The radio astronomy community is busy building and planning a number of giant new generation
radio telescopes (ALMA, LOFAR and SKA), whose sensitivity will surpass that of existing
instruments by several orders of magnitude. During the URSI General Assembly earlier this
year a Resolution was adopted on the establishment of ``International Radio Quiet Reserves''
aimed at protecting the sites of these future instruments (see elsewhere in this Newsletter).
CRAF supports this laudable initiative and will participate in the world-wide efforts that
need to be made towards their definition and establishment.
The 35th CRAF meeting was held on 10-11 October 2002 at the Osservatorio Astronomico di Cagliari,
Italy.
In response to the article in the CRAF Newsletter 2002/1 expressing CRAF's concerns regarding
interference in the 1400-1427 MHz band (the 21cm HI line band) from the Global Transmission
System experiment on board the International Space Station, CRAF received a request from the
ESA Frequency Management Office to publish the following statement to clarify ESA's position:
``ESA has no direct involvement in the operations of GTS. The erroneous
impression that ESA was in charge of the GTS experiment may have been created by
numerous publications about GTS on ESA websites.
The principal responsibilities for implementing the GTS experiment on the
Russian segment of the ISS are as follows:
(a) The GTS flight hardware has been developed - using non-ESA funds - by the
Steinbeiss Transferzentrum Raumfahrt, Stuttgart.
(b) ESA has only funded the flight opportunity (i.e. integration) for GTS on the
Russian Segment of the ISS.
(c) The two GTS transmission frequencies (400.1 MHz and 1,428 GHz) have been
assigned by the Russian Authorities in July 1998.
(d) The Russian Authorities are in charge to operate the GTS onboard the ISS.
(e) The experiment user is the Steinbeiss Transferzentrum Raumfahrt, Stuttgart.
The NASA ISS Frequency Baseline shows that the GTS frequencies were agreed
at ISS coordination level and that the GTS was correctly classified as a
Russian/German experiment (not ESA).
Consequently ESA cannot take any responsibility for interference caused to the
Radioastronomy community as result of the frequency choice in non-compliance
with the ITU Radio Regulations by the Russian authorities. It is suggested that
official regulatory complaints, in accordance with Article 4.4 and Article 15,
be addressed to the Russian Administration rather than to ESA or ESA
administrations.''
ITU-R Region 1 is currently making preparations for an ITU-R Regional
Radiocommunication Conference, RRC, presumably to be held in 2004/2005.
This RRC-04/05 will revise the Stockholm 1961 agreement on the channel arrangements
for the broadcasting service. ITU-R installed a new Task Group, TG6/8, to prepare
a report for the conference (due in 9 months).
CRAF has some concern about the developments w.r.t. the Stockholm channel 38, i.e.
the frequency band 608-614 MHz which has a secondary status in Region 1.
The RRC, however, does not have the mandate to considered secondary services
nor to change the provisions for these services, e.g. for radio astronomy.
In the case of radio astronomy, footnote 5.149 applies
which states that ``administrations are urged to take all practicable steps to protect
radio astronomy ...''. Furthermore, footnotes 5.305 and
5.306 apply to Region 1. 5.305
states that in China radio astronomy has a primary allocation in the band 608-614 MHz.
5.306 states that ``in Region 1, except in the African
Broadcasting Area (see Nos. 5.10 to 5.13), and in Region 3, the
band 608 - 614 MHz is also allocated to the radio astronomy service on a
secondary basis''. This implies that administrations of
those countries that want to protect radio astronomy, take into account the
interests of radio astronomy. These countries need to coordinate
with the countries involved and press the point that the broadcasting
requirements for the conference and the DVB-T stations that are currently planned
under the Chester agreement. Sharing criteria etc. are extensively documented in CEPT.
CRAF will pay further attention to the allocation status of radio astronomy in
the band 608-614 MHz and to the progress of ITU-R TG6/8. CRAF will also participate
in the related CEPT work when required and its CRAF members will
contribute to the related discussions in ITU-R WP7D.
In the CEPT WG FM meeting held in Warsaw during 16-20 September 2002, France (Astrium)
proposed a project for satellite broadcasting in the band 620 to 790 MHz. The system
will use High Elliptical Orbit, HEO, stations. The
report from WG FM reads as follows on this matter:
`A number of Administrations expressed concern about the protection of current and
future services operating in this band, including analogue television, DVB-T and
SAB/SAP. The French Administration assured the meeting that the implementation of
the system would have no impact on the RRC04/05.'
