ionospheric scintillation effects on gps measurements · ionospheric scintillation effects on gps...
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1
Ionospheric Scintillation Effects on GPS Measurements
Professor Terry Moore
Institute of Engineering Surveying and Space Geodesy
The University of Nottingham
2
hEPSRC funded project qStudy effects of ionospheric scintillation and of North/South TEC
gradients in Northern Europe and mid-latitudes (UK)by
qInvestigating impact on GPS applications
qAssessing impact on GPS accuracy, integrity and availability
h3 years duration
hIESSG with collaborators:
hThales Geosolutions Group Ltd
hTrinity House Lighthouse Service
hUniversity of Calgary
Ionospheric Scintillation Effects on GPS Measurements
3
WP1 Establishment of a scintillation observing GPS network
Using an array of GPS scintillation monitorsCo-located with dual-frequency receivers
WP2 Develop data processing and archiving strategies
WP3 Assess impact on EGNOS
WP4 Assess impact on Maritime DGPS
WP5 Assess impact on different receiver technologies
WP6 Application to other satellite systems
Also: Form data base for future (next solar maximum)
Develop warning & mitigation mechanisms ?
Work Packages
4
ID Task Name
1 WP1 - Establish Network
2 WP2 - Software Development
3 WP3 - EGNOS Performance
4 WP4 - DGPS Performance
5 WP5 - Impact on Receivers
6 WP6 - Other Applications
7
8 Progress Report #1
9 Progress Report #2
10 Progress Report #3
11 Progress Report #4
12 Final Report
13
14 Progress Meeting #1
15 Progress Meeting #2
16 Progress Meeting #3
17 Progress Meeting #4
30/08
28/02
27/02
27/11
25/03
06/09
07/03
06/03
04/12
Qtr 1 Qtr 2 Qtr 3 Qtr 4 Qtr 1 Qtr 2 Qtr 3 Qtr 4 Qtr 1 Qtr 2 Qtr 3 Qtr 4 Qtr 1 Qtr 2 Qtr 32001 2002 2003 2004
01 March 2001
Time Scale
5
hThales SkyFix Europe Network
hNorth South Distribution (red ellipses)
hGPS Iono Scintillation Monitors
hCo-located with 2-freq receiversNOTTINGHAM
The MonitoringNetwork
6
hGPS Silicon Valley GSV 4004
hDual Frequency 12 channel NovAtel OEM4 card
hStable ovenized crystal oscillator
hWide bandwidth to insure that all spectral componentsof amplitude and phase scintillation are measured (50 Hz raw data)
hLogs and Outputs Statistics of Phase and AmplitudeScintillation (60 seconds data)
Ionospheric Scintillation Monitor
hAlso outputs TEC and dTEC
The monitor can also track one SBAS satellite (e.g. EGNOS or WAAS)
7
Experimental IESSG Interactive Scintillation Plots Web Interface
8
Experimental IESSG Interactive Scintillation Plots Web Interface
9
Station with Scintillation Data(current monitoring network, part of Thales SkyFix Network)
Station with dual frequency Data
Stations with Dual-frequency/Scintillation Data
Ny Alesund
Tromso
BergenLerwick
Hammerfest
Nottingham
Bronnoysund
79N 12E 71N 23E
70N 19E
65N 12E
60N 01W 60N 05E
53N 01W
10
Dual-Frequency Model Residuals24 Hrs, 30 sec dual-freq data from Nottingham
