Browsing by Author "Sanyaolu, Modupe"

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    1-Minute Rain Rate Distribution for Communication Link Design Based on Ground and Satellite Measurements in West Africa
    (Begell House, Inc., 2020) Sanyaolu, Modupe
    West Africa is in the tropical region and it is characterized by intense rainfall. Rain is a significant factor causing signal degradation on microwave links due to its variability; it causes scattering, absorption, and refraction of electromagnetic waves. Experimental studies have shown that rainfall intensities above 64 mm/h at 0.01% in this region results in noticeable digital television signal fading, squelching and complete outages. Hence the need for estimating rain rate distribution across West Africa. This paper analyzed the rain rate from six countries in West Africa, namely Benin, Cameroon, Cote d'Ivoire, Ghana, Nigeria, and Togo. Three locations were selected in each country. Rain data were obtained from the Tropical Rain Measuring Mission-Precipitation Radar (TRMM-PR) and the Global Precipitation Measurement (GPM) missions, and Tropospheric Data Acquisition Network (TRODAN) weather stations in Nigeria. This study used ITU-R and Moupfouma models for the conversion of the 5-minute rain rate to 1-minute integration time at a probability of exceedance ranging from 1% to 0.001%. The cumulative rain rate distribution from the measured rain rate is presented alongside the predictions of the models. ITU-R and Moupfouma predicted similar results at 0.1% probability of exceedance. ITU-R overestimates the rain rate above 0.01% probability of exceedance. On the other hand, the Moupfouma models prediction plots at 0.01% overlap for all locations, indicating that there will be a signal loss at 0.01% probability of exceedance across these locations. The result shows that the 5-minute conversion provides satisfactory performance and suitable for estimating the 1-minute rain rate statistics required for propagation planning over West Africa.
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    Assessment of Musculoskeletal Discomfort among Mini-Bus Drivers in Osun State, Nigeria
    (International Journal of Progressive Sciences and Technologies (IJPSAT), 2022) Sanyaolu, Modupe
    There have been many reports on the physical factors contributed to the development of work-related musculoskeletal disorders (WMSD) which have a negative influence on the health of employee across different occupations including bus drivers. This study focuses on the assessment of musculoskeletal disorders among mini-bus drivers popularly called “Korope” in the Osun State of Nigeria. This research is based on questionnaires extracted from the standard Nordic questionnaire for the assessment of musculoskeletal disorders (MSDs). The results obtained from the questionnaire showed that the low back, knee and the ankle/feet were found to be the most common areas of discomfort among the population. The elbow showed the least area of musculoskeletal discomfort while the shoulder,upper back, neck, thigh/hips and the wrist/ hands showed moderate discomfort. Some of the subjects experienced at least two of the discomforts.
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    Characteristics of Rain Fade Slope on Microwave Communication in Mowe, Nigeria
    (IOP Publishing, 2021) Sanyaolu, Modupe
    In this paper, the rain fade characteristics at Ka-band (30 GHz) in Mowe (Lat 6.80º N, Lon 3.40º E) Nigeria have been presented. The analysis includes both the first- and second order statistics of rain rate and rain attenuation, and fade duration and fade slope, respectively. Both parameters are useful for planning the point-to-point microwave link for various communication feeder networks. The estimated fade duration and the fade slope were compared with the ITU-R P.837-5 model. The results of this study would be valuable for improving rain fade mitigation techniques in Nigeria.
