Validation of Egli Model and Estimation of Pathloss Exponent of a Radio Signal at VHF Band in Hilly Terrain

International Journal of Research and Innovation in Applied Science (IJRIAS) | Volume V, Issue III, January 2020 | ISSN 2454–6186

 Validation of Egli Model and Estimation of Pathloss Exponent of a Radio Signal at VHF Band in Hilly Terrain

 Aremu Olaosebikan Akanni¹, Anie Nicholas Oliseloke^2
1Physics Department, The Polytechnic, Ibadan. P.M.B 22, UI Post Office, Ibadan, Nigeria
²Physics unit, General Studies Department, Federal School of Surveying, Oyo. P.M.B. 1024, Oyo, Nigeria

Abstract: Pathloss exponent is one of the most important parameter which has been considered widely in wireless communications analysis. It determines the rate at which the signal reduces as the distance (LOS) between the transmitter and the receiver increases and this parameter enhances the effective propagation of radio signal. This paper investigated the radio signal propagation profiles at 88 MHz at various elevation levels. In this work, a Retekess TR501 FM long range instrumentation was used as transmitter. This instrument is capable of transmitting audio signal at VHF band and the signal strength was measured quantitatively across the regions along several routes with the aid of a hand held spectrum analyzer. A global positioning system (GPS) receiver was used to determine the elevation above ground level and the geographic coordinates for four different itinerary in hilly environment. The line of sight (LOS) of the various data points from the transmitter was determined using a digital distance meter. The measured data obtained were compared with existing standard models (Free-space, Egli and Irregular terrain model). The findings revealed that, the average measured values was in good agreement with optimized Egli model having the MAE of 7.10 dB, MAPE of 3.20% and RMSE of 4.80 dB which is within the acceptable international standard range while Free space model underestimated the measured values. The work also shows that the path loss increases with increasing line of sight and the mean path loss exponent obtained in this region is 2.18 which is within the acceptable international standard range for urban environment. Furthermore, it was revealed that, radio signal strength depend directly on elevation regardless of LOS between transmitter and receiver, that is, the signal strength is enhanced at higher elevation point than lower elevation.
Key words: Hilly terrain, LOS, pathloss, signal strength, VHF.

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