International Journal of Engineering Trends and Technology (IJETT) – Volume 27 Number 2- September 2015
Global Navigation Satellite Systems and Their Evolution
Gabriel Chomik1
1
Department of Avionics and Control System
Rzeszow University of Technology
Rzeszow, Poland
Abstract – Changing global trends make that satellite
navigation systems play an increasingly important
role not only for military purposes but also for the
whole global economy and modern man as well.
Satellite navigation systems are still under
development and they are constantly improved and
upgraded. All these improvements make that we, as a
people becoming increasingly dependent from their
proper operation. This research paper presents the
evolution of satellite navigation systems and the main
development trends.
constantly modernized and expanded. Having a
satellite navigation system is very important from
strategic point of many countries, so beyond GPS,
other satellite systems are under development: Galileo
(EU), Glonass (Russian Federation), Beidou (China)
and others.
Keywords — GPS, Galileo, Glonass, Beidou,
Navigation, Satellite
I. INTRODUCTION (SIZE 10 & BOLD)
Nowadays, it is difficult to imagine the functioning
the global economy and modern man as well without
accurate time. The clock has become one of the
essential elements of our civilisation, often even
conditioning the smooth running of daily life. In the
short period of time navigational receivers with
accurate position can achieve a similar status as clock
with accurate time. Over the centuries, people
invented many methods for determining the position.
However, in the late 60s and 70s of the last century,
technical idea led to the creation of the position
determination satellite system, which is so far, the
most complete solution to the problem of location and
special orientation of objects and people.
Today, “satellite” is very popular word and we meet
with him very often. Its sounds familiar to almost
everyone regardless of our education or professional
qualification. Modern satellite navigation systems like
GPS, have an impact on almost all sectors of the
modern economy. Its high-performance standards
already make it an essential tool for very demanding
professional systems. These systems have grown from
a relatively humble beginning as a support technology
to that of a critical player used in the vast array of
economic, scientific and military applications. In
2010, the total annual worldwide turnover of products
and services of satellite navigation systems is
amounted to over 100 billion €. In 2020, it could be
over 200 billion €. [1] The most popular of satellite
navigation system created by government of USA–
GPS is freely accessible to anyone with a GPS
receiver. According to policy of US, GPS should
remain free for anyone. The benefits of universal
access to GPS services largely outweigh the costs of
maintaining it. The popularity and increasing demand
for services make development of GPS which is
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Fig. 1. Total annual global turnover for satellite
navigation [1]
II. EVOLUTION OF SATELLITE SYSTEMS
The precursor of today’s satellite navigation
systems was system called “Transit” (also known as
Navy Navigation Satellite System – NNSS or
NAVSAT). Transit System made its debut in the early
60s and like most inventions of that time has been
developed for military purposes. Transit was used for
accurate and independent of the weather maritime
navigation for 35 years. [2] In 1967 Transit was made
available for civilian users, but was suited almost
exclusively for marine navigation. The restriction of
NNSS was a long time of positioning, up to few or
even several minutes. In addition, the Transit
converter required data entry speed and height of the
receiving antenna above sea level. Finally, a system
ensuring accuracy of 200 meters in the latest version
was replaced by GPS in 1996.
Implementation of NAVSAT did not stop work on
other solutions. In 1960, Raytheon Company has
developed a satellite system MOSAIC (Mobile
System for Accurate ICBM Control). The purpose of
MOSAIZC was to determine the precise location of
mobile ballistic missile launchers. Finally, the system
has not been started due to discontinuation of work on
the rocket system. In 1964, SECOR (Sequential
Collation of Range) system was launched. It was
satellite navigation and localization system similar to
transit but designed for the purposed of land forces.
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International Journal of Engineering Trends and Technology (IJETT) – Volume 27 Number 2- September 2015
Today, GPS is the most modern of satellite
navigation systems. Navstar GPS is based on a set of
satellites orbiting 20200 km (11 000 NM) above the
Earth (orbiting the Earth twice a day). [4] GPS
satellite system is designed to determine: spatial
coordinates (longitude, latitude and altitude), object
airspeed in every place on the globe and in near-Earth
space, regardless of the time of year and weather
conditions. The GPS system is a passive system,
which means that the signal is transmitted only by
satellite, as a result the number of users is unlimited.
