Empirical and Measured Analysis of FM Signal Attenuation at 91.1 MHz and 101.5 MHz in Adamawa State, Nigeria

Abstract

FM signal is one of the major and fastest channels for information dissemination in Nigeria, especially in times of security treats due to the rising insecurity in the nation. However, the quality of radio broadcasting in North-Eastern Nigeria is very poor due to the nature of the terrain that causes interference with the transmitted signals. In this study, analysis of signal attenuation on FM 91.1MHz and 101.5MHz was studied in Adamawa State using propagation models. Primary and secondary data were taken from the field and the radio stations respectively. The field data were that of signal strength of both stations at a mean distance of 20km through a 250km radius of coverage along Adamawa Central and Adamawa North senatorial districts using a field strength meter (TM-195, 3-axis). Calculated attenuation using the Okumura’s model was compared to the measured attenuation. The effect of some atmospheric parameters such as temperature and pressure were also measured. The results show that signal attenuation is directly proportional to linear and vertical distance. The correlation between attenuation and distance is 0.85 for FM91.1 and 0.80 for FM101.5. Attenuation of signal strength appears to be directly proportional to temperature and inversely proportional to increased pressure. It was also discovered that the radio stations do not cover a 250km radius as calculated and documented, which means that there is a disagreement between the field and documented values of the signal strength of the radio stations owing to the high attenuation of the signals in the region. This study will have application in telecommunication, especially in the procurement and installation of transmitters both for public and private sectors within this region of the country.