Master Thesis Final Presentation: Ionosphere monitoring in GBAS using Dual Frequency GNSS measurements
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The motivation: Detection of different Ionosphere gradients, which cause different ionospheric delays in aviation applications (GBAS) The objectives: First, estimate the airborne and ground ionospheric delays and second, monitor the ionospheric. Bias between both estimates and compare it to a threshold The contribution: Present a GBAS Ionospheric monitor monitor that allows to estimate the ionospheric differential delay without moving to a whole Dual-Frequency GBAS concept.
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Master Thesis Final Presentation: Ionosphere monitoring in GBAS using Dual Frequency GNSS measurements
- 1. Ionosphere monitoring in GBAS using dual frequency GNSS measurements Joan Erencia Guerrero Supervisors: Thomas Dautermann (DLR) Michael Felux (DLR) Gabriele Giorgi (TUM)
- 2. 2 Ionosphere monitoring in GBAS using DF measurements INTRODUCTION Satellite Subsystem Satellite Subsystem GBAS differential GNSS approach and landing Airborne Subsystem Airborne Subsystem Ground Subsystem Ground Subsystem Aviation Benefits: Safety, efficiency, capacity and cost
- 3. 3 Outline 1. Motivation, objectives and contribution 2. Theory and methods 3. Results 4. Conclusions and future work
- 4. 4 Ionosphere monitoring in GBAS using DF measurements MOTIVATION Ionospheric delay [m] Ionosphere Time [s] Nominal Ionosphere (No ionospheric events) No biases Similar trends
- 5. 5 Ionosphere monitoring in GBAS using DF measurements MOTIVATION Ionospheric delay [m] Ionosphere Time [s] 1. Ionospheric spatial gradient
- 6. 6 Ionosphere monitoring in GBAS using DF measurements Ionospheric delay [m] MOTIVATION Time [s] 2. Ionospheric temporal gradient (ionospheric gradient stationary or not moving w/airplane) Converging trend during approach
- 7. 7 Ionosphere monitoring in GBAS using DF measurements Ionospheric delay [m] MOTIVATION Time [s] 3. Ionospheric moving gradient (ionospheric gradient moving w/airplane speed and direction)
- 8. 8 Ionosphere monitoring in GBAS using DF measurements OBJECTIVES OBJECTIVE 2 Threshold Ionospheric delay [m] Ionospheric Diff. delay [m] OBJECTIVE 1 Time [s] Time [s] Monitor ionospheric differential delay between Airborne and Ground
- 9. 9 Ionosphere monitoring in GBAS using DF measurements MOTIVATION, OBJECTIVES AND CONTRIBUTION MOTIVATION OBJECTIVES CONTRIBUTION All ionospheric gradients cannot be detected with single-frequency GNSS. The proposed ionospheric monitor estimates the ionospheric differential delay without moving to a whole Dual-Frequency GBAS concept.
- 10. 10 Outline 1. Motivation, objectives and contribution 2. Theory and methods 3. Results 4. Conclusions
- 11. 11 Ionosphere monitoring in GBAS using DF measurements Ionospheric delay [m] OBJECTIVE 1 Time [s]
- 12. 12 Ionosphere monitoring in GBAS using DF measurements THEORY OBJECTIVE 1 1.1. Single rx Estimate the ionospheric delay for a single receiver Geometry-free ionosphere preserving lin.comb. Frequency dependent
- 13. 13 Ionosphere monitoring in GBAS using DF measurements THEORY OBJECTIVE 1 1.1. Single rx Estimate the ionospheric delay for a single receiver Geometry-free ionosphere preserving lin.comb. Frequency dependent
- 14. 14 Ionosphere monitoring in GBAS using DF measurements THEORY OBJECTIVE 1 1.1. Single rx Estimate the ionospheric delay for a single receiver Geometry-free ionosphere-preserving lin.comb. Ionospheric delay* (*using GIM) (Phase-based approach) (Code-based approach) 1. Reduce code noise 2. Estimate biases
- 15. 15 Ionosphere monitoring in GBAS using DF measurements THEORY OBJECTIVE 1 1.1. Single rx LPF
