![Page 1: Ionosphere effects on GNSS positioning : data collection, models and analyses](https://reader031.vdocuments.net/reader031/viewer/2022012914/56816471550346895dd655b0/html5/thumbnails/1.jpg)
Ionosphere effects on GNSS positioning: data collection, models and analyses
João Francisgo Galera Monico, Paulo De Oliveira Camargo, Haroldo Antonio Marques, Heloisa Alves Da SilvaUNESP – FCT – Presidente Prudente, SP.
Bruno BourgardSeptentrio NV, Leuven.
Luca SpogliINGV, Rome.
![Page 2: Ionosphere effects on GNSS positioning : data collection, models and analyses](https://reader031.vdocuments.net/reader031/viewer/2022012914/56816471550346895dd655b0/html5/thumbnails/2.jpg)
Outline• Infra-structure available for GNSS research and
applications in Brazil• GNSS Services required in Brazil
• Brazilian Ionospheric Model– Mod_ION– Rinex_HO
• CIGALA Project– Objectives– Preliminary results
• Final Comments
![Page 3: Ionosphere effects on GNSS positioning : data collection, models and analyses](https://reader031.vdocuments.net/reader031/viewer/2022012914/56816471550346895dd655b0/html5/thumbnails/3.jpg)
Troposphere / GNSS Met
Precise Agriculture
![Page 4: Ionosphere effects on GNSS positioning : data collection, models and analyses](https://reader031.vdocuments.net/reader031/viewer/2022012914/56816471550346895dd655b0/html5/thumbnails/4.jpg)
Available Infra-structurein South America/Brazil
![Page 5: Ionosphere effects on GNSS positioning : data collection, models and analyses](https://reader031.vdocuments.net/reader031/viewer/2022012914/56816471550346895dd655b0/html5/thumbnails/5.jpg)
SIRGAS GNSS data
• SIRGAS-CON GNSS Network
![Page 6: Ionosphere effects on GNSS positioning : data collection, models and analyses](https://reader031.vdocuments.net/reader031/viewer/2022012914/56816471550346895dd655b0/html5/thumbnails/6.jpg)
Brazilian GNSS data (IBGE/INCRA)
• Brazilian Continuous GPS Network (RBMC). Some stations are operational since 1996
• ~100 stations
![Page 7: Ionosphere effects on GNSS positioning : data collection, models and analyses](https://reader031.vdocuments.net/reader031/viewer/2022012914/56816471550346895dd655b0/html5/thumbnails/7.jpg)
RBMC Real Time – RBMC_IP • Data of about 30 Brazilian
GNSS stations are distributed in real time, using NTRIP protocol.
•
![Page 8: Ionosphere effects on GNSS positioning : data collection, models and analyses](https://reader031.vdocuments.net/reader031/viewer/2022012914/56816471550346895dd655b0/html5/thumbnails/8.jpg)
GNSS/GPS Active Networkat São Paulo State – Real time data
![Page 9: Ionosphere effects on GNSS positioning : data collection, models and analyses](https://reader031.vdocuments.net/reader031/viewer/2022012914/56816471550346895dd655b0/html5/thumbnails/9.jpg)
Meteorological and GNSS stations
• Meteorological stations are required to be collocated with GNSS for GNSS/Met support– 18 are available at São Paulo State (all stations were
calibrated)
![Page 10: Ionosphere effects on GNSS positioning : data collection, models and analyses](https://reader031.vdocuments.net/reader031/viewer/2022012914/56816471550346895dd655b0/html5/thumbnails/10.jpg)
GNSS demands in Brazil
Off shore applicationsAir Navigation
Positioning in generalPrecision agriculture
Rural Cadastre (50 cm or better – 1 sigma)
….
![Page 11: Ionosphere effects on GNSS positioning : data collection, models and analyses](https://reader031.vdocuments.net/reader031/viewer/2022012914/56816471550346895dd655b0/html5/thumbnails/11.jpg)
PA in Brazil is demanding 24 hours RTK service
![Page 12: Ionosphere effects on GNSS positioning : data collection, models and analyses](https://reader031.vdocuments.net/reader031/viewer/2022012914/56816471550346895dd655b0/html5/thumbnails/12.jpg)
Concerning Air Navigation, Brazilian authorities decided to invest in GBAS
instead of SBAS.
