NATIONAL INSTITUTE FOR SPACE RESEARCH INPEMCT - PowerPoint PPT Presentation

Title: NATIONAL INSTITUTE FOR SPACE RESEARCH INPEMCT


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NATIONAL INSTITUTE FOR SPACE RESEARCH INPE/MCT
SOUTHERN REGIONAL SPACE RESEARCH CENTER
CRS/CIE/INPE - MCT SOUTHERN SPACE OBSERVATORY SS
O/CRS/CIE/INPE MCT FEDERAL UNIVERSITY OF SANT
A MARIA UFSM TECHNOLOGY CENTER CT/UFSM SPACE
SCIENCE LABORATORY OF SANTA MARIA LACESM /CT/
UFSM
RADIO QUITE SITE QUALIFICATION FOR THE BRAZILIAN
SOUTHERN SPACE OBSERVATORY BY MONITORING THE LOW
FREQUENCY 10240 MHZ ELETROCMAGNETIC SPECTRUM
Guilherme S. Rosa(1), Nelson J. Schuch(1),
Casio E. Antunes(1), Natanael R. 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 S
pace Science Laboratory of Santa Maria Center
for Technology (DELC/CT - LACESM/CT) -UFSM,
Santa Maria, RS, Brazil guilherme_at_lacesm.uf
sm.br/ Fax 55-55-3301-2213
ABSTRACT
The 2006 RF Spectrum monitoring at SSO in the
frequency range of 20 230 MHz is presented in
Fig. 5. 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. 6. 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.
METHODOLOGY
It was used a radio interference data acquisition
system installed at INPEs Southern Space
Observatory, which is located at São Martinho da
Serra, in South of Brazil, subunit of the
Southern Regional Space Research Center
CRS/CIE/INPEMCT, as Fig 1. A radio interference
(RF) data acquisition system kit was installed
and operated at the Southern Space Observatory.
The RF system kit consisted of antenna,
spectrum analyzer, GPIB board and controlling PC,
as presented in Fig. 2.
Characterization of electromagnetic interference
originated from natural or anthropogenic radio
frequency sources is essential information to
evaluate the radio noise level and the site
quality in order to study the possibility for
installation of sensitive radio astronomic
instrumentation at the Southern Space Observatory
SSO/CRS/INPE-MCT (29S, 53ºW), in São Martinho
da Serra, RS, Brazil. The monitoring of the
Electromagnetic Spectrum in the frequency range
of 10 240 MHz has been carried out at the SSO -
Observatory since 1992. The radio interference
data acquisition is carried out by an integrated
system of omnidirectional antenna, amplifier,
spectrum analyzer and controlling computer, which
is used to control the spectrum analyzer and for
data storage. The omnidirectional antenna is
installed outside at the Observatory and the
detected radio signals are transmitted via
coaxial cable to the amplifier system. After the
amplification procedure, the signals are
processed and digitalized by the spectrum
analyzer. The data communication between the
spectrum analyzer and the computer is made by a
GPIB interface. For a remote controlling of the
data flux, reduction and analysis, the data are
sent via TCP/IP Protocol (Internet) to the
Southern Regional Space Research Center
CRS/INPE MCT, in Santa Maria, RS, Brazil. The
todays observed data is analyzed and is compared
with the results and analysis of the observed
local electromagnetic spectrum at the SSO
Observatory since 1992. The results indicate no
significant variations of the site noise quality
and of the interference level on the local
electromagnetic spectrum for the last 16 years.
From the observations of the systematic
monitoring of radio interference one may say that
in southern Brazil there is a very good
radio-quiet site potential for installation of
sophisticated and sensitive passive radio
instrumentation for data acquisition for space
science or for radio astronomy, similar to LOFAR
stations, at the Southern Space Observatory
SSO/CRS/INPE-MCT, in São Martinho da Serra,
Brazil, RS.
Fig. 5 RF Spectrum in the frequency range of 20
230 MHz observed at SSO, in 2006.
Fig. 2 Radio interference data acquisition
system
The RF Spectrum in the frequency range of 20 -
200 MHz observed at SSO, in 1992, is illustrated
in Fig. 3.
Fig. 6 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)
SOUTHERN SPACE OBSERVATORY A RF PASSIVE SITE FOR
INSTRUMENTATION SYSTEMS
CONCLUSIONS
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.
Fig. 3 RF Spectrum in the frequency range of 20
200 MHz observed at SSO, in 1992
The 2003 data of the RF Spectrum monitoring at
the SSO is presented in Fig. 4, which shows that
most of the RF Spectrum is free of
electromagnetic radio interference.
REFERENCES
? 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. An
tennas for the Next Generation of Low Frequency
Radio Telescopes, IEEE Trans. Antennas and
Propagation, Vol. 53, No. 8, Agosto de 2005, p.
2480-2489.
Fig. 1 Southern Regional Space Research Center

CRS/CIE/INPE - MCT Santa Maria, RS Brazil
ACKNOWLEDGMENTS
The authors would like to acknowledge the Program
PIBIC/INPE CNPq/MCT for fellowship and COSPAR
for grant.
Geographic Coordination Latitude 29º 26 24
S Longitude 53º 48 38 W Ellipsoidal Altitude
488 m

Geomagnetic Coordination Latitude 19º 13 4
8 S Longitude 16º 30 E Inclination or dip
33º S
Total Geomagnetic Field 22,800 nT
Fig. 4 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
Main gate and buildings 1, 2, 3, 5 and 6 at São
Martinho da Serra, RS, Brazil
37TH COSPAR, Montreal, Canada, July 13 - 20, 2008