- 16. 16 Ionosphere monitoring in GBAS using DF measurements THEORY OBJECTIVE 1 1.1. Single rx
- 17. 17 Ionosphere monitoring in GBAS using DF measurements THEORY OBJECTIVE 1 1.1. Single rx Sv IFB Rx IFB Sv IFB Rx IFB [1] Sardon et al, “Estimation of the transmitter and receiver differential biases and the ionospheric total electron content from global positioning system observations”
- 18. 18 Ionosphere monitoring in GBAS using DF measurements THEORY OBJECTIVE 1 1.1. Single rx
- 19. 19 Ionosphere monitoring in GBAS using DF measurements THEORY OBJECTIVE 1 1.1. Single rx Sv IFB Rx IFB Estimate the ionospheric delay for a single receiver Summary of the method
- 20. 20 Ionosphere monitoring in GBAS using DF measurements Ionospheric delay [m] OBJECTIVE 1 Time [s]
- 21. 21 Ionosphere monitoring in GBAS using DF measurements THEORY OBJECTIVE 1 Code-phase approach Phase-based approach Single receiver estimate Single receiver estimate Average over Ground station receiver estimates Average over Ground station receiver estimates Airborne Subsystem Airborne Subsystem AIRB Ground Subsystem Ground Subsystem BR01 BR02 BR03
- 22. 22 Ionosphere monitoring in GBAS using DF measurements Ionospheric delay [m] OBJECTIVE 1 Time [s]
- 23. 23 Ionosphere monitoring in GBAS using DF measurements Ionospheric delay [m] OBJECTIVE 2 Time [s]
- 24. 24 Ionosphere monitoring in GBAS using DF measurements THEORY OBJECTIVE 2 2.1. Threshold [2] “GBAS CAT II/III Development Baseline SARPs,
- 25. 25 Ionosphere monitoring in GBAS using DF measurements Ionospheric delay [m] OBJECTIVE 2 Time [s]
- 26. 26 Ionosphere monitoring in GBAS using DF measurements THEORY OBJECTIVE 2 Code-phase approach Phase-based approach
- 27. 27 Ionosphere monitoring in GBAS using DF measurements Ionospheric delay [m] OBJECTIVE 2 Time [s]
- 28. 28 Outline 1. Motivation, objectives and contribution 2. Theory and methods 3. Results 4. Conclusions and future work
- 29. 29 Ionosphere monitoring in GBAS using DF measurements RESULTS GROUND SUBSYSTEM AIRBORNE SUBSYSTEM GNSS RX Monitor performance 1. Smoothing 2. Elevation 3. Distance to airport 4. Cycle slips 5. User dynamics
- 30. 30 Ionosphere monitoring in GBAS using DF measurements RESULTS Code-based Monitor performance using different smoothing constant Residual noise: Caused by code noise Reduced with larger smoothing constants
- 31. 31 Ionosphere monitoring in GBAS using DF measurements RESULTS Phase-based monitor performance using different smoothing constant
- 32. 32 Ionosphere monitoring in GBAS using DF measurements RESULTS Monitor performance considering the user dynamics GNSS RX
- 33. 33 Ionosphere monitoring in GBAS using DF measurements RESULTS Monitor performance considering the user dynamics Phase-based approach (red) Jumps in the estimates. No line-of-sight during turns for a satellite with low elevation. Bias in the iono. estimates Code-based approach (blue) Large noise/MP in some epochs Problem in smoothing code-based estimate due to phase jumps Bad trend in the filter initialization Measure Waiting after losing phase measurements
- 34. 34 Outline 1. Motivation, objectives and contribution 2. Theory and methods 3. Results 4. Conclusions and future work
- 35. 35 Ionospheric delay [m] Ionosphere monitoring in GBAS using DF measurements Monitor ionospheric differential delay between Airborne and Ground subsystems Ionospheric Diff. delay [m] Time [s] Threshold Time [s]
- 36. 36 Ionosphere monitoring in GBAS using DF measurements CONCLUSIONS
- 37. 37 Ionosphere monitoring in GBAS using DF measurements FUTURE WORK
- 38. Ionosphere monitoring in GBAS using DF measurements Thank you for your attention Questions?
