Rain Attenuation at Tropical Region- Site Diversity Gain Models' Sensitivity

Rain is the major impairment to the signal propagation from satellite to earth. The signal that brings an important data might be lost in a sudden due to heavy rainfall especially in the region with tropics climate. The undesirable effect mainly occurred at above of 10 GHz signal frequency which is expected to bring more data compared to a lower frequency. One of the possible solutions that was proven to be effective to overcome this impairment is the implementation of site diversity. The empirical model that has been developed to measure the effectiveness of the diverse site is yet to be finalized in tropical region. This article compares ITU-R, Hodge, Panagopoulos, Semire and Yeo Model to observe their sensitivity to the major factors that contributes to the site diversity gain such as frequency, site separation distance, elevation angle and baseline orientation angle. These major factors are used as input to the models. The default factors’ value was set to 20.2 GHz frequency, 68.8° of elevation angle, 42.52 km site separation distance and 65° of baseline angle. The factors were interchangeably with 12.255 GHz frequency, 25° of elevation angle, 10 km distance and 4° of baseline angle, which created 16 sets of combinations. The percentages of increment or decrement of the gain predicted by each model with respect to the default parameter were calculated. In overall, each model has their own discrepancy towards these factors and a more dynamic model should be developed to improve the weaknesses.Rain is the major impairment to the signal propagation from satellite to earth. The signal that brings an important data might be lost in a sudden due to heavy rainfall especially in the region with tropics climate. The undesirable effect mainly occurred at above of 10 GHz signal frequency which is expected to bring more data compared to a lower frequency. One of the possible solutions that was proven to be effective to overcome this impairment is the implementation of site diversity. The empirical model that has been developed to measure the effectiveness of the diverse site is yet to be finalized in tropical region. This article compares ITU-R, Hodge, Panagopoulos, Semire and Yeo Model to observe their sensitivity to the major factors that contributes to the site diversity gain such as frequency, site separation distance, elevation angle and baseline orientation angle. These major factors are used as input to the models. The default factors’ value was set to 20.2 GHz frequency, 68.8° of elevation angle, 42.52 km site separation distance and 65° of baseline angle. The factors were interchangeably with 12.255 GHz frequency, 25° of elevation angle, 10 km distance and 4° of baseline angle, which created 16 sets of combinations. The percentages of increment or decrement of the gain predicted by each model with respect to the default parameter were calculated. In overall, each model has their own discrepancy towards these factors and a more dynamic model should be developed to improve the weaknesses

Development Of Rain And Scintillation Models At Ku-Sand In Southeast Asia Tropical Countries

A two year rainfall rate, attenuation and scintillation measurement was conducted in Southeast Asia Tropical countries (USM, KMITL,USP, AdMU and ITB). The data obtained are useful to investigate the impairment due to rainfall in satellite links operating in tropical and equatorial climates. The cumulative distributions of rainfall rate, attenuation and scintillation derived from the measured data are presented and compared with those obtained with existing prediction models. Existing model for prediction of slant-path have not shown good agreement with available experimental data, confirming the need of suitable models for tropical region. Results were analysed in order to understand the potentials and the limits of each prediction model. Based on the limitations of the existing models, 1-minute rainfall rate and attenuation prediction model was developed from the knowledge of the ground point rainfall rate and attenuation cumulative distribution representative of the area where the earth station is located. Comparison between predicted and experimental results has shown significant improvements in terms of reduced prediction error over existing models. The proposed models were also used for prediction against the measured data from different location such as Brazil, Singapore and Papua New Guinea. The proposed model gave a good representation of cumulative distribution with an overall low rms for measurement sites and the three different locations mentioned above. The agreement with the measured data was found to be mainly dependent on the proper parameterization of the proposed models to the radiometeorological variables along the satellite link. Therefore, it can be concluded that the proposed models has high prediction accuracy for the whole cumulative distribution of rainfall and scintillation data

Kajian model penukaran kadar hujan untuk integrasi masa 60 minit kepada 1 minit di Malaysia

