847
1 INTRODUCTION
Reliable positioning is recognized as one of the
fundamental requirements for the safety at sea. For
almost 50 years after the WW2 hyperbolic systems
(Decca, Loran etc.) dominated in sea navigation.
HoweversincefirstNavySatelliteNavigationSystem
(Transit) this state gradually changed and now, for
many years
Global Navigation Satellite Systems are
recognized as the primary source in positioning. In
factweobserverealmonopolyofGPSinthisfield.
On the other hand we know that these systems
haveaweakresistanceonmanydisturbances[1].So
reliance on a single position source when its
vulnerability
is known, bring us to not acceptable
risk.Itisespeciallyessential when many devices on
theshiprequirepositioninputtoitswork.Thisisnot
only mariners’ problem, as today many crucial
aspectsofthesocietylifeisdomineeredbyGPS.This
statement refers not only to the navigation,
nevertheless in the general feeling the system is
treated as the element of the navigational
infrastructure. A lot of critical infrastructure
applications involving safety, security, and the
economic flow of goods is dependent from
Positioning,NavigationandTimingsystemsas well.
Let Us Prepare the Officer of the Watch on Jamming
and Spoofing
A.Felski
PolishNavalAcademy,Gdynia,Poland
ABSTRACT:ThegeneralaccessibilityandhighaccuracyofGPScausedthatforadozenorsoyearsitisapplied
commonly, not only in marine navigation. We can ascertain that in this regard there exists the monopoly.
However,nowitis apparentlythat thissystem can
beeasilydisturbed,whattestifynumerous reports. The
problem has been treated as troubles in land navigation, however nowadays became every‐day reality on
coastalwatersaswell,especiallyontheMediterraneanandBlackSeasandPersianGulf.
Officerswhosurvivedthistellthatthefirstimpulseinsuchsituation
istoverifyGPSreceiver,regardlessofthe
situationaroundtheship.Theconcentrationoftheofficer’sattentionontheGPSreceiver,especiallyoncoastal
waterscreatesthethreatfortheship,howeverinthissituationappearotherthreatswhichmanyofficersdoes
not associate with GPS. Usually on the present
ship GPS receiver is not only the source of positioning
information. It is a source of information for many other devices, so inappropriate work of it generates
problemswithmanyotherprocessesontheship.TodayquestioniswhoonthebridgecannoticeGPSproblems
andhow?Thereare
receiverswhichdonotinformabouttheproblem,orpresentnotrealisticdata.Sometimes
onlyECDISpictureshowssomeabnormality,forexamplestillthesamepositionwhileshipisundertheway.
On the paper the analysis of possibly aspects of the problem is discussed. Presented analysis goes to the
conclusion
thatshouldbepreparedsomeprocedurehowtoproceedincaseofthelackofGPSsignals,aswell
asthewatchofficershouldbepreparedtoactinsuchsituation.Thisisataskformarineacademies.
http://www.transnav.eu
the International Journal
on Marine Navigation
and Safety of Sea Transportation
Volume 13
Number 4
December 2019
DOI:10.12716/1001.13.04.18
848
Formanyapplications,likecellularphones,itsuseis
essentialandthemostofusersisfamiliarwithit.
The absolutely new perspective in this aspect
drawstoustheappearanceofunmannedships.From
theonesidewecannottoallow,thatunmannedship
willsailwithoutpositioningdata,
whenexperienced
man can manage this for some time. The second
aspect of this problem is possibility to capture the
unmannedshipbypirates,whatwasdemonstratedas
opportunity by Iranian forces against US Predator
drone in 2013 by means of manipulations with GPS
signals[10].
2 KINDSOFDISTURBANCES
ANDTHESCALE
OFTHEPROBLEM
GPSwasbuiltastheinterferenceproofthankstothe
useofthetechniqueofwidespectrum.Butalreadyin
the first half of 90‐these first report about the
possibilityofthedisturbanceofGPSsignalhasbeen
published [Falen, 1994]. Then possibilities of
interferenceswasforeseen.Asfarasin2001thereport
of the American Department of the Trade widely
analyses potential possibilities of the interference of
the signal GPS with broadband wireless
communicationsystems,thanin2011RoyalAcademy
of Engineering report [Global Navigation, 2011],
[Space Weather, 2013] as the greatest
threat attends
the problem of the intended perturbation of GPS
signal with portable devices. Today is clear, that
Space‐based PNT systems have many limitations,
amongwhich interference, jamming, meaconingand
spoofingarementionedasrealandmostessential.
Figure1. The most common “personal” jammers. Source:
[gpsworld.com].
The problem of anti‐GPS activity isn’t a new
threat.Therootsofthisandsimilartechnologiescan
befind in the WW2eraandlater, inColdWar. The
first attempts to produce some “radio‐noise” for
counteractagainstenemy radio transmission we can
observeduring theWWII.Later,attempt
to transmit
fakeradarechoestobuildfalsepictureontheenemy
radarscreen–inseventies.
Generally speaking there are three options to
disturb GPS signal in intentional mode: jamming,
meaconingandspoofing[Cameron,2014].
Ja mming seems to be the easiest method, as its
sense is to produce enough power of the radio
noiseinreceiver’sspectrum.Thisistruth,thatGPS
receiver works even below of the noise level,
howevertheSignaltoNoiseratioislimited.Ifthe
ratioofthenoiseis
overthelimitinspiteofallthe
receiverdoesnotreceivetheusefulsignal.
Meaconing means a manipulation in the time of
the delivery of satellite signals tothe receiver, in
fact‐introducingsomedelaytotheirpropagation.
Finally coordinates of the position will be
incorrectlycalculated,asthisprocessbasedonthe
timeofsignalpropagation.
Spoofing is the method of transmitting to the
receiver signals which seems to be GPS signals,
however there are produced out of the system –
not by satellites, but by enemy generator.
Reportedly for this the perfect means are GPS
simulators. The threat of spoofing for GPS was
discussed many
times by specialist, during open
discussed,aswellasprobablyintheclosedbodies.
For long time many specialist argued that in
realityspoofingis“toohard”toconductitinareal
conditions. Today many evidences show, that it
works.
Asjammingneedsimpledevices,nowadaysthisis
observed in
many areas and for different reason.
ComplaintsofScottishfishermenalmosttenyearsago
provethatNATOproducessuchdisturbances forits
ownexercises.Ontheotherhand,accordingtopublic
pronouncements of Prime Ministers of Finland and
Norway in February this year, after last NATO
exercises, Russia acts so
in case of exercises of pact
forces. Many experienced ship officers report such
evidences in the west part of Mediterranean Sea in
2017and2018.
For long time Spoofing has been treated as not
workable, up to 2013, when Psiaki with his team
demonstrate it in famous experiment on
Mediterranean Sea
[Psiaki, 2016]. In this experiment
the team from University of Texas (Radionavigation
Laboratory) were carried out an experiment where
GPS‐guided drone was fooled into “thinking” its
altitudewasincreasingandthiscausedittolowerthe
flight and finally – landing. In 2014 the same team
demonstratedhowyacht
couldbesteered off‐course
by means of spoofing attack. In this experiment
yacht’s GPS receiver was spoofed into “believing”
that it was veering off its course, set northwards to
Venice, and heading south to Libya at a very high
speed[Cameron,2014].
Figure2. Photo of GPS receiver on the spoofed yacht.
Reader should notice altitude of the yacht (minus 4000
meters)andspeed(449knots).Source:[Cameron,2014].