Notas del editor
- Good morning...I will present a summary of the work I did for my master Thesis at DLR with the supervision of TD,MF and GG titled: « Integrity considerations in GBAS using dual frequency measurements»20 sec for this slide (TOTAL TIME = 00:20)
- This slide contains the OUTLINE of my presentation. First, I will present motivation and objectives Then, the theory and methods. I will follow with the results. And finally the conclusions and future work.. I start with the first point.20 sec for this slide (TIME = 01:40)
- Starting from the inital GBAS.With a NOMINAL IONOSPHERE. At the start of the approachthe ionospheric delays seen by GS and AS are similar.On the right, it is shown how the ionospheric delay evolves over time.In this case, it is observed that GS/AS ionospheric delays are similar during the approach.40 sec for this slide (TIME = 02:20)
- Now, if instead of having Nominal IonosphereThere is an IONOSPHERIC GRADIENT. The initial ionospheric delay for GS/AS is different.If we put those delays on the graphs, it is observed an ionospheric bias2 things can happen during the approach40 sec for this slide (TIME = 03:00)
- The first thing is that the gradient remains stationary or it does not move with the airplaneIn this case, one would observe that 𝐼𝐴𝐼𝑅 has a converging trend towards 𝐼𝐺𝑁𝐷This is referred to as IONOSPHERIC TEMPORAL GRADIENT30 sec for this slide (TIME = 03:30)The first thing is that the gradient remains stationary or it does not move with the airplaneIn this case, one would observe that 𝐼_𝐴𝐼𝑅 has a converging trend towards 𝐼_𝐺𝑁𝐷This is referred to as IONOSPHERIC TEMPORAL GRADIENT30 sec for this slide (TIME = 03:30)
- The second thing that can happen is that the gradient moves with the airplane speed and directionIn this case, one would observe that the initial bias between AS and GS remains constant during approach.Eventually, the delay will converge when the aircraft is very close to the ref. Station.This is referred to as the IONOSPHERIC MOVING GRADIENTTHE MOTIVATION for this thesis is to design a monitor able to detect these ionospheric gradients50 sec for this slide (TIME = 04:20)
- In this slide I present the two objectives of my master thesis:My 1st OBJECTIVE is estimating the ionospheric delay, as seen by the AS /GS, during an approach.My 2nd OBJECTIVE is estimating the iono. diff. delay, between AS/GS, and compute an alarm threshold based on specs.With these 2 objectives I accomplish THE GOAL of my thesis (as the title says): estimate the ionospheric delay between GS/AS40 sec for this slide (TIME = 05:00)
- Before moving on, let me summarise:The motivation: Detection of different Iono. gradients, which cause different iono. delays in GBAS SSThe objectives: (1- estimate AS/GS ionospheric delays) and (2- monitor the iono. Bias between SS)The contribution: (with 1Freq you can’t detect gradients)(Monitoring does not involve using the whole GBAS DF)30 sec for this slide (TIME = 05:30)LET’S IMAGINE I AM A BIT SLOWER, SO IT TAKES 6 MIN, UP TO THIS POINT
- Next,I will talk now about Theory and methods10 sec for this slide (TIME = 06:10)
- I am going to present the theory and methods to fulfil my first objective, which I divided in two parts:The first would be to estimate the iono delay for a single receiver. The second the delay for each subsystem.20 sec for this slide (TIME = 06:30)
- The method to estimate the iono delay is the Geo-free Iono-preserving LC. It consist of scaling the diff of measurements.If we write different tems describing the pseudoranges in two frequencies. The diff. would leave the freq.dep terms.So, lets rewrite these frequency-dependent terms. They are due to the Ionos, SV and RX IFB and noise.These terms can be grouped as due to the Ionosphere, biases and noise.1 min for this slide (TIME = 07:30)
- If we use same method, but with carrier phase measurements instead of Pseudoranges.If we write different tems describing the phases in two frequencies. The diff. would leave the freq.dep terms.So, lets rewrite these frequency-dependent terms. They are due to the Ionos, SV and RX IFB, Int. Ambig. and noise.These terms can be grouped as due to the Ionosphere, biases, integer ambiguities and noise.1 min for this slide (TIME = 08:30)
