A filtering method developed to improve GNSS receiver data quality

A filtering method developed to improve GNSS receiver data quality

Ionospheric Scintillation Impacts on
GNSS Positioning using
CIGALA/CALIBRA Network
Jéssica Saldanha Souza
Dra. Daniele Barroca Marra Alves
Departamento de Cartografia, Universidade Estadual Paulista Júlio
de Mesquita Filho
CALIBRA DAY – 09/05/2014
Outline
• Introduction
– Ionospheric Scintillation
– Affected regions
•
Methods and Tools
– CIGALA / CALIBRA network
– ISMR Query Tool
• Results
– Analyzes of S4 Index, PP and Network RTK
• Conclusions
Introduction
The ionosphere scintillation can be
described as a fast change in the phase
and amplitude
of GNSS signal caused by irregularities in
the electron density along the signal’s path
The occurrence of equatorial ionospheric scintillation is related to the equatorial
anomaly with a larger intensity in the anomaly’s local peak and
in the ionospheric bubbles that are formed in this region after the sunset.
The magnitude and frequency of these scintillations are
correlated with the solar cycle that occurs in 11 years
intervals, the most recent peak was
between the end of 2013 and the early 2014
The periods when it is reached the highest levels of
scintillation are approximately during the months of:
March, April, September and October
The minimum levels occur in the months of
May to August
Analysis for different periods of the
year
June 2013
October 2013
Experiments
The analysis for ionospheric scintillation were performed with:
S4 Index
PP (Point Positioning)
Network RTK
S4
CLASS
S4 > 1
STRONG
0,5 < S4 < 1
MODERATE
0 < S4 < 0,5
WEAK
Results
2011
2012
2013
2011
2012
2013
2011
2012
2013
2011
2012
2013
Analysis for different periods of the day
24 h
06 h
24 h
06 h
Concentration of S4 index
PP
PRU2 24h - 2013
PRU2 06h - 2013
6
5
4
4
3
Março
Junho
2
Outubro
EMQ - 3D (m)
EMQ - 3D (m)
5
3
Março
2
Junho
Outubro
1
1
0
0
01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
Dias
Dias
POAL 06h - 2013
5
4
4
3
Março
2
Junho
Outubro
EMQ - 3D (m)
EMQ - 3D (m)
POAL 24h - 2013
5
3
Março
2
Junho
Outubro
1
1
0
0
01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
Dias
Dias
S4 Index and PP
June
October
S4 Index and PP
June
October
Network RTK
The basic idea of VRS concept is
to generate a station that doesn’t
exist physically, but that simulates
a base station next to the mobile
receiver
Data used in
network positioning
GNSS-SP Network
Summer
16/02/2012
Winter
08/07/2012
Spring
08/10/2012
Autumn
03/04/2012
Summer
18/01/2012
Winter
09/07/2012
Spring
26/09/2012
Autumn
25/03/2012
Summer
12/02/2012
Winter
18/07/2012
Spring
09/10/2012
Autumn
02/04/2012
S4 < 0,3
0,3 < S4 < 0,7
S4 > 0,7
S4 < 0,3
Spring
Autumn
Summer
Winter
0,3 < S4 < 0,7
Spring
Autumn
Summer
Winter
S4 > 0,7
Spring
Autumn
Summer
Winter
PP – 24h
Summer
4,5
4
3,5
3
2,5
2
1,5
1
0,5
0
EMQ (m)
EMQ (m)
Spring
Low
Moderate
4,5
4
3,5
3
2,5
2
1,5
1
0,5
0
Low
High
4,5
4
3,5
3
2,5
2
1,5
1
0,5
0
Low
Moderate
High
Winter
EMQ (m)
EMQ (m)
Autumn
Moderate
High
4,5
4
3,5
3
2,5
2
1,5
1
0,5
0
Low
Moderate
High
PP – 06h
Summer
4,5
4
3,5
3
2,5
2
1,5
1
0,5
0
EMQ (m)
EMQ (m)
Spring
Low
Moderate
4,5
4
3,5
3
2,5
2
1,5
1
0,5
0
High
Low
4,5
4
3,5
3
2,5
2
1,5
1
0,5
0
Low
Moderate
High
Winter
EMQ (m)
EMQ (m)
Autumn
Moderate
High
4,5
4
3,5
3
2,5
2
1,5
1
0,5
0
Low
Moderate
High
Conclusions
•The ionospheric scintillation has great impact on network
positioning and PP;
•The POAL station is less affected by the scintillation;
•The scintillation is more intense in spring and autumn
and less intense in winter;
•It is possible to see clearly the effects of scintillation in
VRS because the effects in the base station are
transferred to the user.
•For 6h, the results are more impacted by the scintillation.
Thank You !