This paper proposes a quad anchor noise characterization of an Ultra-Wide Band (UWB) Real Time Localization System (RTLS) under various real-world indoor conditions, with the goal of improving AMR localization across wide range of applications. Although characterizing the UWB RTLS is not compulsory in the application of indoor mobile robot, this approach will allow us to understand how well the system can adapt to varying levels of environment complexity and identify the operational scenarios where it excels or struggles. This is achieved by evaluating the system performance under different levels of floor space occupancy ranging which include open space, moderate and heavily occupied space. A total of 27,000 positioning data were recorded and compared to the ground truth within a test area of 100 m2. The data were then thoroughly analyzed using one factor ANOVA and Tukey’s Honest Significance Difference (HSD) test. The results of the experimental investigation showed that the degree of floor space occupancies has a major impact on the UWB RTLS performance. A one factor ANOVA that produced a p-value of less than 0.05, suggesting a statistically significant effect at the 95% confidence level, supports this finding. To better identified the specific group means are different were also being done afterwards. The approach presented in this paper shows how to generate a unique probability distribution to be used in indoor localization correction algorithm applications with multi environment operational needs. This approach can be useful for other researchers seeking robust localization solutions for their work.