Diseño de un modelo estadístico de propagación para la banda de radiodifusión FM aplicable en la ciudad de Riobamba.

Abstract

The objective of this study was to design a statistical propagation model for the FM band, adjusted specifically to Riobamba city, this allows more accurate coverage ant power lost calculations of the engineering studies for broadcasting, since the used models are designed for other environments, generating a large margin of error. In order to achieve this goal, a campaign was conducted to measure the electric field intensity in the urban area of the city, these data were then used in power balance to calculate losses presented in each system. For reliability, visits to each one of the FM broadcast stations in Cacha hill were carried out, where transmission equipment data about power loss or gain were collected and which are important for the overall estimate. The propagation losses were obtained using the Okumura, Okumura- Hata, Ericsson, Walfisch-Bertoni and Walfisch-Ikegami models and compared with the actual values. The two best approximation models and their variables were used in the successive regression process which finally define GMC-FM-R model with this formula: L (db) = −170,929 + 30,194Fht (db) + 1909,284 log d (km) − 647, 17 log d (km) log ht (m) − 72,375 log f (MHz), describing the behavior of the electromagnetic waves in the FM broadcast band in Riobamba. The obtained results by applying this new formula were compared again with the previous models to finally verify that they improve effectiveness delivering a de 6.339 RMS error better than 14.8414 and 23, 0434 with the most approximate models Ericsson and Okumura. It is concluded that it is possible to improve the effectiveness of the loss predictions by propagation adapting the models to specific environments or designing a specific one. It is recommended to use limited frequency band, to avoid excessive complexity in the model design process.