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.

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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.

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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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