DOWNSTREAM APPLICATIONS AND SERVICES OF
EARTH OBSERVATION, SATELLITE NAVIGATION
AND TELECOMMUNICATION
Tutorial
Author(s):
Geoff Busswell, Logica
Nick Green, Logica
Rob Postema, Logica
Reviewer(s):
Pat Norris, Logica
Kristo Reinsalu, Invent Baltics
Status:
Final
Issued by:
Logica
EC.231207-LOG-A-001
Issue 1.0
Date
09 April 2010
© Logica 2010. Copyright statement:
This document contains information which is confidential and of value to Logica. It may be used only for the
agreed purpose for which it has been provided. Logica’s prior written consent is required before any part is
reproduced. Except where indicated otherwise, all names, trade marks, and service marks referred to in this
document are the property of a company in the Logica group or its licensors.
Logica - Downstream Applications and Services of Earth
Observation, Satellite Navigation and Telecommunication
Contents
CONTENTS
Background
5
1
Earth Observation
7
1.1
Introduction
7
1.2
Where is Earth Observation Used?
7
1.3
Acquisition Techniques
8
1.4
Benefits of Earth Observation
9
1.5
Data Provision
9
1.6
ESA-EC GMES Programme
13
1.7
Service Provision Architecture
16
1.8
Service and Business Models
18
1.9
Examples of Downstream Applications and Services
19
2
Global Navigation Satellite Systems
23
2.1
Introduction
23
2.2
2.2.1
2.2.2
2.2.3
Principle of Satellite Navigation
Geometric Principles of Navigation
The Navigation Signal
Support and Augmentation Signals
23
23
24
25
2.3
2.3.1
2.3.2
2.3.3
2.3.4
Position Errors
Atmospheric Effects
Multipath Effects
Ephemeris Errors
Clock Errors
28
29
29
29
29
2.4
2.4.1
2.4.2
2.4.3
2.4.4
GNSS System of Systems
Overview
Global Positioning System
GLONASS
Galileo
30
30
30
31
31
2.5
2.5.1
2.5.2
2.5.3
Architecture of GNSS based applications and services
Overall Architecture
Receiver types and performance
Mobile Phones
32
32
32
36
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Contents
2.5.4 Communications
2.5.5 Back Office
37
38
2.6
Value chain for GNSS based applications and services
2.6.1 Value chain
2.6.2 Business Model
38
38
39
2.7
2.7.1
2.7.2
2.7.3
2.7.4
2.7.5
2.7.6
2.7.7
Examples of Applications
Route-Navigation
Tracking and Tracing
Surveying
Location Based Services
Automated/Guided Systems
Location based games
Precise time reference
40
40
40
41
42
42
42
42
3
Satellite Telecomunication
43
3.1
Introduction
43
3.2
Satellite Communications Network and its Functioning
43
3.3
Advantages of Satellite Communication
47
3.4
3.4.1
3.4.2
3.4.3
Major Service Categories and Promising Applications
Current FSS Services and Applications
Current MSS Services and Applications
Future trends
48
49
50
53
Abbreviations
56
Glossary
57
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Background
BACKGROUND
Space systems play a notable role in numerous facets of our daily lives, both from a global as well as a
national, Estonian, perspective: each person can watch television programmes reflecting their own
interests; data from earth observation satellites are at the basis of our weather forecasts; satellite
navigation applications are increasingly used in cars and boats, and even in waste management projects
satellite pictures and positioning technology helps to clean our environment. Also medical emergency
situations are coordinated with the same satellite services. These are but a few of the space applications
affecting our life in Estonia. This is an important moment in the history of Estonian space activities. Today,
more than ever before, Estonia has to search for innovative solutions to improve its economy and
functioning of the society. The public is still unaware of the variety, breadth and importance that space
activities play in their everyday lives (Towards an Estonian space policy & strategy, July 2008, p. 5).
There is enormous potential for Estonian industry and organisations to benefit from the development of
applications and services under the two major European space “flagship” programs - Global Monitoring for
Environment and Security (GMES) and Galileo. There could be direct benefits for the emerging Estonian
space community, or indirect benefits for other parts of the space sector and more widely in other sectors of
Estonian economy. In securing these benefits it is important to consider our strengths in order to exploit all
opportunities which both GMES and Galileo could offer in the future. The illustration below (© Euroconsult)
provides an overview on the worldwide revenue in the value chain for earth observation, navigation and
satellite telecommunications.