A system from Honeywell Aerospace is under certification at Rio de Janeiro
Airport (Galeão). (Cosendey presentation on Nov 09).
![Page 13: Ionosphere effects on GNSS positioning : data collection, models and analyses](https://reader031.vdocuments.net/reader031/viewer/2022012914/56816471550346895dd655b0/html5/thumbnails/13.jpg)
Challenges for such GNSS applications
Ionospheric Scintillation!
![Page 14: Ionosphere effects on GNSS positioning : data collection, models and analyses](https://reader031.vdocuments.net/reader031/viewer/2022012914/56816471550346895dd655b0/html5/thumbnails/14.jpg)
São Paulo State Network RTK (VRS)
![Page 15: Ionosphere effects on GNSS positioning : data collection, models and analyses](https://reader031.vdocuments.net/reader031/viewer/2022012914/56816471550346895dd655b0/html5/thumbnails/15.jpg)
Preliminary results.
Local Base/RTK Initialization Sart End N. points collected
TUPÃ
VRS (GNSS) 1min 24 seg 13:07:01 as 13:18:17 205ARAC (GNSS) 84,13km 8 min 4 seg 13:24:52 as 13:43:41 205
VRS_S (GPS) 2 min 23 seg 13:47:55 as 14:08:33 205ARAC_S (GPS) 84,13 km 12 min 19 seg 14:18:35 as 14:44:30 205
![Page 16: Ionosphere effects on GNSS positioning : data collection, models and analyses](https://reader031.vdocuments.net/reader031/viewer/2022012914/56816471550346895dd655b0/html5/thumbnails/16.jpg)
Ionospheric Index (I95) based on São Paulo
State GNSS Network
![Page 17: Ionosphere effects on GNSS positioning : data collection, models and analyses](https://reader031.vdocuments.net/reader031/viewer/2022012914/56816471550346895dd655b0/html5/thumbnails/17.jpg)
Developments on GNSS/Ionosphere at FCT/UNESP
![Page 18: Ionosphere effects on GNSS positioning : data collection, models and analyses](https://reader031.vdocuments.net/reader031/viewer/2022012914/56816471550346895dd655b0/html5/thumbnails/18.jpg)
GNSS and Ionosphere• A Ion-model based on GNSS has been under
development at FCT/UNESP since 1997;– Mod_Ion (in-house iono model) generates Ionospheric
maps and coefficients for L1 users• Ionospheric Index (Fp)• Ionex files from Brazilian GNSS data • Real time ionosphere maps of TEC/ROT and of the
correspondent delays on L1 (Aguiar – presentation on Nov 9th).
![Page 19: Ionosphere effects on GNSS positioning : data collection, models and analyses](https://reader031.vdocuments.net/reader031/viewer/2022012914/56816471550346895dd655b0/html5/thumbnails/19.jpg)
n 4 m 4s s s s s s
1 2 j j 1 n*2 3 j j 1i 1 i 1j 2i 1 j 2i 10
VTEC a a B {a cos(i h ) a sin(i h )} a h {a cos(i B ) a sin(i B )}
2 2 2i 2i 1i 2iF f /(f f )
n 4s s s s s s s2 1 r r 1 2 j j 1 n*2 3
i 1j 2i 1
m 4s s s s
j j 1 P2 P1 r P2 P1 P21i 1j 2i 10
F(P P ) SF (a a B {a cos(i h ) a sin(i h )} a h
{a cos(i B ) a sin(i B )} F(R R ) F(S S ) F .
TEC s s TEC s s TECi 2r 1r i p2 p1 p2 p1 r i P21s
r
VTECF (P P ) + F [(S -S ) + (R -R ) ] + Fcos(z )
• • = > i = G, Rk
Ionospheric Regional Model (MOD_Ion) (GPS & GLONASS)
![Page 20: Ionosphere effects on GNSS positioning : data collection, models and analyses](https://reader031.vdocuments.net/reader031/viewer/2022012914/56816471550346895dd655b0/html5/thumbnails/20.jpg)
Mod_Ion with inequality equation
• Problem: at some situations, even with calibrated equipments, negative values of TEC are obtained.
