We investigate the influence of population density on radio-frequency inter- ference (RFI) affecting radio astronomy. We use a new method to quantify the thresh- old of population density in order to determine the most suitable lower limit for site selection of a radio quiet zone (RQZ). We found that there is a certain trend in the population density-RFI graph that increases rapidly at lower values and slows down to almost flat at higher values. We use this trend to identify the thresholds for pop- ulation density that produce RFI. Using this method we found that, for frequencies up to 2.8 GHz, low, medium and high population densities affecting radio astronomy are below 150 ppl km i2 , between 150 ppl km i2 and 5125 ppl km i2 , and above 5125 ppl km i2 respectively. We also investigate the effect of population density on the environment of RFI in three astronomical windows, namely the deuterium, hydro- gen and hydroxyl lines. We find that a polynomial fitting to the population density produces a similar trend, giving similar thresholds for the effect of population density. We then compare our interference values to the standard threshold levels used by the International Telecommunication Union within these astronomical windows.

https://iopscience.iop.org/article/10.1088/1674-4527/14/2/012/pdf

Selection of radio astronomical observation sites and its dependence on human generated RFI

The solar flare and Coronal Mass Ejections (CMEs) are well known as one of the most massive eruptions which potentially create major disturbances in the interplanetary medium and initiate severe magnetic storms when they collide with the Earth’s magnetosphere. However, how far the solar flare can contribute to the formation of the CMEs is still not easy to be understood. These phenomena are associated with II and III burst it also divided by sub-type of burst depending on the physical characteristics and different mechanisms. In this work, we used a Compound Astronomical Low-cost Low-frequency Instrument for Spectroscopy in Transportable Observatories (CALLISTO) system. The aim of the present study is to reveal dynamical properties of solar burst type II and III due to several mechanisms. Most of the cases of both solar radio bursts can be found in the range less that 400 MHz. Based on solar flare monitoring within 24 hours, the CMEs that has the potential to explode will dominantly be a class of M1 solar flare. Overall, the tendencies of SRBT III burst form the solar radio burst type III at 187 MHz to 449 MHz. Based on solar observations, it is evident that the explosive, short time-scale energy release during flares and the long term, gradual energy release expressed by CMEs can be reasonably understood only if both processes are taken as common and probably not independent signatures of a destabilization of pre-existing coronal magnetic field structures. The configurations of several active regions can be sourced regions of CMEs formation. The study of the formation, acceleration and propagation of CMEs requires advanced and powerful observational tools in different spectral ranges as many ‘stages’ as possible between the photosphere of the Sun and magnetosphere of the Sun and magnetosphere of the Earth. In conclusion, this range is a current regime of solar radio bursts during CMEs events.

Probability of Solar Flares Turn out to Form a Coronal Mass Ejections Events due to the Characterization of Solar Radio Burst Type II and III

Space weather has a close connection with the interaction of the Earth and the Sun. As equatorial country, the characteristic features of the climate of Malaysia are uniform temperature, very high humidity and copious rainfall. Malaysia has an average of temperature of 26.7 °C per year. Therefore, it is suitable to monitor the Sun. In the following work, we will emphasize the development of Sun monitoring in Malaysia. The number of observatories are increasing. A dedicated work to understand the Sun activity in radio region is a part of an initiative of the United Nations together with NASA in order to support developing countries participating in ‘Western Science’ research. Realizing how important for us to monitor the space weather, therefore, we have been utilizing the new radio spectrometer, CALLISTO (Compound Low Cost Low Frequency Transportable Observatories) spectrometer. Malaysia is one of the earliest country from South- East Asia (ASEAN) that involve this research. One of the advantages to start the solar monitoring in Malaysia is because our strategic location as equator country that makes possible to observing a Sun for 12 hours daily throughout a year. We strongly believe that Malaysia as one of contributor of solar activity data through ECALLISTO network. This is a very good start for developing a space weather in Malaysia. With the implementation of CALLISTO systems and development of solar monitoring network, a new wavelength regime is becoming available for solar radio astronomy. Overall, this article presents an overview of space weather in Malaysia. With the present level of the international collaboration, it is believed that the potential involvement of local and international scientist in space weather will increase.