WG FM noted also the concerns expressed by FM PT 24 (Broadcasting issues) and the
reference made by FM PT 24 to the preliminary CEPT position with regard to WRC-03
agenda item 1.37 (to consider the regulatory and technical provisions for satellite
networks using highly elliptical orbits):
`Europe supports the adoption of appropriate technical criteria and associated
regulatory provisions wherever required to insure the protection of terrestrial
services from HEOs in particular in the following bands: 620 – 790 MHz,
Associated studies should continue and be completed in time before WRC-03.'
It seems until now that the plans for satellite broadcasting in 620 – 790 MHz are not
widely supported because of the impact it may have on terrestrial services, i.e.
broadcasting and radio astronomy. WG SE will be asked to carry out sharing studies to
show the impact on radio services operating in the frequency range 620 – 790 MHz including
analogue television, DVB-T and SAB/SAP.
Recently, CRAF was informed directly by Astrium about the plans for a broadcasting-satellite
application in the 620-790 MHz band. CRAF has much concern on the protection
of radio astronomy in the band 608-614 MHz (adjacent band emission from BSS),
and 1330-1400 MHz and 1400-1427 MHz (second harmonic of
the BSS signal). Astrium requested from CRAF an opinion on the compatibility of the
system with radio astronomy: due to lack of technical information,
no opinion could be given yet. Until today, no compatibility study on the impact of
the proposed system and other services or applications has been undertaken.
CRAF participates in the discussions in WG SE PT27 on this matter. It referred to
Recommendation ITU-R RA.769 for the protection criteria for radio astronomy. However, until now
neither CRAF nor the CEPT has experience with a compatibility study in which a system in
HEO orbits is included. CRAF will address this specific aspect in SE27 and request
confirmation that radio astronomy in the mentioned frequency bands is well protected.
CRAF will follow the developments with great care.
The International Union of Radio Science, URSI, held its 27th General Assembly from August 17-24, 2002,
in Maastricht, the Netherlands.
In view of the development of a new generation of radio astronomy telescopes that will need adequate
protection from interference, and in order to enable further development of radio astronomy, URSI
adopted a Resolution on ``International Radio Quiet Reserves'', which reads as follows:
``The URSI Council,
Considering that:
a. to explore the far reaches of the Universe, a limited number of very large, extremely sensitive
radio telescopes is being planned for construction in the coming 10 - 20 years;
b. because the spectral features of distant sources are shifted in frequency by the universal
cosmic expansion to well outside the frequency bands allocated to the Radio Astronomy Service,
these new radio telescopes will need to operate across a wide range of spectrum;
c. such telescopes will therefore be extremely vulnerable to interference from emissions from
space stations, especially those using non-geostationary satellites;
d. the current Radio Regulations make no provision for protecting radio astronomical
observation outside the designated frequency bands;
e. developing such protection will involve cross-sectoral issues in the areas of global
telecommunications, international trade, regulation of radio spectrum utilization, as well
as scientific research, which issues taken together lie outside the competency of any single
existing regulatory body;
f. the inter-governmental Global Science Forum of the OECD has therefore sponsored a Task
Force on Radio Astronomy and the Radio Spectrum, which has brought together international
experts drawn from the telecommunications satellite industry, the radio spectrum regulatory
community, and the radio astronomical research community, to consider whether this diversity
interests might be reconciled;
g. said Task Force has made proposals to this end, including a proposal for a small number
of internationally recognized radio quiet reserves in which the planned new radio telescopes
might be located;
h. although designation of such reserves is not within the established procedures of the ITU,
that body currently provides the most appropriate forum in which to consider the possibility;
Recommends that:
1. the draft agenda of the WRC-2006 include the following item: ``To consider the possibility
of creating one or more internationally recognized radio quiet reserves, and take appropriate action.''
2. the ITU-R undertake the necessary preparatory studies, possibly soliciting input from the
Scientific Committee on Telecommunications of URSI, the Commission on Frequency Allocations
for Radio Astronomy and Space Science (IUCAF) of ICSU, and other bodies of experts as appropriate.''
CRAF considers that a proper regulation of international radio quiet reserves is required to
enable further development of radio astronomy, for which a wide access to the radio frequency
spectrum for observations with very high sensitivity is needed. CRAF is also of the opinion
that these new giant instruments will not simply supersede the existing facilities, and that
therefore the establishment of a limited number of such Reserves does not replace, or diminish,
the need for the continued adequate protection of the numerous smaller-sized radio telescopes
in operation.
WRC-03 Agenda item 1.32 is one of the most complex on the agenda for the
forthcoming WRC-03. Briefly the item is
"to consider technical and regulatory provisions concerning the
band 37.5-43.5 GHz, in accordance with Resolutions 128 (Rev.WRC-2000)
and 84 (WRC-2000)."
