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The Mobile Laboratory for Radio-Frequency Interference Monitoring at the Sardinia Radio Telescope

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The Mobile Laboratory for Radio-Frequency Interference Monitoring at the Sardinia Radio Telescope 11. D. E. Acuna, S. Allessina, and K. P. Kording, “Future 21. Peer Review in Scientifi c Publications, Science and Impact: Predicting Scientifi c Success,” Nature, 489, pp. 201- Technology Committee, House of Commons, UK, July 18, The Mobile Laboratory for Radio-Frequency 202. 2011 (http://www.publications.parliament.uk/pa/cm201012/ cmselect/cmsctech/856/85602.htm). 12. S. Alonso, F. Cabrerizo, E. Herrera-Viedma, and F. Herrera, Interference Monitoring at the “h-Index: A Review Focused in its Variants, Computation and 22. Swedish Research Council, Quality Assessment in Peer Standardization for Different Scientifi c Fields,” Journal of Review, November 5, 2009 (www.cm.se/webbshop_vr/pdfer/ Sardinia Radio Telescope Informetrics, 3, 2009, pp. 273-289. 2011_01L.pdf). 13. G. F. Gaetani and A. M. Ferraris, “Academic Promotion in 23. European Physics Society, “On the Use of Bibliometric Pietro Bolli1, Francesco Gaudiomonte1, Roberto Ambrosini2, Claudio Bortolotti2, Mauro Italy,” Nature, 353, 1991, pp. 10. Indices During Assessment,” http://c.ymcdn.com/sites/ www. 2 3 3 eps.org/resource/collection/B77D91E8-2370-43C3-9814- Roma , Carlo Barberi , and Fabrizio Piccoli 14. P. Lawrance, “The Politics of Publications,” Nature, 422, 250C65E13549/EPS_statement_June2012.pdf. 1National Institute of Astrophysics – Astronomical Observatory of Cagliari 2003, pp. 259-261. Capoterra (Cagliari), Italy 24. http://www.ieee.org/publications_standards/publications/ Tel: +39-070-71180226; Fax: +39-070-71180222; E-mail: [email protected] 15. P. Lawrance, “The Missmeasurement of Science,” Current journmag/journalcitations.html. Biology, 17, 15, 2007, p. R583-R585. 2National Institute of Astrophysics – Institute of Radio Astronomy 25. http://altmetrics.org/manifesto/. Bologna, Italy 16. F. Guilak and C. R. Jacobs, “The h-Index: Use and Overuse,” Journal of Biomechanics, 44, 2011, pp 208-209. 26. P. Campbell, “Escape from the Impact Factor,” Ethics in 3Offi cina Meccanica G. Barberi Science and Environmental Politics, 8, 2008, pp. 5-7. Sesto Calende (Varese), Italy 17. A. Abbott , D Cyranoski , N. Jones , B. Maher, Q. Schiermeier, and R. Van Noorden, “Metrics: Do metrics Matter?,” Nature, 27. P. O. Seglen, “Why the Impact Factor of Journals Should 465, 2010, pp. 860-862. not be Used for Evaluating Research,” BMJ, 314, February 15, 1997. 18. National Health and Medical Research Council, Australia, April 2010, “NHMRC Removes Journal Impact Factor from 28. P. O Seglen, “Causal Relationship Between Article Abstract Peer Review of Individual Research Grant and Fellowship Citedness and Journal Impact,” Journal of the American Society Applications,” http://www.nhmrc.gov.au/_fi les_nhmrc/fi le/ for Information Science, 45, 1994, pp. 1-11. grants/peer/impact%20factors%20in%20peer%20review.pdf . In this paper, a quite unique mobile laboratory for monitoring radio-frequency interference with a radio-astronomical 29. “San Francisco Declaration on Research Assessment observatory is described. The unit is fully operational at the new Sardinia Radio Telescope, a 64-m antenna now in 19. Institut de France, Académie des Sciences, “On the Proper (DORA),” 2013, http://am.ascb.org/dora/. the commissioning phase in Italy. The mobile laboratory is mainly used to identify the source of interference with the Use of Bibliometrics to Evaluate Individual Researchers,” radio astronomy service using iterative triangulations in the azimuth directions. Both the design and realization of 17 January 2011, http://www.academie-sciences.fr/activite/ this prototype were handled with outstanding care to limit the emission of self-interference as much as possible. The rapport/avis170111gb.pdf . laboratory was equipped with excellent microwave instruments in terms of sensitivity, frequency coverage, dynamic range, and various demodulation and signal-analysis facilities. The unit can be quickly switched to different RF and 20. European Science Foundation, European Peer Review power-supply confi gurations, while offering operators a safe and effi cient workplace, even in adverse meteorological Guide, Integrating Policies and Practices for Coherent and driving conditions. In the past months, the mobile laboratory has proven to be successful in detecting and identifying Procedures, March 2011 (http://www.esf.org/activities/mo- many radio interferers. Two examples of measurement campaigns are described. fora/peer-review.html). Keywords: Radio astronomy; radio spectrum management; radio frequency interference; electromagnetic compatibility; radiowave propagation 1. Introduction objective requires fi rst the absolutely mandatory “a priori” activity dedicated to the