International Civil Aviation Organization. Bangkok, Thailand, July 2011

Transcription

1 CNS/MET SG/15 - WP/38 Internatinal Civil Aviatin Organizatin FIFTEENTH MEETING OF THE COMMUNICATIONS/NAVIGATION/SURVEILLANCE AND METEOROLOGY SUB-GROUP (CNS/MET SG/15) OF APANPIRG Bangkk, Thailand, July 2011 Agenda Item 5: Navigatin 2) discuss issues related t implementatin f GNSS and review develpments that have taken place in the Regin THREATS TO GNSS JAMMERS, PSEUDOLITES & REPEATERS (Presented by Australia) SUMMARY This paper discusses threats t satellite based navigatin frm natural and manmade surces with cncentratin n manmade surces. The recmmendatins f the paper are prhibitin f malicius and unintentinal interference surces and strict regulatin f tls and systems which have legitimate uses. This paper relates t Strategic Objectives: A: Safety Enhance glbal civil aviatin safety Glbal Plan Initiatives: GPI-21 Navigatin systems 1. Intrductin 1.1 The Glbal Navigatin Satellite System (GNSS) and in particular the Glbal Psitining System (GPS) has becme the ubiquitus utility f the current age. GNSS supprts psitining, navigatin and precisin timing applicatins fr cnsumer electrnics, tracking devices, system synchrnizatin, transprtatin and many mre. Aviatin is a critical user requiring cntinuity, availability and (unusually high level f) integrity, f service, but aviatin represents a small prprtin f the ttal user cmmunity. 1.2 The aircraft use GNSS fr; enrute navigatin, navigatin in the terminal maneuvring area, apprach and landing guidance surface navigatin

2 CNS/MET SG/15 WP/38-2- TAWS (EGPWS) autmatic dependent surveillance bradcast Air Navigatin Service Prviders (ANSP) use GNSS fr: time system synchrnizatin surveillance Natinal Infrastructure used by ANSPs als use GNSS: Telecmmunicatins Bearers Satellite Cmmunicatins services Electrical mains pwer 2. Threats t GNSS 2.1 GNSS signals are lw level with the required signals being recvered thrugh crrelatin f the required signal frm the backgrund nise. 2.2 Threats t the effective receptin can result frm natural phenmena and human generated surces. 2.3 GNSS signals pass thrugh the insphere and trpsphere as they transit frm the satellite t a grund r airbrne receiver. The characteristics f the insphere vary with the level f inising radiatin received frm the sun. Thus the insphere characteristics change day t night and summer t winter. Users f HF radi will be familiar with these changes. Mst f the time these changes are reasnably predicable and d nt threaten use f GPS. 2.4 Sun spts, slar flares and crna mass ejectin events can cause very high levels f slar radiatin and crrespnding high levels f disturbance f the insphere and GNSS signals. In rare, extreme cases GNSS signals can be disrupted. Natural phenmena will nt be further discussed in this paper but are being cnsidered by the inspheric studies f APANPIRG wrking grups and Air Navigatin Cmmissin panels. 2.5 Human generated threat surces can be cnsidered in the general classificatins f: Inadvertent interference Deliberate interference 2.6 Surces f inadvertent interference include: Harmnics, inter-mdulatin prducts and parasitic scillatin These are nrmal RF interference issues and can be managed with existing mechanisms Inapprpriate allcatin f adjacent frequency bands Addressed with sund spectrum management and enfrcement Pseudlites devices intended t supplement and aid GNSS services by the generatin and transmissin f a GNSS cmpliant signals frm a fixed grund lcatin

