Browsing by Author "Dada, Joseph Babatunde"

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    Diurnal, Seasonal and Annual Variation of Microwave Radio Refractivity Gradient over Akure, South West Nigeria
    (Physical Science International Journal, 2019-11) Adediji, Adekunle Titus; Dada, Joseph Babatunde; Ajewole, Moses Oludare
    In this study, four years in-situ measurements of atmospheric parameters (pressure, temperature and relative humidity) were carried out. The measurement was by placing an automatic weather station at five different heights: ground surface, 50, 100, 150 and 200 m respectively on a 220 m Nigeria Television Authority TV tower in Akure, South Western Nigeria. The four years Data collected (January 2007 to December 2009 and January to December 2011) were used to compute radio refractivity and its gradient. The local effect of a location/ region cannot but looked into when designing effective radio link, hence the diurnal, seasonal and annual variations of the radio refractivity gradient were studied. Results showed that refractivity gradient steadily increases in the hour of 8:30 and 9:30 to 18:00 during dry season throughout the years investigated, and decreases two hours in the rainy season than the dry season. The record shows that at 50 m altitude, the maximum and minimum values are 158 N-unit/km around 14:30 and - 286 N-unit/km around 13:30 to 14:00 hrs, LT during the dry and rainy season respectively. Seasonally, refractivity gradient is steeper with greater variability in the dry season months than in the wet season months.
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    Spectral Analysis of Ku-Band Scintillation Dataset for Satellite Communication in a Tropical Location
    (IEEE, 2020) Ashidi, Ayodeji Gabriel; Dada, Joseph Babatunde; Lawal, Yusuf Babatunde
    This study undertakes the determination of suitable cutoff frequency for extracting scintillation amplitude dataset from radio propagation beacons on satellite link within Akure (7.17oN, 5.18oE), Southwest Nigeria. Attempt was also made towards evaluating the spectral characteristics of scintillation parameters through power spectra density (PSD) analysis. Concurrent measurement of satellite beacon signals and meteorological parameters was carried out on Earth-space path over the location for tropospheric amplitude scintillation studies. Tektronix Y400 NetTek Analyzer and Davis Vantage Vue weather station were used for beacon and weather parameters measurements at 1 second and 1 minute integration times respectively. Data spanning one (1) year of measurement were used for the investigation. Results show that extra contributions to signal distortions by nonscintillation mechanisms during extraction of scintillation dataset from satellite radio beacon series may be eliminated by using a cutoff frequency, fc of 0.25 Hz for high pass filtering. Also, spectral slopes with lower magnitudes were found to occur more predominantly than those with higher magnitudes