Abstract In this paper, we investigated the occurrence of GPS Loss of Lock(LOL) events and its characteristics in Ethiopia using three dual-frequency geodetic GPS receivers in Bahir Dar (geographic 11.599°N,37.359°E), Debark (geographic 13.150°N, 37.893°E), and Assosa (geographic 10.051°N,34.553°E) during the period from January to December for the year 2015. On average at the three stations,we confirmed that LOL events occurred within the hours of 19:00 LT-25:00 LT,while the maximum number of LOL events had been localized within the hours of 21:00 LT-23:00 LT. This implice that LOL events were more common during the post-sunset hours. On monthly basis, a maximum number of LOL events were observed in the months of April,and March, with a limited number of LOL events observed in the remaining months of the year at low latitudes,such as Bahir Dar, Debark, and Assosa stations. Seasonally, at the three stations and throughout 2015 studied maximum number of LOL occurrences were observed during equinoxes and substantially decreased during solstices. In particular, the months around the December solstice recorded the smallest number of LOL events for each station included here. We found that over the length of the 12 months of data included in this analysis, 551,782 and 160 LOL events had been observed in the Bahir Dar, Debark, and Assosa stations, respectively, inflicting extreme damage to GPS navigation. This implice that Debark station had the most LOL events, while Assosa station had the least number of LOL events, and Bahir Dar station had intermediate number of LOL events. We also found that the majority of LOL events in all stations took place when the elevation angle was low (between 30° and 40°),but Debark also has some LOL cases at higher elevations(greater than 50°) than other stations and Assosa had no LOL occurrences for higher elevations angle. Aside from that, LOL events show special azimuth distribution characteristics, with the discovered LOL events at the three stations concentrated in the northern areas of the sky between North-West and North-East [330°-360°; 0°-30°]. Finally, it may also open up the opportunity of the usage of the quantity of LOL events as a proxy measure of ionospheric irregularity or ionospheric scintillation for low latitudes such as Ethiopia’s Bahir Dar, Debark, and Assosa.
Investigation of GPS Loss of Lock occurrence and Its characteristics over Ethiopia using Geodetic GPS receivers of the IGS network
Advances in Space Research ; 69 , 2 ; 939-950
2021-10-20
12 pages
Aufsatz (Zeitschrift)
Elektronische Ressource
Englisch
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