• One solution: to apply inequality equation as follows:n 4
s s s1 2 j j 1
i 1j 2i 1
m 4s s s
n*2 3 j j 1 i 1j 2i 10
VTEC a a B {a cos(i h ) a sin(i h )}
a h {a cos(i B ) a sin(i B )} 0
![Page 21: Ionosphere effects on GNSS positioning : data collection, models and analyses](https://reader031.vdocuments.net/reader031/viewer/2022012914/56816471550346895dd655b0/html5/thumbnails/21.jpg)
![Page 22: Ionosphere effects on GNSS positioning : data collection, models and analyses](https://reader031.vdocuments.net/reader031/viewer/2022012914/56816471550346895dd655b0/html5/thumbnails/22.jpg)
GNSS Ionospheric Products
• TEC Maps
![Page 23: Ionosphere effects on GNSS positioning : data collection, models and analyses](https://reader031.vdocuments.net/reader031/viewer/2022012914/56816471550346895dd655b0/html5/thumbnails/23.jpg)
IONEX Files
![Page 24: Ionosphere effects on GNSS positioning : data collection, models and analyses](https://reader031.vdocuments.net/reader031/viewer/2022012914/56816471550346895dd655b0/html5/thumbnails/24.jpg)
![Page 25: Ionosphere effects on GNSS positioning : data collection, models and analyses](https://reader031.vdocuments.net/reader031/viewer/2022012914/56816471550346895dd655b0/html5/thumbnails/25.jpg)
2nd and 3rd order Ionosphere corrections• In-house software was developed (RINEX_HO)
• GPS Solutions, Online First: 21 April 2011, DOI: 10.1007/s10291-011-0220-1, "RINEX_HO: second- and third-order ionospheric corrections for RINEX observation files" by H. A. Marques, J. F. G. Monico and M. Aquino
![Page 26: Ionosphere effects on GNSS positioning : data collection, models and analyses](https://reader031.vdocuments.net/reader031/viewer/2022012914/56816471550346895dd655b0/html5/thumbnails/26.jpg)
2nd and 3rd order Ionosphere corrections• The earth’s magnetic field
– Dipolar Approximation– International Geomagnetic Reference Field (IGRF) model
(IGRF11 model)– Corrected Geomagnetic Model from PIM (Parameterized
Ionospheric Model)
• TEC– From raw pseudoranges, from pseudoranges smoothed by
phase, or from Global Ionosphere Maps (GIM).
![Page 27: Ionosphere effects on GNSS positioning : data collection, models and analyses](https://reader031.vdocuments.net/reader031/viewer/2022012914/56816471550346895dd655b0/html5/thumbnails/27.jpg)
2nd order Ionosphere correctionsBipolar – IGRF and Differences
![Page 28: Ionosphere effects on GNSS positioning : data collection, models and analyses](https://reader031.vdocuments.net/reader031/viewer/2022012914/56816471550346895dd655b0/html5/thumbnails/28.jpg)
CIGALA Project“Concept for Ionospheric scintillation mitiGAtion for professional GNSS in Latin America”
Goal: Understand the cause and implication of IS disturbances at low latitudes, model their effects and develop mitigations through:– Research of the underlying causes of IS and the development of state-of-the-art models
capable of predicting signal propagation and tracking perturbations– Field measurement via the deployment in close collaboration with local academic and
industrial partners of multi-frequency multi-constellation Ionospheric Scintillation Monitoring (ISM) network
– Design and implementation of novel IS mitigation techniques in state-of-the-art GNSS receivers
– Field testing the mitigation techniques, leveraging the same partnership as during the measurement campaign.
