EFFECT OF ATMOSPHERIC IMPAIRMENTS ON KU-BAND FREE-TO-AIR DIGITAL SATELLITE TELEVISION SIGNALS IN LAGOS STATE

Abstract

With the rapid deployment of free-to-air satellite television, there is an increasing need for an accurate propagation prediction tool for satellite link planning. This paper presents an evaluation of deterministic propagation model that is best for the analysis of satellite signal quality at Ku-band in Lagos state, Nigeria. The paper aims at comparing accurate measurements of channel-to-noise (C/N₀) and bit error rate (BER) taken at six locations within Lagos state with simulation results derived from the Institut für Rundfunktechnik (IRT) model and modified irregular terrain model (ITM) deterministic propagation models. The work considered the effect of the type of modulation scheme and error correction code used on the C/N₀ and BER received using these deterministic propagation models. Results show a deviation of 0.732 dB and 0.285 dB from C/N_o measurements using the IRT and modified ITM models respectively. This work shows that at more than 1% of the time, both models performed well when compared with measurements. However, at less than 1% of the time, which accounts for periods of heavy rainfall, the modified ITM model performed better. The paper also shows that when error correction code is not used with the modulation scheme deployed, the BER increases rapidly and the effect of using a higher alternate modulation symbol is not evident on achievable data rates.

http://dx.doi.org/10.4314/njt.v39i1.27