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Papers by Boniface Chomba

Interference that causes partial loss of intelligence in air navigation signal is largely depende... more Interference that causes partial loss of intelligence in air navigation signal is largely dependent on the environment around radio navigation aids (navaids). Buildings around airports have been restricted partly because they pose a technical threat to flight navigation. Previous studies have shown that about 50% of air accidents occur during landing. However no data has been availed to determine the contribution of navaids to these accidents. The purpose of this paper was to determine the effects of roofing materials on air navigation signal strength. Radio transmitters, receivers and computers were used in a laboratory to measure signal level transmitted through six different roofing materials at a frequency of 9.4GHz. Decra offered the highest attenuation whereby 90% of the signal propagated was lost, out of which 60% was due to reflection. The equivalent transmission path field strength was 57dBmV/M against an International Civil Aviation Organization (ICAO) recommended minimum ...

Fade depth prediction on airborne line-of-sight communication links is considered. There is no sp... more Fade depth prediction on airborne line-of-sight communication links is considered. There is no specific model for this scenario at the moment. The two ray multipath model, adapted to a realistic scenario of hilly or mountainous terrain, was used to account for flight and terrain geometry and for antenna parameters. Surprisingly, it was found that (i) in many practically important cases the fade depth depends on the path clearance angle only and (ii) the two-ray model predicts roughly the same fade depth dependence on the path clearance angle as the well-known Olsen-Segal model. This may be considered as a theoretical justification, to the best of our knowledge for the first time, of the path elevation angle factor in that model

Effects of Selected Roofing Materials and Angle of Incidence on Navaids Signal Strength

Industrial Engineering Letters, 2015

ET journal

For different wall thicknesses, the effect of varying angle of incidence on wireless signal propa... more For different wall thicknesses, the effect of varying angle of incidence on wireless signal propagation through concrete walls is presented in this paper. In indoor and outdoor built sites RF signal attenuations are caused by losses due to reflected wave among other causes for example multipath, and non-line of sight blockage. The effects of varying angle of incidence on signal strength at 2.457 GHz were determined by using a Hameg HM8135 signal generator and a spectrum analyzer Tektronix RSA3303B. Results showed that signal attenuation levels reduced with an increase of angles of incidences. It was found that there were no significant differences between the model and measured values with 95% confidence for all tests. Results also showed that the Friis model for wireless link need to be modification depending on what type of site conditions and equipment used.

Effects of Varying Distance on Wireless Signal Propagation in Indoor and Outdoor Built Sites

International Journal of Engineering Research in Africa, 2011

ABSTRACT The effects of varying distance on wireless signal propagation in indoor and outdoor bui... more ABSTRACT The effects of varying distance on wireless signal propagation in indoor and outdoor built sites is presented in this paper. In indoor and outdoor built sites the major RF signal attenuation is due to Multipath interference, signal loss(fading), and non-line of sight signal blockage. A number of mobile communication systems are currently and frequently being used in indoor environments based on IEEE 802.11b standards which is currently on 2.4GHz frequency ISM band at the rate of 11Mbps. To determine the effects of varying distances on signal strengths at 2.457GHz, a Spykee spy Wi-Fi robot was used as the transmiter and a laptop installed with a Wi-Fi card and spykee console software to control the robot was used as the receiver. Results showed that the signal attenuation levels increased as distance increased.

Effects of Varying Distance on Wireless Signal Propagation in Indoor and Outdoor Built Sites

International Journal of Engineering Research in Africa, 2011

ABSTRACT The effects of varying distance on wireless signal propagation in indoor and outdoor bui... more ABSTRACT The effects of varying distance on wireless signal propagation in indoor and outdoor built sites is presented in this paper. In indoor and outdoor built sites the major RF signal attenuation is due to Multipath interference, signal loss(fading), and non-line of sight signal blockage. A number of mobile communication systems are currently and frequently being used in indoor environments based on IEEE 802.11b standards which is currently on 2.4GHz frequency ISM band at the rate of 11Mbps. To determine the effects of varying distances on signal strengths at 2.457GHz, a Spykee spy Wi-Fi robot was used as the transmiter and a laptop installed with a Wi-Fi card and spykee console software to control the robot was used as the receiver. Results showed that the signal attenuation levels increased as distance increased.