- If we take real data and plot these two expressions and compare them to the Ionosphere this is what we would see.If we compare the comb. using pseudoranges and the iono delay, we identify two terms adding to the iono.If we do the same with phases, we identify phase biases and the int. Ambig. Term (phase noise is in the order of mm)So, it is necessary to reduce code noise and estimate biases to estimate the iono. Delay using codes and phases1 min for this slide (TIME = 09:30)The real question is:Is this good enough to describe the Iono behavior? CLICKFor Iono temporal gradient YES, because the noise is low. CLICKFor the Iono delay NO, because of the noise introduced by the 𝐼_𝑓𝑟𝑒𝑒 combination. CLICKWhat Konno proposed in his work is to find a threshold in which we switch from the Dfree to the Ifree so we always protect against Ionosphere gradients. However, using the Ifree combination results in an increase of the noise, that produces an increase of the Protection levels and results in a downgrade of the GBAS Service type (not allowing GAST-D)The idea here is to find a low-noise estimate of the Ionosphere. CLICKUsing code measurement, one can get a noisy but ambiguous estimate of the Iono delay, Using phase measurements one can get a smooth but ambiguous estimate of the Iono delay. If both are combined, e.g. By smoothing the Iono code estimate with the phase estimate or finding the bias between both, then, we would be able to find an «not-noisy» estimate of the iono. CLICKFinally if we subtract this «low-noise Iono» from the Dfree combination we would be able to cancel the iono delay both in the air and in the GND receivers. CLICKSolving the problem of the different Iono delay between the Ground and the Airborne receivers.01:00 (15:00)
- To technique used to reduce code noise is filtering: noisy pseudoranges can be smoothed out by using phases. However, In my approach I do not use GNSS meaurements as an input, but the code and phase-based LC.If we look at the right, we will see how the noise is reduced after filtering with several time constants: (100s, 300s, 600s)It is observed a larger noise reduction for larger smoothing time constants1 min for this slide (TIME = 10:30)
- To estimate iono. Delays, we also need to estimate the biases present in the code-based and phase-based approaches.The bias in the code-based approach consists of code IFB in the RX and SV(and you can see it in the graph on the right).The bias in the phase-based approach consists of phase IFB in the RX and SV and also the int. Ambig. Term.So, all these biases should be estimated. Among all these biases, the bias due to int. Amb. is very hard to estimate.My approach involve another bias, the code-phase differential bias, between the code and phase-based LC.This way, phase biases are not necessary to estimated, instead the phase bias is given by this expressionWith this approach, estimating the biases will involve now estimating the code biases and the diff. bias1:30 min for this slide (TIME = 12:00)The real question is:Is this good enough to describe the Iono behavior? CLICKFor Iono temporal gradient YES, because the noise is low. CLICKFor the Iono delay NO, because of the noise introduced by the 𝐼_𝑓𝑟𝑒𝑒 combination. CLICKWhat Konno proposed in his work is to find a threshold in which we switch from the Dfree to the Ifree so we always protect against Ionosphere gradients. However, using the Ifree combination results in an increase of the noise, that produces an increase of the Protection levels and results in a downgrade of the GBAS Service type (not allowing GAST-D)The idea here is to find a low-noise estimate of the Ionosphere. CLICKUsing code measurement, one can get a noisy but ambiguous estimate of the Iono delay, Using phase measurements one can get a smooth but ambiguous estimate of the Iono delay. If both are combined, e.g. By smoothing the Iono code estimate with the phase estimate or finding the bias between both, then, we would be able to find an «not-noisy» estimate of the iono. CLICKFinally if we subtract this «low-noise Iono» from the Dfree combination we would be able to cancel the iono delay both in the air and in the GND receivers. CLICKSolving the problem of the different Iono delay between the Ground and the Airborne receivers.01:00 (15:00)
- The BIAS IN THE CODE-BASED APPROACH are due to teh SV IFB and the RX IFBIn this work, these biases are considered constant over 24h.The SV IFB are obtained from IONEX files. Several institutions estimate the SV IFB and update them in the internet.The RX IFB are calibrated: using the the ionospheric delay given by GIM and the SV IFB Receiver. The RX IFB are estimated by averaging: The difference between Iono delay and the Smoothed code-based plus SV IFB. This is described with more detail in the document.1 min for this slide (TIME = 13:00)The real question is:Is this good enough to describe the Iono behavior? CLICKFor Iono temporal gradient YES, because the noise is low. CLICKFor the Iono delay NO, because of the noise introduced by the 𝐼_𝑓𝑟𝑒𝑒 combination. CLICKWhat Konno proposed in his work is to find a threshold in which we switch from the Dfree to the Ifree so we always protect against Ionosphere gradients. However, using