02 Apr 2001Peak of the Solar Cycle(major GeomagneticStorm)
08 Jun 1997Low of the Solar Cycle
All Satellites
Bernese software
11
Phase Scintillation Data for PRN 10, starting at 22:00 UT on 01 Apr 2001
Correlation of TEC residuals with Phase Scintillation (Iono Storm Apr 2001)
R e s id u a l s in T E C U
- 2
- 1 .5
- 1
- 0 .5
0
0 .5
1
S V 1 0 N o t t i n g h a m 0 1 - 0 2 A p r i l 2 0 0 1
0
0 . 0 5
0 . 1
0 . 1 5
0 . 2
0 . 2 5
0 . 3
2 2 2 3 0
T i m e o f D a y ( h o u r s )
Ph
ase
Sig
ma
(Rad
ian
s)
0
1 0
2 0
3 0
4 0
5 0
6 0
7 0
8 0
Ele
vatio
n A
ng
le (
Deg
rees
)
P h a s e S i g m a
E le v a t i o n a n g le
12
L e r w i c k K i n d e x H o u r l y S t a n d a r d D e v i a t i o n 3 1 M a r c h 2 0 0 1
0 . 0
5 0 . 0
1 0 0 . 0
1 5 0 . 0
2 0 0 . 0
2 5 0 . 0
3 0 0 . 0
3 5 0 . 0
4 0 0 . 0
Correlation of TEC Variations, GPS Positioning Errors and
Hourly Standard Deviation of Geomagnetic Field
Lerwick 31 March 2001
HourlyStdev of GeomagField from Lerwick
TEC Variationsat Lerwick
40
-120
L e r w i c k - 3 D P o s i t i o n E r r o r - 3 1 M a r c h 2 0 0 1
0 . 0
2 0 . 0
4 0 . 0
6 0 . 0
8 0 . 0
1 0 0 . 0
1 2 0 . 0
GPS 3D PositioningErrors at Lerwick
120
0
13
Spatial Analysis ofPhase Scintillation07 September 2002
14
North-South Gradient in TEC ChangeIono Storm Nov 2001
Lat 70o NLong 19o E
Lat 60o NLong 01o W
Lat 53o NLong 01o W
Lerwick
Nottingham
Ny Alesund
Lat 79o NLong 12o E
Tromso
04 Nov 05 Nov 06 Nov 07 Nov 08 Nov
15
TEC Change Observed at Tromso and Hammerfest on 7 November 2001
Tromso -IGS 2-freq dataprocessed with Bernese
Hammerfest -output data from GSV4004
TROMHAMM
16 05 Nov 06 Nov 07 Nov
TEC change per 30 seconds
Dual Frequencyresiduals
HourlyStandard Deviationof geomagnetic field (Lerwick Observatory) 0
5 0
1 0 0
1 5 0
2 0 0
2 5 0
3 0 0
3 5 0
4 0 0
4 5 0
All satellites plotted
Lerwick Nov 01 - Correlation of TEC Variations, GPS Residuals, Phase Scintillation (Bergen) and Hourly Standard Deviation of Geomagnetic Field
GPS 3D positionResiduals
- 1 0 0
- 8 0
- 6 0
- 4 0
- 2 0
0
2 0
4 0
6 0
8 0
1 0 0
Res
idua
ls (m
eter
s)
100
Phase Scintillation(at Bergen)
17
4th - 8th November 2001 - Sumburgh Head (TRIMBLE SSI) LERWICK (ASHTECH ZX11)
0.00
10.00
20.00
30.00
40.00
50.00
60.00
0:3004/11/2001
06:3004/11/2001
12:3004/11/2001
18:3004/11/2001
00:3005/11/2001
06:3005/11/2001
12:3005/11/2001
18:3005/11/2001
0:3006/11/2001
06:3006/11/2001
12:3006/11/2001
18:3006/11/2001
00:3007/11/2001
06:3007/11/2001
12:3007/11/2001
18:3007/11/2001
0:3008/11/2001
06:3008/11/2001
12:3008/11/2001
18:3008/11/2001
Time of Observation
% o
f obs
erva
tions
with
No
L2
0
1
2
3
4
5
6
7
8
9
10
1.504/11/2001
10.504/11/2001
19.504/11/2001
4.505/11/2001
13.505/11/2001
22.505/11/2001
7.506/11/2001
16.506/11/2001
1.507/11/2001
10.507/11/2001
19.507/11/2001
4.508/11/2001
13.508/11/2001
22.508/11/2001
Lerwick K Index- Time
Lerw
ick
K In
dex
SUM1
LERW
K Index
K i n d e x T o t a l S i g m a f o r 0 4 t o 0 8 N o v 2 0 0 1
0
5 0
1 0 0
1 5 0
2 0 0