Estonian Government, industry and the science community have recognised the importance of additional
benefits through the use of space technology applications based on earth observation, satellite navigation
and communication. For this reason Enterprise Estonia (EAS) has initiated an EU financed project;
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Background
“Introduction of downstream applications and opportunities of space technology to the Estonian
entrepreneurs to increase awareness and competitiveness”, which is oriented towards raising space
awareness and building the required capabilities in Estonia.
In the course of the abovementioned “space project”, Invent Baltics and Logica, supported by Black Holes,
organised a seminar on 23rd of September in Tallinn addressing individual entrepreneurs and organisations
interested in developing downstream services or applications, enabled by earth observation, satellite
navigation and telecommunication (EO, SatNav, SatCom), and want to understand its key characteristics
and framework conditions. The seminar was also open to representatives from national and/or international
governmental organisations wishing to understand the key characteristics and framework conditions of
downstream applications of satellite navigation for regulatory, policy or business purposes.
Following this seminar, Logica prepared a tutorial (this document) within the scope of our contract with
Invent Baltics and Enterprise Estonia. The tutorial is based on the seminar materials and collated feedback
from participants of the seminar. The tutorial provides an overview of the elements necessary to develop
downstream applications and services, based on EO, SatNav and SatCom and their introduction into an
operational environment. The tutorial has the following objectives:
• Provide a comprehensive overview of the potential satellite data available from different sources and
possible areas of information used and provided by/through those satellites.
• Introduce the most important technical requirements, specifications etc.
• Present successful examples.
By becoming better acquainted with the abovementioned three fields which are covered comprehensively in
this tutorial, the Estonian space community are provided with:
• An insight to the EO, SatNav and SatCom systems market and perspectives (roadmaps) with the
aim of understanding the niches within which major growth is expected.
• An understanding of the underlying service and business models and prominent players (references
included) in order to introduce an EO, SatNav and/or SatCom service or application successfully.
• An understanding of the scope of an architecture and main elements needed to provide an EO,
SatNav or SatCom downstream service or application to the target customers or users;
• Sufficient information to enable the initiation of EO, SatNav and SatCom related international
projects, and the processes involved (presenting best practice cases where SMEs have been
successful in initiating downstream services cross-border projects).
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1
EARTH OBSERVATION
1.1
Introduction
Earth Observation
Earth Observation can contribute to more efficient use of natural resources worldwide, such as the
management of water resources and forests as well as agricultural practices that are important elements of
social and economic prosperity for populations around the world. Furthermore, remote sensing applications
can provide invaluable input for better exploitation of various energy sources, like wind and solar energy,
through improved data collection. In the context of continuous deforestation and systematic increases in
food prices, Estonia can take advantage of remote sensing applications for planning, estimation and
surveillance in forest management and agriculture. Remote sensing data can provide useful information
about the aerial extent, conditions and boundaries of wetlands. With continuous industrialisation of Estonian
agriculture, the methods of precision agriculture, which is based on remote sensing and positioning
applications, could reduce labour as well as supply costs for farmers. (Towards an Estonian space policy &
strategy, July 2008, p. 26).
It is useful to attempt to define what Earth Observation is. A good definition is:
“The acquisition and exploitation of data from aerial or satellite-based observations of the Earth”.
The following two terms are worth elaborating on:
• Acquisition – collecting data from aerial or satellite-based observations, putting it into a usable
format, and making it accessible to the users of the data
• Exploitation – putting the data to use, e.g. in weather forecasting, flood damage assessment, or
selling posters of famous landmarks seen from space.
1.2
Where is Earth Observation Used?
Earth Observation is used in a variety of market sectors:
• Meteorology & Climate – to provide up-to-the-minute information on weather systems from global to
local/regional scales – this is the best known and most operational form of Earth Observation. Used
for climate science e.g. in analysing global warming trends, greenhouse gases, etc.
• Environmental Monitoring – to check regulation issues on behalf of governments, companies or
individuals; to measure and monitor the Earth's environment; to map resources and pollution; to
observe the influence of mankind on the environment etc. The main sub-domains include
oceanography, the atmosphere, land monitoring, the water cycle, cryosphere & polar regions
• Defence & Security – maps for army, navy and air force for use in wartime or when part of UN
peacekeeping forces; surveillance of enemy positions on the battlefield; detect drug trafficking boats
crossing the ocean, etc.