the Ifree combination results in an increase of the noise, that produces an increase of the Protection levels and results in a downgrade of the GBAS Service type (not allowing GAST-D)The idea here is to find a low-noise estimate of the Ionosphere. CLICKUsing code measurement, one can get a noisy but ambiguous estimate of the Iono delay, Using phase measurements one can get a smooth but ambiguous estimate of the Iono delay. If both are combined, e.g. By smoothing the Iono code estimate with the phase estimate or finding the bias between both, then, we would be able to find an «not-noisy» estimate of the iono. CLICKFinally if we subtract this «low-noise Iono» from the Dfree combination we would be able to cancel the iono delay both in the air and in the GND receivers. CLICKSolving the problem of the different Iono delay between the Ground and the Airborne receivers.01:00 (15:00)
- The BIAS IN THE PHASE-BASED APPROACH are estimated by using the code bias, 𝐵𝜌, and the diff. Bias, 𝐵𝜌Φ. In the last slide, I presented the code-phase bias estimation. In this, I present the estimation of this other diff. bias.First, it is necessary to wait until smoothing has finished.Then the code-phase differential bias, is estimated as the difference between the smoothed code and phase-based comb.The phase bias is indirectly estimted as the difference between code bias and this differential code phase bias.If the bias are finally subtracted from the code and phase based approaches we will have the iono. Delay estimates.1 min for this slide (TIME = 14:00)The real question is:Is this good enough to describe the Iono behavior? CLICKFor Iono temporal gradient YES, because the noise is low. CLICKFor the Iono delay NO, because of the noise introduced by the 𝐼_𝑓𝑟𝑒𝑒 combination. CLICKWhat Konno proposed in his work is to find a threshold in which we switch from the Dfree to the Ifree so we always protect against Ionosphere gradients. However, using the Ifree combination results in an increase of the noise, that produces an increase of the Protection levels and results in a downgrade of the GBAS Service type (not allowing GAST-D)The idea here is to find a low-noise estimate of the Ionosphere. CLICKUsing code measurement, one can get a noisy but ambiguous estimate of the Iono delay, Using phase measurements one can get a smooth but ambiguous estimate of the Iono delay. If both are combined, e.g. By smoothing the Iono code estimate with the phase estimate or finding the bias between both, then, we would be able to find an «not-noisy» estimate of the iono. CLICKFinally if we subtract this «low-noise Iono» from the Dfree combination we would be able to cancel the iono delay both in the air and in the GND receivers. CLICKSolving the problem of the different Iono delay between the Ground and the Airborne receivers.01:00 (15:00)
- Repeat main steps done so far in the process showing graph on the right...1:30 min for this slide (TIME = 15:30)LET’S IMAGINE I AM A BIT SLOWER, SO IT TAKES 16 MIN, UP TO THIS POINTThe real question is:Is this good enough to describe the Iono behavior? CLICKFor Iono temporal gradient YES, because the noise is low. CLICKFor the Iono delay NO, because of the noise introduced by the 𝐼_𝑓𝑟𝑒𝑒 combination. CLICKWhat Konno proposed in his work is to find a threshold in which we switch from the Dfree to the Ifree so we always protect against Ionosphere gradients. However, using the Ifree combination results in an increase of the noise, that produces an increase of the Protection levels and results in a downgrade of the GBAS Service type (not allowing GAST-D)The idea here is to find a low-noise estimate of the Ionosphere. CLICKUsing code measurement, one can get a noisy but ambiguous estimate of the Iono delay, Using phase measurements one can get a smooth but ambiguous estimate of the Iono delay. If both are combined, e.g. By smoothing the Iono code estimate with the phase estimate or finding the bias between both, then, we would be able to find an «not-noisy» estimate of the iono. CLICKFinally if we subtract this «low-noise Iono» from the Dfree combination we would be able to cancel the iono delay both in the air and in the GND receivers. CLICKSolving the problem of the different Iono delay between the Ground and the Airborne receivers.01:00 (15:00)
- The second part of the first objective was to estimate the delay for each subsystem.0:10 min for this slide (TIME = 16:10)
- With this, I will have completed my first objectiveThe first part involved estimating the iono. Delays for each receiver.The 2nd part involved estimating the iono. delay for each SS, using all receivers0:20 min for this slide (TIME = 17:30)
