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Implications of GNSS SiS Disruption on Safety of PBN

Operations – Risks, Solutions and Steps Forward

Non-Intentional & Intentional RFI of the GNSS SiS

Silvio Semanjski - Royal Military Academy Belgium

Royal Military Academy Belgium

Content

GNSS SiS disruption - Extent of risks

ECTL and ICAO activities on GNSS SiS disruption

Mitigation of GNSS SiS disruption

GSINTA Project

Safety Assessment with Scenarios of GNSS deteriorated environment

Proposed steps forward

1st ICAO PBN TF & ECTL RAISG Meeting Paris, 11 to 13 September 2013

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GNSS Policy: the vision for the use of a multi-constellation and multi-frequency GNSS in 2020+ This EUROCONTROL policy on GNSS is based on a gradual reliance on Satellite navigation that has as final goal its use as sole service, to the extent that this can be shown to be the most cost beneficial solution and if is supported by a successful safety and security analyses.

AMC 20-28 on NAVAID Infrastructure assumptions The acceptability of the risk of loss of LPV approach capability for multiple aircraft due to satellite failure or SBAS system failure, loss of availability of satellite signal or radiofrequency interference, will be considered by the ANSP providing the approach.


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Meaconing


Un-intentional RFI

Spoofing

Intentional RFI


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Counterfeit GNSS Signal

Delay & Rebroadcast

Current ATM systems for PBN OPS unprotected from injection of misleading GNSS information !

GNSS SiS disruption



Excerpt from AIC A 21/12 FRANCE 4.4 Missed approach “Most of missed approach paths in France are RNAV procedures based on a level of performance at least compatible with the use of a GNSS ABAS receiver (of RAIM-reinforced GPS type).

Note: The availability of RAIM-reinforced GPS for missed approach is higher than the availability required for final approach. As a matter of fact, the accuracy of navigation required for missed approach is 1 NM for 95% of time vs. 0.3 NM for 95% of time for final approach. Therefore, RAIM availability forecasts obtained through NOTAM or tools specific to operators are not representative of missed approach availability. For similar reasons, a GNSS SBAS receiver may become unavailable for LPV minima, whereas its capability to follow the missed

approach has not been affected. The main event leading to a simultaneous loss of GNSS guidance during final approach and missed approach is interference due to jamming.

If the missed approach path is a RNAV procedure (not relying on conventional radio-navigation means):

The operator may have defined previously in their procedures, an emergency procedure for the case

where the loss of RNAV guidance during the approach does not allow to follow the missed approach procedure provided for the considered runway.”


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Example of safety risks associated with GNSS SiS degradation/loss for PBN OPS



Several issues:

Are the LSAs covered risks of GNSS SiS disruption/denial for GNSS based PBN OPS already implemented?

What are current GNSS reversion modes for RNP operations where missed approach are GPS based?

Are the operators supposed to develop contingency procedures for operations in GNSS disrupted or denied environment?

How pilots / ATCOs / NAV system know if the GNSS SiS spoofing is undergoing?

etc.


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Current scheduled and non-intentional GNSS jamming threats:

DME/TACAN on L5/E5

GNSS repeaters

GNSS pseudolites

Higher harmonics and intermodulation products of various RF emitters

LightSquared GPS Interference (in USA)


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Un-intentional RFI types & sources




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Un-intentional RFI types & sources

Interference Type Telecommunication Systems GNSS Bands

Aeronautical Communication

Systems

DME

Galileo E5a E5b GPS L5

TACAN

Secondary Surveillance Radar (SSR)

Multifunction Information Distribution System (MIDS)

Joint Tactical Information Distribution System (JTDS)

TCAS

Identity Friend and Foe (IFF)

ADS-B

Radar Air Traffic Control radar Galileo E6

GPS L2 Solid State radar

Satellite Communication Systems Mobile Satellite Service (MSS) close to GPS L1

Secondary harmonics

TV Channels Galileo E1

GPS L1 Digital Video Broadcasting – Terrestrial (DVB-T)

Digital Audio Broadcasting (DAB)

Others

Personal Electronic Device (PED)

all VOR

ILS harmonics

Ultra Wide Band (UWB) Systems




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Effects of jamming on unprotected GPS performance


ECTL and ICAO activities on GNSS SiS disruption

ECTL

Navigation Steering Group (GNSS & Infrastructure Session)

ICAO

CNS SG

PBN/GNSS TF

ICAO EANPG (FMG)

Other groups

Aeronautical Spectrum Frequency Consultation Group (ASFCG)


