Assessment of GNSS Ionospheric Scintillation and TEC Monitoring Using the Multi-constellation GPStation-6 Receiver Rod MacLeod Regional Manager Asia/Pacific NovAtel Australia Pty Ltd
Outline Ionospheric Monitoring using GNSS GNSS update Ionospheric effects on GNSS GPStation-6 technical summary Real Time GPStation-6 Results of TEC/Scintillation Chile (2012) GPS+GLONASS India (2013/2014) GPS+GLONASS+BEDIOU+SBAS Australia (2015) GPS+GLONASS+BEDIOU Summary 2 GPStation-6
GNSS Constellations Status at Oct 2015 US GPS currently 31 L1/L2 MEO satellites, going through slow replacement program to add L5 and L2C Russian GLONASS currently 23 G1/G2 MEO satellites, First K Satellite in test with planning to move to L5 (G3) and CDMA within next 10yrs Chinese BeiDou system reached Asian regional coverage in late 2012 and currently has 5 Geostationary, 5 Geosynchronous and 7 MEO satellites. Full global B1/B2/B3 operations of 30 satellites by 2020. 1 st Japanese Quasi-Zenith Satellite System (QZSS) Geosynchronous satellite launched in 2010 covering Japan to Australia with L1/L2/L5/LEX. 3 more by 2017. Galileo has 10 (6 FOC + 4 IOV) MEO satellites with E1/E2/E5a/E5b and full global operations of 30 satellites planned for 2020. IRNSS (India) has 4 Geosynchronous satellites in test mode and plans full 7 satellite S1/L5 operation in 2016. 3 GPStation-6 +28 GNSS Satellite Currently Visible in Bangkok (ex IRNSS) 86 SATELLITES IN OPERATION NOW/ +120 PLANNED BY 2020
GNSS/RNSS Current + Proposed Frequencies L-band (1176-1609 MHz) except IRNSS S1 (Wi-Fi band) CDMA transmission except GLONASS (currently FDMA but moving to CDMA) PPP services ARNS Protected C1 S1 1539.95 2492.028 MHz Representation of the signals of the radionavigation-satellite service (L-band) seen in Australia Modified from ACMA 2015 4 GPStation-6
GNSS Modernization Benefits New signals Civilian signals (L2 and L5) Multiple frequencies (L1, L2, L5, E5B) Improved signal design Pilot component, L5 higher power (x4 L2C) Better error correction (CNAV, CNAV2) Better bit synchronization, cross-correlation, lower interference Multiple GNSS better than any single system GPS, GLONASS (established) Galileo, Beidou (developing) Regional: QZSS, IRNSS (initial stages) 5 GPStation-6
Ionospheric Effects on GNSS Dispersive medium Refraction: change in propagation delay (ray bending) Scintillation: rapid fluctuations in amplitude and phase Refraction Code delay and phase advance Scintillation Deep signal fades (Loss of lock) Stress PLL loops Frequent cycle slips Degraded navigation data Carrier phase positioning L1 C/A tracking amplitude scintillation L2 P(Y) amplitude & phase scintillation 6 GPStation-6
GNSS Space Weather Monitoring GNSS Ionospheric monitoring offers: Global basis, all-weather and continuous fashion Multi Constellation: more pierce points Multi Frequencies: more measurement combinations Refraction: Total Electron Content (TEC) Scintillation: Amplitude (S 4 ) and phase ( ) 7 GPStation-6
GNSS Space Weather Monitoring (Cont) Challenges for a GNSS receiver Need to track new signals (not just GPS) Scintillation Phase: Receiver oscillator phase noise needs to be very low Scintillation Amplitude: Reduce Multipath fading TEC: Semi-codeless L2 P(Y) tracking TEC: Not all new signal biases known: Satellite & receiver Move to real time results Needs a specialised Monitoring Receiver 8 GPStation-6