![Page 29: Ionosphere effects on GNSS positioning : data collection, models and analyses](https://reader031.vdocuments.net/reader031/viewer/2022012914/56816471550346895dd655b0/html5/thumbnails/29.jpg)
CIGALA partners
![Page 30: Ionosphere effects on GNSS positioning : data collection, models and analyses](https://reader031.vdocuments.net/reader031/viewer/2022012914/56816471550346895dd655b0/html5/thumbnails/30.jpg)
• 8 ISM stations• Latitudinal and longitudinal
distribution over Brazil• Two stations at São José dos
Campos (crest of EIA) and Pres. Prudente
• Data stored locally and sent to repository at UNESP, Pres. Prudente
• Data mirrored at INGV, Rome
IS Monitoring Network in Brazil
![Page 31: Ionosphere effects on GNSS positioning : data collection, models and analyses](https://reader031.vdocuments.net/reader031/viewer/2022012914/56816471550346895dd655b0/html5/thumbnails/31.jpg)
CIGALA IS Monitoring Network in BrazilContinuous recording of :
• Amplitude scintillation index S4 : standard deviation of received power normalized by its mean value
• Phase scintillation index σΦ : standard deviation of de-trended carrier phase, with Phi60 its 60” version
• TEC (Total Electron Content)• Lock time• Code – Carrier Divergence• Spectral parameters of phase Power Spectral Density:
– Spectral slope p– Spectral strength T
• Raw high-rate I&Q correlation values (50Hz)
![Page 32: Ionosphere effects on GNSS positioning : data collection, models and analyses](https://reader031.vdocuments.net/reader031/viewer/2022012914/56816471550346895dd655b0/html5/thumbnails/32.jpg)
Septentrio PolaRxS ISM receiver is the base of the CIGALA network
(c) CIGALA Consortium
![Page 33: Ionosphere effects on GNSS positioning : data collection, models and analyses](https://reader031.vdocuments.net/reader031/viewer/2022012914/56816471550346895dd655b0/html5/thumbnails/33.jpg)
PolaRxS: facts Track GPS, GLONASS, GALILEO, COMPASS, SBAS L1, L2, L5, E5a, E5b signals, including GPS L2C, GLONASS
L2C and Galileo E5 AltBOC Very low phase noise OCXO 100Hz signal intensity and phase output for all signals Computation of S4, sf , TEC, spectral parameters,... for all
satellites and signals Interoperable ISMR file format Multiple Interfaces: 4 RS232, USB, Ethernet Rugged IP65 housing Temperature range: -40C to 60C Powering: 9-30V ; 6W
![Page 34: Ionosphere effects on GNSS positioning : data collection, models and analyses](https://reader031.vdocuments.net/reader031/viewer/2022012914/56816471550346895dd655b0/html5/thumbnails/34.jpg)
PolaRxS Phi60 Noise Floor <0.03rad
24-h Spirent simulation, Perfect GPS signal, L1
![Page 35: Ionosphere effects on GNSS positioning : data collection, models and analyses](https://reader031.vdocuments.net/reader031/viewer/2022012914/56816471550346895dd655b0/html5/thumbnails/35.jpg)
Receiver optimize for Maximum Tracking availability during Strong Scintillation
Optimized ISM receiver
0.40.6
0.81
5
10
15
200
10
20
30
40
50
60
S4 levelPLL bandwidth [Hz]
Loss
-of-l
ock
prob
abilit
y [%
]
0.40.6
0.81
5
10
15
200
2
4
6
8
10
S4 levelPLL bandwidth [Hz]
Loss
-of-l
ock
prob
abilit
y [%
]
Normal Receiver
Simulated with CSM on Spirent
Data bearing signals
![Page 36: Ionosphere effects on GNSS positioning : data collection, models and analyses](https://reader031.vdocuments.net/reader031/viewer/2022012914/56816471550346895dd655b0/html5/thumbnails/36.jpg)
Receiver optimize for Maximum Tracking availability during Strong Scintillation
0.40.6
0.81
5
10
15
200
10
20
30
40
50
60
S4 levelPLL bandwidth [Hz]
Loss
-of-l
ock
prob
abilit
y [%
]
0.40.6
0.81
5
10
15
200
2
4
6
8
10
S4 levelPLL bandwidth [Hz]