Fig. 2. TIMATION-1 spacecraft on the launcher [9]
In the 60s United States was not the only country
capable of forming a global navigation system. In
November 1967, the Soviet Union launched his first
satellite to the earth orbit implementing their first
global navigation system called Cyclone (Cosmos192). Subsequently, Cyclone system was constantly
developed and modernized and in 1974 could be
applied for operational use, ensuring accuracy of 100
meters in determining position. In May 1967, the US
Navy launched the first satellite of TIMATION series.
TIMATION system has been primarily designed in the
aim of tests global time synchronization accuracy,
which was unattainable previously. [2] In Russia,
similar to the concept of TIMATION system, two
satellite navigation systems were developed and
launched: Military Cicada-M (6 satellites) and civilian
Cicada (4 satellites). TIMATION was the precursor of
GPS (Global Positioning System) Navstar.
III. THE ERA OF GPS
Americans, in the 60s had at least four independent
projects of navigation systems and after a few years
decided to join forces which were dispersed so far. In
1973 there was a meeting of representatives of various
branches of the military, during which it was decided
to merge all projects in one called DNSS (Defense
Navigation Satellite System), then the name was
changed to GPS Navstar. [3] Challenges associated
with new program were very ambitious: unlimited
number of users determining position with an
accuracy of 5 meters, global reach and stealth receiver.
Additional independent function was to put in each
satellite module system responsible for detecting
nuclear explosions on the earth’s surface. The first
satellite of the new system came into orbit in 1978, but
about fully operational system we can speak only from
1995.
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Fig. 3. GPS satellite constellation [10]
GPS consists of three
cooperating segments:
closely related
and
Space segment
Control segment
User segment
The system is based on determining the distance
between the point of measurement and satellites.
Determination of the position of the GPS receiver
requires signal from at least three satellites (four is
required). Distance measurement is carried out by
controlling the time at which the radio signal is
coming from the satellite to the GPS receiver. The
GPS system provides two levels of system accuracy:
PPS (Precise Positioning System) and SPS (Standard
Positioning System).
IV. NOT ONLY GPS
Although GPS is the most popular navigation
system, some countries implementing their own
solutions, independent of the American system. The
most famous is the Russian GLONASS, developed
since 1976. Despite the serious problems in the 90s
and a shorter operating time of satellites than was
expected, Glonass is now operated. [10]
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Fig. 5. Number of satellites placed in orbit [11]
Fig. 4. Glonass satellite constellation [10]
In 2002 the European Union decided to create its
own global navigation system – GALILEO. The
system will consist of 30 satellites (27 operating and
three in reserve) on three circular orbits. The estimated
cost of Galileo is 3.0 billion EUR. [7] Initially, the
systems was supposed to become fully operational in
2014. The first experimental satellite was launched on
28 December 2005. It is assumed that Galileo will be
fully compatible with the modernized GPS system.
The receiver will be able to combine signals both from
Galileo and GPS satellites which significantly increase
accuracy. Currently, Galileo is expected to be in full
service after 2020.[5]
Own navigation system called “Beidou” is created
by the China from the beginning of the 21 century.
The first version of that system “Beidou-1” was used
to test satellite communication technology. Currently,
Beidou-2 is implemented, formerly known as
Compass, which assures the locations in China and in
the border areas by now. By 2020, the Chinese
navigation, supported by 35 satellites will service into
global coverage.[8]
Since the 90s from the initiative of France
international system DORIS (Doppler Orbitography
and Radio-positioning Integrated by Satellite) is also
implemented. Official launch took place in 2003.[6]
By combining satellites with a network of ground
tracking stations, it became possible to get
a determination of position with accurate to one
centimeter. Although Doris can be used for navigation,
its main purpose is something else. It is primarily used
for geodetic research.
V. GNSS
Conclusions from the experience of satellite
navigation systems inevitably lead to create
a worldwide civil navigation system, known as Global
Navigation Satellite System (GNSS). Nobody need to
be convinced of the advantages of satellite navigation,
and existing satellite systems are properly designed for
military purposes. The first step of forming a common
satellite system is called “GNSS-1”. Concept of that
system envisages the elimination of the typical
shortcomings of GPS such as accuracy, reliability,
continuity and availability. Methods of improving
navigation systems are multiplying the positional
information sources, ensuring the uninterrupted flow
of data correction and continuous monitoring of the
quality of positioning data. In the future, GNSS is
intended to include Navstar GPS satellites, Glonass M
and satellites from Galileo.
