will be able to deliver the promised scientific results. An important aspect is that the receiver amplifiers behave linearly across the entire range of signal strengths that are to be expected. In addition, the signals are to be digitized with sufficient precision (in number of bits and spectral resolution) to enable the recognition and elimination of disturbing signals. The public introduction of broad band radio-noisy systems in the LOFAR frequency range requires, however, special attention: power line communication systems will generate broad band noise, that may be a serious threat considering the aggregate noise of installed systems in populated areas. Removing broadband noise-like interference is virtually impossible.

LOFAR is planned to become fully operational by the end of 2007. This is a good time to start operations in a frequency range where the signals are affected significantly by the Earth’s ionosphere since at that time the solar activity is minimum. Before that there will be stages in the project where intermediate results can be gathered that will allow fine-tuning of algorithms and techniques.


6. Short Range Radar, SRR

The European Commission, EC, has identified automotive SRR systems among others as a significant technology for the improvement of road safety in Europe. SRR at ~24 GHz is one of the key issues of the e-Safety programme of the EC and is seen as a major instrument to improve road safety.

A major difficulty with SRR at ~24 GHz is that there is no allocation in the ITU-R Radio Regulations for the SRR application (which uses a bandwidth of 5 GHz). Compatibility studies done within CEPT have shown that SRR at ~24 GHz is incompatible with radio services in the frequency ranges covered by SRR, including radio astronomy in the frequency range 22.01-24.0 GHz. Furthermore, as noted in our previous Newsletter, the frequency band 23.6-24.0 GHz is covered by ITU Radio Regulations footnote 5.340 which states that all emissions are prohibited.

The EC has mandated the CEPT "to undertake all necessary work to ensure the availability of harmonised radio spectrum in the European Union for the deployment of automotive short-range radar systems to be used for improving road safety. In order to expedite the introduction of this type of radio application in the EU, additional appropriate frequency bands ought to be considered for a limited temporary introduction of SRR systems, besides the identification of permanent SRR spectrum bands for the long term." This mandate includes a statement that the protection of other services operating in or near the temporary band(s) must be ensured by introducing specific operating limits for such SRR systems and by moving their operation to the permanent band by a fixed transition date."

The CEPT ECC has identified the frequency range 77-81 GHz as the permanent frequency band for SRR in Europe, and this band should be made available not later than 1 January 2005 (see ECC Decision (04)03). It needs to be noted that the EC strongly favours the introduction of SRR at ~24 GHz since the technology is cheaper at the moment. The idea is that at a later stage SRR should move from ~24 GHz to ~79 GHz. When SRR is deployed at ~79 GHz, the ECC Decision (04)03 states that studies have concluded that "regulatory measures could be identified enabling the coexistence between SRR in the frequency band 77-81 GHz and the Radio Astronomy Service, which is dependent on the aggregated impact of SRR devices transmitting in the direction of a radio astronomy station". The development of such regulations is very likely to be a matter for National Administrations only.

In April 2004, the CEPT Working Group FM concluded on SRR that:
(1) the maximum penetration of SRR at ~24 GHz should not exceed 5.9%;
(2) the absolute reference date after which SRR at 24 GHz must no longer be placed on the market is 2012;
(3) SRR must be equiped from the beginning with an automatic deactivation to switch off its transmission within a specified distance from a radio astronomy station to protect concerned radio astronomy sites;
(4) the centre frequency 24.125 GHz is used for the UWB as well as for the narrow band component of the system;
(5) a review process be carried out by the Radio Spectrum Committee in 2009 to consider actual market penetration level and any action to be taken in order to avoid interference if the actual market penetration level is higher than expected.

Further provisions need to be developed to provide the necessary regulatory and legal bases for this scenario.

Items 1 and 2 of this concluded scenario are important for the EESS (passive). Item 3 is essential for radio astronomy.

The passive services participated actively and with great concern in the discussions. CRAF considers that the conclusions of WG FM are probably the least bad scenario for radio astronomy. However, it should be noted that the introduction of SRR at ~24 GHz is not consistent with the EC mandate that requests protection of existing services and it forces EU Member states to agree with a position in conflict with an international treaty, i.e. the ITU Radio Regulations (such as footnote 5.340). Therefore, CRAF follows the developments with much attention and concern since it seems that the EC seems to be prepared to relax exisiting regulations to reach its objectives.


7. Henceforth RadioNet Funding

RadioNet is an EC initiative to support state-of-the-art research infrastructures, funded within the 6th Framework Programme for Community Research and Development, 2002-2006 (FP6). The Integrated Infrastructure Initiative, RadioNet, has pulled together all of Europe's leading astronomy facilities to produce a focused, coherent and integrated project that will significantly enhance the quality and quantity of science performed by European astronomers.

RadioNet has the following networking activities, which include frequency management:

The objectives of the pan-European radio frequency management networking activities under NA8 are:

CRAF is actively seeking to intensify and formalize its relation with the European Commission, which is at present rather incidental. The RadioNet initiative is one of the in struments for CRAF to improve its relations with the European Commission whose role on radio frequency matters is incresing.


8. Abbreviations used in this Newsletter

BSS = Broadcasting-Satellite Service
CEPT = Conference of European Post and Telecommunication administrations
CNES = Centre National d'Etudes Spatiales (France)
CRAF = Committee on Radio Astronomy Frequencies (ESF)
DG = Directorate General (European Commission)
DLR = Deutsches Zentrum für Luft- und Raumfahrt (Germany)
EC = European Commission
ECC = Electronics Communications Committee (CEPT)
EESS = Earth Exploraration-Satellite Service
ESA = European Space Agency
ESF = European Science Foundation
EU = European Union
EUMETSAT = European Meteorological Satellite Organization
IPCF-CNR = Istituto per i Processi Chimico-Fisici - Consiglio Nazionale delle Ricerche (Italy)
IRAM = Institut de Radio Astronomie Millimétrique
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)
JBO = Jodrell Bank Observatory (UK)
LOFAR = Low Frequency Array
PESC = Standing Committee for Physical and Engineering Sciences (ESF)
PLT = Power Line Transmissions
RAS = Radio Astronomy Service
RFI = Radio frequency interference
SKA = Square Kilometre Array
SRR = Short Range Radar
TG = Task Group (ITU)
UWB = Ultra Wide Band
WG FM= Working Group Frequency Management (CEPT)
WMO = World Meteorological Organization
WP = Working Party (ITU-R)
WRC = World Radiocommunication Conference (ITU-R)
WRC-03 = WRC 2003
WRC-07 = WRC 2007
WRC-10 = WRC 2010


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


Last modified: 10 June, 2004