GPStation-6 ISM Technical Features Ultra-stable low noise OCXO Ensures accurate phase scintillation measurement Facilitates narrow loop bandwidths Proprietary multipath mitigation Pulse aperture correlation (PAC) (limits to 5 m or less) Code-minus-carrier output Specialized software Dedicated receiver commands and logs Configurable loop bandwidths Detrending algorithms Comprehensive real time measurements Raw amplitude and phase (50 Hz) S 4,, code and carrier TEC 9 GPStation-6
GPStation-6 Technical Features (Cont) Only receiver to: have a inbuilt onsite TEC Auto Calibration function provide comprehensive real time S 4,, code and carrier TEC values as well as the raw measurement data (for post-analysis) GPS+GLONASS+GALILEO L1/L2/L5 tracked globally QZSS L1/L2/L5 and SBAS L1/L5 tracked regionally BeiDou B1/B2 currently provided as a special release (for Asian regional operations) Fully backward compatible with existing GSV4000B (GPS only) receivers Over 400 GNSS Ionospheric Scintillation Monitor Receivers (GSV and GPS-Station-6) sold worldwide. 10 GPStation-6
Chile - Equatorial Scintillation Study (2012) To investigate reported extended periods of degraded GPS+GLONASS RTK performance in the precise positioning required for mine machine operations. Scintillation suspected as it was Correct geographic location Calama, Chile (~ 22 0 Latitude) Correct solar cycle period Approaching Solar Max (2013) Correct part of the year and time Early summer Post- sunset period 11 GPStation-6
GPS Block IIF PRN 25 (L1/L2C/L5) GPS PRN 01, 25 broadcast GPS L5 besides L1 and L2C (clear) signal Measured C/N 0 (db-hz) 60 55 50 45 40 GPS PRN 25 L1 C/A L2-CL L5-Q 35 21:00 22:00 23:00 00:00 01:00 Local Time (Hrs) All 3 frequencies show same scintillation trends, but S 4 and not always correlated. Amplitude Scintillation Index (S 4 ) Phase Scintillation Index ( ) (60-seconds) (rad) 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 L1 C/A L2-CL L5-Q GPS PRN 25 0 21:00 22:00 23:00 00:00 01:00 Local GPS Time PRN (Hrs) 25 0.7 L1 C/A 0.6 L2-CL L5-Q 0.5 0.4 0.3 0.2 0.1 0 21:00 22:00 23:00 00:00 01:00 Local Time (Hrs) 12 GPStation-6
Amplitude Scintillation Index (S 4 ) 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 GLONASS & GPS Measurements Match 0 00:00 01:00 02:00 03:00 04:00 05:00 10:00 Local Time (Hrs) GLONASS PRN 16 GPS PRN 16 Higher Phase Scintillation on GLONASS is due in part to the high noise on its satellite clock. Phase Scintillation Index ( ) (60-seconds) (rad) Similar trend was observed between GPS and GLONASS satellites 0.4 0.35 0.3 0.25 0.2 0.15 0.1 GLONASS PRN 16 GPS PRN 16 0.05 00:00 01:00 02:00 03:00 04:00 05:00 10:00 Local Time (Hrs) 13 GPStation-6
Hyderabad BeiDou/QZSS Validation (2013) Beidou regional coverage is in blue Hyderabad, India 17 o N, 78 o E GPStation-6 set up in Hyderabad, India in June 2013 Hyderabad is within the Beidou regional coverage area Tracking B1 and B2 frequencies, code and carrier on all Beidou Satellites QZSS Satellite can be seen in the East and L1, L2C and L5 tracked Provided TEC and Scintillation indices over a full 24 hour period 14 GPStation-6
Beidou Satellite Availability (>10 o ) - Hyderabad 4 x Medium Earth Orbit (sometimes in view) 5 x Geosynchronous (mostly in view) 4 x Geostationary (always in view), 1 can t be seen 15 GPStation-6
Beidou Results - TEC Uncalibrated TEC B1-B2 values for 13 satellites obtained in Hyderabad, India June 2013. 4 Geostationary satellites track throughout the whole 24hr period. 16 GPStation-6
