CRAF Newsletter 2002/1

June 2002


The European Science Foundation (ESF) acts as a catalyst for the development of science by bringing together leading scientists and funding agencies to debate, plan and implement pan-European scientific and science policy initiatives.
The ESF is the association of its 70 major national funding agencies devoted to scientific research in 27 countries. The ESF brings European scientists together to work on topics of common concern, to coordinate the use of expensive facilities, and to discover and define new endeavors that will benefit from a co-operative approach.
The ESF represents all scientific disciplines: 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 and coordination 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

In previous Newsletters the point was made that the radio astronomy community regards the criteria given in Recommendation ITU-R RA.769 for the protection of the radio astronomy service as absolutely necessary. In recent discussions at international level, however, there has been a tendency by other spectrum users to try to limit the protection of our entire service to that of certain radio astronomy sites (observatories): only those actually in operation at a certain frequency or those registered with the ITU before a certain date in the near future. As such a limitation is not supported by the ITU Radio Regulations and would seriously endanger the protection of future radio astronomy sites, some of which will host telescopes of unprecedented size and sensitivity (like ALMA, LOFAR and SKA), it is not acceptable to CRAF. For us the issue is the protection of the radio astronomy service, not just its sites (see also section 6 of this Newsletter).

Wim van Driel - Paris Observatory


2. Report of 34th CRAF meeting [8-9 April 2002]

The 34th CRAF meeting was held on 8-9 April 2002 at the Dwingeloo Radio Observatory, the Netherlands.

Key items discussed were:
- GLONASS: in 1993 the GLONASS administration and IUCAF reached an Agreement for a step-by-step process to clean the radio astronomy band 1610.6-1613.8 MHz from GLONASS interference. It was noted that GLONASS is working to keep the Agreement. Within IUCAF it is considered time to evaluate the present interference situation in the mentioned band. CRAF fully supports this.
- Global Transmission System Experiment on the International Space Station, GTS: CRAF expressed its concerns to ESA on the space-to-Earth transmissions from the GTS experiment at 1428 MHz, noting that it is adjacent to the passive band 1400-1427 MHz and in conflict with the ITU Radio Regulations. ESA informed CRAF that it brought the issue of the GTS experiment to the attention of the Russian Space Authorities, who assigned the frequency of 1428 MHz to the experimenter. CRAF also brought the issue to the attention of the CEPT GMR. European radio astronomy stations operating at 1.4 GHz are monitoring the band 1400-1427 MHz to see whether the GTS transmissions are causing interference (see further section 4).
- The progress of SE24 on the Ultra Wide Band and 24-GHz Short Range Radar issues is monitored with great attention and concern by CRAF. CRAF participates actively in the studies within CEPT on these issues.
- GONETS: Russia is developing a MEO satellite system, which will operate in the band 387-390 MHz (space-to-Earth). CRAF has requested CEPT SE28 to study the compatibility of this system with the radio astronomy service in the band 406.1-410 MHz.
- CRAF initiated a discussion on the definition of reference bandwidths appropriate for the protection of the radio astronomy service. IUCAF is discussing this issue at global level, in consultation with CRAF.
- CRAF continues to participate actively in CEPT discussions on European Common Positions on WRC-03 agenda items relevant for radio astronomy.
- The CRAF database facilities for interference and spectrum occupancy reports from observatories is now operational and data from observatories in the CRAF format for these databases is are eagerly awaited by the CRAF clearing house.


3. CRAF Handbook for Frequency Management

ESF has recently published the CRAF Handbook for Frequency Management, edited by Titus Spoelstra.

This Handbook reviews various aspects of frequency management relevant for radio astronomy and other scientific applications of radio frequencies, addressing the professional scientific community and a wide readership outside it.

For the sake of the continuation and progress of the science of radio astronomy, the editor of the Handbook adopted the principle that frequency protection of the radio astronomy service should be maintained at least to the level that has been applied until now.

The Handbook provides a comprehensive review of the organisations involved in frequency management and their interrelationship, guidance for scientists for frequency management in their organisations and positions on several frequency management issues, such as on defective space systems. It also includes a perspective of frequency management developments.

The Table of contents of this Handbook is in summary:

For more information about the CRAF Handbook for Frequency Management, please contact the committee's secretary, T.A.Th.Spoelstra.


4. Global Transmission System experiment at 1428 MHz

"Transmitting from Space: the Global Transmission Services Experiment" is the title of an article by Mr. Jens D. Schiemann in the ESA/MSM "On station" Newsletter (Number 5, March 2001) explaining the Global Transmission Service (GTS) Experiment Payload to be installed on the International Space Station, ISS. This system is intended for time service and it is planned that it will emit (space-to-Earth) using the frequencies 400.1 MHz and 1428 MHz. The system started test-operations mid-February 2002 and is now ready for full operation.

