MSc. Student Tran Thanh Trung Politecnico di Torino, Italy Japan, 2 nd August 2014
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MSc. Student Tran Thanh Trung
Politecnico di Torino, Italy
Japan, 2nd August 2014
Ionospheric Scintillation
Ionospheric Scintillation (1)
Scintillation - GNSS radio signal is scattered by
ionospheric irregularities.
Delay - Signal is delayed by Ionospheric layer.
02/08/2014 Summer School on GNSS 2014 2
Scintillations are fluctuations in received amplitude and phase of
the signals due to zones with irregular concentration of electrons.
Ionospheric Scintillation (2)
Global occurrence characteristics of scintillation.
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Solar activity affecting Earth’s magnetic field
Ionospheric Scintillation
Ionospheric Scintillation (3)
Ionosphere v
GNSS Receiver
impact
Plasma
perturbations
signal
fluctuations
GNSS Satellite
TEC
• C/N0 degradation
• Pseudorange and carrier phase
measurement noise increases
• Cycle slips
• Loss of lock
• Degradation of positioning
accuracy
• Loss of positioning availability
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Scintillation Measurement (0)
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Scintillations are fluctuations in received amplitude and phase of
the signals due to zones with irregular concentration of electrons.
Scintillations are fluctuations in received amplitude and phase of
the signals due to zones with irregular concentration of electrons.
Amplitude scintillation is monitored by computing the index S4
Scintillations are fluctuations in received amplitude and phase of
the signals due to zones with irregular concentration of electrons.
Phase scintillation is monitored by computing the Sigma Phi
Measuring Amplitude Scintillation
S4𝑇 = <𝑆𝐼2>−<𝑆𝐼2><𝑆𝐼2>
Scintillation Measurement (1)
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The amplitude scintillation
index is called S4 and it is
the normalized standard
deviation of the detrended
intensity of the received
signal over a certain
interval, typically over 60
seconds.
The amplitude scintillation
index is called S4 and it is
the normalized standard
deviation of the detrended
intensity of the received
signal over a certain
interval, typically over 60
seconds.
The amplitude scintillation
index is called S4 and it is
the normalized standard
deviation of the detrended
intensity of the received
signal over a certain
interval, typically over 60
seconds.
The amplitude scintillation
index is called S4 and it is
the normalized standard
deviation of the detrended
intensity of the received
signal over a certain
interval, typically over 60
seconds.
S4𝑁0 = 100
𝑆 𝑁0 1+
500𝑆 𝑁0
S4𝑐 = <𝑆𝐼2>−<𝑆𝐼2><𝑆𝐼2>
− 100𝑆 𝑁0
1+500𝑆 𝑁0
Scintillation Measurement (3)
Measuring Phase Scintillation.
Scintillation Measurement (2)
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Phase scintillation monitoring is accomplished by monitoring the
standard deviation, 𝜎∆𝜑𝑆 of detrended carrier phase from signals
received from the GPS satellites. The 𝜎∆𝜑𝑆 are computed over 1, 3,
10, 30 and 60-second intervals every 60 seconds. These five values
are averaged over a minute.
Phase scintillation monitoring is accomplished by monitoring the
standard deviation, 𝜎∆𝜑𝑆 of detrended carrier phase from signals
received from the GPS satellites. The 𝜎∆𝜑𝑆 are computed over 1, 3,
10, 30 and 60-second intervals every 60 seconds. These five values
are averaged over a minute.
Phase scintillation monitoring is accomplished by monitoring the
standard deviation, 𝜎∆𝜑𝑆 of detrended carrier phase from signals
received from the GPS satellites. The 𝜎∆𝜑𝑆 are computed over 1, 3,
10, 30 and 60-second intervals every 60 seconds. These five values
are averaged over a minute.
Phase scintillation monitoring is accomplished by monitoring the
standard deviation, 𝜎∆𝜑𝑆 of detrended carrier phase from signals
received from the GPS satellites. The 𝜎∆𝜑𝑆 are computed over 1, 3,
10, 30 and 60-second intervals every 60 seconds. These five values
are averaged over a minute.
Phase scintillation monitoring is accomplished by monitoring the
standard deviation, 𝜎∆𝜑𝑆 of detrended carrier phase from signals
received from the GPS satellites. The 𝜎∆𝜑𝑆 are computed over 1, 3,
10, 30 and 60-second intervals every 60 seconds. These five values
are averaged over a minute.
03/08/2014 Summer School on GNSS 2014 8
2nd – order Butterworth filter
Compute
𝑍
𝜏𝑜
𝑆4
Nomalized
Z(t)=𝑍 + ξ(𝑡)
A schematic describing the Cornell Scintillation Model
Scintillation Simulation (1)
Scintillation Simulation (1)
scintillation fluctuations in amplitude and phase for the GNSS signals.
δA(t)= |Z(t)| δϕ(t)= ∠Z(t)
𝑆 𝑡 = 𝛿𝐴 ∗
A∗D(t)∗C(t)∗sin(2ߨ𝑓𝑖𝑓 + 𝜑
+𝛿𝜑 𝑡)
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Tau0 = 0.1 S4 = 0.8
Tau0 = 0.1 S4 = 0.5
Tau0 = 2 S4 = 0.5
Tau0 = 0.5 S4 = 0.5
Scintillation Simulation (2)
An example about input of a scintillation model:
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Scintillation Simulation (3)
S4 and Phi60 indices estimated from
receiver measurements .
Simulate scintillating GPS L1 C/A signal using Matlab
Drive scintillation model with input parameters:
𝜏𝑜 = 0.1, 𝑆4= 0.5
The length of signal is 15 minutes
Scintillation is simulated from minute 6th to 9th.
Signal acquired and tracked using a software RX.
Demonstration (1)
Acquire & Track Simulated Signal
Simulation Results (1)
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S4 Measurement.
Simulation Results (2)
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Tracking
Scintillation Measurement (4)
Phi60 Measurement.
Simulation results(3)
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Detrend the carrier phase
Index– Phi 60
Carrier Phase Measurement
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