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    Estimation of Rain Fade Durations on Communication Links at Ka-band in Equatorial and Tropical Regions
    (Begellhaouse, 2020) Sanyaolu, Modupe
    Duration of rain fade events is a major parameter to be considered when designing a communication link. Fading is a phenomenon responsible for intermittent fluctuations of radio signals observed in the tropical region. The prevalence of rain in the tropics accounts for the frequency of fading observed in this region. Despite, the efforts of researchers to help systems designers give due consideration to fade mitigation techniques in other parts of the world, there is still a dearth of fade duration data from the African equatorial and tropical regions. Hence, this study estimates the number of fade events per fade duration interval exceeding attenuation thresholds ranging from 1 dB to 18 dB at ka-Band (26.5 GHz−40 GHz), leading to nonavailability of satellite systems during raining events in the African equatorial regions. The range of fade durations is from 10 s to 5000 s. The International Telecommunication Union (ITU-RP) propagation model and data from the Tropospheric Data Acquisition Network (TRODAN) were used for the analysis. The eight TRODAN observatories, under the Centre for Atmospheric Research (CAR), cover the major climatic regions in the sub-Saharan region, namely equatorial, humid tropical and tropical zones (Geo. 4.82єN to 9.58єN). Fade duration decreases latitudinally as the attenuation threshold increases from low to higher latitudes. The equatorial region suffers the highest frequency of fade events while the tropical zones recorded the lowest. In addition, the 10 s fade duration recorded the highest occurrence of fade events. The implication is that heavy rains, causing higher attenuation, occur for a shorter time duration. Similarly, higher attenuation depends on raindrops size and rain intensity. Consequently, the number of fade events exceeding 1 dB threshold is higher than other thresholds with respect to the fade duration.
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    Evaluation of Vertical Refractivity Profile over Microwave Link in Mowe, Nigeria
    (International Journal Of Microwave Engineering (JMICRO), 2021) Sanyaolu, Modupe
    The radio refractive index structure of the lower section of the atmospheric boundary layer is critical in the planning and construction of microwave communication connections. This study analyses the refractivity profile carried out in Mowe (6.8085° N, 3.4367° E) South – Western Nigeria. Ground measurements of air pressure, temperature, and relative humidity used in this investigation were collected from the rain gauge of the Tropospheric Observatory Data Acquisition Network (TRODAN). The radio refractivity, associated refractivity gradient and climatic factor were computed using data from January 2012 to December 2013. The vertical distributions of radio refractivity were then calculated using these parameters. Seasonal fluctuations in refractivity are visible over the location, with high values in the wet season and low values in the dry season. The findings also suggest that propagation circumstances fluctuate in frequency, with sub-refractive situations being most common between April and September. This is an indication that microwave link in Mowe will suffer higher signal loss during wet season, while the loss may be mild during the dry season. The refractivity values in this study are expected to aid in determining the necessary mitigation to be put in place to reduce loss of signal in Mowe
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    Laser Communication and Atmospheric Impairments
    (Global Scientific Journals, 2021) Sanyaolu, Modupe
    Varieties of signal-loss components in transmitting a laser signal beam from one point to another over microwave link are usually encoun tered due to absorption and dispersion by airborne molecules and aerosols and distortion of the wave-front due to atmospheric turbulence resulting from the variation of the refraction index along the direction of the beam. This paper provided information on calculating attenua tions generated as a result of these aerosols and hydrometeors effect on laser beams. Effective linking equipment, open-loop power control and feedback loop power control are suggested as mitigation techniques that significantly reduce attenuations when laser signals are transmitted
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    Performance of Rain-Induced Attenuation Prediction Models for Terrestrial Link in Cameroon
    (IJEAST (http://www.ijeast.com), 2022) Sanyaolu, Modupe
    Weather, notably rain, has a negative impact on radio wave propagation between terrestrial and earth-space links at frequencies above 10 GHz. Therefore rain-induced attenuation is a significant propagation impact that must be considered when designing satellite communication systems. Analysis of rain attenuation for earth-space links in three locations in Cameroon at V, Ku and Ka bands is investigated using four rain attenuation models: The ITU-R P.618 model, Svjatogor model, Garcia Lopez model and Bryant model at 42.5° elevation angles. The major goal is to figure out which rain attenuation prediction models are best for satellite communication in this area. Five years (2013–2017) daily rainfall data obtained from the Tropical Rain Measuring Mission-Precipitation Radar (TRMM-PR) and Global Precipitation Measurement (GPM) mission's Core Observatory were used for this study. The results showed that the ITUR P.618, Garcia-Lopez, and Svjatogor models performed best in this region. Attenuation ranged from 15 dB to 16 at 42.5° elevation angle for time exceedance of 0.01% at Ku band in all the study locations. For the Ka-band, attenuation varied between 32 dB and 38 dB. Signal availability at Ku-band is possible based on predicted rain attenuation values for 0.01 %-time exceedance. At Ka and V-band, the predicted rain attenuation values for 0.01%-time exceedance have shown that availability of signal is impossible, which infers losses of the signal during such rainfall events across the selected locations in Cameroon.
