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Near-real time detection of solar radio bursts
impacting the GNSS signal reception
J.-M. Chevalier, N. Bergeot, C. Marqué and C. Bruyninx
Solar Radio Bursts
• The Sun emits in radio over a wide frequency range (from few kHz to GHz)
• Solar Radio Bursts (SRB) are intense radio emissions (durations from 10s to few hours)
The SRB power is measured in solar flux units (1 SFU = 10-22 W.m-2.Hz-1) at different frequencies [250 MHz; 34 GHz]
ESWW13 2016 - Near-real time detection of solar radio bursts impacting the GNSS signal reception - Chevalier et al.
GNSS signals (e.g. GPS, GLONASS )
Solar Radio Bursts
• The Sun emits in radio over a wide frequency range (from few kHz to GHz)
• Solar Radio Bursts (SRB) are intense radio emissions (durations from 10s to few hours)
The SRB power is measured in solar flux units (1 SFU = 10-22 W.m-2.Hz-1) at different frequencies [250 MHz; 34 GHz]
ESWW13 2016 - Near-real time detection of solar radio bursts impacting the GNSS signal reception - Chevalier et al.
Impact on GNSS signal reception
• GNSS signals:
– L1 [ 1550 ; 1610 ] MHz
– L2 [ 1170 ; 1300 ] MHz
– Right Hand Circular Polarized (RHCP)
– Low power (~-160dBW)
→ vulnerable to Radio Frequency Interferences
• SRBs increase the noise level of GNSS ground stations
• Carrier-to-Noise density (C/N0) [35; 55] dB-Hz
Cerruti et al. 2006
ESWW13 2016 - Near-real time detection of solar radio bursts impacting the GNSS signal reception - Chevalier et al.
Impact on GNSS applications
Sreeja et al. 2013
Muhammad et al. 2015
SRB of the 24/09/2011
ESWW13 2016 - Near-real time detection of solar radio bursts impacting the GNSS signal reception - Chevalier et al.
Motivation
Real-Time Index detecting fades of GNSS signal reception due to SRB over a regional area
(e.g. EU, AF, SAm)
Implementation into ROB-IONO software (Bergeot, et al. 2014) already
delivering European ionospheric maps in near-real time (www.gnss.be)
Developed and tested on 11 past SRB events occurring during the sunlit of Europe from 1999 until 2015 based on the solar radio observatory data from NOAA and with GNSS data (GPS and GLONASS) from the dense EUREF Permanent Network
ESWW13 2016 - Near-real time detection of solar radio bursts impacting the GNSS signal reception - Chevalier et al.
EUREF Permanent Network (EPN)
• ~290 stations (Bruyninx et al. 2012)
• ~115 provide C/N0 in real-time
C/N0 extracted from RINEX files (S1
and S2 observations at respectively L1
and L2 frequencies)
But : no standardized unit
- C/N0 in dB-Hz
- Signal to Noise Ratio (SNR) in dB
SNR must be converted into C/N0 using
the manufacturer technical notes (Trimble,
Ashtech and Allen Osburn Associates)
Data input
www.epncb.oma.be
Daily Station Real-Time Station Real-Time Station delivering C/N0
http://epncb.oma.be
ESWW13 2016 - Near-real time detection of solar radio bursts impacting the GNSS signal reception - Chevalier et al.
• C/N0 (t, sat) depends on : receiver and antenna type satellite elevation multipath ε (unidentified noise)
• Repeatable patterns removed by subtracting the C/N0 quiet normal
behaviour, i.e. the median <C/N0(t, sat)> of the 7 previous Ground Track Repeat Cycles (GTRC) :
∆C/N0(t, sat) = C/N0(t, sat) - <C/N0(t, sat)>7 GTRC With GPS GTRC: 1 sidereal day and GLONASS GTRC: 8 sidereal days
Detect abnormal fades of GNSS signal reception
ESWW13 2016 - Near-real time detection of solar radio bursts impacting the GNSS signal reception - Chevalier et al.
SRB of the 24th September 2011
Post-processing on a past event
ESWW13 2016 - Near-real time detection of solar radio bursts impacting the GNSS signal reception - Chevalier et al.
Post-processing on a past event SRB of the 24th
September 2011
∆C/N0 (t, sat, rec) ∆C/N0 (rec, t, sat) Median StD
ESWW13 2016 - Near-real time detection of solar radio bursts impacting the GNSS signal reception - Chevalier et al.
∆C/N0 (t, sat, rec) Median StD Solar Radio Flux
Post-processing on a past event SRB of the 24th
September 2011
∆C/N0 (rec, t, sat)
ESWW13 2016 - Near-real time detection of solar radio bursts impacting the GNSS signal reception - Chevalier et al.
Post-processing on past events
5 dB.Hz
5 dB.Hz
Max. Solar Flux in SFU
1700
1800 3000
10000 10000 22000 34000
54000 110000
7300
DATE
15/04/2001
28/10/2003
18/11/2003 14/07/2005
01/08/2010
03/08/2011
24/09/2011
04/03/2012
11/04/2013
04/11/2015
ESWW13 2016 - Near-real time detection of solar radio bursts impacting the GNSS signal reception - Chevalier et al.
1700
1800 3000
10000 10000 22000 34000
54000 110000
7300
GPS and GLONASS
• Good agreement: the ∆C/N0 median agrees at the 0.1±0.2dB.Hz level
GPS GLONASS
ESWW13 2016 - Near-real time detection of solar radio bursts impacting the GNSS signal reception - Chevalier et al.
Near-real time
detection in Europe
In collaboration with the Humain Radioastronomy Station http://sidc.be/humain/index.php
Reported on www.gnss.be
ESWW13 2016 - Near-real time detection of solar radio bursts impacting the GNSS signal reception - Chevalier et al.
Index Level
Level GNSS ∆C/N0
Fade Effect
Quiet >-1dB-Hz none
Moderate -1 dB-Hz SRB detected but should not impact GNSS applications
Strong -3 dB-Hz Potential impact on GNSS applications
Severe -10 dB-Hz Potential failure of the GNSS receivers
Klobuchar et al., 1999
ESWW13 2016 - Near-real time detection of solar radio bursts impacting the GNSS signal reception - Chevalier et al.
Africa
South America
Daily IGS GNSS Station Real-Time IGS GNSS Station
Applicable in other regions
ESWW13 2016 - Near-real time detection of solar radio bursts impacting the GNSS signal reception - Chevalier et al.
Summary - Perspectives • GNSS signal reception fades due to SRB are now routinely monitored in
near-real time using the EPN with an index for each GNSS frequency bands.
• Developed based on the investigation of 11 SRB affecting GNSS receivers over Europe from 1999 until 2015. GPS and GLONASS showed good agreement.
• The monitoring is also applicable in other regions (Africa/S. America) and was tested with IGS data.
• Next steps: – 1Hz – Index <∆C/N0>=f(∆C/N0 , elsun)
ESWW13 2016 - Near-real time detection of solar radio bursts impacting the GNSS signal reception - Chevalier et al.
SOLAR RADIO BURST EVENT 2015-11-04 IN EUROPE (1HZ)