According to the ITU Radio Regulations, the band around 400.1 MHz is allocated to the international time service. The band 1427-1429 MHz, however, does no allow any use by the GTS system, as it contains no allocation to any radio communication service for space-to-Earth transmissions.

The bandwidth of the transmissions at 1428 MHz by the GTS system is 1 MHz. This could imply that the GTS system will generate unwanted emission into the band 1400-1427 MHz, one of the most important bands for radio astronomy (not to mention for ESA's own SMOS satellite), into which all emissions are explicitly prohibited by Footnote 5.340 of the ITU-R Radio Regulations.

The emissions of the GTS system at 1.4 GHz are in clear conflict with the ITU-R Radio Regulations, which is an international treaty to which all ESA Member States are signatories.

CRAF brought this to the attention of ESA and drew also ESA's attention to Article 4.4 of the ITU-R Radio Regulations, which states that "Administrations of Member States shall not assign to a station any frequency in derogation of either the Table of Frequency Allocations in this Chapter or the other provisions of these Regulations [...]".

CRAF considers that violating the ITU-R Radio Regulations by emissions from the International Space Station at 1.4 GHz is therefore clearly incompatible with the internationally adopted Regulations for the use of the electromagnetic spectrum to which ESA, through its Member States, has bound itself.

In September 2001, CRAF requested, as a matter of urgency, a revision of the frequency scenario for the GTS experiment, to make it fully compatible with the ITU-R Radio Regulations. Obviously, no emissions whatsoever from the International Space Station at 1.4 GHz should be allowed to take place at any time, not even as an `experiment'.

ESA responded that it had brought the issue of the Global Transmission experiment to the attention of the Russian Space Authorities, who assigned to the experimenter the frequency of 1428 MHz, for further discussions `to avoid violation of existing treaties'.

CRAF discussed the issue further with the CEPT General Milestone Review Committee, GMR, and some Administrations of ESA Member States and requested their attention to the issue. In addition European radio astronomy stations operating at 1.4 GHz have started to monitor the International Space Station to investigate interference events in the band 1400-1427 MHz to identify interference from the GTS experiment.


5. GONETS

The Russian LEO satellite communication system GONETS was developed within the framework of the Russian Federal Space Program under the guidance of the Russian Space Agency. The GONETS system provides a fixed or mobile facility to receive and transmit messages from any point of the globe, providing a personal communications service. The system is intended for civil and military use.

Some parameters of the GONETS system are given in Table (source: official GONETS website).

Table 1: some GONETS system parameters
Type of orbit Circular
Height 1400 km
Inclination 82o.5
Number of satellites (planned to be in use in 2005) 48
Frequency band for space-to-Earth transmissions 387 - 390 MHz
Type of modulation GMSK
Number of servicing beams of satellite 1
Fixed direction antenna or non-fixed Fixed
Maximum spectral power density per carrier -37.4(dBW/Hz)
Number of simultaneously operating carriers 24
Maximum gain of transmitting antenna of the satellite 2(dBi)
Relative level of unwanted emissions -100(dB)
Radiation pattern diagram of transmitting antenna ND

Footnote 5.208A concerns the protection of the radio astronomy bands 150.05-153 MHz, 322-328.6 MHz, 406.1-410 MHz, and 608-614 MHz from unwanted emissions from space stations in mobile satellite services using the frequency band 387-390 MHz. It states that "In making assignments to space stations in the mobile-satellite service in the band 137 - 138 MHz, 387 - 390 MHz and 400.15 - 401 MHz, administrations shall take all practicable steps to protect the radio astronomy service in the bands 150.05 - 153 MHz, 322 - 328.6 MHz, 406.1 - 410 MHz and 608 - 614 MHz from harmful interference from unwanted emissions. The threshold levels of interference detrimental to the radio astronomy service are shown in Table 1 of Recommendation ITU-R RA.769-1".

From the system parameters of the GONETS system given in Table 1, in particular its orbital parameters, it can be deduced that the visibility radius of a GONETS satellite is of the order of 4000 km, which implies that a Europe-wide approach is necessary to study the compatibility issue between the GONETS system and the radio astronomy service, taking into account the information given above and relevant ITU-R documentation.

Since the issue of the compatibility between the GONETS system and the radio astronomy service had not yet been addressed within CEPT and footnote 5.208A explicitly states that systems like GONETS must protect radio astronomy, CRAF requested CEPT ECC project team SE28 to study this issue.