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Earth Observation
• Governments – law enforcement (building regulations, illegal logging, illegal fishing); policy
development
• Commercial – civil engineering, insurance, mapping (multimap etc)
• Public Interest – imagery of earth for public consumption (Google Earth etc)
• Natural Disasters – spot and analyse disasters caused by fire, flooding, landslides, volcanoes, etc
• Agriculture – to see crops growing and map tropical forest coverage
With improvements in technology and acquisition, the list of uses is growing.
1.3
Acquisition Techniques
It is worth summarising the different Earth Observation techniques used with satellites. The techniques can
be split into 5 main types:
• Optical – this is the most well known and is where a satellite measures reflected sunlight from the
ground or ocean. The important point to note is that we rely on the illumination of the sun and so
optical observations are not possible at night. An example application of an optical measurement
might be a town planning project or disaster monitoring (e.g. after-effects of an earthquake).
• Infra-red – this is where the satellite measures the thermal emission from the land or ocean. The
police use this technique from helicopters to detect people (via their body heat) at night. An example
application is to calculate the sea or land surface temperature in a particular region based on the
thermal emission received at the satellite.
• Atmospheric – this is where optical or infra-red radiation from the sun is reflected from the
atmosphere. Most radiation from the sun penetrates the atmosphere and reaches us on the ground,
but a portion is reflected and can be measured by a satellite. Because this technique is reliant on the
sun’s illumination, atmospheric measurements cannot be made at night. Example applications are
measurements of gases in the atmosphere such as carbon dioxide (CO2) or ozone (O3).
• Radar Altimetry – this is where the satellite bounces radar signals (microwaves) of the ground or
ocean and measures the reflected signal (or echo). The measurement is then effectively taken over
a region but averaged to a point. An example application would be the average sea surface height
over a 2500 km2 area. Note that we are not relying on the sun’s illumination here so this technique
can be used day or night and in cloudy conditions.
• Synthetic Aperture Radar (SAR) – this is similar to Altimetry in the sense that microwaves are
bounced off the Earth, but the SAR instrument has many antennas which measure the various echo
waveforms. This information is used to build up a radar image of the source target. As with Altimetry
this technique can also be used day or night and in cloudy conditions. An example application would
be detection and monitoring of oil spills in the ocean.
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1.4
Earth Observation
Benefits of Earth Observation
Earth Observation has several benefits to users. Much wider spatial coverage is
possible than with
terrestrial/airborne methods as the satellite travels ~10 km/s and can take very frequent measurements
(e.g. 1 observation per second for an Altimeter). Sometimes a satellite will observe a large area such as the
UK, but building up measurements taken over several orbits. In this way spatial coverage of a large area
can be performed much quicker than by using a ground or airborne technique.
Another benefit is that, by using satellites, regular, consistent, repeat coverage can be achieved over
several years. This allows trends over time for a specific region to be analysed over time e.g. forest cover in
South America.
Finally, once a satellite is operational the costs of purchasing data can be much less than obtaining the
equivalent observation from an airplane, vehicle or ship-borne method. It also allows observations in hardto-access areas. However, it should be noted that a satellite observation does not always achieve the same
resolution as that of a ground or airborne method.
1.5
Data Provision
In the last 20 years significant achievements have made by space agencies, academic institutions and
commercial companies with regard to the design, manufacture and operations of Earth Observation
satellites as well as the modelling and exploitation of the resulting data. In this tutorial we will focus on the
data provided by satellites associated with ESA and other European countries as well as outlining the main
commercial operators. However, it should be noted that relatively small countries throughout the world
(e.g. Chile, Spain, Kazakhstan, Taiwan, South Korea, Vietnam, and Malaysia) are buying or building their
own satellites and so Estonia might consider this, possibly in collaboration with neighbouring countries.
Figure 1-1 shows a timeline from 1990 to 2010 and beyond with an overview of past, present and planned
future satellites by ESA. The satellites are separated into 3 main groups:
• the area with the blue background shows the meteorological satellites developed in conjunction with
Eumetsat
• the area with the white background shows the Earth Explorer satellites which are designed to help us
better understand our planet (e.g. oceans, gravity and magnetic fields, wind fields, etc.)
