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All Journal International Journal of Electrical and Computer Engineering TELKOMNIKA (Telecommunication Computing Electronics and Control) Bulletin of Electrical Engineering and Informatics Indonesian Journal of Electrical Engineering and Computer Science
Jafri Din
Universiti Teknologi Malaysia
Computer Science & IT Electrical & Electronics Engineering

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Journal : telkomnika telecommunication computing electronics and control

 1 
A methodology for precise estimation of rain attenuation on terrestrial millimetre wave links from raindrop size distribution measurements Manhal Alhilali; Mustafa Ghanim; Jafri Din; Hong Yin Lam
TELKOMNIKA (Telecommunication Computing Electronics and Control) Vol 17, No 5: October 2019
Publisher : Universitas Ahmad Dahlan

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12928/telkomnika.v17i5.12798

Abstract

Attenuation by atmospheric rain is the most significant impairment in millimetre wave frequencies (mmWave). Modern instruments could provide detailed measurements of rain, such as raindrop size distributions (DSDs). The analysis of DSDs could estimate their effects on past or co-located links measurements. This study presents propagation analysis in the mmWave bands using measurements of two terrestrial links working at 26 and 38 GHz carried out in Johor, Malaysia. Statistics obtained have been analysed in detail to extract any excess attenuation. The DSDs provided by a disdrometer have been used to estimate rain attenuation. The derived results show that the estimation can provide reasonable accuracy after extracting the wet antenna effects and having the advantage of the availability of measurements from various types of equipment.
TURTLE HEARING CAPABILITY BASED ON ABR SIGNAL ASSESMENT Anton Yudhana; Sunardi Sunardi; Jafri Din; Syed Abdullah; Raja Bidin Raja Hassan
TELKOMNIKA (Telecommunication Computing Electronics and Control) Vol 8, No 2: August 2010
Publisher : Universitas Ahmad Dahlan

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12928/telkomnika.v8i2.620

Abstract

Sea turtles have existed for millions of years. International Union for Conservation of Nature (IUCN) has reported that the Hawksbill Turtle (Eretmochelys imbricata) is classified as critically endangered. Turtle excluder device (TED) deployment on shrimpnet fisheries is needed for turtle conservation.TED using sound technique is challenge method in fisheries development.The knowledge on turtle hearing capability is limited. The auditory brainstem response (ABR) assessment is method to determine turtle hearing capability. Turtle hearing assessment is basis to design TED. The objective of this paper is to determine turtle hearing cability by analyze its ABR spectral.The subject is Hawksbill turtle with number 2 turtles ie: 3 and 2 years. The measurement was taken at Pusat Pengurusan Penyu (Turtle Management Centre) Padang Kemunting Masjid Tanah Melaka Malaysia. The results shows that turtle 3 years have peak power frequencies 50.78, 101.6, 152.3, 304.7, 355.5, 457, and 507.8Hz respectively whereas the spectral amplitude is ranging 0.03-32.44% spectral. Turtle 2 years has peak power at 457Hz in whole stimulus frequencies while the spectral amplitude is ranging 0.01-2.5% spectral.
Rain attenuation statistics for mobile satellite communications estimated from radar measurements in Malaysia Mohammad Ibrahim Abozeed; Manhal Alhilali; Lam Hong Yin; Jafri Din
TELKOMNIKA (Telecommunication Computing Electronics and Control) Vol 17, No 3: June 2019
Publisher : Universitas Ahmad Dahlan

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12928/telkomnika.v17i3.12040

Abstract

Mobile satellite communications will play a significant role in the next 5th generation mobile services. The use of high-frequency bands will be the enabler of this advancement. However, at high frequencies, excess rain attenuation causes severe signal losses and presents a major threat for the system availability, especially in the tropical region. To that end, this study presents the rain attenuation impact on mobile satellite communications estimated using long-term radar measurements in Malaysia, by exploiting the horizontal structure of rain from the radar database and simulating inner-city and highway mobile terminals scenarios. Additionally, a scaling factor was presented to scale available fixed satellite terminals measurements to mobile terminals operating at the same locality under similar conditions. In comparison to the available link measurements, the radar database was reliable enough to provide highly accurate estimates. In all simulation scenarios, the mobile terminal will depart the rainy area soon enough and experience lower attenuation statistics in comparison with the fixed terminal. The provided results will help determine the overall future system performance, especially in tropical regions.
SWIMBLADDER ON FISH TARGET STRENGTH Sunardi Sunardi; Anton Yudhana; Jafri Din; Raja Bidin Raja Hassan
TELKOMNIKA (Telecommunication Computing Electronics and Control) Vol 6, No 2: August 2008
Publisher : Universitas Ahmad Dahlan

