Ionosphere Scintillation-Induced Deep Fades
Brian Breitsch\(^1\) Jade Morton\(^1\)
Dongyang Xu \(^2\) Yang Rong \(^1\)
and Their Effect on GNSS Carrier Phase
ION/IEEE PLANS 2018
1. University of Colorado Boulder
2. Colorado State University
Motivation: Impact of Deep Fades Due to Ionosphere Scintillation
Theory: Scintillation Simulation and Modeling Deep Fades
Data: Examples of Canonical Fades and Fulle-Cycle Transitions
Next Steps: Triple-Frequency Potential for Mitigation and Correction
Carrier Phase Measurement
\Phi_i = G + I_i + B_i + S_i
IONOSPHERE ERROR
AMBIGUITY / BIAS TERMS
SYSTEMATIC ERRORS / SCINTILLATION / MULTIPATH
FREQUENCY INDEPENDENT EFFECTS
carrier frequency \(f_i\)
I_i \approx -\frac{\kappa}{f_i^2} \text{TEC}
particularly present in signals from satellites at low elevation
Triple-Frequency Range and TEC Estimates
\text{TEC} = \displaystyle -\frac{\Phi_1 - \Phi_2}{\kappa \left(\frac{1}{f_1^2} - \frac{1}{f_2^2}\right)}
G = \displaystyle \frac{f_1^2 \Phi_1 - f_2^2 \Phi_2}{f_1^2 - f_2^2}
ionosphere-free
geometry-free
Dual-Frequency Analogy:
\text{G} = 2.3 \cdot \Phi_\text{L1} - 0.3 \cdot \Phi_\text{L2} - 1.0 \cdot \Phi_\text{L5}
Ionosphere-Free Range Estimate
\text{TEC} = 8.3 \cdot \Phi_\text{L1} - 2.9 \cdot \Phi_\text{L2} - 5.4 \cdot \Phi_\text{L5}
Geometry-Free TEC Estimate
\Phi_i = G + I_i + B_i + S_i
(they exist)
Ionosphere Scintillation
L5
L2
L1
ionosphere phase screen
2013, Ascension Island, PRN 24
fading of 15 to 20 dB or more in signal amplitude
Deep Fading
canonical fades: associated with half-cycle phase changes
L5
L2
L1
Impact on Range and TEC Estimates
Motivation: Impact of Deep Fades Due to Ionosphere Scintillation
Theory: Scintillation Simulation and Modeling Deep Fades
Data: Examples of Canonical Fades and Fulle-Cycle Transitions
Next Steps: Triple-Frequency Potential for Mitigation and Correction
Simulating Scintillation
- stochastic scintillation realizations using iterative parameter estimation (IPE) technique
fit real SI PSD to scintillation theory
generate random field realizations
simulation
Simulating Scintillation
shows validation of occurrence of full-cycle transitions during canonical fades
simulation
Modeling Deep Fades
A_1 \exp(\phi_1) + A_2 \exp(\phi_2)
A_1 \exp(\phi_1) \left(1 + \alpha \exp(\Delta \phi) \right)
detrended scintillation: colored complex noise
What Can Happen To Phase During a Deep Fade?
Motivation: Impact of Deep Fades Due to Ionosphere Scintillation
Theory: Scintillation Simulation and Modeling Deep Fades
Data: Examples of Canonical Fades and Fulle-Cycle Transitions
Next Steps: Triple-Frequency Potential for Mitigation and Correction
Phase Behavior in Real Data
L5
L2
L1
Phase Behavior in Real Data
L5
L2
L1
Phase Behavior in Real Data
L5
L2
L1
Motivation: Impact of Deep Fades Due to Ionosphere Scintillation
Theory: Scintillation Simulation and Modeling Deep Fades
Data: Examples of Canonical Fades and Fulle-Cycle Transitions
Next Steps: Triple-Frequency Potential for Mitigation and Correction
Information From Triple-Frequency Measurements
\text{GIFC} = 0.226 \cdot \Phi_\text{L1} - 1.226 \cdot \Phi_\text{L2} + 1.0 \cdot \Phi_\text{L5}
Geometry-Ionosphere-Free Combination
deep fading
deep fading
Geometry-Ionosphere-Free Combination
potential use in identifying / correcting full-cycle transitions
Take-Aways
- strong ionosphere scintillation contains deep fades with associated canonical fade phase behavior
- sometimes, these canonical fades are associated with full-cycle phase transitions, which cause large errors in TEC and range measurements
- multi-frequency signal measurements are necessary to discriminate when full-cycle transitions occur
Next Steps
- detect and remove full-cycle transitions
- improve tracking performance during deep fading
Acknowledgements
This research was supported by the Air Force Research Laboratory.
Contact
Brian Breitsch
brianbreitsch@gmail.com
Ionosphere Scintillation-Induced Deep Fades and Their Effect on GNSS Carrier Phase
By Brian Breitsch
Ionosphere Scintillation-Induced Deep Fades and Their Effect on GNSS Carrier Phase
ION PLANS meeting 2018