Loss
-of-l
ock
prob
abilit
y [%
]
Optimized ISM receiverNormal Receiver
Simulated with CSM on Spirent
Pilot Signal (L2C)
![Page 37: Ionosphere effects on GNSS positioning : data collection, models and analyses](https://reader031.vdocuments.net/reader031/viewer/2022012914/56816471550346895dd655b0/html5/thumbnails/37.jpg)
Comparison with currently deployed GSV equipment
• Scintillation free mid-latitude location (Nottingham)
• GPS L1CA• 24h recording
• S4: correlation coefficient = 0.9
• Phi60:– PxS: 0.0292– GSV: 0.0547
PRN19
![Page 38: Ionosphere effects on GNSS positioning : data collection, models and analyses](https://reader031.vdocuments.net/reader031/viewer/2022012914/56816471550346895dd655b0/html5/thumbnails/38.jpg)
Field Validation (C/N)
• CIGALA receivers PRU1 and PRU2 at Presidente Prudente• February to April 2011
L1 L2
![Page 39: Ionosphere effects on GNSS positioning : data collection, models and analyses](https://reader031.vdocuments.net/reader031/viewer/2022012914/56816471550346895dd655b0/html5/thumbnails/39.jpg)
Field Validation (CCSTDDEV)
• CIGALA receivers PRU1 and PRU2 at Presidente Prudente• February to April 2011
L1 L2
![Page 40: Ionosphere effects on GNSS positioning : data collection, models and analyses](https://reader031.vdocuments.net/reader031/viewer/2022012914/56816471550346895dd655b0/html5/thumbnails/40.jpg)
Using GLONASS for IS monitoring
• GPS and GLONASS orbits are complementary to increase spatial and temporal observability of the ionosphere
• GLONASS provides open signals on both L1 and L2 in all SV
![Page 41: Ionosphere effects on GNSS positioning : data collection, models and analyses](https://reader031.vdocuments.net/reader031/viewer/2022012914/56816471550346895dd655b0/html5/thumbnails/41.jpg)
Moderate Scintillation Occurrence (S4) observed using GPS vs. GLONASS
• INGV GBSC software is used to draw maps of rate of occurrence of S4>0.25 as a function of lat/long or lat/time
• Maps plotted for L1 observations between Feb and April 2011• Increased probability of scintillation clearly observable in EIA post-sunset• Very good match between GPS and GLONASS observation => data can be merged
GPS GLONASS
EIA EIA
![Page 42: Ionosphere effects on GNSS positioning : data collection, models and analyses](https://reader031.vdocuments.net/reader031/viewer/2022012914/56816471550346895dd655b0/html5/thumbnails/42.jpg)
Moderate Scintillation Occurrence (Phi60) observed using GPS vs. GLONASS
GPS GLONASS
• INGV GBSC software is used to draw maps of rate of occurrence of Phi60>0.25 as a function of lat/long or lat/time
• Maps plotted for L1 observations between Feb and April 2011• EIA observable for GPS• No match GPS and GLONASS observations
![Page 43: Ionosphere effects on GNSS positioning : data collection, models and analyses](https://reader031.vdocuments.net/reader031/viewer/2022012914/56816471550346895dd655b0/html5/thumbnails/43.jpg)
Understanding lack of Phi60 observability when using GLONASS signal
• Short term stability of the GLONASS satellite clock lower than GPS
• Small scale phase scintillation cannot be measured from single frequency observation
• Solution: Using differenced L1/L2 measurement to cancel the satellite clock effect
![Page 44: Ionosphere effects on GNSS positioning : data collection, models and analyses](https://reader031.vdocuments.net/reader031/viewer/2022012914/56816471550346895dd655b0/html5/thumbnails/44.jpg)
Strong Scintillation Event on Sept 25, 2011
![Page 45: Ionosphere effects on GNSS positioning : data collection, models and analyses](https://reader031.vdocuments.net/reader031/viewer/2022012914/56816471550346895dd655b0/html5/thumbnails/45.jpg)
