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    Wyświetlanie 1-6 z 6
    Tytuł:
    Investigation of Radio Frequency Interference (RFI) Profile and Determination of Potential Astronomical Radio Sources
    Autorzy:
    Hamidi, Z. S.
    Shariff, N. N. M.
    Powiązania:
    https://bibliotekanauki.pl/articles/411988.pdf
    Data publikacji:
    2014
    Wydawca:
    Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
    Tematy:
    Radio Frequency Interference (RFI)
    radio astronomy
    RFI sources
    Opis:
    In this article, we have recognized a Radio Frequency Interference (RFI) sources that can potentially affect for radio astronomical observation. The main objective of this surveying is to test and qualify the potential of radio astronomical sources that can be observed in Malaysia generally. Analysis process focuses on the high sources that contribute the pollution and the significant region that can be considered for astronomical purpose beginning 1-2000 MHz. It was found that 13 individual sources contribute as a noise and mostly are telecommunication and radio navigation applications. We then compared of the RFI profiles based on three different periods in order to observe the variety of the signals. The main regions that still excellent to do an observation are: 13.36 -13.41 MHz (solar), (25.55-25.67) MHz (Jupiter) and (37.50-38.25) MHz (Continuum) respectively. This work is also an initiative of the International Space Weather Initiative (ISWI) project where Malaysia is one of the countries that involve in e-CALLISTO (Compound Astronomical Low Cost Low Frequency Transportable Observatory) network project. Some suggestions are recommended in order to improve the quality of the radio frequency profile.
    Źródło:
    International Letters of Chemistry, Physics and Astronomy; 2014, 5; 43-49
    2299-3843
    Pojawia się w:
    International Letters of Chemistry, Physics and Astronomy
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Nonlinear Behavior of the Radio Frequency Interference (RFI) Sources at Faculty of Applied Sciences, MARA University of Technology
    Autorzy:
    Hamidi, Z. S.
    Shariff, N. N. M.
    Powiązania:
    https://bibliotekanauki.pl/articles/412047.pdf
    Data publikacji:
    2014
    Wydawca:
    Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
    Tematy:
    Radio Frequency Interference (RFI)
    RFI sources
    solar radio burst
    CALLISTO
    Opis:
    In this article, we describe and compare several sources of the nonlinear of Radio Frequency Interference (RFI) based on classification methods. It is very important to characterize and understand the nature of interference in as much of the candidate spectrum as possible. Preliminary analysis has been done in 2011. As data sizes of observations grow with new and improved solar monitoring system, the need for completely automated, robust methods for RFI mitigation is highlighted. The current status of RFI noise level is being compared at two different sites (i) indoor and (ii) outdoor. The main objective is to evaluate and find the best range of low frequency in MHz for the solar monitoring purpose. Our findings are consistent with those of previous studies. There is not much different in terms of the sources of RFI. However, the level of RFI is become increase. Based on the results, it was found that the distribution of RFI sources in indoor site is in the range from -(80-105) dBm. A strong and moderate RFI can be identified in the range of -100 dBm. The dominant sources in this region are due to the fixed mobile signal with 10 points of this signal from 1-2000 MHz. If we compare with outdoor site, the distribution of RFI sources in indoor site is in the range from -(75-105) dBm. It means that the signal of noise is larger compared with indoor site. While new sources strive to remain the increasing of RFI signal levels, numerous factors interact to influence the pattern of this noise. Reporting to the authoritative body should be made to make sure the allocation of the solar monitoring frequency region was not used by other applications. This work is a current scenario of the nonlinear RFI level at our site.
    Źródło:
    International Letters of Chemistry, Physics and Astronomy; 2014, 15; 39-47
    2299-3843
    Pojawia się w:
    International Letters of Chemistry, Physics and Astronomy
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Current Situation of Radio Frequency Interference (RFI) Profile at Outdoor and Indoor Sites of Faculty of Applied Sciences, UITM, Malaysia
    Autorzy:
    Hamidi, Z. S.
    Nizamudin, Nur Izzani
    Shariff, N. N. M.
    Syazwan, M.
    Husien, Nurulhazwani
    Ali, M. O.
    Zainol, N. H.
    Ramli, Nabilah
    Sabri, S. N. U.
    Monstein, C.
    Powiązania:
    https://bibliotekanauki.pl/articles/1191429.pdf
    Data publikacji:
    2016
    Wydawca:
    Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
    Tematy:
    Radio Frequency Interference (RFI)
    radio astronomy
    RFI sources
    Opis:
    This Radio Frequency Interference (RFI) study is currently one of a main sub-research in radio astronomy in Malaysia. The main objective of this monitoring is to test and qualify the potential of radio astronomical sources that can be observed in Malaysia generally. Analysis process focuses at indoor and outdoor of Faculty of Applied Sciences, UITM Shah ALAM, Malaysia (latitude: 03°06.534’N, longitude: 101°50.396’E). There are three mobile network communications that operate at the upper band frequency of 1800MHz, which are Maxis (1805-1830 MHz), Celcom (1830-1855 MHz) and Digi (1855-1880 MHz) for GSM/LTE network. We observed that both sites having the highest and second highest peak at the same frequency of 420 MHz and 1835 MHz with the same source, which were due to mobile application followed by the lowest peak due to radio navigation satellite. We verified that the source of RFI of 1835 MHz at the Faculty of Applied Sciences may come from Celcom mobile telecommunication network signal because there is transmitter on top of two Celcom towers. This observation must be continuously done to ensure that RFI level does not increase drastically and to ensure that allocation spectrum band that was reserved for radio astronomy activities was always protected.
