183

1 INTRODUCTION

While the industrial revolution brought an

unprecedentedrevolutioninmaterialwealthtomany

nationsinthe19

and20

centuries,theturnof the

centurysawtechnologyenablingthecreationofa

virtual global village. The internet and increase in

computational speed increased the pace of

individuals’ lives, accelerated change and brought

nearlyeverypointoftheglobemuchclosertogether

in virtual space. Satellite navigation systems

augmented this by both providing an enabling

precise, synchronized ti

ming capability, and by

making it much easier to overcome physical spaces

thatstillseparatedindividualsandsocieties.

Thedawnofsatellitenavigationdatesto1958,and

the TRANSIT system created by the Johns Hopkins

University Applied Physics Laboratory, USA.

TRANSIT was used by naval vessels for navigation,

and as a surveying aid and frequency reference.

While there were some limit

ed civilian uses, the

inflection point for the technical revolution was not

reached until NAVSTAR GPS became fully

operationalonJuly17,1995.Sincethenithasbecome

asilentutilitysupportingeverythingfromelectronic

banking to cellular telephone systems and electrical

grids – not to mention tra

nsportation. Few can

imagine life without these and other services. Many

havebecomenecessitiesasthesystemsandmethods

theyreplacedarenolongeravailable.

LaunchofthefirstNAVSTARGPSsatellitein1978

beganthisnewtechnologicalera.Itwasfollowedby

the first launches of GLONASS (Russia) in 1982,

GALILEO(Europe)in2005,QZSS(Japan‐regional)in

2010, IRNSS (India‐regional) in 2013, and Bei Dou

(China)in2015.

Global Navigation Satellite Systems

–

Perspectives on

Development and Threats to System Operation

K.Czaplewski

GdyniaMaritimeUniversity,Gdynia,Poland

ResilientNavigationandTimingFoundation,USA

D.Goward

ResilientNavigationandTimingFoundation,USA

ABSTRACT:Therapiddevelopmento

satellitenavigationandtimingtechnologiesandthebroadavailability

ofuserequipmentandapplicationshasdramaticallychangedtheworldoverthelast20years.Ittook38years

fromthelaunchoftheworld’sfirstartificialsatellite,Sputnik1,(October4,1957)tothedayNAVSTARGPS

becamefullyoperational(July17,1995).Inthenext20yearsuserequipmentbeca

mewidelyavailableatthe

consumer level, and 10 global and regional satellite systems were partially or fully deployed. These highly

precise signals provided free to the user have been incorporated by clever engineers into virtually every

technology.Atthesameti

meinterferencewiththesesignals(spoofingandjamming)havebecomeasignificant

daytodayprobleminmanysocietiesandposeasignificantthreattocriticalinfrastructure. Thispaperprovides

informationonthecurrentstatusanddevelopmentofnavigationsatellitesystemsbasedondataprovidedby

thesystemsʹadministrators.Italsoprovidesinformat

iononLoran/eLoran,asystemwhichmanynationshave

selectedasacomplementandbackupforsatellitenavigationsystems.

http://www.transnav.eu

the International Journal

on Marine Navigation

and Safety of Sea Transportation

Volume 10

Number 2

June 2016

DOI:10.12716/1001.10.02.01

184

The first retail consumer GPS receivers, the

MagellanGPSNAV1000,wereshippedin1989.With

an increasing number of satellites and the

proliferation of receivers, the idea of regarding all

satellite navigation systems holistically was born. In

1994 the European Commission, European Space

AgencyandEurocontrolproposedcreatingthe

Global

Navigation Satellite System (GNSS). European talks

withtheU.S.governmentthattookplacefrom1995–

1999resultedinanofficialagreementoncooperation

and Europe’s continental EGNOS augmentation

system was established. Originally, “GNSS” was

intended to be an EGNOS complemented

combination of GPS and GLONASS. With the

emergenceofthe

GalileoandBeiDousystems,GNSS

hascometomeanallthesystemsgenerally.Moreand

more frequently receivers are configured to access

and use any and all navigation satellite systems

available.AsProfessorDavidLasthaspointedout,

the national systems have become interchangeable

andinvisibletotheuser.