• the area with the pink background shows the satellites which are related to applications and services
and is where we concentrate in this tutorial.
Note that the merged shading between the white and pink backgrounds (into orange as we go back in time
towards 1990. This is to illustrate the dual (science and applications) purposes of the ERS and ENVISAT
satellites when they were launched.
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Earth Observation
Figure 1-1: Overview of past, present and future ESA related satellites
ERS-1 was launched on July 17th, 1991 and was a major technical accomplishment. It contains several
instruments used to measure various quantities related to the land, sea, ice and atmosphere. ERS-1 came
to the end of its life on March 10th, 2000 lasting far longer than planned. ERS-2 was launched on April 21st,
1995 and contained similar, but improved instruments to ERS-1. This was important to allow cross
comparison of the data between the two satellites. ERS-2 is still operational
ENVISAT was launched on 1st March, 2002 and was the largest EO satellite ever. It was an incredible
achievement and contained 10 different types of instrument. The satellite generates 280 GBytes of data per
day and is expected to be operational until 2011.
One of the major accomplishments of the ERS and ENVISAT satellites was to highlight the issue of climate
change. Data was used to show that small overall increases in the Earth’s climates were affecting the polar
ice caps, sea levels and sea temperature as is shown by Figure 1-2, Figure 1-3 and Figure 1-4.
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Figure 1-2: The break-up of the Wilkins Ice Shelf between 1992 and 2008
Figure 1-3: Time series graph to show sea level rise between 1992 and 2005
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Figure 1-4: Time series graph to show satellite-derived sea temperature rise from
1992 to 2000
In the commercial market there are several companies who either operate satellites or use the data to
provide a service to public and private sector organisations. Some of the operators will provide satellite data
to the GMES programme (so-called GMES Contributing Mission’s - GCM’s) and these are contained along
with the other GCM’s in Table 1-1. However, since not all the operators will do this it is useful to list the
main commercial satellites and the associated operators:
Mission
Type of Mission
Operator
Launch date
GeoEye-1
Optical
GeoEye
2008
GeoEye-2
Optical
GeoEye
2012
IKONOS
Optical
GeoEye
1999
Quickbird
Optical
DigitalGlobe
2001
WorldView-1
Optical
DigitalGlobe
2007
WorldView-2
Optical
DigitalGlobe
2009
RADARSAT-2
SAR
CSA
2007
TerraSAR-X
SAR
DLR
2007
TanDEM-X
SAR
DLR
2010
DMC
Optical
DMCII
2002
RapidEye
Optical
MDA
2008
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Mission
Type of Mission
Operator
Launch date
SPOT-4
Optical
Spot Image Corp
1999
SPOT-5
Optical
Spot Image Corp
2002
Table 1-1: A non-exhaustive list of commercial satellite missions and operators
The biggest operators by far are DigitalGlobe, GeoEye and Spot Image Corporation who focus on high
resolution imagery and together have 63% of the market share. Their largest customer group is
government defence and security agencies, with 62% of data sales coming from this sector. Optical
resolutions will be as high as 25cm for GeoEye-2. The commercial demand for radar observations has also
grown significantly in recent years and the highest resolution images currently are from Radarsat-2 at 1m.
1.6
ESA-EC GMES Programme
GMES is a joint European Commission (EC) and European Space Agency (ESA) initiative that has been
established to fulfil the growing need amongst European policy-makers to access accurate and timely
information services, to better manage the environment, understand and mitigate the effects of climate
change and ensure civil security.
The GMES programme is built on four main pillars:
• Management and requirements of the overall programme is overseen by the EC
• GMES services are managed by the EC.
• GMES Space Component (GSC) is managed by ESA
• GMES in situ (i.e. ground based or airborne) component is managed by the European Environment
Authority (EEA)
The services offered by GMES are split into five main themes:
• Ocean – marine safety and transport, oil spill monitoring, water quality, weather forecasting and the
polar environment,
• Land - water management, agriculture and food security, land-use change, forest monitoring, soil
quality, urban planning and natural protection services
• Emergency response - natural and manmade disasters, flood, forest fire, earthquakes and
humanitarian aid
• Atmosphere - air quality ultraviolet radiation forecasting, and climate change studies
• Security - peace-keeping efforts, maritime surveillance and border control
Figure 1-5 shows the overall architecture of the GMES programme. The in situ and space infrastructures
provide the data which is then fed into various core services. The core services process this data and
provide “added value”, which is the basis for a user service. See the Service Architecture section (1.7) for a
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more complete description of the “added value” concept. An example of a core service might be wave
height as a function of position on the globe.