2 5 0
3 0 0
3 5 0
4 0 0
4 5 0
1 4 7 1 0 1 3 1 6 1 9 2 2 1 4 7 1 0 1 3 1 6 1 9 2 2 1 4 7 1 0 1 3 1 6 1 9 2 2 1 4 7 1 0 1 3 1 6 1 9 2 2 1 4 7 1 0 1 3 1 6 1 9 2 2
t i m e ( 5 d a y s )
L2 Data Loss for Different Receivers at Lerwickand Sumburgh, 4 to 8 Nov 01
Hourly Standard Deviationof Geomagnetic Field
LERW
SUMB
18
DGPS Solution at Lynas from Flamborough - Hourly 2drms (m)
0.0
5.0
10.0
15.0
20.0
25.0
0:00 04/11/01
12:00 04/11/01
0:00 05/11/01
12:00 05/11/01
0:00 06/11/01
12:00 06/11/01
0:00 07/11/01
12:00 07/11/01
0:00 08/11/01
12:00 08/11/01
2drm
s (m
)
0
1
2
3
4
5
6
7
8
9
10
HD
OP
GIRD
FLAM
DGPS Solution at Girdleness from Flamborough - Hourly 2drms (m)
0.0
5.0
10.0
15.0
20.0
25.0
0:00 04/11/01
12:00 04/11/01
0:00 05/11/01
12:00 05/11/01
0:00 06/11/01
12:00 06/11/01
0:00 07/11/01
12:00 07/11/01
0:00 08/11/01
12:00 08/11/01
2drm
s (m
)
0
1
2
3
4
5
6
7
8
9
10
HD
OPNorth-South
East-West
North-South vs East-West Baseline DGPS (4 to 8 Nov 01)
2drms error (whole period) = 2.66m
2drms error (whole period) = 3.5m
FLAM
LYN
19
DGPS Solution at Girdleness from Flamborough - Hourly 2drms (m)
0.0
5.0
10.0
15.0
20.0
25.0
0:00 04/11/01
12:00 04/11/01
0:00 05/11/01
12:00 05/11/01
0:00 06/11/01
12:00 06/11/01
0:00 07/11/01
12:00 07/11/01
0:00 08/11/01
12:00 08/11/01
2drm
s (m
)
0
1
2
3
4
5
6
7
8
9
10
HD
OP
DGPS Solution at Girdleness from Flamborough - Hourly 2drms (m)EGNOS Corrections applied at both ends
(SVs without correction in solution, min 4 SVs)
0.0
5.0
10.0
15.0
20.0
25.0
0:01 04/11/01
12:01 04/11/01
0:01 05/11/01
12:01 05/11/01
0:01 06/11/01
12:01 06/11/01
0:01 07/11/01
12:01 07/11/01
0:01 08/11/01
12:01 08/11/01
2drm
s (m
)
0
1
2
3
4
5
6
7
8
9
10
HD
OP
2drms error (whole period) = 2.57m
North-South
Improvement with the EGNOS Corrections on a North/South Baseline (4 to 8 Nov 01)
GIRD
FLAM
20
0.0
5.0
10.0
15.0
20.0
25.0
0:01 04/11/01
12:01 04/11/01
0:01 05/11/01
12:01 05/11/01
0:01 06/11/01
12:01 06/11/01
0:01 07/11/01
12:01 07/11/01
0:01 08/11/01
12:01 08/11/01
2drm
s (m
)
0
1
2
3
4
5
6
7
8
9
10
HD
OP
2drms error (w h o le period) = 2.85m
Only 4 SVs with corrections coveredby EGNOS grid
0.0
5.0
10.0
15.0
20.0
25.0
0:01 04/11/01
12:01 04/11/01
0:01 05/11/01
12:01 05/11/01
0:01 06/11/01
12:01 06/11/01
0:01 07/11/01
12:01 07/11/01
0:01 08/11/01
12:01 08/11/01
2drm
s (m
)
0
1
2
3
4
5
6
7
8
9
10
HD
OP
2drms error (w h o le period) = 2.57m
Additional 3 SVs, even without EGNOS correction,improve solution
GIRD
FLAM
0
5 0
1 0 0
1 5 0
2 0 0
2 5 0
3 0 0
3 5 0
4 0 0
4 5 0
(SVs without correction in solution, min 4 SVs)
(SVs without correction NOT in solution, min 4 SVs)
Hourly Standard Deviation of Geomagnetic Field
However . . . .
21
Possible Development of Warning Mechanisms
Prediction of Scintillation Levels with WBMOD (Wide Band Model)
hBased on climatological models of global distribution of ionospheric irregularities + propagation theory
hDeveloped by NorthWest Research Associates Inc.