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    Prediction of Rain-Induced Attenuation Along Earth-Space Links at Millimetre Wave Bands over West African Region.
    (Begellhaouse, 2022) Sanyaolu, Modupe
    The present work characterizes the degree of rain-induced attenuation on 15–80 GHz earth-space commu nication links. Eutelsats 36B and 36C, and NigComSat-1R satellite links over five West African countries were considered through the International Telecommunication Union Radiocommunication Sector (ITU-R) [International Telecommunications Union (ITU)], Bryant, and Syjatogor rain attenuation models. Three locations were selected in each country for the analysis using 2013–2017 rain data obtained from the Global Precipitation Measurement (GPM) missions. ITU-R predicted higher attenuation values than the other two models; while Svjatogor values were close to ITU-R, and the Bryant model predicted the lowest. At 99.99% signal availability, rain attenuation along the earth-space link over the five countries ranged between 22.1 and 34.2 dB for Ku-band (15 GHz) but exceeded the satellites’ link margins at Ka-band (30 GHz). At 0.1% unavailability, the range is 6–21 dB across all the locations for V-band (60 GHz), which implies that the satellites can sustain 99.9% of signal availability across the countries. However, for 99.99% and 99.9% sig nal availability at W-band, earth-space links can experience a total outage across the selected stations. Some locations in the northern parts can have 99% availability, which is an ~ 87 h/yr outage. Hence, the result could be a benchmark for planning trans-horizon radio communication links across West Africa
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    Rain Fade Analysis at C, Ka and Ku Bands in Nigeria
    (iiste.org, 2019) Sanyaolu, Modupe
    Rain fade has continued to be a major concern to communication systems designers. The effect of these dynamic fluctuations of the received signal due to rain is very pronounced in the tropical region. This paper pertains to the analysis of rain fades at C, Ku and Ka bands at some selected stations covering the main geographical zones of Nigeria. The ITU-RP propagation model was used to calculate the fade depth at 6 GHz, 8 GHz, 12 GHz, 16 GHz, 20 GHz, 30 GHz and 40 GHz. The rain fade correlate with signal attenuation. Attenuation distributions for percentages of time for signal unavailability were also estimated. The results show that values of attenuation for vertically and circularly polarized signals are less than those of the horizontal polarization at all the frequencies. It is found that rain fade is less severe in the Northern part of the country and is most severe in the southern part of Nigeria, with Port Harcourt, Lagos and Nsukka experiencing the highest rain impairment
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    Recent Developments in Polymer Optical Fibre Strain Sensors: A Short Review
    (Springer, 2021) Sanyaolu, Modupe
    Polymer optical fiber (POF) strain sensors have attracted increasing attention owing to the unique features of polymer over silica such as lower Young’s modulus, larger elastic strain limit, higher fracture toughness, bio compatibility, and lower production cost. Several POF strain sensors have been developed in recent years for applications in various technological fields, including structural health monitoring in civil construction and aerospace industries, biomedicine, and robotics. The prin ciples of operation, prospects, and challenges of the POF strain sensors are discussed in this article under five broad categories: POF fiber Bragg grating sensors, intensity based POF sensors, multimodal interference- based sensors, Brillouin-frequency-based sensors, and Fabry–Perot cavity sensor. This review aims to highlight areas where further research is required for improving the performance and operating range of POF strain sensors.