Figure 1-5: Overall Architecture of the GMES Programme
The downstream services provide specific and niche applications which might use a core service. For
example an application giving surfers in Newquay, England an overview of the surf conditions might utilise
the wave information provided from a core service. Note that users can access both core and downstream
services directly, but a core service would tend to provide a more generic offering than the specialised
downstream services, which are utilised for specific applications.
The GMES Space Component is particularly important to focus on for this tutorial as it is where the satellite
data will come from in the future. Satellite data will come from a series of core sources, called the Sentinel
satellites. There will be five Sentinel satellites:
• Sentinel 1: SAR instrument to provided all-weather, day and night radar imaging to support land and
ocean services. Launch is planned for May 2011.
• Sentinel 2: Optical instrument to provide high resolution imagery to support land services. Launch is
planned for 2012.
• Sentinel 3: Altimeter and optical/infra-red instruments to support ocean and global land monitoring
services. Launch is planned for 2012.
• Sentinel 4: Optical/infra-red instruments to monitor atmospheric composition. This will reside in a
geostationary orbit and will be carried on a Meteosat Third Generation (MSG) satellite operated by
EUMETSAT. Launch is planned for 2017.
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• Sentinel 5: Optical/infra-red instruments to again monitor atmospheric composition, but from a low
earth polar orbit. It is will be carried on the post-EUMETSAT Polar System (EPS) satellite operated by
EUMETSAT. Launch is planned for 2020.
There are also so-called GMES Contributing Missions (GCM’s) which tend to be managed by national space
agencies or commercial entities. They will provide data before and during operations of the Sentinel
satellites to ensure that the whole range of observational requirements are covered. Table 1-2 gives a list of
the current list of GCM’s:
Name of GCM
Type of Mission
Operator
Launch date
ERS-2
All
ESA
1995
ENVISAT
All
ESA
2002
COSMO-SkyMed
SAR
ASI
2007
RADARSAT-2
SAR
CSA
2007
TerraSAR-X
SAR
DLR
2007
TanDEM-X
SAR
DLR
2010
DMC
Optical
DMCII
2002
EnMap
Optical
DLR
2012
Eros
Optical
IAI
2000
Pléiades
Optical
CNES
2010
RapidEye
Optical
MDA
2008
SEOSAT-INGENIO
Optical
INTA
2012
SPOT-5
Optical
CNES/SNSB
2002
TopSat
Optical
BNSC
2005
Jason-1
Altimetry
NASA/CNES
2001
Jason-2
Altimetry
NASA/CNES
2008
Altika
Altimetry
CNES/ISRO
2010
MSG
Atmospheric
ESA/EUMETSAT
2002
MetOp
Atmospheric
ESA/EUMETSAT
TBD
Table 1-2: Current list of GMES Contributing Missions
The GMES service segment will be responsible for providing all data and services to users. The service
segment will obtain data from the GMES Space Component Data Access System, which itself is served by
both the Sentinel satellites and the GCM’s. When data is required from a Sentinel satellite a request is made
to the Flight Operations Segment, which incorporates this request into the mission plan.
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Figure 1-6: Overall Architecture of the GMES Space Component Data Access (GSCDA)
System
Once the data is acquired by the satellite it is down-linked to a ground acquisition station and disseminated
to the GSCDA by the Payload Data Ground Segment (PDGS) before it is passed to the service segment,
where it can be sent to the user/organisation. There are, in general, separate PDGS’s and FOS’s for each
Sentinel satellite. Figure 1-6 shows an overall view of the GSC architecture.
More information on the GMES programme can be found on
• http://www.boss4gmes.eu/,
• http://www.esa.int/esaLP/SEMRRI0DU8E_LPgmes_0.html
• http://www.defra.gov.uk/evidence/gi/earthobservation/gmes/index.htm.