- The second objective was also divided in two parts: Computing an alarm threshols and estimating the IDD.I will start with the first part ....30 sec for this slide (TIME = 18:00)
- It is defined in the SARPS for CAT II/III, that an iono. Gradient is considered dangerous if bigger than 300 mm/KmFor us, this value means a difference of 300 mm between 𝐼𝐴𝐼𝑅 and 𝐼𝐺𝑁𝐷 for a distance between AS/GS of 1 Km.There is also another limitation considering a miniminum value threshold. This is 1.5 m when the AS is closer than 5 KmIf the airplanes is farther than 5 Km, the threshold will be computed based on the distance.Therefore, we can say that the threshold computation, based on specs, depends on the distance between AS/GS.1 min for this slide (TIME = 19:00)The real question is:Is this good enough to describe the Iono behavior? CLICKFor Iono temporal gradient YES, because the noise is low. CLICKFor the Iono delay NO, because of the noise introduced by the 𝐼_𝑓𝑟𝑒𝑒 combination. CLICKWhat Konno proposed in his work is to find a threshold in which we switch from the Dfree to the Ifree so we always protect against Ionosphere gradients. However, using the Ifree combination results in an increase of the noise, that produces an increase of the Protection levels and results in a downgrade of the GBAS Service type (not allowing GAST-D)The idea here is to find a low-noise estimate of the Ionosphere. CLICKUsing code measurement, one can get a noisy but ambiguous estimate of the Iono delay, Using phase measurements one can get a smooth but ambiguous estimate of the Iono delay. If both are combined, e.g. By smoothing the Iono code estimate with the phase estimate or finding the bias between both, then, we would be able to find an «not-noisy» estimate of the iono. CLICKFinally if we subtract this «low-noise Iono» from the Dfree combination we would be able to cancel the iono delay both in the air and in the GND receivers. CLICKSolving the problem of the different Iono delay between the Ground and the Airborne receivers.01:00 (15:00)
- The second part of the second objective is the estimation of the IDD....This will be done by simply subtracting the airborne and ground Ionospheric delay estimates.20 sec for this slide (TIME = 19:20)
- The iono. differential delay using pseudorange will be the difference of the Iono delay estimates of the GS/ASThe same way the IDD using phases will be found as the difference of subsystem w/ the phase-based approach.40 sec for this slide (TIME = 20:00)The real question is:Is this good enough to describe the Iono behavior? CLICKFor Iono temporal gradient YES, because the noise is low. CLICKFor the Iono delay NO, because of the noise introduced by the 𝐼_𝑓𝑟𝑒𝑒 combination. CLICKWhat Konno proposed in his work is to find a threshold in which we switch from the Dfree to the Ifree so we always protect against Ionosphere gradients. However, using the Ifree combination results in an increase of the noise, that produces an increase of the Protection levels and results in a downgrade of the GBAS Service type (not allowing GAST-D)The idea here is to find a low-noise estimate of the Ionosphere. CLICKUsing code measurement, one can get a noisy but ambiguous estimate of the Iono delay, Using phase measurements one can get a smooth but ambiguous estimate of the Iono delay. If both are combined, e.g. By smoothing the Iono code estimate with the phase estimate or finding the bias between both, then, we would be able to find an «not-noisy» estimate of the iono. CLICKFinally if we subtract this «low-noise Iono» from the Dfree combination we would be able to cancel the iono delay both in the air and in the GND receivers. CLICKSolving the problem of the different Iono delay between the Ground and the Airborne receivers.01:00 (15:00)
- With this, I will have completed the second objectiveThe 1st part involved the threshold computation based on specs, and depending on the distance between GS/AS.The 2nd part involved estimating the iono. Diff. Delay, as the difference of the iono. Estimates for each SS, using both the code and phase-based approaches.30 sec for this slide (TIME = 20:30)
- Now, I will present the results10 sec for this slide (TIME = 20:40)
