Embed Size (px)
Citation preview
Protecting the RF environment at the Cerro Chascón Science Preserve
Guillermo DelgadoEuropean Southern Observatory
La Serena 07/03/02 [email protected]
ITU and the international frequency spectrum regulation
The International Telecommunication Union (ITU) was created in 1865 and today is an specialized agency of the UN
ITU issue treaties after WARCs or can issue recommendations. As all cases of International Law, the countries have sovereign privileges within their borders
ITU recommends, the local administrations can accept or not. The good-will of the local administrations is fundamental
La Serena 07/03/02 [email protected]
Radio astronomy as a radiocommunication service
Recognised as a radiocommunication service by ITU at the WARC of 1959
Represented at ITU by the Inter-Union Commission for the Allocation of Frequencies for Radio Astronomy and Space Science –IUCAF – (IAU, URSI, COSPAR), has no voting rights
Passive service
La Serena 07/03/02 [email protected]
ITU recommendations
Interfering signal are all those unwanted signals exceeding in 10% the sensitivity of the system (ITU-R RA.769-1)
The local authorities are reminded that it is very difficult for the radio astronomy service to share frequencies with other services (ITU-R RA.769-1)
It is suggested to create “coordination zones” for transmitters (ITU-R RA.1031-1)
La Serena 07/03/02 [email protected]
International protection of radio astronomy
There are some frequency bands assigned internationally for the radio astronomy service:
Assigned as primary service shared with other passive services
Assigned as primary service shared with other active services
Assigned as secondary service
La Serena 07/03/02 [email protected]
Telecommunication authority in Chile
Jaime EtcheberrySecretary of Infrastructure, transport and telecommunications
Ricardo LagosPresident of Chile
Christian NicolaiSub-secretary of Telecommunications
Patricio TomboliniSub-secretary of Transport
Juan Carlos LatorreSub-secretary of Infrastructure
La Serena 07/03/02 [email protected]
Atacama Large Millimeter Array (ALMA)
Scientific Preserve of Cerro Chascón, 5000 m altitude, 60 km NE of San Pedro de Atacama
64 antennas 12 m diameter Collecting area ~ 7.200 m2
Surface accuracy < 25 m Baselines 18 to 14.000 m Resolution comparable to the
Hubble Space Telescope Operating frequency 30 to 950
GHz Bandwidth 4 GHz
La Serena 07/03/02 [email protected]
ALMA sensitivity
Using ITU criteria (Handbook on Radio Astronomy, ITU-R RA.769-1) and ALMA parameters (Antenna diameter 12 m, frequency 230 GHz, bandwidth 8 GHz, integration time 2000 s, Tsys 80 K) we obtain a sensitivity at the antenna aperture of 600 Jy
1 Jansky (Jy) = 10-26 W m-2 Hz-1
La Serena 07/03/02 [email protected]
Frequency bands required by ALMA
Band No. Frequency range
[GHz]
1 31,3 – 45
2 67 – 90
3 84 – 116
4 125 – 163
5 163 – 211
6 211 – 275
7 275 – 370
8 385 – 500
9 602 – 720
10 787 - 950
La Serena 07/03/02 [email protected]
What have been done internationally to protect against radio interference at the radio astronomy stations
Local assignment of frequency bands attributed to other services
Radio quite zone around the radio astronomy stations (small geographic area)
Coordination zone around the radio astronomy stations (large geographic area)
La Serena 07/03/02 [email protected]
Our proposal to achieve protection against radio interference at Chajnantor
Local assignment of the ALMA required frequency bands (small geographical area) SUBTEL
Creation of a coordination zone around Chajnantor (larger geographical area) SUBTEL
Radio quite zone around the radio astronomy stations (small geographical area) ¿CONAMA?, ¿SUBTEL?,
La Serena 07/03/02 [email protected]
What we have done
Made a presentation at SUBTEL of the ALMA project and our protection request to the Subsecretario and other technical managers
Obtained a compromise of collaboration from SUBTEL and created a joint working group
Produced a 52 pages document about the need of RFI protection, including legal background and protection precedence in other countries. This document was used in our presentation at SUBTEL
La Serena 07/03/02 [email protected]
What we still need to do
Complete technical data requested by SUBTEL to define the size of the coordination zone
Obtain a formal recognition from SUBTEL to avoid future policy changes
Educate the general public (and the politicians) about radio astronomy and the need to protect the observing environment
La Serena 07/03/02 [email protected]
Other astronomical projects at the Chajnantor area
Cosmic Background Imager (CBI), Caltech Mobile Anisotropy Telescope (MAT), Princeton Millimeter Interferometer (MINT), Princeton Atacama Pathfinder Experiment (APEX), MPIfR, ESO,
NSF Atacama Submillimeter Telescope (ASTE), NAOJ Infrared telescopes
– University of Tokyo Atacama Observatory (TAO)– Cornell Atacama Telescope (CAT)