6. Protection of "services" or stations

To satisfy WRC-03 agenda item 1.15 and related with it Resolution 604 (WRC-2000), discussions are developing to clarify the protection criteria for radio astronomy observations in the band 4990-5000 MHz, in particular the issue of regulating the protection of specific radio astronomy stations rather than the entire radio astronomy service. Some consider it an issue to regulate the extent of the area around a radio astronomy station, and to which radio astronomy stations exactly the protection criteria apply. This question applies specifically to transmissions from space.

This issue is important indeed. Some go as far as stating that "radio astronomy stations to be protected ... are those for which complete notification information has been received by the Bureau prior to the 31st December 2003 or the date of reception of the complete advance publication information of the GSO or non-GSO RNSS systems, whichever is the latest".

CRAF has great difficulties which such an opinion, since it hampers development of future radioastronomy facilities and the progress of the science of astronomy. It is of course important that radio astronomy stations are properly notified at the Radiocommunication Bureau of the International Telecommunication Union, ITU, but setting a specific limiting date for their notifiaction in the context of one specific compatibility issue may well create insurmountable difficulties.

CRAF considers that the ITU Radio Regulations provides regulations for the protection of radiocommunication services, not of specific individual stations. Therefore, it is of the opinion that limiting protection to only those stations of a particular radiocommunication service of which the notifications have been received by the Radiocommunication Bureau before a certain date, would lead to great difficulties for the development of that service, e.g. when it needs to put new stations into operation; a well-known example of this is the broadcasting service.

It is uncertain how a proposal to protect only those stations of a particular service of which the notification has been completed before a certain date can be applied to practical situations. Such a scenario will lead to impracticable situations and to an undesirable burden on all affected parties. In the case of the protection of the radio astronomy service from unwanted emissions from RNSS systems (because of the above-mentioned WRC-03 agenda item), which cause approximately the same levels of interference over all parts of the Earth’s surface, the protection of one radio astronomy station should automatically lead to the protection of all stations in that service.

CRAF also considers that the protection of specific radio astronomy stations is an issue for national Administrations and should not be articulated in the ITU Radio Regulations. Therefore, CRAF cannot support proposals that restrict protection against interference to specific radio astronomy observatories only.


7. Power Line Communications

CEPT is in the process of finalizing a study on Powerline Transmissions, Digital Subscriber Line technology (i.e. transmitting high data rates on existing copper wire telecommunication networks), cable communications (including cable TV) and their effect on radiocommunication services. This issue is particular important for frequencies below 30 MHz. Two frequency bands in this range are allocated to radio astronomy: 13.36 – 13.41 MHz and 25.55-25.67 MHz. Since the new giant LOFAR array will also operate at such low frequencies, the issue of power line communications (PLC) is very important for CRAF. An ECC Report on this issue is in the final drafting stage. This Report includes the protection of radio astronomy according to Recommendation ITU-R RA.769. In addition, an ECC Recommendation on this issue is in preparation. This Recommendation provides Administrations with regulatory guidance.

Of serious concern to CRAF is the fact that different pfd levels for PLC have already been adopted in some CEPT countries, some of which are significantly above those of Recommendation ITU-R RA.769. At present, CEPT Administrations did not reach agreement on the draft ECC Recommendation.

Since the PLC issue is not a simple radiocommunication matter but rather an issue of electromagnetic compatibility (EMC), ETSI and CENELEC will work on standard development for PLC. This work is in progress.


8. Abbreviations used in this Newsletter

ALMA = Atacama Large Millimetre Array
CENELEC = European Committee for Electrotechnical Standardization
CEPT = Conference of European Post and Telecommunication administrations
CRAF = Committee on Radio Astronomy Frequencies (ESF)
EC = European Commission
ECC = European Communications Committee
EMC = Electro-Magnetic Compatibility
ESA = European Space Agency
ESF = European Science Foundation
ETSI = European Telecommunication Standardization Institute
GLONASS = Global Navigation Satellite System (Russia)
GMR = General Milestone Review Committee (CEPT)
GSO = Geostationary Orbit
GTS = Global Transmission System
ISS = International Space Station
ITU = International Telecommunication Union
ITU-R = International Telecommunication Union - Radiocommunication Sector
IUCAF = Scientific Committee on the Allocation of Frequencies for Radio Astronomy and Space Science (UNESCO)
LEO = Low Earth Orbit
LOFAR = Low Frequency Array
MEO = Medium Earth Orbit
MSM = Manned Spaceflight and Microgravity (ESA)
pfd = power flux density
PLC = Power Line Communication
RNSS = Radionavigation-Satellite Service
SE = Spectrum Engineering
SKA = Square Kilometer Array
SMOS = Soil Moisture and Ocean Salinity Mission (ESA)
WRC = World Radiocommunication Conference (ITU-R)
WRC-03 = WRC 2003
WRC-2000 = WRC 2000


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


Last modified: 20 June, 2002