S4 During Scintillation
0 0.5 1 1.5 20
0.2
0.4
0.6
0.8
1
1.2
1.4
UTC time [hours]
S4 fr
om L
1CA
(elev
atio
n m
ask
of 2
0 de
g)PRU2, Sep-25, 2011
0 0.5 1 1.5 20
0.2
0.4
0.6
0.8
1
1.2
1.4
UTC time [hours]S4
from
L2C
(ele
vatio
n m
ask
of 2
0 de
g)
PRU2, Sep-25, 2011
PRN2PRN15PRN26
PRN15
• S4 reported continuously during scintillation• S4 in L2 reported thanks to PRN15 (L2C) pass
L1CA L2C
![Page 46: Ionosphere effects on GNSS positioning : data collection, models and analyses](https://reader031.vdocuments.net/reader031/viewer/2022012914/56816471550346895dd655b0/html5/thumbnails/46.jpg)
SigmaPhi during Scintillation
0 0.5 1 1.5 20
0.5
1
1.5
UTC time [hours]
Phi6
0-L1
CA [r
ad] (
elev
atio
n m
ask
of 2
0 de
g)
PRU2, Sep-25, 2011
0 0.5 1 1.5 20
0.5
1
1.5
UTC time [hours]Ph
i60-L
2C [r
ad] (
elev
atio
n m
ask
of 2
0 de
g)
PRU2, Sep-25, 2011
PRN2PRN15PRN26
PRN15
L1CA L2C
• sphi reported continuously on ISM optimized receiver
![Page 47: Ionosphere effects on GNSS positioning : data collection, models and analyses](https://reader031.vdocuments.net/reader031/viewer/2022012914/56816471550346895dd655b0/html5/thumbnails/47.jpg)
Tracking robustness (Cycle Slips)
1500 2000 2500 3000
-0.5
-0.4
-0.3
-0.2
-0.1
0
0.1
0.2
0.3
0.4
0.5
UTC time [hours]
Detre
nded
L1
carri
er p
hase
[cyc
les]
PRU2, PRN15, Sep-25, 2011
carrier phasenav bit error
Phase tracking continuous during the whole event despites the very high S4 level
3 cycles slips seen on L1CA (PRN15) No cycles slips on L2C!
![Page 48: Ionosphere effects on GNSS positioning : data collection, models and analyses](https://reader031.vdocuments.net/reader031/viewer/2022012914/56816471550346895dd655b0/html5/thumbnails/48.jpg)
Effect on Real Time Precise Point Positioning
0 0.5 1 1.5 2 2.5 30
0.2
0.4
0.6
0.8
1
1.2
1.4
UTC time [hours]
S4 (e
leva
tion
mas
k of
20
deg)
PRU2, Sep-25, 2011
PRN2PRN15PRN26
0 0.5 1 1.5 2 2.5 3432.6
432.8
433
433.2
433.4
433.6
433.8
434
UTC time [hours]
PPP
Heig
ht [m
]
PPP service continuous during the whole eventUp to 40cm error during event(service specification is 12cm 95%)
![Page 49: Ionosphere effects on GNSS positioning : data collection, models and analyses](https://reader031.vdocuments.net/reader031/viewer/2022012914/56816471550346895dd655b0/html5/thumbnails/49.jpg)
![Page 50: Ionosphere effects on GNSS positioning : data collection, models and analyses](https://reader031.vdocuments.net/reader031/viewer/2022012914/56816471550346895dd655b0/html5/thumbnails/50.jpg)
![Page 51: Ionosphere effects on GNSS positioning : data collection, models and analyses](https://reader031.vdocuments.net/reader031/viewer/2022012914/56816471550346895dd655b0/html5/thumbnails/51.jpg)
![Page 52: Ionosphere effects on GNSS positioning : data collection, models and analyses](https://reader031.vdocuments.net/reader031/viewer/2022012914/56816471550346895dd655b0/html5/thumbnails/52.jpg)
• Brazil is a very challenge place for GNSS applications, mainly due to the Ionosphere behavior in the equatorial region;
• Several applications are already suffering the effects of such problem (IS) and will increase in the next two years;
• In the PA and aviation there is a need for more developments and tests;
• CIGALA network will continue collecting data after the final of the project (March 2012) and may provide data for scientific purpose.
Final comments
![Page 53: Ionosphere effects on GNSS positioning : data collection, models and analyses](https://reader031.vdocuments.net/reader031/viewer/2022012914/56816471550346895dd655b0/html5/thumbnails/53.jpg)
More information?http://gege.fct.unesp.br