The Institute of Navigation (ION) will be hosting a complimentary webinar, “Impact of Sample Correlation on SISRE Overbound for ARAIM,” at 12 p.m. ET on May 28.
This topic was originally presented at ION GNSS+ 2018 and published in the Spring 2020 issue of Navigation, Journal of the Institute of Navigation, Volume 67, No. 1, pp 197-212, by Dr. Santiago Perea Diaz, Prof. Michael Meurer and Dr. Boris Pervan.
According to ION, this paper analyzes the effect of error correlation on the SISRE bounding for GPS and Galileo satellites. For a given period of data collection, it computes the effective number of independent samples contained in a dataset applying an estimation variance analyses. Results show that the time between effective independent samples is highly dependent on the constellation and onboard clock type. On one hand, GPS satellites equipped with Rubidium clocks exhibit significantly longer error correlation than those with onboard Cesium clocks. On the other hand, Galileo satellites show substantially shorter correlation time among samples with less variability on a monthly basis, ION added.
This paper also introduces a methodology to compute SISRE bounding accounting for the limited number of independent samples, ION said. Using a Bayesian approach, it computes the so-called uncertainty factor by which the Gaussian distribution needs to be inflated in order to account for the observation data independence.