regulatory management of the radio adio waves coming from the far universe reach the Earth spectrum on all scales: international, regional, and local (for Rwith power levels many orders of magnitude lower than example, with the defi nition of a radio-quiet zone around the manmade radio signals. For instance, a 1 Jy spectral power fl ux telescope site). Second, a proper continuous RFI monitoring density (where Jy stands for the astronomical unit called a activity is also crucial to assure optimal operation of a radio Jansky, equivalent to 10−26 W/m 2 /Hz , frequently used in the telescope. Such activity implies different tasks, and offers many context of radio astronomy) is considered to be a strong celestial benefi ts: source, as compared with the usual targets of radio-astronomical observations. All the radio observatories therefore spend a lot • The early identifi cation of any new signal not of effort trying to keep their sites as quiet as possible, keeping complying with the International Telecommunication away any radio-frequency interference (RFI). Obtaining this Union (ITU) regulations. RFI occurring in the IEEE Antennas and Propagation Magazine, Vol. 55, No. 5, October 2013 ISSN 1045-9243/2012/$26 ©2013 IEEE 19 AP_Mag_Oct_2013_Final.indd 19 12/15/2013 3:53:11 PM frequency bands allocated to the radio astronomical due, for example, to multipath refl ections from surrounding usage, as outlined in Figure 3. The van walls were internally service (RAS) has to be reported, with its obstacles, and consequent wasting of time. Moreover, in all covered with thermally insulating panels. An auxiliary air- (experimentally detected) harmful characteristics, cases when the interferer is barely detectable, the possibility conditioning system for either cooling or heating and ergonomic to the national administration. of driving closer to origin of the radio emission or into the seats assured safe and good comfort for a maximum of two line of sight (such as the top of a mountain) allows greatly operators. Additionally, two photovoltaic cells were installed in • The statistical evaluation of the actual spectral improving the signal-to-noise ratio until a solid identifi cation the roof of the van to provide power for ventilating the inside occupancy in other frequency bands, not allocated can be guaranteed. It is indeed worthwhile noting that the air volume, thereby preserving the electronic instruments from to the radio astronomical service, can be utilized fi nal sensitivity of a large radio telescope – with cryogenically dangerously hot temperatures in the summertime. to increase the receivers’ bandwidths, and then cooled, state-of-the-art microwave receivers, integrating signals to improve the sensitivity of the passive radio- for hours over extremely wide bandwidths – can be many orders The aluminum retractable telescopic mast can lift one astronomical observations. of magnitude higher than the level obtainable by a high-quality antenna and the front-end box a maximum height of 11 m. It commercial RF receiving chain, such as the chain we have in can be rotated in azimuth either electronically, under computer • The dynamic range of the radio-astronomical the mobile laboratory. control, or manually (much faster). An electronic compass receivers can be improved by selecting amplifi er displays the azimuth angle of the antenna’s pointing. A second gains, fi lter characteristics, and conversion schemes The decision to provide the Sardinia Radio Telescope motor at the top of the mast can rotate the antenna, selecting suitable to match the real RF environment receivable (SRT) with this kind of mobile station came after the decade either horizontal or vertical polarization. All the devices to at the observatory site. of operational experience gained with a similar unit developed be installed on the top of the mast are provided with a quick for the Medicina radio-astronomical observatory, located in mechanical interface to speed up the operation of switching • This last knowledge can also allow identifying Northern Italy, close to the city of Bologna [2, 3]. from one confi guration to another. After stopping the vehicle, the operational parameters and strategies that best four electro-hydraulic jacks automatically horizontally level the optimize the effi ciency of applying mitigating In this paper, we give a general overview of the mobile van in such a way that the mast can be safely raised. techniques to make astronomical observations more laboratory in Section 2. Section 3 describes the antennas and effi cient. On this subject, see the proceedings of the microwave front ends, while Section 4 deals with the back ends The upper operational frequency limit of the RF receiving RFI mitigation workshop held in Groningen, the used for data processing. Finally, Section 5 describes two short system is 18 GHz under normal conditions, but with minor Netherlands,
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