1.7
Service Provision Architecture
The provision of an EO service can be broken down into 3 main steps. These are:
• Data Acquisition – the EO data must be obtained (e.g. from ESA’s satellite archive) as well as
necessary auxiliary/ancillary data (e.g. ground control points, in-situ, calibration data etc). The
user/organisation might require access to EO & other data catalogue and ordering systems.
• Data Processing or “Value “Adding” – this is the heart of the downstream service operation and
involves complex algorithms. These algorithms could perform image correction, mosaicing,
mathematical modelling, etc. In general this process requires specialist tools and expertise
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• Product Generation and Dissemination – the processed data must be converted into usable products
that can be easily understood or integrated by the target end-user e.g. web portal/service or ftp.
Requires end-user domain knowledge
A good example of an EO service is provided by the GlobWave project (www.globwave.info). The GlobWave
services will come into operation in Q1, 2010. The main purpose of the project is to process wave data from
a number of European and American satellites into a common format. The tools and readers to ingest the
data will be made available and this will make it much easier to use and compare data from different
sources.
GlobWave gives a real example of each of the stages of the service provision process. The boxes in the top
left of Figure 1-7 are good examples of the data acquisition process. Here, historical and NRT satellite
data and ancillary data (e.g. wind vectors, sea surface temperature info) are ingested into the GlobWave
processor. Also, in situ buoy data, which makes measurements of ocean parameters (such as wave height)
is ingested from various sources.
The value adding step involves several things. Firstly the GlobWave processor transcribes the satellite data
in the common format to give the GlobWave satellite data. The satellite versus in situ processing facility
then looks for overlapping satellite and buoy measurements, and calculates the differences. These
differences help characterise the errors of the satellite measurements and this information is then inserted
back into the relevant GlobWave data products. This means that users can see what the errors are of the
GlobWave satellite data when they have downloaded them. Finally, a satellite versus satellite processing
facility looks for overlaps of satellite observations and calculates the differences.
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Figure 1-7: Service Architecture for Project GlobWave
The product dissemination is performed via the GlobWave web portal. The portal allows users to
download the GlobWave satellite data via online tools or with an ftp service. A monthly quality control report
summarises the statistical differences between the satellite and buoy data. Finally, there is also an annual
report which summarises all the relevant monthly reports as well as giving the statistics of the satellite
observation overlaps.
1.8
Service and Business Models
There are a number of possible service models via which EO data can be disseminated. These could be:
• Routine – data is delivered at regular intervals e.g. crop health monitoring may require
monthly/fortnightly data generation during the growing season, less frequent at other times
• On-demand (low priority) – customer places non-urgent ad-hoc order for a specific image or product
e.g. town planning project
• On-demand (high priority) – customer places urgent ad-hoc order e.g. e.g. emergency response
situations, security applications
• Automated browsing – service provider can use software to browse product data for those of interest
e.g. rogue wave analysis where you don’t know where they are going to be in advance, or
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identifying places where a quantity has changed by more than a required amount such as wind
speed or sea surface temperature.
The types of business models are centred around recovering the costs of the satellite development, launch
and maintenance. This is critical to enabling a viable business case. Possible business models are:
• Subscription based service – the customer pays for regular delivery of the data. It is possible that
certain regions may be in demand e.g. an oil platform location
• Pay-per-product – low priority orders (<24 hours) would cost less than high priority ones (< 1hour).
The customer might pay more for specific constraints on the data e.g. <1% cloud coverage for an
optical image
• Pay-per region – this is where a customer requires data coverage of a large area e.g. whole of
Europe. This would cost much more than a single data acquisition because a large region would
require several weeks of satellite overpasses.
• Pay-per-target constraint – this is where you don’t have a specific region in mind but want the data
to satisfy a particular constraint e.g. a shipping company wants to know whenever there is a 50m
wave in the North Atlantic or an oil company wants to know if there is a sudden change in the
position of a rig. This could also be relatively expensive because the service provider much search all
required data in the region of interest. Possible payment schemes involve a one-off payment for the
data search with thumbnails offered to the users. For each thumbnail they choose to purchase they
are charged supplementary amounts.
• Free services – The more basic services could be offered free and perhaps demonstrations could be
offered of the more complex services over a trial period. The free services in particular are something
Google and Microsoft have championed with IT services (such as email, mapping) and these are
funded by advertising.
1.9
Examples of Downstream Applications and Services
In this section we present various examples of where EO data is being (or has been) used.