Interference that causes partial loss of intelligence in air navigation signal is largely depende... more Interference that causes partial loss of intelligence in air navigation signal is largely dependent on the environment around radio navigation aids (navaids). Buildings around airports have been restricted partly because they pose a technical threat to flight navigation. Previous studies have shown that about 50% of air accidents occur during landing. However no data has been availed to determine the contribution of navaids to these accidents. The purpose of this paper was to determine the effects of roofing materials on air navigation signal strength. Radio transmitters, receivers and computers were used in a laboratory to measure signal level transmitted through six different roofing materials at a frequency of 9.4GHz. Decra offered the highest attenuation whereby 90% of the signal propagated was lost, out of which 60% was due to reflection. The equivalent transmission path field strength was 57dBmV/M against an International Civil Aviation Organization (ICAO) recommended minimum ...

Fade depth prediction on airborne line-of-sight communication links is considered. There is no sp... more Fade depth prediction on airborne line-of-sight communication links is considered. There is no specific model for this scenario at the moment. The two ray multipath model, adapted to a realistic scenario of hilly or mountainous terrain, was used to account for flight and terrain geometry and for antenna parameters. Surprisingly, it was found that (i) in many practically important cases the fade depth depends on the path clearance angle only and (ii) the two-ray model predicts roughly the same fade depth dependence on the path clearance angle as the well-known Olsen-Segal model. This may be considered as a theoretical justification, to the best of our knowledge for the first time, of the path elevation angle factor in that model

Effects of Selected Roofing Materials and Angle of Incidence on Navaids Signal Strength

Industrial Engineering Letters, 2015

ET journal

For different wall thicknesses, the effect of varying angle of incidence on wireless signal propa... more For different wall thicknesses, the effect of varying angle of incidence on wireless signal propagation through concrete walls is presented in this paper. In indoor and outdoor built sites RF signal attenuations are caused by losses due to reflected wave among other causes for example multipath, and non-line of sight blockage. The effects of varying angle of incidence on signal strength at 2.457 GHz were determined by using a Hameg HM8135 signal generator and a spectrum analyzer Tektronix RSA3303B. Results showed that signal attenuation levels reduced with an increase of angles of incidences. It was found that there were no significant differences between the model and measured values with 95% confidence for all tests. Results also showed that the Friis model for wireless link need to be modification depending on what type of site conditions and equipment used.

Effects of Varying Distance on Wireless Signal Propagation in Indoor and Outdoor Built Sites

International Journal of Engineering Research in Africa, 2011

ABSTRACT The effects of varying distance on wireless signal propagation in indoor and outdoor bui... more ABSTRACT The effects of varying distance on wireless signal propagation in indoor and outdoor built sites is presented in this paper. In indoor and outdoor built sites the major RF signal attenuation is due to Multipath interference, signal loss(fading), and non-line of sight signal blockage. A number of mobile communication systems are currently and frequently being used in indoor environments based on IEEE 802.11b standards which is currently on 2.4GHz frequency ISM band at the rate of 11Mbps. To determine the effects of varying distances on signal strengths at 2.457GHz, a Spykee spy Wi-Fi robot was used as the transmiter and a laptop installed with a Wi-Fi card and spykee console software to control the robot was used as the receiver. Results showed that the signal attenuation levels increased as distance increased.

Effects of Varying Distance on Wireless Signal Propagation in Indoor and Outdoor Built Sites

International Journal of Engineering Research in Africa, 2011

ABSTRACT The effects of varying distance on wireless signal propagation in indoor and outdoor bui... more ABSTRACT The effects of varying distance on wireless signal propagation in indoor and outdoor built sites is presented in this paper. In indoor and outdoor built sites the major RF signal attenuation is due to Multipath interference, signal loss(fading), and non-line of sight signal blockage. A number of mobile communication systems are currently and frequently being used in indoor environments based on IEEE 802.11b standards which is currently on 2.4GHz frequency ISM band at the rate of 11Mbps. To determine the effects of varying distances on signal strengths at 2.457GHz, a Spykee spy Wi-Fi robot was used as the transmiter and a laptop installed with a Wi-Fi card and spykee console software to control the robot was used as the receiver. Results showed that the signal attenuation levels increased as distance increased.