Investigation of radio astronomical windows between 1 MHz and 2060 MHz in Universiti Malaya, Malaysia Zamri Zainal Abidin * , Zainol Abidin Ibrahim, Syed Bahari Ramadzan Syed Adnan, Norwati Khairul Anuar Physics Department, Faculty of Science, Universiti Malaya, 50603 Kuala Lumpur, Malaysia article info Article history: Received 2 December 2008 Received in revised form 29 January 2009 Accepted 15 February 2009 Available online 23 February 2009 Communicated by J. Silk Keywords: Radio astronomy Astronomy Astrophysics Radio frequency interference abstract An indoor and an outdoor radio frequency survey was conducted in Universiti Malaya, Malaysia, as a test site, for the purpose of developing radio astronomy research in Malaysia. This is the first radio astronomi- cal survey of any such done in Malaysia. Observation and analysis were done in the radio frequency spec- trum between 1 MHz and 2060 MHz. In this paper, the experimental setup and procedure of surveying are outlined and the measured data are interpreted. The eight radio astronomical windows were inves- tigated from a 24 h observation, with the emphasis on two of the most important radio astronomical win- dows which are protected by the Malaysian Communications and Multimedia Commission (MCMC). Some intermittent observations were also done for referencing purposes. The radio frequency interfer- ences (RFIs) are found to be relatively low. The overall relative Interference-to-Noise ratio (INR) at this test site ranges between 5.72% and 11.74%. The average strength of RFI in the eight focused radio astro- nomical windows at this site ranges between 100 dBm and 90 dBm (equivalently between 9.23  10 4 Jy and 93.29  10 4 Jy at resolution bandwidth of 125 kHz). Ó 2009 Elsevier B.V. All rights reserved. 1. Introduction Radio astronomy is an important subfield of astronomy that studies celestial objects in the radio frequency portion of the elec- tromagnetic spectrum. Radio astronomy techniques are similar to optical techniques but radio telescopes have to be much larger in size due to the longer wavelengths being observed. The field orig- inated from the discovery that most astronomical objects emit radiation in the radio wavelengths as well as in the optical wavelengths. To start any radio astronomical observation, it is important to initially identify all the possible radio frequency interference (RFI) in the targeted observational windows. The sources of the RFIs are generally monitored by Malaysian Communications and Multimedia Commission (MCMC) while radio astronomical sources are listed by International Astronomical Union (IAU). We will care- fully identify all RFIs in between the chosen RF window of 1 MHz and 2060 MHz. Within this range, there are eight radio astronom- ical windows. We measure the levels of RFIs within these windows and deduce whether there is any possible radio astronomical observation that can be done in any of the windows at the location chosen. An indoor survey is also done to identify indoor RFIs. RFI is considered the disturbances that affect electrical circuits due to electromagnetic radiation emitted from an external source. The disturbance may interrupt, obstruct, or otherwise degrade or limit the effective performance of the circuit. The source may be any object, artificial or natural, that carries rapidly changing elec- trical currents, such as from some electrical circuits and also from the Sun. Because of these possibilities, and the need to observe 1420 MHz frequency, a set of radio frequency survey is conducted. Significant signals are discovered within the frequency range of 1 MHz–2060 MHz and we compare the signal that we have with the signal from the frequency plan obtained from the Malaysian Communications and Multimedia Commission (MCMC) (MCMC Manual of Spectrum Plan, 2006) to estimate the origin of the sig- nals. In this paper, the methods and the results of RFI surveys are presented. It should be worth noted again that the work done for this paper is aimed at investigating the eight windows in the MCMC fre- quency allocations allocated for radio astronomy. We do not aim to scrutinize the designated windows in the MCMC data as it is al- ready been fixed by the law. We merely try to quantify the level of RFI in the allocated radio astronomical windows for the purpose of future radio astronomical observations in Universiti Malaya. 2. Materials and methods The broad-spectrum outdoor surveys which cover from 1 MHz to 2060 MHz are performed just outside the block B building of the Physic Department of Universiti Malaya. The site is 10 km away from the city centre of Kuala Lumpur. Fig. 1 illustrates the local 1384-1076/$ - see front matter Ó 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.newast.2009.02.003 * Corresponding author. E-mail address: zzaa@um.edu.my (Z.Z. Abidin). New Astronomy 14 (2009) 579–583 Contents lists available at ScienceDirect New Astronomy journal homepage: www.elsevier.com/locate/newast