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ECTL and ICAO activities on GNSS SiS disruption ICAO 12th Air Navigation Conference recommendations related to GNSS vulnerability

Recommendation 6/7 – Assistance to States in Mitigating Global Navigation Satellite System Vulnerabilities

ICAO to assess the need for, and feasibility of, an APNT system

Recommendation 6/8 – Planning for Mitigation of Global Navigation Satellite System Vulnerabilities

States to: Assess the likelihood and effects of GNSS vulnerabilities in their airspace and apply, as

necessary, recognized and available mitigation methods; Provide effective spectrum management and protection of GNSS frequencies to reduce the

likelihood of unintentional interference or degradation of GNSS performance; Report to ICAO cases of harmful interference to GNSS that may have an impact on

International Civil Aviation operations; Develop regulatory framework governing the use of GNSS repeaters, pseudolites, spoofers

and jammers; Support introduction on-board mitigation techniques, particularly INS Where terrestrial NAVAIDs are part of a mitigation strategy, give priority to retention of DME

in support of INS/DME or DME/DME area navigation, and of ILS at selected runways.


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Passive measures

Multi Constellation /

Frequency GNSS

APNT system RFI Monitoring

Networks

Aircraft on-board IDLM

Real time RFI Detection & Localization

ECTL NSG currently coordinating development of GNSS RFI mitigation framework and action plan at ECAC level!


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Real time RFI Mitigation

Legal prosecution

GRF Spectrum

protection



APNT required capabilities

In TMA APNT should be able to provide RNP 0.3 to support NPA and to allow aircraft to get to the FAF of terrestrial based PA as an ILS.

Support for 3NM separations by providing 0.1NM position accuracy.

“Previous coverage and performance studies conducted show that current specified accuracy of DME must improve by about a factor of two to support RNP 0.3 in the areas studied. The accuracy has to be even better if separation standards need to be met.”

APNT – Alternative Position, Navigation & Timing


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BAE Systems Small Antenna System Advantages:

Effective against large intentional

Disadvantages:

High cost and size

Jammer sources difficult to localize

Inefficient for multiple jammers

Adaptive Spatial Nulling Antenna/CRPA


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Assessment of the LightSquared Ancillary Terrestrial Component Radio Frequency Interference Impact on GNSS L1 Band Airborne Receiver Operations – RTCA Report to FAA Adaptive Spatial (Antenna) Processing

“… There are limitations to the number of interference sources that can be simultaneously suppressed. The FAA has dismissed the use of such technologies for civil aircraft since they are export-controlled, which combined with the above high costs makes this technology impractical for civil aviation.”


Mitigation of GNSS SiS disruption NAVAID supporting GNSS reversions to RNP


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DME/DME/INS system

Currently not capable to support RNP specifications for APCH OPS and 3NM separations

APNT system

Under definition and development

The most promising DME/GBT (Ground Broadcast Transceiver – ADS-B) – modified system with use of signals of opportunity in DME band

Multilateration & Pseudolite alternatives

Signals for passive ranging: • DME based Passive Ranging (DMPR) • UAT Passive Ranging (by ADS-B GBT)

Potential signals for passive ranging: • Mode S on 1030/1090 MHz • VHF communications • Future Communication System (FCS)


Mitigation of GNSS SiS disruption Other means of mitigation


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eLORAN Robust Position & Timing Capability as timing subsystem for APNT Multilateration & Pseudolite

Alternatives) Real-time differential corrections Corrections and integrity status via eLoran data channel

Supported application Prototype eLORAN eLORAN

Resilient PNT

Non-Precision APCH

Stratum 1 frequency

UTC

Precise timing

Interference detection & mitigation


Objectives:

Maintaining and recovery of GNSS SiS integrity in intentional or un-intentional RFI environment

Real-time IDLM on-board the aircraft

Oriented on exploiting of aircraft FRPA-TSO antennas (instead of multi-antenna array/ CRPA; multiple TSO antennas)

Minimum alterations of CNS sub-systems (adding signal processing component in the line between antenna assembly and GNSS Rx)

GSINTA Project Gnss Sis INTegrity Assurance

“This research was supported by a Marie Curie IEF within the 7th European Community Framework Programme”

Supporters: Technische Universität Braunschweig – Institute of Flight Guidance

Septentrio nv

Host research institution: Royal Military Academy (Belgium) - CISS


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Methodology

RFI Data acquisition:

Laboratory OTA RFI measurements

Real world flight campaign measurements (controlled RFI by on-ground jammers)