hInputs: location, day of the year, local time, SSN, Kp
hRelevant outputs: S4 and Phase RMS (SPHI)
hPredictions based on the L1 GPS frequency
22
Hourly Standard Deviationof Geomagnetic Field
K i n d e x T o t a l S i g m a f o r 0 4 t o 0 8 N o v 2 0 0 1
0
5 0
1 0 0
1 5 0
2 0 0
2 5 0
3 0 0
3 5 0
4 0 0
4 5 0
1 4 7 1 0 1 3 1 6 1 9 2 2 1 4 7 1 0 1 3 1 6 1 9 2 2 1 4 7 1 0 1 3 1 6 1 9 2 2 1 4 7 1 0 1 3 1 6 1 9 2 2 1 4 7 1 0 1 3 1 6 1 9 2 2
t i m e ( 5 d a y s )
0 . 0 0
2 . 0 0
4 . 0 0
6 . 0 0
8 . 0 0
1 0 . 0 0
1 2 . 0 0
0 : 3 0 0 6 : 3 0 1 2 : 3 0 1 8 : 3 0 0 0 : 3 0 0 6 : 3 0 1 2 : 3 0 1 8 : 3 0 0 : 3 0 0 6 : 3 0 1 2 : 3 0 1 8 : 3 0 0 0 : 3 0 0 6 : 3 0 1 2 : 3 0 1 8 : 3 0 0 : 3 0 0 6 : 3 0 1 2 : 3 0 1 8 : 3 0
T i m e o f O b s e r v a t i o n
% o
f o
bse
rvat
ion
s w
ith
no
L2
TEC changes
W B M O D P r e d i c t e d L 1 S P H I - L e r w i c k , 0 4 t o 0 8 N o v 0 1
0
0 . 2
0 . 4
0 . 6
0 . 8
1
1 . 2
1 . 4
1:30
7:30
13:3
0
19:3
0
1:30
07:3
0
13:3
0
19:3
0
1:30
07:3
0
13:3
0
19:3
0
1:30
07:3
0
13:3
0
19:3
0
01:3
0
07:3
0
13:3
0
19:3
0
t i m e - s t a r t i n g a t 0 : 0 0 o n 4 N o v 0 1
Pre
dic
ted
SP
HI i
n r
adia
ns
9 9 % p e r c e n t i l e l e w r _ 5 d a y s 9 9
Predicted Phase Sigma(99% percentile)
Percentage ofL2 loss on a semicodelssGPS receiver
Correlation of TEC Changes with hourly standard deviationof Geomagnetic Field, WBMOD prediction and Data Loss,
Lerwick, 4 to 8 November 2001
23
D G P S S o lu t io n a t T r o n d h e im f r o m O s lo - H o u r l y 2 d r m s (m )
0 .0
5 .0
1 0 .0
1 5 .0
2 0 .0
2 5 .0
0 : 0 0 0 4 / 1 1 / 0 1
1 2 : 0 0 0 4 / 1 1 / 0 1
0 : 0 0 0 5 / 1 1 / 0 1
1 2 : 0 0 0 5 / 1 1 / 0 1
0 : 0 0 0 6 / 1 1 / 0 1
1 2 : 0 0 0 6 / 1 1 / 0 1
0 : 0 0 0 7 / 1 1 / 0 1
1 2 : 0 0 0 7 / 1 1 / 0 1
0 : 0 0 0 8 / 1 1 / 0 1
1 2 : 0 0 0 8 / 1 1 / 0 1
2drm
s (m
)
0
1
2
3
4
5
6
7
8
9
1 0
HD
OP
2 d r m s e r r o r (w h o le p e r io d ) = 4 . 3 0 m
Correlation of WBMOD phase and amplitude scintillation predictions with DGPS and EGNOS user 2drms - Trondheim, 4 to 8
Nov 2001
0
0 . 1
0 . 2
0 . 3
0 . 4
0 . 5
0 . 6
0 . 7
1:30
4:30
7:30
10:3
0
13:3
0
16:3
0
19:3
0
22:3
0
1:30
04:3
0
07:3
0
10:3
0
13:3
0
16:3
0
19:3
0
22:3
0
1:30
04:3
0
07:3
0
10:3
0
13:3
0
16:3
0
19:3
0
22:3
0
1:30
04:3
0
07:3
0
10:3
0
13:3
0
16:3
0
19:3
0
22:3
0
01:3
0
04:3
0
07:3
0
10:3
0
13:3
0
16:3
0
19:3
0
22:3
0
0
0 . 0 5
0 . 1
0 . 1 5
0 . 2
0 . 2 5
1:30
7:30
13:30
19:30 1:3
007:
3013:
3019:
30 1:30
07:30
13:30
19:30 1:3
007:
3013:
3019:
3001:
3007:
3013:
3019:
30
Mean Predicted Phase Scintillation
Mean Predicted AmplitudeScintillation
D G P S S o lu t io n a t T r o n d h e im f r o m O s lo - H o u r l y 2 d r m s (m )E G N O S C o r r e c t io n a p p lie d a t b o th e n d s
(S V s w ith o u t c o r r e c t io n in s o lu t io n , m in 4 S V s )
0 .0
5 .0
1 0 .0
1 5 .0
2 0 .0
2 5 .0
0 : 0 1 0 4 / 1 1 / 0 1
1 2 : 0 1 0 4 / 1 1 / 0 1
0 : 0 1 0 5 / 1 1 / 0 1
1 2 : 0 1 0 5 / 1 1 / 0 1
0 : 0 1 0 6 / 1 1 / 0 1
1 2 : 0 1 0 6 / 1 1 / 0 1
0 : 0 1 0 7 / 1 1 / 0 1
1 2 : 0 1 0 7 / 1 1 / 0 1
0 : 0 1 0 8 / 1 1 / 0 1
1 2 : 0 1 0 8 / 1 1 / 0 1
2drm
s (m
)
0
1
2
3
4
5
6
7
8
9
1 0
HD
OP
2 d r m s e r r o r (w h o le p e r io d ) = 3 .6 9 m TRDS
OSLO