/pdf/understanding-climate-changes-in-malaysia-through-space-456gx2e0e0.pdf

Understanding Climate Changes in Malaysia Through Space Weather Study

In tropospheric layer, radio waves can propagate in a number of different physical mechanisms such as free-space propagation or line-of-sight propagation, reflection, transmission, diffraction, scattering and wave guiding The constituents in weather such as the wind, air temperature and atmospheric water content may combine in many ways Certain combinations can cause radio signals to be heard hundreds of miles beyond the ordinary range of radio communications This study investigates the effect of weather (temperature) on radio wave propagation up to 9GHz Continuous-wave (CW) envelope fading waveforms were recorded over a period of the one-hour using patch antenna The observations were conducted at KUSZA Observatory, East Coast Environmental Research Institute (ESERI), UniSZA which is situated in Merang, Terengganu Spectrum Analyser was used for RFI measurement and weather station for weather effect The graphs of radio signal attenuation for weather parameter (temperature) against time were plotted The findings indicate that there is a relationship between radio signals with the change of temperature The correlation between RFI frequencies and temperature give negative effect for frequency 945 MHz, was r = -0085, while for 383 MHz (r = 0249), 1800 MHz (r = 0268) and 2160 MHz (r = 0134) These findings will benefit radio wave propagation research field which includes radio astronomy observations, space science, wireless communication, satellite, antenna and mobile communication and also electromagnetic radiation (EMR) research for health

Temperature Effect on the Tropospheric Radio Signal Strength for UHF Band at Terengganu, Malaysia

This paper provides a short review of some of the basic concepts related to the origin of Coronal Mass Ejections (CMEs). The numerous ideas which have been put forward to elucidate the initiation of CMEs are categorized in terms of whether this event is a gradual CME or impulsive CME. In this case, an earth-directed Coronal Mass Ejection (CME) was observed on April 2, 2014 by the Large Angle Spectrometric Coronagraph (LASCO) C2. This recent observations obtained a large impulsive CMEs. The CME, originating from the active region AR2027. The speed of CMEs is 1600 kms -1 . A halo CME, a bright expanding ring at the North- West region is exploded beginning at about 14:36 UT, and the process of departing, expansion and propagation are highlighted. We discuss the correspondence of this event with the structure of the CME in the LASCO data. It is believed that the high solar flare and a Moreton waves initiate this kind of CMEs.

/pdf/the-propagation-of-an-impulsive-coronal-mass-ejections-cmes-h5lk83e143.pdf

The Propagation of an Impulsive Coronal Mass Ejections (CMEs) due to the High Solar Flares and Moreton Waves

Radio astronomical observation is infected by wide range of Radio Frequency Interference (RFI). We will also use information gathered from on-site RFI level measurements on selected 'good' areas generated by this study. After investigating a few suitable sites we will commence to the site and construct the RFI observation. Eventually, the best area we will be deciding from the observations soon. The result of this experiment will support our planning to build the first radio telescope in Malaysia. Radio observatories normally are located in remote area, in order to combat RFI from active spectrum users and radio noise produced in industrial or residential areas. The other solution for this problem is regulating the use of radio frequencies in the country (spectrum management). Measurement of RFI level on potential radio astronomical site can be done to measure the RFI levels at sites. Seven sites are chosen divide by three group, which is A, B and C. In this paper, we report the initial testing RFI survey for overall spectrum (0-2GHz) for those sites. The averaged RFI level above noise level at the three group sites are 19.0 (±1.79) dBm, 19.5 (±3.71) dBm and 17.0 (±3.71) dBm and the averaged RFI level above noise level for without main peaks are 20.1 (±1.77) dBm, 19.6 (±3.65) dBm and 17.2 (±1.43) dBm respectively.