Perkembangan pesat teknologi komunikasi tanpa wayar telah menyebabkan penggunaan jalur frekuensi mencapai tahap tepu terutamanya di negara-negara maju. Ini telah mendorong jurutera sistem telekomunikasi meneroka jalur frekuensi di atas jalur Ku (10 GHz). Namun begitu, titisan hujan amat memberi kesan kepada isyarat yang merambat pada jalur frekuensi di atas 10 GHz. Justeru, ramalan pelemahan hujan ke atas perambatan isyarat elektromagnet menggunakan kadar hujan bersela masa 1 minit adalah penting. Di kebanyakan negara, data kadar hujan bersela masa 60 minit lebih mudah diperolehi berbanding data hujan yang bersela masa lebih pendek. Oleh sebab itu, kaedah penukaran taburan hujan dengan sela masa 60 minit diperlukan untuk mendapatkan kadar hujan bersela masa 1 minit. Kajian ini dijalankan dengan menggunakan data hujan dari 10 buah stesen pencerap hujan Jabatan Pengairan dan Saliran di seluruh Malaysia untuk tempoh 3 tahun dari 2011 hingga 2013 bagi menentukan model penukaran kadar hujan untuk sela masa 60 minit yang terbaik di Malaysia. Beberapa model penukaran kadar hujan untuk sela masa 60 minit kepada 1 minit dikaji di antaranya adalah model Segal, model Burgueno et al., model Chebil dan Rahman, model Lee et al., model Lavergnat dan Golé dan model Moupfouma dan Martin. Daripada keputusan yang diperolehi, didapati model Chebil dan Rahman memberikan keputusan terbaik untuk diguna pakai di Malaysia dengan memberikan nilai ralat Root Mean Square (RMS) di bawah 20% bagi kesemua lokasi. Hasil kajian yang diperolehi daripada projek ini adalah sangat berguna dalam menentukan pelemahan hujan bagi merekabentuk sebuah sistem perhubungan satelit yang mempunyai kebolehsediaan dan kebolehcapaian yang tinggi

Empirijske metode za konverziju razdiobe intenziteta oborine s nekoliko dužih intervala na 1-minutni intenzitet u Maleziji

The rapid development of the radio communications system, especially in developed countries, has drawn the attention of telecommunication systems engineers to explore the frequency band above the Ku band. Because radio communication systems operating in the frequency band above the Ku band (10 G Hz) suffer from rain attenuation during rainy conditions, prediction of rain attenuation using a 1-min rainfall rate distribution is indeed vital. However, a 1-min rainfall rate distribution is not widely available compared to rainfall rate distributions with longer integration times. Therefore, a suitable conversion method is required to predict 1-min rainfall rate distributions of distinct integration times. This paper presents several conversion methods such as Segal, Burgueno et al., Chebil and Rahman, Joo et al., EXCELL RSC and LG . The Segal method provides an overall Root Mean Square (RMS ) error below 5% at different integration times and is suitable to be used in Malaysia.Brzi razvoj sustava radio komunikacija, a što je naročito izraženo u razvijenim zemljama, potaknuo je inženjere na istraživanje frekvencijskog pojasa iznad tzv. Ku pojasa. Naime, radiokomunikacijski sustavi koji rade u frekvencijskom pojasu iznad Ku-pojasa (10 GHz) podložni su prigušenju u oborinskim uvjetima. Stoga je predviđanje atenuacije radio signala korištenjem 1-min intenziteta oborine od velike važnosti. Međutim, za razliku od razdioba intenziteta oborine za duža kumulacijska vremena, razdiobe 1-min intenziteta nisu široko dostupne. Stoga je neophodna metoda konverzije za predviđanje distribucije 1-min intenziteta oborine za različita kumulacijska vremena. U ovom radu je prikazano nekoliko metoda konverzije kao što su metode Segala, Burguena i suradnika, Chebila i Rahmana, Jooa i suradnika, te EXCELL RSC i LG metoda. Metoda Segala daje ukupnu srednju kvadratnu pogrešku (Root Mean Square Error – RMS ) ispod 5% za različita kumulacijska vremena i pokazuje se prikladnom za upotrebu u Maleziji

