The Influences of Meteorological Parameters on Digital Terrestrial Television (DTT) Signal in the Tropics

The medium of propagation for Digital Terrestrial Television (DTT) is the troposphere, where most weather phenomena occur. Thus the need to study the effect of meteorological parameters on DTT signal has become necessary in Nigeria now that DTT will soon replace the existing analog transmission. This study therefore investigates the influences of meteorological parameters of temperature, atmospheric pressure, humidity, amount of rainfall or precipitation. Also investigated, is the influence of surface radio refractivity on the Received Signal Strength (RSS) of a Digital Terrestrial Broadcast Station (DTTBS) in Akure metropolis, South West Nigeria. The Received Signal Strength (RSS) of the base station was measured at intervals of 1km along three selected routes around the station using a digital Satlink signal meter model WS-6936 with a DTT UHF receiving antenna connected. A GPS receiver (Garmin Map 78s) was used to monitor the line of sight with the station as reference and was equally used to log data geographic coordinates and heights. For the measurement of meteorological parameters of data locations, a USB Mobile Weather Station model N96FY was used whereas the surface refractivity values were calculated using the atmospheric parameters obtained. Data were collected during dry and wet seasons for comparative studies. Two sets of Signal Strength values were obtained corresponding to two receiver antenna heights of 1.5 m and 3.0 m. Analyses were carried out on the obtained data using necessary soft ware. Result showed that higher values of surface refractivity degrade DTT signal while lower values enhance it. This was observed for both dry and wet seasons, though higher average value of surface refractivity was recorded during wet seasons compared to the dry seasons, meaning that DTT signal surfers' more attenuation effect of surface refractivity during the rainy season compared to dry seasons. A correlation coefficient of -0.26 was determined for DTT Signal and RSS. In addition, the higher the rainfall or precipitation values the lower the signal strength recorded and vice versa. A high negative correlation coefficient of -0.80 and -0.82 were determined between precipitation and Received Signal Strength (RSS) for both dry and wet seasons respectively. Result further revealed that higher values of humidity do not necessarily lead to attenuation of DTT signal rather lower values enhance its attenuation. Furthermore as atmospheric pressure increases, RSS