3 -3- CNS/MET SG/15 - WP/38 Signal generatrs /simulatrs devices design t prduce a GNSS cmpliant signal frmat fr the purpse f testing and maintenance f GNSS devices. Repeater/retransmitters devices designed t receive GNSS satellite signals, amplifier the signals and re-transmit the signal t prvide GNSS service in areas bscured frm direct receptin f signals frm satellites 2.7 Out-f-band surces can be generated by a single transmitter with spurius emissins frm the centre frequency f the allcated service r harmnics f the service frequency which result in radiatin frequency signals with the GNSS band. Examples are high pwered terrestrial wireless transmitters lcated in the band ( MHz) immediately adjacent t the GPS band ( MHz), third rder harmnics f analgue televisin services and harmnics (13 th ) f VHF aircraft transmitters. Out-f-band surces can be mitigated by diligent spectrum management, systems engineering and rigrus maintenance. 2.8 Surces f deliberate interference include: Jammers devices that seek t deny the use f GNSS by transmissin f a signal t prevent the receptin f the GNSS signals. Spfers - devices that transmit GNSS like signals with the intent t cause the GNSS receivers t utput inaccurate and misleading infrmatin. 2.9 Jamming is a deliberate act intended t deny use f GNSS. Spfing is a deliberate act intended t mislead the GNSS receiver States may perate jammers and spfers fr defence and security reasns. Fr cntinuity f service States shuld minimise the ccasin n which jammers and spfers are perated. Risk and peratinal assessment shuld be cmpleted and ntificatin prvided t aernautical users f service denial and hazardus infrmatin transmissin Jammers and t a less likely extent spfers may be perated by nn-state entities t disable specific GNSS applicatins such as tracking, tlling and mnitring systems. Examples include: jammers emplyed by drivers t defeat GNSS vehicle tracking used by fleet management; jammers used by car thieves t defeat GNSS tracking f stlen vehicles; jammers used by persn under liberty restraint t defeat GNSS tracking bracelets/anklets.; sme peple cnsider GNSS a threat t persnal privacy Lw cst jammers are available as cnsumer prducts as persnal privacy devices The intentinal jamming f GNSS t defeat a nn aviatin system may have the unintended cnsequence f jamming an aviatin GNSS system. Interference detectin algrithms f the GBAS installed at Newark Airprt USA have repeatedly detected transient jamming. Investigatin revealed that the driver f a curier truck equipped with a GNSS tracking system was using a GNSS jammer t defeat the vehicle tracking. As the vehicle passed the airprt, the jammer was detected by the GBAS It can be seen that jamming f GNSS is an issue nt cnfined t aviatin. The prhibitin f the sale, peratin and pssessin f jammers and spfers is in place by a grwing number f States.

4 CNS/MET SG/15 WP/ Develpment f in-band pseudlites fr aviatin applicatins has been discntinued by ICAO technical panels. Pseudlites are still being pursued by ther sectrs f the GNSS user cmmunity fr applicatin such as mining where the depth f the mine prevents unbstructed sky views. The relatively clse prximity, even with lw pwer f a pseudlite can swamp the wanted signals frm distance satellites. States are urged t avid in-band pseudlites and if actually used shuld cmplete a safety analysis with regulatry enfrcement f necessary mitigatin Signal generatrs, simulatrs and replay devices are used t test, validate and maintain the perfrmance f GNSS devices. The intended applicatin is within labratry and wrkshp with tight cntrls t prevent leakage f the signal utside the test envirnment. The signal frm these signal generatrs can spf GNSS users and result in received utputting hazardus and misleading infrmatin Repeaters and retransmitters have legitimate uses such as maintaining the state f readiness f navigatin systems f emergency vehicles and aircraft when garaged r hangared. When crrectly designed, installed and maintained repeaters are lw risk fr the value f the functinality they prvide. A prly designed r installed repeater can pse an unacceptable risk. German authrities 1 lcated such deficient device installed in a hangar that caused false alarms f an enhanced grund prximity warning device and deviatin f an internal psitin f an aircraft with that reprt by the installed GNSS navigatin receiver. Eurpean and Nrth American guidance 2 is available n licensing and regulatin practices f repeaters Australia prvides prtectin fr GNSS services via the Radicmmunicatins Act 3. Sectins 46 and 47 f the Act prhibit the peratin and pssessin fr the purpse f peratin unlicensed transmitting devices. Sectins 189 and 190 f the Act allw the declaratin f prhibited devices and create ffenses fr perating r supplying prhibited devices. RNSS (GPS) jammers were declared Prhibited Devices in NSP Nvember 2010 WGW/WP3 2 A Framewrk Fr Authrisatin Regime f Glbal Navigatin Satellite System (GNSS) Repeaters Manual f Regulatins and Prcedures fr Federal Radi Frequency Management (Redbk)

5 -5- CNS/MET SG/15 - WP/38 3. Actin by the Meeting 3.1 The meeting is invited t: a) Nte the threats frm man made surces t aviatin applicatins f GNSS b) Cnsider the fllwing draft cnclusin: Draft Cnclusin 15/xx - Prtectin f aviatin utility f GNSS That, State aviatin authrities in partnership with ther agencies f the State prhibit malicius and unintentinal interference t GNSS and regulate legitimate uses f technlgy t preserve aviatin utility f GNSS. _ Cntact: jeffrey.bllard@airservicesaustralia.cm