Evaluation of Global Ionospheric Maps for Single Frequency PPP in - - PowerPoint PPT Presentation
Evaluation of Global Ionospheric Maps for Single Frequency PPP in Egypt Amr El-Demiry, Mahmoud Abd Rabbou, and Adel El-Shazly Department of Civil Engineering, Cairo University Presented by; Prof. Adel El-Shazly Outlines Introduction
Amr El-Demiry, Mahmoud Abd Rabbou, and Adel El-Shazly Department of Civil Engineering, Cairo University
Presented by;
from about 50 km up to about 1,000 km or more above the Earth depending on the sun activities.
atoms.
layer, is affected by the sun activities .
number of the electrons along the path of the signals called the total electron content TEC and the signal frequecy.
causes a delay in code pseudorange measurement and advances the phase measurement by the same amount .
http://www.wirelessdictionary.com/Wireless-Dictionary-Ionospheric-Delay- Definition.html
for the ionospheric error for single frequency PPP due to its superior accuracy compared with the empirical methods.
precise satellite ephemerides, clock corrections and ionospheric maps,------
effort from all, or most of the IGS centers.
the world. Presently IGS manages a network of 384 stations
Centres (IAACs) are contributing their ionospheric products to the IGS.
(UPC).
refer to a 450km shell height.
Acquired from IGS website
distribution and network resolution.
which in role affected the IGS product accuracy for PPP accuracy.
GIM ionospheric models for single frequency PPP in Egypt, To do so;
frequency PPP under well distributed stations network ( North America) to be considered as a reference for these products accuracy in Egypt.
free to roughly investigate the behaviour of the ionospheric delay effect in Egypt.
for SF PPP in Egypt using number of data sets.
s s 1 r 1 r p1 p1
P =ρ (t,t-τ)+c[dt (t)-dt (t-τ)]+T+I +c[d (t)-d (t-τ)] +m +e
1 1 1 1 1 s s 1 r 1 r 1 1 s r
= ρ(t,t-τ)+c[dt (t)-dt (t-τ)]+ T - I +c[ (t)- (t-τ)] + m +e + [ N + (t )- (t ) ]
free technique is used.
2 2 2 1 12 1 2 1 2 2 2 2 2 1 12 1 2 1 12 2 2 noise noise
f f P P P I DCB e f f f I DPB N f ( )
DCB is the differential code bias and DPB is the differential phase bias
such as DPB and the ambiguity parameters should be removed from the Geometry free observations
ionosphere is required to insure that the geometry free contains only the total ionosphere.
which worse the accuracy. In this research, GIM ionosphere products are used instead code-GF to investigate the difference between the GIM and real ionosphere variation trend.
SF PPP Positioning accuracy using final and rapid GIM for North America network.
different latitudes (low, medium and high).
October), each for three days of the years: 2008 and 2012to reflect the seasonal variations of the ionospheric delay.
stations were downloaded from IGS website.
with default atmospheric parameters, and the Neil mapping function is used.
Station name Latitude (degree) Longitude (degree) MDO1 30.68
QUIN 39.97
PRDS 50.87
SASK 52.19625
CRO1 17.75
example).
January 2008 and 2012 (as an example)
Jan-12 GIM final rapid station name DLAT(m) DLON(m) DHGT(m) DLAT(m) DLON(m) DHGT(m) cro1
0.91
0.43
1.83 mdo1 0.96
0.19
0.98 0.76 prds 0.78
0.69
quin 0.74
1.75
0.98
sask
1.26 1.15 Jan-08 GIM final rapid station name DLAT(m) DLON(m) DHGT(m) DLAT(m) DLON(m) DHGT(m) cro1
0.07
0.05
mdo1
0.49
0.52
prds 0.09
0.09
quin 0.24 0.12
0.33 0.13
sask
0.52
0.39
combination compared with GIM delay products
Comparable vertical ionospheric delay is extracted from GIM for Station CRO1.
linear combination compared with GIM delay products in Egypt.
GPS data at Alexandria GPS data at Helwan In contrast, the GIM ionospheric delay products trend variation is far from the leveling geometry-free ionospheric delay estimated trend.
Egypt using final and rapid GIM model.
geographic regions in Egypt mainly Alexandria, Helwan and Aswan.
products.
with default atmospheric parameters, and the Neil mapping function is used.
convergence is detected compared with dual frequency results due to the effect
the ionosphere.
the ionospheric effect is eliminated in dual- frequency model, the convergence time extended to 50 minutes due to the clock and
products accuracy in weak stations resolution.
single frequency PPP ended up accuracy with 1.5 meter for both latitude and altitude after 4 hours of continues data using final GIM model.
GIM ionospheric model is assessed for single frequency PPP in Egypt.
accuracy of the GIM ionospheric products as a reference for the accuracy of these products in Egypt.
investigate the accuracy of the GIM final ionospheric map products in Egypt in comparison with North America station case.
actual trend and variation of the ionosphere affected the GPS data in Egypt. As seen from the results, the GIM delay products are affected from the low resolution of IGS stations in Egypt.
achieve decimeter- level to meter-level accuracy after two hours of continues GPS data processing in well distributed station network such as North America IGS station network. However, the final GIM model present better convergence time than the rapid.
achieve meter-level accuracy after four hours of continues GPS data processing with no convergence in the positioning solution using three sets of static data at Helwan, Alexandria and Aswan.
ionosphere-free solution present encourage positioning solution compared with the traditional differential positioning solution in Egypt with convergence time extend to 50 minutes.
the cost and complexity compared to the traditional differential solution.
show the great needing of set up number of distributed stations which can be linked to the IGS network to enhance the PPP products such as orbital, clock and ionosphere maps,….
benefited from the local stations which set up in Egypt to start produce local products by processing the data of these stations to build local (regional) network such as NOAA and Australia network (RMIT)