GNSShasbecomeasystem

ofsystems.

Butasystemofsystemstillrequiresitscomponent

parts to function properly for users to access the

servicestheyneed.Thefollowingparagraphsdescribe

the operational and construction status of national

satellitesystems thatare most frequently referredto

in the context of

 the Global Navigation Satellite

System.Theinformationpresentedhasbeenupdated

frominformationobtainedbynationalauthorities,at

the 15

 IAIN World Congress held in Prague in

October2015,and at the 10

AnnualMeeting of the

International Committee on Global Navigation

Satellite Systems held inBoulder, CO, in November

2015.

Becausethesesystemsaresoimportanttovirtually

everyfacetofdailylifeintechnologicalsocieties,itis

also important to understand their vulnerabilities,

threatsagainstthem,andmitigationmeasures.Sucha

discussionisincludedafterthesystemdescriptions.

While readers of this paper may be primarily

interested in the positioning and navigation

propertiesofGNSS,itisessentialtorecognizethatthe

mostimportantandbroa dest useofGNSSsignals is

forhighlypreciseandsynchronizedtime.Thetiming

function supports IT

 networks, telecommunications,

broadcast, financial, transportation, and energy

industries. Professor Brad Parkinson of Stanford

University, widely acknowledged as the “father of

GPS”assaidthatthesystemshouldmoreproperlybe

renamed Global Positioning and timing Services

(GPtS)[Parkinson2012].

2 NAVIGATIONSIGNALTIMINGAND

RANGINGGLOBALPOSITIONINGSYSTEM

(NAVSTARGPS)

ThesystemcommonlyknownasGPSwascreatedfor

theU.S.ArmedForces.Workaimedatdevelopinga

system began in 1960 when Dr. Ivan Getting, was

elected the President of Aerospace Corporation.In

1973, Air Force Major Bradford Parkinson and his

small group of engineers took over from

 earlier

researchersandcreatedthefinalsystemconceptthat

was subsequently launched in 1978. The system

achievedfull operationalcapabilityonJuly17, 1995.

Currently the GPS system is utilized by more than

onetrillionofusersandtransmits4civiliansignals:

 L1C/A‐thelegacysignal;

 L2C‐

thesecondcivilian‐usesignal;

 L5‐aviationsafetyoflifesignal;

 L1C‐internationalsignal

Also, the GPS satellites transmit signals for the

militaryuse.

Presently, the system constellation consists of 31

satellites.Table1presentsadetailedlistofblocksof

currentlyoperationalsatellites.

Table1. Current GPS constellation‐status at 10 January,

2015[Brennan2015]

_______________________________________________

Satellite Quantity Average  AgeoftheOldest

BlockAgeSatellite

_______________________________________________

GPSIIA  2  23.424.8

GPSIIR  12  13.718.2

GPSIIR‐M 7  8.210.0

GPSIIF  10  2.15.3

Total31  9.324.8

_______________________________________________



Itmustbenotedthatthesystemconstellationhas

been intensely rejuvenated throughout its life. For

example,5BlockIIFsatellitesweredeployedin2015.

From the year 2016 the constellation will be

supplementedby newgenerationsatellites.TheGPS

BlockIIIsatelliteswilltransmit4civilian‐usesignals:

L1 C/A,

 L1C, L2C, L5 and 4 military‐use signals:

L1/L2 P(Y), L1/L2M. The first GPS III satellite is

planned to be launched in August 2016 [Brennan

2015].

Thecurrentlyactivegroundsegmentofthesystem

ispresentedinFig.1.



Figure1.ThegroundsegmentoftheGPSsystem[Brennan

2015]

Presently, the NavSTaR GPSsystem provides for

better accuracythan the published system standard.

Theaccuracylevelsaredifferentforthecivilianusers

(Fig.2)andmilitaryusers(Fig.3).