There are strong forces at work here, involving three satellite
services (fixed, broadcasting and mobile), both GSO and non-GSO,
together with the fixed services and radio astronomy.
In particular, the fixed satellite service has
more than 250 filings with the ITU to operate systems in the band
41.5-42.5 GHz, which became a worldwide FSS allocation at WRC-2000.
The adjacent band 42.5-43.5 GHz has been allocated to the radio
astronomy service since 1979, and contains spectral lines of
silicon monoxide (SiO) which are often seen as intense cosmic masers.
Resolution 128 (Rev.WRC-2000) covers 'Protection of the Radio
Astronomy Service in the 42.5-43.5 GHz Band.'
WRC-2000 forsaw difficulties in the FSS allocation and added
Footnote 5.551G placing provisional
limits on the aggregate power flux density
produced by NGSO satellite networks or GSO space stations into
the radio astronomy band 42.5-43.5 GHz.
Resolution 128 called on ITU-R to study these limits and
to identify technical and operational measures which could be
implemented by the two services to reduce the level of
unwanted emissions into the radio astronomy band, and/or the susceptibility
of radio telescopes to this form of interference.
The ITU-R has studied the issue from both sides, in Working Parties
4A (fixed satellite) and 7D (radio astronomy), but has not reached
consensus. The state of play is reported in the recently published
CPM text, which was produced by WP4A.
The good news is that VLBI observations can be protected
without unduly constraining the FSS. The bad news is that
single telescope observations, both line and continuum, cannot be
adequately protected by measures that the FSS considers
practicable.
The CPM text now offers proposals to weaken Footnote 5.551G
in several respects.
Instead of protecting all radio telescopes it is proposed to protect
only those notified to ITU-R by the close of WRC-03. Instead of
protecting against FSS in the band 41.5-42.5 GHz it is proposed to
protect only against FSS in the band 42.0-42.5 GHz. Instead of
protecting observations at all elevation angles it is proposed to
protect only observations above 5 o elevation, unless the
radio observatory notifies ITU otherwise. Instead of protecting
against GSO satellites all the time it is proposed to protect
against them for 98% of the time. Some administrations
are even considering whether to protect spectral line observations
in the whole radio astronomy band 42.5-43.5 GHz, or only part of it.
Reading all this it seems that the future development
of the radio astronomy service in the band 42.5-43.5 GHz where it
has a primary allocation is to be constrained by the introduction of
FSS systems which have no allocation at these frequencies.
The FSS community are used to negotiating tough deals with each
other, involving give and take over the shared use of common frequency
bands. It seems that the same mentality has been carried over into
discussions of adjacent frequency bands. But the radio astronomy
and fixed satellite services are neighbours in the
radio spectrum, not cohabiting in the same frequency bands.
Radio astronomy does not have any concessions to make, other than
sacrificing the use of its frequency bands. It would be a travesty
of the ITU system if WRC-03 were to sanction such a sacrifice of
all or part of the radio astronomy band 42.5-43.5 GHz.
Jim Cohen
Jodrell Bank Observatory
ALMA = Atacama Large Millimetre Array
BSS = Broadcasting-Satellite Service
CEPT = Conference of European Post and Telecommunication administrations
CPM = Conference Preparatory Meeting (ITU)
CRAF = Committee on Radio Astronomy Frequencies (ESF)
DVB-T = Digital Video Broadcasting - Terrestrial
ECC = Electronic Communications Committee (CEPT)
ESA = European Space Agency
ESF = European Science Foundation
FM = Frequency Management (WG FM of CEPT)
GSO = Geostationary Orbit
GTS = Global Transmission System Experiment
HEO = High Elliptical Orbit
HI = neutral atomic hydrogen (spectroscopic notation)
ICSU = International Council for Scientific Unions (UNESCO)
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)
LOFAR = Low Frequency Array
NASA = National Aeronautics and Space Administration (USA)
NGSO = Non-GSO
OECD = Organization for Economic Co-operation and Development
PLT = Power Line Transmission
PT = Project Team (CEPT)
RRC = Regional Radiocommunication Conference (ITU-R)
SAB = Services Ancillary to Broadcasting
SAP = Services Ancillary to Programme making
SE = Spectrum Engineering (WG SE of CEPT)
SKA = Square Kilometre Array
TG = Task Group (ITU)
URSI = International Union of Radio Science
UWB = Ultra-Wide Band
WG = Working Group
WP = Working Party (ITU)
WRC = World Radiocommunication Conference (ITU-R)
WRC-03 = WRC 2003
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Editorial Group: R.J.Cohen, P. Scott, W.van Driel
