# Analysis of the Relationship between Scintillation Parameters, Multipath and ROTI
## 4 Discussion
[8] also shows that a high percentage of the higher S4 values and CCD are below 30\({}^{\circ}\). In this study, all data has a 30\({}^{\circ}\) satellite mask applied which should significantly reduce any MP effect in the vicinity of the station. Therefore, the high values of S4, \(\sigma_{\varphi}\) and MP in this study all occur for satellites at high elevations (\(>\)30\({}^{\circ}\)), giving support to the theory that the higher values of MP are being influenced by the scintillation events evidenced from the high scintillation indices values during the corresponding time window. The relationship between MP values from the TEQC software and \(\sigma_{\varphi}\) was observed by [PERSON] et al. [10] through occurrence number plots and time series plots from data collected in Hong Kong, which provided initial evidence that the study of the relationship between MP and scintillation parameters may be interesting and of possible use in the mitigation of errors during scintillation events. Following on [PERSON] et al. [8] and [PERSON] et al. [10] this study provides a much deeper statistical analysis of the relationships between MP, S4 and \(\sigma_{\varphi}\). Furthermore, the ionospheric index ROTI is added in this study to give additional evidence that scintillation is real rather than a product of the physical environment around the receiver as claimed by [PERSON] et al. [8]. The relationship between ROTI and scintillation has been investigated [9; 11; 31; 32; 33]. The scatter plot and the time series plot are common methods used in recent studies to demonstrate the linear relationship between ROTI, S4 and \(\sigma_{\varphi}\)[9; 11; 31; 32]. Additionally, the relationship between ROTI and scintillation has been shown to be affected by changes in elevation angle [11]. Correlation coefficients have shown distinctly higher values when the satellite elevation angle exceeds 60\({}^{\circ}\) when compared to satellites with elevation angles lower than 60\({}^{\circ}\). However, this investigation focuses on elevations higher than 30\({}^{\circ}\), focusing on satellites with higher elevation angles thus taking advantage of the stronger relationship between scintillation and ROTI shown by [PERSON] and [PERSON] [11]. Analysis of the relationship between MP and the scintillation parameters with respect to the effects of elevation angle are not part of this study. [PERSON] and [PERSON] [33], used statistical analysis to conclude that the probability density distribution of S4 can be obtained using ROTI, thereafter, the occurrence probability of scintillation can be estimated. Therefore, [PERSON] and [PERSON] [33] gives the conclusion about strong evidence of a relationship between ROTI and S4, which in general agrees with the analysis from this study. In addition, [PERSON] et al. [31] also demonstrated the theoretical relationship between ROTI and S4 and has demonstrated that this relationship is highly dependent on the sampling rate. They also provide reasons why this relationship varies between different dates and in different regions. These factors have not been investigated in this study and further work is required in this area. Therefore, the investigation on the relationship based on first principles and on the formulae between MP and scintillation is required in future work. Investigations [9; 31; 32; 33] focus on S4, where \(\sigma_{\varphi}\) was not investigated. Therefore, the investigation on \(\sigma_{\varphi}\) is less thorough than that on S4 based on the past research [9; 31; 32; 33]. Though \(\sigma_{\varphi}\) was investigated by [PERSON] and [PERSON] [11], a comparison of how both scintillation indices are related to ROTI was not undertaken. According to the graphs given by [PERSON] and [PERSON] [11], S4 is more correlated with ROTI than \(\sigma_{\varphi}\), which is caused by the relative inactivity of \(\sigma_{\varphi}\) (\(\sigma_{\varphi}\) shows a maximum value less than 0.4).