- I’d like to describe the DLR facilities in Braunschweig airport that were used (GROUND SS, AIRBORNE SS)Different tests were accomplished to assess the monitor performance. Among them I will present those related w/ smoothing and user dynamics. The data collected was typically between 1h and 2h and several appraches were realized1:20 min for this slide (TIME = 22:00)The real question is:Is this good enough to describe the Iono behavior? CLICKFor Iono temporal gradient YES, because the noise is low. CLICKFor the Iono delay NO, because of the noise introduced by the 𝐼_𝑓𝑟𝑒𝑒 combination. CLICKWhat Konno proposed in his work is to find a threshold in which we switch from the Dfree to the Ifree so we always protect against Ionosphere gradients. However, using the Ifree combination results in an increase of the noise, that produces an increase of the Protection levels and results in a downgrade of the GBAS Service type (not allowing GAST-D)The idea here is to find a low-noise estimate of the Ionosphere. CLICKUsing code measurement, one can get a noisy but ambiguous estimate of the Iono delay, Using phase measurements one can get a smooth but ambiguous estimate of the Iono delay. If both are combined, e.g. By smoothing the Iono code estimate with the phase estimate or finding the bias between both, then, we would be able to find an «not-noisy» estimate of the iono. CLICKFinally if we subtract this «low-noise Iono» from the Dfree combination we would be able to cancel the iono delay both in the air and in the GND receivers. CLICKSolving the problem of the different Iono delay between the Ground and the Airborne receivers.01:00 (15:00)
- Self-explanatory1 min for this slide (TIME = 23:00)The real question is:Is this good enough to describe the Iono behavior? CLICKFor Iono temporal gradient YES, because the noise is low. CLICKFor the Iono delay NO, because of the noise introduced by the 𝐼_𝑓𝑟𝑒𝑒 combination. CLICKWhat Konno proposed in his work is to find a threshold in which we switch from the Dfree to the Ifree so we always protect against Ionosphere gradients. However, using the Ifree combination results in an increase of the noise, that produces an increase of the Protection levels and results in a downgrade of the GBAS Service type (not allowing GAST-D)The idea here is to find a low-noise estimate of the Ionosphere. CLICKUsing code measurement, one can get a noisy but ambiguous estimate of the Iono delay, Using phase measurements one can get a smooth but ambiguous estimate of the Iono delay. If both are combined, e.g. By smoothing the Iono code estimate with the phase estimate or finding the bias between both, then, we would be able to find an «not-noisy» estimate of the iono. CLICKFinally if we subtract this «low-noise Iono» from the Dfree combination we would be able to cancel the iono delay both in the air and in the GND receivers. CLICKSolving the problem of the different Iono delay between the Ground and the Airborne receivers.01:00 (15:00)
- Self-explanatory1 min for this slide (TIME = 24:00)The real question is:Is this good enough to describe the Iono behavior? CLICKFor Iono temporal gradient YES, because the noise is low. CLICKFor the Iono delay NO, because of the noise introduced by the 𝐼_𝑓𝑟𝑒𝑒 combination. CLICKWhat Konno proposed in his work is to find a threshold in which we switch from the Dfree to the Ifree so we always protect against Ionosphere gradients. However, using the Ifree combination results in an increase of the noise, that produces an increase of the Protection levels and results in a downgrade of the GBAS Service type (not allowing GAST-D)The idea here is to find a low-noise estimate of the Ionosphere. CLICKUsing code measurement, one can get a noisy but ambiguous estimate of the Iono delay, Using phase measurements one can get a smooth but ambiguous estimate of the Iono delay. If both are combined, e.g. By smoothing the Iono code estimate with the phase estimate or finding the bias between both, then, we would be able to find an «not-noisy» estimate of the iono. CLICKFinally if we subtract this «low-noise Iono» from the Dfree combination we would be able to cancel the iono delay both in the air and in the GND receivers. CLICKSolving the problem of the different Iono delay between the Ground and the Airborne receivers.01:00 (15:00)
- Self-explanatory1 min for this slide (TIME = 25:00)The real question is:Is this good enough to describe the Iono behavior? CLICKFor Iono temporal gradient YES, because the noise is low. CLICKFor the Iono delay NO, because of the noise introduced by the 𝐼_𝑓𝑟𝑒𝑒 combination. CLICKWhat Konno proposed in his work is to find a threshold in which we switch from the Dfree to the Ifree so we always protect against Ionosphere gradients. However, using the Ifree combination results in an increase of the noise, that produces an increase of the Protection levels and results in a downgrade of the GBAS Service type (not allowing GAST-D)The idea here is to find a low-noise estimate of the Ionosphere. CLICKUsing code measurement, one can get a noisy but ambiguous estimate of the Iono delay, Using phase measurements one can get a smooth but ambiguous estimate of the Iono delay. If both are combined, e.g. By smoothing the Iono code estimate with the phase estimate or finding the bias between both, then, we would be able to find an «not-noisy» estimate of the iono. CLICKFinally if we subtract this «low-noise Iono» from the Dfree combination we would be able to cancel the iono delay both in the air and in the GND receivers. CLICKSolving the problem of the different Iono delay between the Ground and the Airborne receivers.01:00 (15:00)