Characterisation of Digital Elevation Models
This is one of many services offered by Fugro NPA, which
allows customers to know the height of the terrain in regions of
interest.
For example oil companies could use this to determine pipeline
routing or the mining industry could plan a drilling campaign.
Resolutions range from 50cm in the optical up to 30m using
radar observations.
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Earth Observation
Monitoring landslides triggered by Earthquakes
This is work performed by the University of Durham, UK. The
Wenchman Earthquake occurred on 12th May, 2008 in Sichman
Province, China and measured 7.9 on the Richter scale.
Preliminary reports suggested tens to hundreds of landslides
were triggered. The motivation of the work is to try and
understand the geological process associated with natural
hazards.
The methodology is to use EO data to examine the spatial
distribution of landslides and then to perform statistical analysis
to correlate the landslides with geological variables such as
earthquake magnitude, slope angle, geology type, etc. The goal
is to be able to predict a likely landslide scenario as a result of
a future earthquake.
Impact Crater Discovery
This is work carried out by Logica for ESA and involves the
processing of EO data to automatically recognize craters on
Earth caused by the impact of large meteorites, asteroids and
comets.
The image shows an impact crater in Gosses Bluff, Central
Australia with the circle illustrating the vector automatically
extracted by Logica software.
Potato Farming
The British Potato Council contracted Logica to verify the
acreage-related fees to be paid by Britain’s potato farmers.
Logica processed EO imagery to show in-field variations in crop
vigour, providing a good indication of crop health and potential
yield.
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Earth Observation
Atmospheric CO2
The University of Leicester, UK has been investigating the CO2
content in the atmosphere using a combination of satellite and
in situ measurement devices. Networks of in situ CO2 sensors
provide
accurate
measurements of global
CO2 but
such
measurements are too sparse to allow accurate measurements
on a sub-continent scale.
EO
infra-red
measurements
from
instruments
such
as
SCIAMACHY (on the ENVISAT satellite) can measure CO2
concentration
in
the
atmosphere
allowing
much
better
characterisation of CO2 content on large scales. Due to this and
other work scientists now believe that human activity has led to
large increases in atmospheric CO2, from 280 ppm to 386 ppm
over the “industrial period” so far.
Subsidence Mapping of the Yellow River Delta
The University of Glasgow has been using EO SAR imaging to
investigate subsidence in the Yellow River Delta region in
China. The subsidence is thought to be a result of the
petroleum, natural gas and water withdrawal.
Class “spirit level” measurements show subsidence of 0.3-0.5m
in several oilfields over the 11 year period between 1986 and
1997. The satellite based SAR images allow high resolution
spatial sampling over a large area with sub-cm accuracy.
Penguin Monitoring
This is work performed by the British Antarctic Society who is
studying the penguin breeding process. This occurs during
winter in a small number of isolated colonies around the coast
of Antarctica.
However, it is difficult to get scientists there during the winter
period because of the weather and by spring the evidence has
been lost as the sea ice breaks up. Optical satellite data (from
Landsat and Quickbird) is therefore very useful to help detect
and assess colony sizes.
EO Data in the Insurance Sector
Logica is developing the use of EO for the insurance market in
the UK. They are working with major names such as Lloyds and
Willis Insurance. Areas of interest include hurricanes, floods,
storms, fires, ‘before and after’ comparisons, risk assessments
etc.
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Earth Observation
Monitoring of Woodland
This work performed by the University of Salford who are
working to characterise the amount of green areas in forest
regions using a statistic called the Leaf Area Index (LAI).
Ground measurements are necessary but it takes a long time to
make observations over a large area.
Optical data from the DMC allows vegetation to be mapped to a
resolution of 32 metres. The satellite observations allow large
regions to be covered extremely quickly. The DMC was used to
measure LAI every two weeks during 2005 and the results
agreed well the ground measurements.
Burned Area Severity in Tropical Forests
The University of Leicester, UK has looked at the frequency of
fires in tropical forests. In recent years it is thought that such
fires have become more frequent and widespread.
There was a need to measure the burn severity and investigate
how the vegetation recovers after the fire. The type, amount
and quality of fuel available for future fires were also
investigated. During this work infra red Landsat images of pre
and post fire regions was correlated with post fire in situ
measurements collected several years after the fire.