Kajian hubung kait tekanan dan suhu terhadap taburan kerpasan di Malaysia ketika fenomena ENSO

Perubahan iklim merupakan ancaman paling besar terhadap alam sekitar dan manusia pada abad ke 21 ini. Suhu tahunan bumi telah beranjak naik dan turun beberapa darjah Celsius sejak beberapa juta tahun yang lampau. Trend suhu yang meningkat di kebanyakan tempat termasuk Malaysia sejak 30 hingga 50 tahun yang lalu. Ini menyebabkan peningkatan kekerapan dan intensiti kejadian cuaca yang ekstrem seperti kemarau, ribut dan banjir. Antara faktor yang mempengaruhi sebahagian besar iklim Malaysia adalah El Niño-Ayunan Selatan atau ringkasnya ENSO yang memberi kesan kepada kepelbagaian hujan. Malaysia adalah salah satu daripada negara-negara di Asia Tenggara yang mengalami kesan El Niño yang ketara dari segi anomali iklim serantau dan sosio-ekonomi kesejahteraan penduduknya. Kajian ini menggunakan data hujan daripada satelit Misi Mengukur Hujan Tropika (“Tropical Rainfall Measurement Mission”, TRMM) yang dikenali sebagai Analisis Kerpasan Satelit Majmuk TRMM (‘TRMM Multi-Satellite Precipitation Analysis’, TMPA). Data ini digunakan untuk memantau keadaan kering dan lembap di Malaysia bagi tempoh lima belas (15) tahun bermula 2000 hingga 2014. Daripada kesemua hasil keputusan, didapati bahawa apabila berlaku fenomena La Nina sederhana pada tahun 2008, suhu pada MAM adalah berkadar songsang dengan kerpasan bagi kebanyakan lokasi. Seterusnya, apabila El Nino lemah pada tahun 2004/2005 dan 2006/2007, SLP pada DJF adalah berkadar songsang dengan kerpasan dan StnP pada DJF adalah berkadar songsang dengan kerpasan bagi kebanyakan lokasi. Data hujan TRMM bulanan juga mempunyai hubungan linear yang baik dengan data hujan stesen tadahan. Hasil kajian yang diperolehi daripada projek ini adalah sangat berguna untuk mengetahui trend kerpasan apabila dibandingkan dengan suhu dan tekanan supaya kita boleh buat persediaan bagi pihak kerajaan malah kepada orang perseorangan

Penganalisaan julat hujan bulanan terburuk di Malaysia dari tahun 2017 hingga 2019

Kemerosotan isyarat gelombang mikro pada jalur frekuensi lebih daripada 10 GHz adalah disebabkan oleh faktor keamatan hujan yang tinggi di kawasan beriklim tropika dimana objektif kajian adalah menganalisa julat hujan di Malaysia.. Justeru itu, ramalan pelemahan hujan ke atas perambatan isyarat elektromagnet menggunakan kadar hujan bersela masa 1 minit adalah penting. Kajian ini menggunakan data hujan bersela masa 60 minit yang dicerap di 10 stesen pencerap Jabatan Pengairan dan Saliran Malaysia di seluruh Malaysia dalam tempoh 3 tahun iaitu daripada 2017 sehingga 2019. Model Segal telah dipilih sebagai model penukaran data hujan berintegrasi 1 minit disebabkan ralat kebarangkalian yang kecil serta bersesuaian untuk kawasan tropika. Ramalan taburan hujan bulanan terburuk pula dilaksanakan dengan memilih model ITU-R P.841-5. Hasil daripada kajian ini medapati bahawa kawasan Sarawak menunjukkan nilai kadar hujan paling tinggi berbanding kawasan Semenanjung Malaysia. Selain daripada itu, ramalan kadar hujan bulanan terburuk turut mendapati nilai pekali bulan yang paling buruk, Q1 (1.2) dan β (0.35) yang diusulkan oleh model International Union Telecommunication (ITU-R) adalah tidak bersesuaian untuk Malaysia yang terletak di kawasan tropika di mana menerusi kajian, nilai baru untuk parameter Q1 dan β telah diperolehi supaya anggaran yang lebih (Q1= 1.7 dan β=1.22) baik untuk persamaan bulan terburuk dapat dihasilkan. Hasil kajian ini bukan sahaja sebagai persediaan menghadapi banjir malahan boleh dijadikan garis panduan dalam mereka bentuk sistem perhubungan satelit yang lebih efisien