- Self-explanatory1 min for this slide (TIME = 26:00)The real question is:Is this good enough to describe the Iono behavior? CLICKFor Iono temporal gradient YES, because the noise is low. CLICKFor the Iono delay NO, because of the noise introduced by the 𝐼_𝑓𝑟𝑒𝑒 combination. CLICKWhat Konno proposed in his work is to find a threshold in which we switch from the Dfree to the Ifree so we always protect against Ionosphere gradients. However, using the Ifree combination results in an increase of the noise, that produces an increase of the Protection levels and results in a downgrade of the GBAS Service type (not allowing GAST-D)The idea here is to find a low-noise estimate of the Ionosphere. CLICKUsing code measurement, one can get a noisy but ambiguous estimate of the Iono delay, Using phase measurements one can get a smooth but ambiguous estimate of the Iono delay. If both are combined, e.g. By smoothing the Iono code estimate with the phase estimate or finding the bias between both, then, we would be able to find an «not-noisy» estimate of the iono. CLICKFinally if we subtract this «low-noise Iono» from the Dfree combination we would be able to cancel the iono delay both in the air and in the GND receivers. CLICKSolving the problem of the different Iono delay between the Ground and the Airborne receivers.01:00 (15:00)
- I will finish with conclusions and future work10 sec for this slide (TIME = 26:10)
- Summary of thesis motivation andn objectives1 min for this slide (TIME = 27:10)
- Self-explanatory1:50 min for this slide (TIME = 29:00)The real question is:Is this good enough to describe the Iono behavior? CLICKFor Iono temporal gradient YES, because the noise is low. CLICKFor the Iono delay NO, because of the noise introduced by the 𝐼_𝑓𝑟𝑒𝑒 combination. CLICKWhat Konno proposed in his work is to find a threshold in which we switch from the Dfree to the Ifree so we always protect against Ionosphere gradients. However, using the Ifree combination results in an increase of the noise, that produces an increase of the Protection levels and results in a downgrade of the GBAS Service type (not allowing GAST-D)The idea here is to find a low-noise estimate of the Ionosphere. CLICKUsing code measurement, one can get a noisy but ambiguous estimate of the Iono delay, Using phase measurements one can get a smooth but ambiguous estimate of the Iono delay. If both are combined, e.g. By smoothing the Iono code estimate with the phase estimate or finding the bias between both, then, we would be able to find an «not-noisy» estimate of the iono. CLICKFinally if we subtract this «low-noise Iono» from the Dfree combination we would be able to cancel the iono delay both in the air and in the GND receivers. CLICKSolving the problem of the different Iono delay between the Ground and the Airborne receivers.01:00 (15:00)
- Self-explanatory1 min for this slide (TIME = 30:00)The real question is:Is this good enough to describe the Iono behavior? CLICKFor Iono temporal gradient YES, because the noise is low. CLICKFor the Iono delay NO, because of the noise introduced by the 𝐼_𝑓𝑟𝑒𝑒 combination. CLICKWhat Konno proposed in his work is to find a threshold in which we switch from the Dfree to the Ifree so we always protect against Ionosphere gradients. However, using the Ifree combination results in an increase of the noise, that produces an increase of the Protection levels and results in a downgrade of the GBAS Service type (not allowing GAST-D)The idea here is to find a low-noise estimate of the Ionosphere. CLICKUsing code measurement, one can get a noisy but ambiguous estimate of the Iono delay, Using phase measurements one can get a smooth but ambiguous estimate of the Iono delay. If both are combined, e.g. By smoothing the Iono code estimate with the phase estimate or finding the bias between both, then, we would be able to find an «not-noisy» estimate of the iono. CLICKFinally if we subtract this «low-noise Iono» from the Dfree combination we would be able to cancel the iono delay both in the air and in the GND receivers. CLICKSolving the problem of the different Iono delay between the Ground and the Airborne receivers.01:00 (15:00)
- Now, if instead of having Nominal IonosphereThere is an IONOSPHERIC GRADIENT. The initial ionospheric delay for GS/AS is different.If we put those delays on the graphs, it is observed an ionospheric bias2 things can happen during the approach40 sec for this slide (TIME = 03:00)