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12928/telkomnika.v6i2.561

Abstract

This paper discusses of Target Strength (TS) for the Selar boops (Oxeye scad) and Megalaspis cordyla (Torpedo scad), the most commercially fish in Malaysia. TS can be determined from in situ measurements and calculation using acoustic fish model. TS value, depth, and position (x-y-z) of fish targeted can be viewed from echogram using FQ-80 Analyzer by in situ measurement. X-ray imaged can be deployed to develop the acoustic fish model. The percentage of length and upper surface area for swimbladder to body fish of Selar boops more than Megalaspis cordyla can be measured after X-ray process. The percentage of width and volume of swimbladders to its each body are no significantly difference for both fish. These data of swimbladder physic are supports the result from in situ measurement which TS of Megalaspis cordyla have more than Selar boops.
Tropospheric Scintillation with Rain Attenuation of Ku Band at Tropical Region Ibtihal F El-shami; Lam Hong Yin; Jafri Din; Ali l Elgayar; Manhal Alhilali
TELKOMNIKA (Telecommunication Computing Electronics and Control) Vol 16, No 5: October 2018
Publisher : Universitas Ahmad Dahlan

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12928/telkomnika.v16i5.10002

Abstract

Tropospheric scintillation can become a significant impairment in satellite communication systems, especially in tropical regions with frequencies higher than 10 GHz, the attenuation is dramatically affecting the scintillation. This work concentrates on those aspects in equatorial Johor Bahru, Malaysia, based on a one-year Ku-band propagation measurement campaign, utilizing the equipment of Direct Broadcast Receiver (DBR) and Automatic Weather Station (AWS). This study investigates the relationship between wet scintillation and rain attenuation using experimental measurement and concentrate on the probability density function (PDF) of different scintillation parameters. From the results, it is concluded that wet scintillation intensity increases with rain attenuation. Thus, the relationship can be phrased by linear equations or power-law. The PDFs of wet scintillation intensity, adapted to a given rain attenuation level, are found lognormally distributed, leading to selection of method for determining the relation between conditional PDFs and rain attenuation.
SOUND OF PADDLE WHEEL ON SEA BASS GROWTH Sunardi Sunardi; Anton Yudhana; Ahmad Syahril Mohd Nawi; Jafri Din; Saberi Mawi
TELKOMNIKA (Telecommunication Computing Electronics and Control) Vol 7, No 1: April 2009
Publisher : Universitas Ahmad Dahlan

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12928/telkomnika.v7i1.570

Abstract

The objective of this research is sound effect for brackish water for Sea bass (Cynoscion nobilis). Breeding farm 25x100m, 2m of depth, and 6 paddle wheels which generate the sound are available for research. Sound profile has been measured to investigate the amplitude at various measurement points at various depths by using Cetacean hydrophone C304. The output of hydrophone has been analyzed by using SpectraPlus software. For the second measurement, two cages which size 3x3m have been used for life fish habitat. Then, fish put in the edge cage (20), center cage (20), and out of cage (12500). Sound profile has been measured for position-based (edge/center cage), time-based (morning/noon/evening), and point-based. Time series, spectrum frequency, and phase have been analysis. Fish growth progress has been monthly measured at every cage. Fish in the cage is growth as linearly, while fish growth for out of cage is exponentially. Size and weight of fish in the both cages is less than out of cage. This research concludes that sound have no significantly effect for fish growth. Limited mobility to look for food and stress are more influences to fish growth than sound effect.
A Mathematical Approach for Hidden Node Problem in Cognitive Radio Networks Felix Obite; Kamaludin Mohammad Yusof; Jafri Din
TELKOMNIKA (Telecommunication Computing Electronics and Control) Vol 15, No 3: September 2017
Publisher : Universitas Ahmad Dahlan

