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Indian Journal of Radio & Space Physics (IJRSP) >
IJRSP Vol.38 [2009] >
IJRSP Vol.38(5) [October 2009] >
| Title: | Ionospheric time delay variations in the equatorial anomaly region during low solar activity using GPS |
| Authors: | Bhattacharya, Soumi
Purohit, P K
Gwal, A K |
| Keywords: | Time delay variation
Equatorial anomaly region
Scintillation
Total electron content
Ionospheric time delay |
| Issue Date: | Oct-2009 |
| Publisher: | CSIR |
| PACS No.: | 94.20.dt; 92.70.Qr |
| Abstract: | Ionosphere can be a greatest variable source of
error in precise time transfer using GPS
satellites. The proposed navigation concept requires that a user
measures the time-delay that satellite emitted signals experience in traversing
the distance between satellite and user. The difference between the apparent
range and the true range, or the free space velocity and the true velocity, is
the quantity of interest. This quantity is directly proportional to the total
electron content along the path of propagating signal. Thus, if the total electron
content is known or is measured, a perfect correction to ranging could be
performed. The equatorial anomaly region, Bhopal (geographic latitude. 23.2ºN,
longitude 77.6°E), India with dual
frequency from the GSV4004A GPS Ionospheric Scintillation and TEC
Monitor (GISTM) receiver have
demonstrated a high degree of accuracy in measuring the ionospheric group
delay. The diurnal and seasonal variations of ionospheric time delay
have been studied during the solar minimum period January to December 2005. It
was found that diurnal variation of ionospheric time delay is maximum in the
month of April and minimum in the month of December. The study reveals that
during low solar activity, equinox season shows the maximum delay while summer
gives the moderate and winter shows the minimum delay. The ionospheric time
delay was also studied during magnetic storm conditions for the same period and
the occurrence of daily maximum ionospheric time delay as a function of day
during this period |
| Page(s): | 266-274 |
| ISSN: | 0975-105X (Online); 0367-8393 (Print) |
| Source: | IJRSP Vol.38(5) [October 2009]
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