CRAF Newsletter 1998/3

September 1998

The European Science Foundation is an association of its 62 member research councils and academies in 21 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. Editorial
• 2. ESF-Iridium LLC Framework Agreement
• 3. ESF Press Release
• 4. Evaluation
• 5. Abbreviations

1. Editorial

On August 11th, 1998, a framework agreement was signed by the European Science foundation, ESF, and Iridium LLC, aiming at the protection of radio astronomy in the band 1610.6 - 1613.8 MHz from out-of-band emissions of the satellite transmissions of the Iridium system in the band 1621.35 - 1626.5 MHz.

The ESF signed the agreement on behalf of CRAF.

This development is new, and other interesting things have happened since, but the problem is old. Almost a decade ago radio astronomers were addressed with the request to agree to a system of "invisible" satellites, planned to operate in one of their bands. This frequency band had a secondary allocation to radio astronomy at that time, and the satellite system was planned to operate under another secondary allocation: Radio Determination Satellite Service (secondary at least in ITU-Region 1, Africa and Europe). The 1992 World Administrative Radio Conference solved the problem: the Radio Astronomy Service was upgraded to primary world-wide, and for the Iridium satellite system a more correct allocation was made: Mobile Satellite Service, MSS. And MSS became co-primary with radio astronomy in the band 1610.6-1613.8 MHz, however only in the Earth-to-space direction; satellite transmissions remained secondary in an adjacent band, i.e. 1613.8-1626.5 MHz. To make the solution complete, a footnote to protect Radio Astronomy from RDSS, which formerly existed for Region 1, was expanded to MSS, and, even more importantly, expanded to include also Region 2, the Americas. This solution was very much welcomed by radio astronomers, but it did not hold forever. After a few years, when it became clear to the satellite designers that protection of Radio Astronomy was very difficult to achieve, they tried to come from a technical to a negotiated solution.

To make a long story short: with the adoption of the framework agreement, the ball is back in their field. The protection criteria of ITU-R Recommendation 769 are enforced again and the long-term protection obligation set forth in the framework agreement requires major technical improvements. Improvements on both sides: it was agreed that CRAF and Iridium LLC undertake collaborative technical studies addressing possible reduction of Iridium satellite out-of-band emissions as well as reduction of the susceptibility of radio astronomy receivers to Iridium interference.

The same technical study will also deal with possible interference from the 23 GHz inter-satellite link transmissions of the Iridium satellites. Until today Iridium refused to provide useful information, but CRAF will not risk a late surprise. Beyond the co-ordination of the 1.6 GHz service links, necessary for licensing, CRAF was able to create awareness of the problem at the European administrations, which accompanied the negotiations. And this issue will be part of the further discussions, to which CRAF already took the initiative to invite.

The latest news, however, makes us vaguely consider the possibility that all the effort and all the strain, all the sleepless nights may have been in vain. After so many years of hard work, after terrible time pressure during negotiations, and after a world-wide advertising campaign the start of the system into operation was delayed by Iridium due to technical problems. And most recently, one of the two so-called strategic partners of Iridium in Europe, the German Vebacom Holding, is reported to try to sell off their nine percent share of Iridium. GOOD LUCK; VEBACOM!!!!

T.A.Th.Spoelstra - Dwingeloo

2. ESF-Iridium LLC Framework Agreement

Between November 1997 and August 1998, CRAF and Iridium LLC worked in several meetings under the auspices of the ERC Milestone Review Committee, MRC towards an agreement to aid European administrations in their licensing work for the Iridium satellite system. CRAF represented the interests of the European radio astronomy community. The key issue in the discussions was the protection of radio astronomy in the frequency band 1610.6-1613.8 MHz from unwanted emissions from the Iridium satellite system intending to operate in the band 1621.35-1626.5 MHz. During high traffic load of the Iridium satellite system, the intermodulation products are expected to exceed the accepted levels for harmful interference for radio astronomy. The regulatory basis for these discussions was the ITU-R Radio Regulations, Recommedation ITU-R RA769-1 as well as the European Commission's licensing directive (97/13/EC) and relevant ERC decisions.

In the course of the discussion process, the MRC adopted on March 27, 1998, its Recommendation #04 which could serve a condition to be incorporated in a license to Iridium LLC to protect the Radio Astronomy Service in Europe. In summary, the conditions are:

• until 1 March 1999: the out-of-band emissions from the transmissions of the Iridium System shall be below the levels of detrimental interference given in ITU-R Recommendation RA769-1, i.e. below -238 dB (Wm^-2Hz^-1) for single dish radio telescopes.
  
• from 1 January 2006: the out-of-band emissions from the transmissions of the Iridium System (space-to-Earth) into the radio astronomy band 1610.6-1613.8 MHz shall be below the levels of detrimental interference given in ITU-R Recommendation RA769-1, i.e. below -238 dB (Wm^-2Hz^-1) for single dish radio telescopes.
  
• between 1 March 1999 and 1 January 2006: an agreement between CRAF and Iridium LLC should be reached on the levels of detrimental interference accepted for specific time windows. In case no agreement can be reached, the MRC will recommend by 1 March 1999 that Iridium meets:
  (a) an interference level of -238 dB(Wm^-2Hz^-1) for a portion of the day to be determined, and
  (b) an interference level between -238 dB(Wm^-2Hz^-1) and -215 dB(Wm^-2Hz^-1), to be determined, for the remaining portion of the day.

On August 11, 1998, a framework agreement was reached between the European Science Foundation on behalf of CRAF and Iridium LLC. This agreement is a formalization of MRC Recommendation #04. The agreement is legally binding for the parties and it contains also guidelines for dispute resolution. The parties of the agreement agreed to collaborate to find adequate and technically practical solutions for reducing both the out-of-band emissions of the Iridium satellite system and the susceptibility of radio astronomy equipment to these emissions. The framework agreement also commits both parties to reaching a further agreement by 1 March 1999 on transitional arrangements, covering the number of hours each day, during which Iridium unwanted emissions are to be restricted and an agreed maximum interference level at other times, for the period 1 March 1999 to 31 December 2005. This second agreement should include a workplan for the technical collaboration between CRAF and Iridium LLC.

CRAF has taken the initiative to start negotiations towards this second agreement already. It expects difficult negotiations.

3. ESF Press Release

The Committee on Radio Astronomy Frequencies, CRAF, is an associated committee of the European Science Foundation, ESF. The ESF in its parent role published a press release where it explained the milestone reached.

4. Evaluation

In the upcoming negotiations towards an interim time sharing agreement, it is CRAF's position that given the fact that radio astronomy used the 1.6 GHz frequencies before the Iridium satellite system, the latter has to comply with the requirements of the existing radio astronomy observatories. This is especially reflected in ITU-R Footnote S5.372 by which the Radio Astronomy Service is explicitely protected. In order to safeguard radio astronomy in Europe, time windows need to contain both night and day time. Given the use of the 1610.6-1613.8 MHz band in Europe more than 50% of the time the unwanted emission from the Iridium satellite system shall be below the levels for detrimental interference of ITU-R Recommendation RA769-1.

Collaborating in technical work to be defined in the second agreement does not imply that only radio astronomers have to improve their systems (what they continuously do!), but also that Iridium LLC has to improve the design of its satellites to comply with the agreed criteria.

CRAF shares the opinion that it is difficult to understand that radio astronomers are expected to sacrifice quality of observations, while the frequency channels from which the interference originates are outside the radio astronomy band 1610.6-1613.8 MHz and protection is guaranteed by ITU-R Radio Regulations footnote S5.372.

5. Abbreviations used in this Newsletter

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