RADIO QUITE SITE QUALIFICATION FOR THE BRAZILIAN SOUTHERN SPACE OBSERVATORY BY MONITORING THE LOW FREQUENCY 10–240 MHZ ELECTROMAGNETIC SPECTRUM GUILHERME SIMON DA ROSA 1, Nelson Jorge Schuch 1, Casio Espindola Antunes 1, Natanael Rodrigues Gomes 2 1. Southern Regional Space Research Center – CRS/CIE/INPE – MCT, in collaboration with the Santa Maria Space Science Laboratory – LACESM/CT – UFSM, Santa Maria, RS, Brazil. 2. Electronic and Computing Department and Space Science Laboratory of Santa Maria –Center for Technology – (DELC/CT - LACESM/CT) -UFSM, Santa Maria, RS, Brazil / Fax: SOUTHERN REGIONAL SPACE RESEARCH CENTER - CRS/CIE/INPE - MCT SPACE SCIENCE LABORATORY OF SANTA MARIA - LACESM/CT - UFSM 37TH COSPAR - Committee on Space Research - Scientific Assembly JULY , 2008 – MONTREAL - CANADA

Fig. 2 – Southern Regional Space Research Center CRS/CIE/INPE - MCT Santa Maria, RS – Brazil SOUTHERN REGIONAL SPACE RESEARCH CENTER - CRS/CIE/INPE - MCT SPACE SCIENCE LABORATORY OF SANTA MARIA - LACESM/CT - UFSM SOUTHERN SPACE OBSERVATORY A RF PASSIVE SITE FOR INSTRUMENTATION SYSTEMS Fig. 1 – Main gate and buildings 1, 2, 3, 5 and 6 at São Martinho da Serra, RS, Brazil Geographic Coordination: Latitude: 29º 26´ 24” S Longitude: 53º 48´ 38” W Ellipsoidal Altitude : 488 m Geomagnetic Coordination: Latitude: 19º 13´ 48” S Longitude: 16º 30´ E Inclination or “dip”: 33º S Total Geomagnetic Field: 22,800 nT

METHODOLOGY A radio interference (RF) data acquisition system kit was installed and operated at the Southern Space Observatory, which is located at São Martinho da Serra, in South of Brazil. The RF system kit consisted of: antenna, spectrum analyzer, GPIB board and controlling PC, as presented in Fig. 3. SOUTHERN REGIONAL SPACE RESEARCH CENTER - CRS/CIE/INPE - MCT SPACE SCIENCE LABORATORY OF SANTA MARIA - LACESM/CT - UFSM Omnidirectional antenna Spectrum AnalyzerGPIB interface Controlling computer Fig. 3 – Radio interference data acquisition system

THE RESULTS OBTAINED FOR THE LAST 15 YEARS WITH THE ELECTROMAGNETIC RADIO SPECTRUM MONITORING AT THE SSO SOUTHERN REGIONAL SPACE RESEARCH CENTER - CRS/CIE/INPE - MCT SPACE SCIENCE LABORATORY OF SANTA MARIA - LACESM/CT - UFSM The RF Spectrum in the frequency range of MHz observed at SSO, in 1992, is illustrated in Fig. 4. The 2003 data of the RF Spectrum monitoring at the SSO is presented in Fig. 5, which shows that most of the RF Spectrum is free of electromagnetic radio interference. Only some signals such as FM band transmission, as expected, were observed. Fig. 4 – RF Spectrum in the frequency range of 20 – 200 MHz observed at SSO, in 1992 Fig. 5 – a) RF Spectrum in the frequency range of 100 – 110 MHz observed at SSO, in 2003; b) RF Spectrum in the frequency range of 110 – 180 MHz observed at SSO, in 2003 ba

RESULTS AND DISCUSSIONS SOUTHERN REGIONAL SPACE RESEARCH CENTER - CRS/CIE/INPE - MCT SPACE SCIENCE LABORATORY OF SANTA MARIA - LACESM/CT - UFSM The 2006 RF Spectrum monitoring at SSO in the frequency range of 20 – 230 MHz is presented in Fig. 6. The observations is for a day of data acquisition, February 4-5, 2006 which are presented in two different formats as diagrams (a) and (b) of Fig. 7. Fig. 6 – RF Spectrum in the frequency range of 20 – 230 MHz observed at SSO, for 2006 It is observe that the electromagnetic spectrum at the SSO remained free of radio interference in most of the observed frequency range. Basically they are the same signals observed in the past, such as signals from FM transmissions, TV and radio amateur. Fig. 7 – a) Composition between all the resulting observations for one day of data acquisition, February 4-5, 2006; b) Different diagram presenting the same results as presented in (a) a b

CONCLUSIONS SOUTHERN REGIONAL SPACE RESEARCH CENTER - CRS/CIE/INPE - MCT SPACE SCIENCE LABORATORY OF SANTA MARIA - LACESM/CT - UFSM The majority of the RF Electromagnetic Spectrum (HF and VHF) at the Southern Space Observatory – SSO/CRS/CIE/INPE-MCT, in São Martinho da Serra, Brazil, RS, is free of intense radio interference and may be used for data acquisition with sophisticated and sensitive passive radio instrumentation and for Radio Astronomy, such as the LOFAR. Boonstra, A. J.; Bregman, J. D.; Mohamoud, A. A. LOFAR spectrum monitoring: dynamic range and spectral occupancy issues, SKA workshop, Agosto de 2000, Jodrell Bank, UK. Ellingson, S. W. Antennas for the Next Generation of Low Frequency Radio Telescopes, IEEE Trans. Antennas and Propagation, Vol. 53, No. 8, Agosto de 2005, p Stewart, K. P.; Hicks, B. C.; Ray, P. S.; Crane, P. C.; Kassim, N. E.; Bradley, R. F.; Erickson, W. C. LOFAR antenna development and initial observations of solar bursts, Planetary & Space Sci., Vol. 1352, no. 15, p. 1351– 1355, Dezembro de REFERENCES The authors would like to acknowledge the Program PIBIC/INPE – CNPq/MCT for fellowship and COSPAR 2008 for grant. ACKNOWLEDGMENTS