RFI model building

IDLM solution development

IDLM solution testing:

Laboratory testing

Real world flight campaign validation




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SPECTRUM ANALYZER

RFI SIGNAL GENERATOR

RFI ACQUISITION CONTROLLER

GNSS SIMULATOR

Horn Antenna Radiator

RHCP Antenna Radiator

GNSS RECEIVER

GNSS Antenna

TSO GNSS Antenna

GNSS Timing

RECEIVER





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SPECTRUM ANALYZER

ACQUISITION & CONTROL

TSO GNSS Rx #1

TSO GNSS Antenna #1

FGS

TSO GNSS Antenna #2

TSO GNSS Rx #2

SYNC SYSTEM GNSS Rx

TSO GNSS/VHF Combo Antenna

INS

GNSS Antenna

SYNC SYSTEM

SPECTRUM ANALYZER

RFI SIGNAL GENERATOR

RFI ACQUISITION CONTROLLER

Reference GNSS

RECEIVER

RFI Emitter Antenna

Isotropic Measurement Antenna

Real world flight campaign - controlled RFI from ground jammers

Initial data acquisition

Solution validation


Types of interferers considered:

CWI

NBI

WBI

Pulsed CWI

Pulsed NBI

Pulsed WBI

Sweep-through




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GNSS frequencies considered:

GPS L1/L2/L5

Galileo L1-E1-L2/E5/E6

GNSS signals/codes considered:

GPS C/A

GPS Y

Galileo CS

Galileo PRS

Galileo SOL


Benefits:

Short term oriented potential on-board IDLM solution

Real-time IDL simultaneously by several aircrafts in TMA affected by RFI and reporting of interferer location to the service authorized to remove interferer



Carrier-to-Noise Ratio (CNR) Degradation Baseline Test

Measurement Accuracy Test

SBAS Message Loss Tests

1st satellite loss threshold [dB]

3D navigation loss threshold [dB]

Reacquisition threshold [dB]


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RFI tests using MOPS-based GNSS receiver :


Scenario A Spoofing or Meaconing of GNSS SiS for RNP APCH and DEP operations GNSS RNAV protected Missed Approach (IMC conditions at minima values for APCH; complex geographic environment)

SA with Scenarios of GNSS deteriorated/denied environment


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Scenario B Spoofing or Meaconing of GNSS SiS for ATSA-AIRB ADS service in IMC or ATSA-SURF service during LVOs

Examples of critical scenarios to consider in LSAs for PBN OPS implementation:


Disruption or loss of GNSS SiS can result in several operational issues especially when reverting to same or lower RNP application:

Transitioning from 3NM to 5NM separation enroute and on arrivals outside of 40NM (DDI unable to assure 3NM separation);

Sudden increase in radar vectoring within airspace volume affected (in RA; number of ATCOs available);

Aircraft diverting to alternative APRTs (Contingency and Holding Fuel policy might not be covering such NAVAID related diversions);

At APRTs with Parallel Runway Operations sudden fall in capacity;

Load of TVs (impact on configurations and sector/TV capacities).

SA with Scenarios of GNSS deteriorated/denied environment


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Proposed steps forward

Consolidation of methodology, techniques and prospective developments in GNSS vulnerability mitigation – initiative by ECTL and ICAO WGs

Formally agree on APNT for the GNSS based PBN navigation applications

Recognizing areas of interest in current R&D to consolidate past and future efforts in SESAR projects supporting on-board IDLM and APNT

Need to consider re-evaluation of NAVAID infrastructure plans due to APNT

Include scenarios with GNSS SiS deteriorated /denied environment into future LSAs for GNSS based PBN navigation applications implementation (including re-application of LSA for past implementations where such scenarios were not considered)

MS to contribute to ECTL NSG lead in GNSS RFI mitigation framework and action plan at ECAC level


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General RFI Effects on Aeronautical GNSS Receivers Backup slide #1


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Example from USAF (source: USAF 746th Test Squadron)

Jamming event in Mesa, AZ

13-18 Dec 2001, GPS jammer caused GPS failures within 180NM of Mesa, AZ

Boeing was preparing for upcoming test

• Accidentally left jammer on L1 frequency radiating at 0.8mW

• Jammer operated continuously for 4.5 days

Impact to ATC operations

• A/C lost GPS 45NM from PHX, performed 35° turn toward traffic

• NOTAM was not issued until 2nd day

• Numerous pilots reported loss of GPS NAVAID

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