    Źródło:
    World Scientific News; 2016, 40; 23-33
    2392-2192
    Pojawia się w:
    World Scientific News
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Comparison of the Radio Frequency Interference (RFI) in the Region of Solar Burst Type III Data At Selected CALLISTO Network
    Autorzy:
    Hamidi, Z. S.
    Shariff, N. N. M.
    Monstein, C.
    Powiązania:
    https://bibliotekanauki.pl/articles/412319.pdf
    Data publikacji:
    2014
    Wydawca:
    Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
    Tematy:
    CALLISTO
    low frequency
    solar burst type III
    Radio Frequency Interference (RFI)
    Opis:
    Compact Astronomical Low-frequency, Low-cost Instrument for Spectroscopy in Transportable Observatories (CALLISTO) is a global network of spectrometer system with the purpose to observe the Sun’s activities. There are 25 stations that are used for this purpose. Radio Frequency Interference (RFI) is a major obstacle when performing observation with CALLISTO. We have confirmed at least 2 stations out of 10 stations with a complete overview spectral (OVS) made available to us showed clear detection of these consistent types of RFI for each specific region. In Malaysia, these RFI are also clearly detected. The major RFI affecting CALLISTO within radio astronomical windows below 1 GHz are local electronic system specifically radio navigation (at 73.1 MHz and 75.2 MHz), broadcasting (at (i) 151 MHz, (ii) 151.8 MHz and 152 MHz), aeronautical navigation (at (i) 245.5 MHz, (ii) 248.7 MHz and (iii) 249 MHz and fixed mobile at (i) 605 MHz, (ii) 608.3 MHz, (iii) 612.2 MHz, (iv) 613.3 MHz). It is obviously showed that all sites within this region are free from interference at 320-330 MHz and is the best specific region to be considered for solar burst monitoring. We also investigate the effect of RFI on detection of solar burst. We have considered type III solar bursts on 9th March 2012 in order to measure the percentage of RFI level during the solar burst. The RFI level is as low as 6.512 % to 80.769 % above solar burst detection.
    Źródło:
    International Letters of Chemistry, Physics and Astronomy; 2014, 10; 38-45
    2299-3843
    Pojawia się w:
    International Letters of Chemistry, Physics and Astronomy
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Evaluation of Spectral Overview and Radio Frequency Interference (RFI) Sources at Four Different Sites in CALLISTO Network at the Narrow Band Solar Monitoring Region
    Autorzy:
    Hamidi, Z. S.
    Shariff, N. N. M.
    Monstein, C.
    Powiązania:
    https://bibliotekanauki.pl/articles/412644.pdf
    Data publikacji:
    2014
    Wydawca:
    Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
    Tematy:
    CALLISTO
    Radio Frequency Interference (RFI)
    RFI sources
    solar radio burst
    Opis:
    Continuous observation of solar radio burst in CALLISTO network was started since 2002 with Blein Switzerland is the first site that launched the system. Since then, there are more than 35 sites around the world that monitor the Sun activity within 24 hours until 2014. However, there is an issue of Radio Frequency Interference (RFI) that need to be considered. This noise is a major obstacle when performing observation with CALLISTO system. We selected 4 sites as preliminary analysis to analyze in detailed at a specific frequency which is very important in solar burst monitoring. The selected sites are (i) Blein, Switzerland (ii) Mauritius (iii) KASI Korea and (iv) ANGKASA, Malaysia. The regime narrow band that we focused are from (i) 72 – 75 MHz (ii) band 145 – 153 MHz (iii) 240 – 250 MHz (iv) 320 – 330 MHz (v) 406 – 410 MHz. The results of the sources of the RFI also will be highlighted. This work is was part of a larger study which focuses on a specific region that can be used for detailed investigation of solar burst. This issue of Radio Frequency Interference (RFI) needs a dialogue and interactions between different actors and networks.It is hoped that the analysis will help the solar physicist to choose a better data.
    Źródło:
    International Letters of Chemistry, Physics and Astronomy; 2014, 11, 2; 135-145
    2299-3843
    Pojawia się w:
    International Letters of Chemistry, Physics and Astronomy
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    An Observation of an Inverted Type U Solar Burst Due to AR1429 Active Region
    Autorzy:
    Hamidi, Z. S.
    Shariff, N. N. M.
    Monstein, C.
    Powiązania:
    https://bibliotekanauki.pl/articles/412209.pdf
    Data publikacji:
    2014
    Wydawca:
    Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
    Tematy:
    CALLISTO
    low frequency
    solar burst
    type U
    Radio Frequency Interference (RFI)
    Opis:
    A detailed investigation of an inverted type U solar burst in meter region and their associated the solar flare and Coronal Mass Ejections (CMEs) has been reported. Solar type U burst has been observed at the National Space Centre, Banting, Selangor detected by the Compound Low Cost Low Frequency Transportable Observatories (CALLISTO) system in the 150 MHz till 400 MHz at the low frequency band. An inverted U type is occurring on 9th March 2012 between 4:00 UT to 4:15 UT within 1 minute (4:12 − 4:13) UT. From the dynamic spectra of CALLISTO, we have identified metric type U burst with maximum emission near the frequency 385MHz. In specific, the continuum type III burst will soon structure this burst due to our observations. Other types such as type II and IV are only appearing only after type U burst is ejected and appear at the same point of the solar flare event. Since the U burst activity coincides with the peak of the hard X-ray flare at 4:12UT in AR1429, we classified that the event is associated with the injection of the high energetic particles. In conclusion, it is confirmed that an inverted type U burst is initiated after a complex and a group solar radio burst type III.
    Źródło:
    International Letters of Chemistry, Physics and Astronomy; 2014, 10; 81-90
    2299-3843
    Pojawia się w:
    International Letters of Chemistry, Physics and Astronomy
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-6 z 6

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