JANGFA T I M O T H Y ZHIMWANG

This work bidirectional automatic room light controller using visitor counter, is a reliable circuit that takes over the task of controlling the room light as well as counting number of persons in the room very accurately. The counting and turning ON and OFF of light is sensor dependent, as light sensor placed at a particular location gets a pulse and the light comes ON and when the person goes out, the same sensor gets another pulse and the light goes OFF. The block diagram of the circuit was achieved by the use of a methodological approach known as "TO DOWN" approach of the development process of microcontroller-base system Crisp (2004). The system circuit was designed with DIPTRACE The microcontoller was programmed using hex file. The soldering procession was done and after completion of the soldering process, the circuit was tested. The phase voltage of 220v ac was stepped down to 12v ac at 50Hz using a step down transformer.

This paper presents the impact of electromagnetic wave scattering due to rain activities on Ku-band link over Jos, Nigeria. Data were measured at University of Jos, Plateau state, Nigeria with Maximum, Average and Minimum Temperatures of 29.8 0 C, 22.8 0 C and 17 0 C respectively. The data were collected for the period of four months (June, July, August, and September, 2018). Both satellite signal and rain measurements were done simultaneously. Data collected were analyzed using Microsoft excel office and the effects of rain activities that causes electromagnetic wave scattering were estimated from the exceeded distribution Frequency of percentage time (%) obtained using ITU-R P.1621 recommendation. The results obtained from this study revealed that high intensities of rainfall above 90 mm/hr which prevail for a long period cause high electromagnetic scattering resulting to signal and power losses.

This paper presents the measurement and analysis of the consistency of rain induced impairment on Line-of-sight links in middle belt region of Nigeria. The experiment was carried out at the Globacom switch house, Jos Plateau state (9.9565° N, 8.8583° E; 1258 meters). Rain rate data were obtained for the period of eight months (April, May, June, July, August, September, October and November 2017). The Davis Vantage Vue weather station was used to measured and recorded one-minute rain-rates. Microsoft Excel application package was used to analyze the obtained rain rate data through which the frequency and exceeded frequency percentage of time was calculated. Results obtained shows that the rain induced impairment within the study area are cause mostly by widespread (>5-25mm/hr) and shower (>25-120mm/hr). Higher rainfall intensities were obtained between 0.01 and 0.001% exceeded percentage of time where maximum rain induced impairment can best be estimated. Keyword: Line-of-sight link, rain rate, rain induced impairment

This paper presents the impact of cloud on free space optical signal in the guinea savannah region of Nigeria. The study was based on the total columnar content of cloud, liquid water density in the cloud and the average surface temperature obtained at three locations: Jos (9.896 0 N, 8.858 0 E), Lafia (8.506 0 N, 8.522 0 E), and Markurdi (7.732 0 N, 8.539 0 E) within the guinea savannah region using the ITU-R (2009) recommendation on cloud attenuation. Results on cloud attenuation were determined at a frequency of 12GHz at different elevation angles (5 0 , 15 0 , 25 0 , 50 0 , 75 0 , and 90 0). At 5 0 elevation angle, cloud attenuation was determined to be 3.97dB while at 90 0 , elevation angle, cloud attenuation was found to be 0.358dB using the same specific attenuation coefficient (0.231(dB/km)/(g/m 3)) and total columnar content of cloud (1.5 kg/m 2) for 1% of the year. From the results obtained, it was discovered that signal and power losses due to cloud on the free space optical signal is more pronounce when the elevation angle is low (below 45 0) at high frequency. This study will enable satellite communication operators to determine the optimum satellite transmission frequency and elevation angle at which there will be the least effect of cloud within the study area.

This paper presents the computational analysis of cross polarization on KU-Band satellite links. The depolarization effects on satellite links are described in terms of cross polar discrimination (XDP). The differential phase shifts mainly responsible for causing depolarization at Ku-band due to scattering by spheroidal raindrops wascomputed. Simultaneous analyses of sample data from Ku-band, EUTELSALAT (W4/W7) satellite beacon footprint at a frequency of 12.245 GH Z and elevation angle of 036 0 E over Jos (9.8965 0 N, 8.8583 0 E, 1192M) were analyzed. Also the distribution of one minute rain rate obtained from Davis Vantage Vue Integrated Sensors Suites (ISS) weather station was computed. These data were applied to the ITU-R procedure in recommendation 618-12(ITU-R, 2015) to estimate the cross polarization discrimination due to rain on earth satellite path. The results shows that XPD at lowervalue imply very high incidences and cross talks are expected in the region. As such frequency re-use is difficult in Jos, Nigeria.