Population density effect on radio frequencies interference (RFI) in radio astronomy

In this paper, the frequency allocation reserved for radio astronomy in the L band set by the International Telecommunication Union (ITU), which is between 1400 and 1427 MHz, is reviewed. We argue that the nearby frequencies are still very important for radio astronomers on the ground by investigating radio objects (H i sources) around 1300–1500 MHz. The L-band window is separated into a group of four windows, namely 1400–1427 MHz (window A), 1380–1400 MHz (window B), 1350–1380 MHz (window C), and 1300–1350 MHz (window D). These windows are selected according to their redshifts from a rest frequency for hydrogen spectral line at 1420.4057 MHz. Radio objects up toz 0.1 or frequency down to 1300 MHz are examined. We argue that since window B has important radio objects within the four windows, this window should also be given to radio astronomy. They are galaxies, spiral galaxies, and galaxy clusters. This underlines the significance of window B for radio astronomers on the ground. By investigating the severeness of radio frequency interference (RFI) within these windows, we have determined that window B still has significant, consistent RFI. The main RFI sources in the four windows have also been identified. We also found that the Department of Civil Aviation of Malaysia is assigned a frequency range of 1215–1427 MHz, which is transmitted within the four windows and inside the protected frequency for radio astronomy. We also investigated the RFI in the four windows on proposed sites of future radio astronomy observatories in Malaysia and Thailand and found the two best sites as Universiti Pendidikan Sultan Idris (UPSI) and Ubon Ratchathani, respectively. It has also been determined that RFI in window B increases with population density.

/pdf/investigation-on-the-frequency-allocation-for-radio-2fa0zeqlvg.pdf

Investigation on the Frequency Allocation for Radio Astronomy at the L Band

In this paper, we will present the current status of radio astronomical research and outreach in Malaysia. We will also present a short history of our research group, which is currently the only radio astronomical facility in Malaysia. Our group is called the Radio Cosmology Research Lab and was established in 2005 by Dr Zamri Zainal Abidin and Prof Dr Zainol Abidin Ibrahim. We will discuss the future plans for this group including our keen interest in being part of a more global network of radio astronomers. We are already an active member of the South-East Asia Astronomy Network (SEAAN) and aims to have a radio astronomical facility in order to join the Global Very Long Baseline Interferometer (VLBI) as well becoming a research hub for the future Square Kilometer Array (SKA) project. We will also present some of the scientific goals of our group including providing a platform for radio astronomers to be able to do observations of weak and high red-shifted radio objects such as galaxy clusters and supernovae.

Radio Astronomy in Malaysia: Current Status and Outreach Activities

The uv-coverage of the current VLBI network between Australia northern Asia will be significantly enhanced with an existence of a middle baseline VLBI station located in Malaysia. This paper investigated the connecting route of the first half of the Asia-Oceania VLBI network i.e. from Malaysia to China. The investigation of transmission network characteristics between Malaysia and China was carried out in order to perform a real-time and reliable data transfer within the e-VLBI network for future eVLBI observations. MyREN (Malaysia) and CSTNET (China) high-speed research networks were utilized for this proposed e-VLBI connection. Preliminary network test was performed by ping, traceroute, and iperf prior to data transfer tests, which were evaluated with three types of protocols namely FTP, Tsunami-UDT and UDT. The results showed that, on average, there were eighteen hops between Malaysia and China networks with 98 ms round trip time (RTT) delay. Overall UDP protocol has a better throughput compared to TCP protocol. UDP can reach a maximum rate of 90 Mbps with 0% packet loss. In this feasibility test, the VLBI test data was successfully transferred between Malaysia and China by utilizing the three types of data transfer protocols.

/pdf/radio-astronomy-interferometer-network-testing-for-a-34cbt2p1na.pdf

Zulfazli Rosli

Papers

Population density effect on radio frequencies interference (RFI) in radio astronomy

Selection of radio astronomical observation sites and its dependence on human generated RFI

Investigation on the Frequency Allocation for Radio Astronomy at the L Band

Radio Astronomy in Malaysia: Current Status and Outreach Activities

Radio astronomy interferometer network testing for a Malaysia–China real-time e-VLBI