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12928/telkomnika.v15i3.6897

Abstract

Cognitive radio (CR) technology has emerged as a realistic solution to the spectrum scarcity problem in present day wireless networks. A major challenge in CR radio networks is the hidden node problem, which is the inability of the CR nodes to detect the primary user. This paper proposes energy detector-based distributed sequential cooperative spectrum sensing over Nakagami-m fading, as a tool to solve the hidden node problem. The derivation of energy detection performance over Nakagami-m fading channel is presented. Since the observation represents a random variable, likelihood ratio test (LRT) is known to be optimal in this type of detection problem. The LRT is implemented using the Neyman-Pearson Criterion (maximizing the probability of detection but at a constraint of false alarm probability). The performance of the proposed method has been evaluated both by numerical analysis and simulations. The effect of cooperation among a group of CR nodes and system parameters such as SNR, detection threshold and number of samples per CR nodes is investigated. Results show improved detection performance by implementing the proposed model.
Spatial variations of rain intensity over a short length propagation for 5G links based on a rain gauge network M. Rashid; Jafri Din; Omar Abdul Aziz
TELKOMNIKA (Telecommunication Computing Electronics and Control) Vol 19, No 2: April 2021
Publisher : Universitas Ahmad Dahlan

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12928/telkomnika.v19i2.16809

Abstract

Millimeter-wave (mm-wave) frequency range is among operating bands designated for terrestrial 5G networks. A critical challenge of link-budgeting in mm-wave 5G networks is the precise estimation of rain attenuation for short-path links. The difficulties are further amplified in tropical and subtropical regions where the rainfall rate has a higher intensity. Different models have been proposed to predict rain attenuation. The distance factor is an important parameter in predicting total attenuation from specific rain attenuation. This study investigates the distance factor based on rain gauge networks and measured rain attenuation at 26 GHz for a 300 m link in Malaysia. Considerable discrepancies between available models were observed especially when applied for shorter path links. Also, significant variability of rain intensity is observed from the rain gauge network. This study recommends further investigation of the distance factor for a shorter link. Hence, a measurement campaign incorporating rain gauge networks was established to examine spatial variations of rain intensity over a less than 1 km link. The motivation is to develop a suitable distance factor model for 5G mm-wave propagation.
Comparison of Raindrop Size Distribution Characteristics Across the Southeast Asia Region Manhal Alhilali; Lam Hong Yin; Jafri Din
TELKOMNIKA (Telecommunication Computing Electronics and Control) Vol 16, No 6: December 2018
Publisher : Universitas Ahmad Dahlan

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12928/telkomnika.v16i6.10091

Abstract

Satellite communication requires reliable estimates of the channel characteristics, especially with the future use of higher frequencies. Regardless of the rain rate, the shape of rain drop size distribution (DSD) start to considerably effect the specific attenuation. In this study DSDs are studied using ground-based two-dimensional video disdrometer measurements taken from Johor, Malaysia as well as two similar datasets from Gan and Manus, two equatorial islands. Integral rain parameters are studied to explain DSD variations across the Southeast Asia region. Slightly higher raindrop concentrations and larger diameters were observed in Johor than in Gan or Manus, which is due to Johor being affected by not only oceanic rain- fall but land rainfall as well. The measured rainfall was classified into convective and stratiform precipitation types; the results showed that the Southeast Asia region is dominated by convective rain in terms of accumulated rainfall amount, but stratiform rain occurred more frequently. Further, seasonal variations observed in Johor were insignificant and the DSD variation was mostly due to changes in percentage occurrence of the precipitation types for each monsoon season.
Co-Authors Ahmad Syahril Mohd Nawi Ali I Elgayar Ali l Elgayar Anton Yudhana Athanasios D. Panagopoulos Felix Obite Hong Yin Lam Hong Yin Lam Ibtihal F El-shami Ibtihal Fawzi Elshami Ibtihal Fawzi Elshami Idrissa Abubakar Kamaludin Mohammad Yusof Lam Hong Yin Lam Hong Yin M. Rashid Manhal Alhilali Masoud Mohebbi Nia Michael Schönhuber Mohammad Ibrahim Abozeed Mustafa Ghanim Omar Abdul Aziz Raja Bidin Raja Hassan Saberi Mawi Sunardi, Sunardi Syed Abdullah