This paper presents results on the analysis of satellite transmission losses due to tropospheric irregularities in Guinea Savanna region of Nigeria. The analysis was based on measured rain rates data, signal strength, and quality of the Ku-band satellite signal during rainfall over the region. Five months (June to October, 2017) data was used to described the monthly variation of precipitation intensity which was further used to estimate the propagation losses on the Ku-band frequency (12.245 GHz) over the region. The Ku-band satellite signal and rain rate measurement were taken simultaneously with symbol rate of 27, 509bps and satellite elevation (orbital) was 036E. It was found that low precipitation intensity below 10 mm/hr has less effects on Ku-band propagation while high precipitation intensity above 20 mm/hr that prevail for more than 15 minutes causes high propagation loss over the region. The troposphere is the lowest portion of the atmosphere. Most of the weather effects takes place in the troposphere. It contains 80% of the atmosphere's mass and 99% of its water vapor. The troposphere begins at ground level to a height of about 17 km. The temperature of the troposphere decreases with height (approximately 6.5 0 C per km) and saturation vapor pressure decreases with decreasing temperature, the water vapor content of the atmosphere decreases strongly

This paper presents the estimation of long term propagation losses due to rain on microwave satellite links over Jos. Data were retrieved from the National Space Research and Development Agency (NASRDA) Abuja, Nigeria. The data collected was rainfall rate (mm/h) for theperiod of three year (2015-2017) over Jos. Results were obtained based on the exceedance distribution frequency of percentage time (%) and cumulative distribution of one-minute rain rate which revealed that higher rainfall rate (above 100 mm/hr) account for about 0.01 and 0.001% time ofexceedance and it is during such times that maximum propagation losses due to rainfall is significant and can be best estimated.

This paper presents the design and construction of a dual regulated ±0-35Volts DC power supply that will serve a dual purpose of providing a positive and negative DC output of different values for use in miniaturize electronic appliances such as laptops, TV, and Telephone. It may also be useful in various domestic and laboratory experimental purposes. LM317 and LM337 were used as positive and negative voltage regulators respectively. The circuit was built with preferred values of components with an AC input of 220Vrms, 50Hz that was step down using a designed center tapped transformer (37V 0 37V). The total output power was found to be 272.34W. The total power loss was determined to be 35.66W with an efficiency of 88.42%. The DC voltage transfer functions at the positive and negative terminals were found to be 0.966 and 0.969 respectively. The differences between the voltages of the developed circuit and the designed values were found to be 3.45% at the positive terminal and 3.18% at the negative terminal which was achieved using the percentage error method. This device is useful in an application that uses bi-directional amplifiers and dual power supply such as operational amplifiers mostly found in TV/Radio systems.

This paper presents the evaluation  of propagation losses due to rain attenuated signal on terrestrial radio link. Rain rate data were measured using Davis weather station for the months of July, August and October 2017 at (9.9565° N, 8.8583° E; 1258 meters) Jos Plateau state of Nigeria. The data were analyzed using Microsoft Excel application package. Results were calculated based ITU-Recommendation. The result for the month of July shows that rain attenuated signals become more severe from rain rate of 90 mm/hr at 0.014% to 160 mm/hr at 0.002% with attenuation of 31.215dB and 105.951dB respectively. Also, the month of August shows that rain attenuated signals become more severe from rain rate of 70mm/hr at 0.017% to 200mm/hr at 0.002% with attenuation of 69.509dB and 108.324dB respectively. Furthermore, the month of October shows that rain attenuated signals become more severe from rain rate of 70mm/hr at 0.014% to 160 mm/hr at 0.004 with attenuation of 50.301dB and 135.336dB respectively. Therefore, results from this study revealed that rain Original Research Article Igbekele et al.; PSIJ, 23(1): 1-8, 2019; Article no.PSIJ.50548 2 attenuated signals on terrestrial radio links in Jos-Nigeria is more severe at higher rainfall rate (above 60 mm/hr) and lower exceeded frequency percentage of time (0.01% to 0.001%).