An integral part of the GNSS-1 is the differential
data system – DGPS (Differential Global Positioning
System). Operation of the differential system is based
on the fact that the errors observed by the two
receivers in the same area are correlated. GPS
reference stations with known coordinates of their
spatial can continuously comparing their coordinates
with the position obtained from satellite signal.
Differential stations communicate with the receiver
through communication channel. GNSS receiver
includes correction for an individual satellites.
Fig. 6. GNSS [12]
Differential GNSS-1 is composed of several
differing in range, precision and independent
component with correction data. The accuracy of
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correction mainly affects the size of area served by
one differential station. Generally, these components
are member of the Wide Area Augmentation System
(WAAS) operated by the Federal Aviation
Administration (FAA). One of this component is
Ground Based Augmentation System (GBAS). GBAS
stations serve as a source of reference data on a local
scale. Combined with the Flight Management System
(FMS) is to providing the possibility of making an
approach to land of Category I. Another component of
the differential segment GNSS-1 is orbital system
called Satellite Based Augmentation System (SBAS).
SBAS is a system that supports wide-area or regional
augmentation by the use of additional satellitesbroadcast messages.
A development of GNSS-1 is GNSS-2. The
constellation of navigation satellites will cover the
Navstar GPS satellites type II F, Glonass M and
satellites from Galileo.
GNSS system are used in many areas such as:
navigation, survey and mapping, archaeology, geology,
military, mobile communications, emergency and
location-based services, marketing, weather prediction,
social networking, and many more.
VI. TRENDS IN DEVELOPMENT
The similarity of structure of satellite navigation
systems make possible to extract some common trends
and directions in which will proceed their
modernization within the next several years. Technical
changes in space and ground segment will aim to:
improving the stability of satellite timers,
increasing the signal transmit power,
extension the lifetime of satellite,
broadcasting signal on new frequencies,
increasing the accuracy and availability of
GPS navigation signals,
correction for ionospheric and stratosphere
delay,
increasing resistance signal for disruptions,
ensuring communication between satellites
within same system and increasing
accuracy of the time scale.
In the 2020-2030 year will become probable move
to higher frequencies. There will be possible also the
modernization of satellite navigation systems based on
radio signals into optical signals. By now its not
developed, mainly because of the high cost of
replacing the entire infrastructure. Another important
change will be implementation of the Galileo system.
Fully operational Galileo will allow the
implementation of GNSS-2, which provide much
better accuracy and integrity monitoring necessary for
civil navigation, including aircraft. Doubling of the
number of navigational satellites orbiting the earth
will greatly enhance the obtained test parameters – the
current horizontal accuracy of GPS for objects in
motion is approximately 10 – 20 m and vertical 8 – 15
m, while using the second system will reduce these
value by half (for static object even to 0.5 – 1 m
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horizontally and 1.5 – 2 m vertically). GPS, Galileo
and Glonass will provide almost 100% signal
availability across the globe, eliminating the current
problems with the use of GPS in the vicinity of the
equator. The existence of several system will
significantly improve, although unfortunately not
eliminate the problem of the availability and accuracy
of the signal in “Urban canyons”, which due to high
barriers are less visible from satellites.
Another important issue is to provide the user
information about the reliability of the signal received
by him and consequently his designated position.
Currently this function comply some satellite support
systems (EGNOS, WAAS, MSAS), but around 2020,
such information will be included in the basic GNSS
signal. Moreover the process of certification of GNSS
signals will be continued for use in marine navigation
and aviation.
VII.
CONCLUSION
This paper present an overview of most popular
satellite systems. The development of satellite
navigation technologies has an impact on all sectors of
modern economies. Satellite technology is a natural
choice for marine and inland navigation. This is
confirmed both by current sale figures receiver for use
in maritime transport (over 1 billion), as well as
adoption of relevant legislation. The same applies to
aviation, where a reliability navigation increase the
system capacity for transport million of people.
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