Effects of Knowledge Management System in Disaster Management through RFID Technology Realization

AbstractBased on experiences through different disasters, particularly earthquakes in Iran, we can assume that one of the main problems is lack of an exact and efficient identification system through which the victims, especially all those under the debris can be identified. Type of knowledge related to the disastrous situation and the relevant technology to handle the knowledge, which can speed up the search, rescue, relief, and as a whole Disaster Management process are highly important. In this paper, we suggest Radio Frequency Identification System used in coordination with Oracle as Data Base Management System with a dedicated network system. Finally, due to the importance of technology and knowledge type and sharing, a Knowledge Management System model is proposed. The proposed model intends to focus on knowledge, human and technology-related issues of Emergency Coordination Center. Emergency Coordination Center is Disaster Management headquarters center in which Knowledge Management System model is designed to address its relevant issues and challenges

Development of microwave brain stroke imaging system using multiple antipodal vivaldi antennas based on Raspberry Pi technology

This paper proposes a Microwave Imaging System (MIS) for brain stroke detection. In the MIS, the primary challenge is to improve in terms of cost, size, and stroke image quality. Thus, the main contribution of this work is the economy and the compact rotation platform integrated with an array of nine antipodal Vivaldi antenna in circular arrangement and single computer board, Raspberry Pi Module (RPM) as microcontroller developed. The design and fabrication of wideband antenna based on Computer Simulation Technology (CST) software and Rogers RO4350B substrate, which operated from 2.06 GHz to 2.61 GHz. In the RPM, the Python programming language used for regulating the angle of rotation and antenna switching process. The process of receiving reflection signals from the head phantom for each antenna supervised by Single-Pole 8-Throw (SP8T) Radio Frequency (RF) switch. The fabricated head phantom based on the primary tissues of the brain, white matter using inexpensive materials, and located in the middle of the platform. Platform rotation is a combination of wood-based platform with the size 0.36m2 and material Perspex. Then, through an interfacing process between Python script and Vector Network Analyzer (VNA), the raw data in S-Parameters transferred to the MATLAB software for analysis. The fabricated antenna able to realize high directivity, 86.92% efficiency, and 2.45 dBi gain. Overall, the proposed system offers the cost-effective, compact, and able to collect the data effectively around the head phantom that consist of a target clot and without a target clot at 50 different positions. It successfully tracked the presence of stroke clots through color differences in color plots

Extracted atmospheric impairments on earth-sky signal quality in tropical regions at Ku-band

Atmospheric condition variations were shown to have a major effect on the earth sky signal quality at Ku band. Moreover, such variations increased in the tropical regions as compared to temperate areas due to their different weather parameters. With the increase of recent satellite communication technology applications throughout the tropical countries and lack of information regarding the atmospheric impairments analysis, simulation and mitigation techniques, there is an ever increasing need for extracting a unique and accurate performance of the signal quality effects during highly natural tropical weather impairments. This paper presents a new method developed for proper analysis with distinctive and highly realistic performance evaluation for signal quality during the atmospheric conditions variations in 14 tropical areas from the four continents analyzed based on actual measured parameters. The method implementation includes signal attenuation, carrier to noise ratio, symbol energy to noise ratio, and symbol error rate at different areas and different modulation schemes. Furthermore, for improvement in analysis in terms of covering more remarkable regions in tropics, the paper provides new measurements data with analysis for certain region in tropics used as a test bed and to add measurement data of such area to the world's data base for future researchers. The results show a significant investigation and performance observation in terms of weather impairments in tropical regions in general and each region in that area in particular regarding the signal attenuation and error rates accompanied for several transmission schemes