Beidou Results - Scintillation B1 values for 13 satellites obtained in Hyderabad, India June 2013. Beidou GEO satellites provided the continuous monitoring of Ionospheric Amplitude (S4) and phase ( ) scintillation as they are always in view. 17 GPStation-6
QZSS results - Scintillation Plots show the amplitude and phase scintillation for QZSS PRN 193 broadcasting L1 C/A, L2C and L5 signals in Hyderabad India L1 C/A most affected while L5 least affected, possibly due to transmission method of signals Amplitude Scintillation (S 4 ) 0.3 0.25 0.2 0.15 0.1 Amplitude Scintillation - QZSS PRN 193 QZSS L5Q QZSS L2C QZSS L1 C/A Phase Scintillation ( ) (60-seconds) (rad) 0.3 0.25 0.2 0.15 0.1 Phase Scintillation - QZSS PRN 193 QZSS L5Q QZSS L2C QZSS L1 C/A 0.05 19:30 21:30 23:30 01:30 03:30 05:30 07:30 Local Time (Hrs) 0.05 19:30 21:30 23:30 01:30 03:30 05:30 07:30 Local Time (Hrs) 18 GPStation-6
Kolkata GPS+GLONASS+BEIDOU+SBAS (2014) Beidou regional coverage is in blue Kolkata, India 22.5 o N, 88.5 o E GPStation-6 set up in Kolkata, India in November 2014 to show Site Calibration and setup procedure to customer. Tracking L1/L2/L5 GPS + GLONASS L1/L2 and BEIDOU B1/B2 frequencies, code and carrier Provided Calibration recommendations and possible TEC and Scintillation correlation 19 GPStation-6
Calibrated TEC Data 24 Hours Unfiltered 19 th November - Spikes in data due to satellites at low elevation or tracked for a short time 20 GPStation-6
Calibrated TEC Data 24 Hours Filtered Same 19 th November Filter using recommended 25 degree elevation mask and minimum 300 second locktime Result is Spikes gone clean data for analysis 21 GPStation-6
Correlation of TEC with Scintillation Observed that Large Amplitude Scintillation correlates with rapid fluctuations in TEC values 22
Brisbane Monitoring Station (2015) Beidou regional coverage is in blue GPStation-6 set up in Brisbane, Australia in July 2015 to monitor the Ionosphere during multireceiver kinematic performance testing. Provided Scintillation indices over the testing period. Look specifically at B1 and B2 carrier phase on all Beidou Satellites post Solar Maximum Brisbane, Australia 27.5 o S, 153 o E 23 GPStation-6
Phase and Amplitude Scintillations at same time S4 RADIAN 0.5 0.4 0.3 0.2 0.1 0 0.5 0.4 0.3 0.2 12:00 PM 6:00 PM 12:00 AM 6:00 AM Local Time BDS#1 B1D2 BDS#1 B2D2 BDS#3 B1D2 BDS#3 B2D2 BDS#4 B1D2 BDS#4 B2D2 BDS#6 B1D1 BDS#6 B2D1 BDS#7 B1D1 BDS#7 B2D1 BDS#8 B1D1 BDS#8 B2D1 BDS#9 B1D1 BDS#9 B2D1 BDS#10 B1D1 BDS#10 B2D1 BDS#11 B1D1 BDS#11 B2D1 BDS#12 B1D1 BDS#12 B2D1 BDS#14 B1D1 BDS#14 B2D1 0.1 0 12:00 PM 6:00 PM 12:00 AM 6:00 AM Local Time All Scintillations (very low)- show low solar activity No effects on carrier phase positioning testing 24 GPStation-6
Summary GNSS modernization provides huge benefits to the ionospheric research community for forecasting and modeling The GPStation-6 receiver provides the only GNSS REAL TIME ionospheric TEC and Scintillation monitor GPS L1/L2 TEC can be considered absolute TEC (after local calibration), all other constellations provide relative TEC as not all biases are currently known even after site calibration. Beidou & QZSS coverage gives unique Asian regional analysis with additional geostationary satellites. 25 GPStation-6
Thank you Further Info Google: GPStation-6 Contact: rod.macleod@novatel.com Web: www.novatel.com 26 GPStation-6