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2
GLOBAL NAVIGATION SATELLITE SYSTEMS
2.1
Introduction
Global Navigation Satellite Systems
Satellite navigation and positioning is the process of determining your location on earth with the use of
satellites. It is a common misunderstanding that these satellites can track and trace someone or something
on earth. This is not possible, only the receiver knows its position. However if the receiver is equipped with a
connection to a back office it can reveal its location. An extra feature of satellite navigation is the ability of
clock synchronization by using the satellites time signal.
Global Navigation Satellite Systems (GNSS) have quickly become a standard feature in everything from
search and rescue services to automobile navigation and leisure goods. The value of location-based services
is strongly influenced by the accuracy of the positioning technology used. When Galileo becomes
operational, the available positioning accuracy will be greater than with GPS and because of the availability
of different service classes and service guarantees provided, the palette of potential applications will be
much larger as well.
The steady increase in commuter traffic in all parts of the world, including Estonia, creates multiple
challenges for sustainable growth. Space-based solutions, notably the use of global navigation satellite
systems (GNSS) and satellite telecommunications, may increasingly help to meet these mobility challenges.
The ability to determine accurately and communicate one’s position at any moment thanks to GNSS is
starting to have a major impact on the management of ship and track fleets, road and rail traffic
monitoring, mobilisation of emergency services, tracking of goods carried by multimodal transport and air
traffic control (Towards an Estonian space policy & strategy, July 2008, p. 27-28).
2.2
Principle of Satellite Navigation
2.2.1
Geometric Principles of Navigation
In this section it is explained how the receiver determines its location. The receiver calculates the distance to
the GPS-satellite by measuring the travel time of the signal. The travel time is the time between
transmission of the signal from the satellite and the time of arrival at the receiver. The radio signal travels
with the speed of light and the travelled distance is calculated by multiplying the speed of light with the
travel time. A sphere, with the satellite as centre and the travel distance as radius, describes all possible
locations of the receiver.
Figure 2-1 shows that when the distance is known to three satellites the receiver’s location is at the
intersection of those three ranging spheres. Geometry states that three spheres can mutually intersect at
no more than two points. Only one of those positions will be close enough to the earth to be the receiver’s
position.
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Figure 2-1: The geometric principles of positioning
Since the receiver does not have an atomic clock like the satellite, its clock time needs to be synchronized
with the GPS-satellites. The receiver uses a fourth satellite for this synchronization.
2.2.2
The Navigation Signal
GPS satellites broadcast three different types of
data in the navigation signals. The first is the
almanac data, which contains all coarse time
information along with status information about
the satellites. This data is current for several
months, so not very accurate. The second is the
ephemeris, which contains orbital information
and clock corrections that allows the receiver to
calculate the position of the satellite at any point
in time. These bits of data are folded into the
37,500 bit Navigation Message, or NM, which
takes 12.5 minutes to send at 50 Hz.
The
mixing of signals is shown in the diagram
opposite.
Third, the satellites also broadcast two forms of accurate clock information, the Coarse Acquisition code, or
C/A, and the military Precise code, or P(Y)-code. The former is normally used for most civilian navigation. It
consists of a 1,023 bit long pseudo-random code broadcast at 1.023 MHz, repeated every millisecond. Each
satellite sends a distinct C/A code, which allows it to be identified. The military P(Y)-code is a similar code
broadcast at 10.23 MHz, but encrypted and can only be decrypted by units with a valid decryption key. All
three signals, NM, C/A and P(Y), are mixed together and sent on the primary radio channel, L1, at 1575.42
MHz. The military P(Y) signal is also broadcast alone on the L2 channel, 1227.60 MHz.
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2.2.3
Support and Augmentation Signals
2.2.3.1
Differential Techniques
Global Navigation Satellite Systems
Differential technique is an augmentation to GPS. It uses a ground based reference station with a known
position and calculates its difference between this position and the position indicated by the satellite
systems. These differential measurements can be based on the mono or dual frequency measurements
using code or carrier phase techniques. These corrections are broadcasted and receiver units that are
capable of receiving this differential signal use it to correct their position measurement to obtain higher
accuracy.
There are several systems broadcasting these corrections. The type of broadcast can be on a short-range
radio frequency, satellite broadcast or even through GSM or internet (GPRS/UMTS). They differ on the type
of connection, costs and the reached accuracy.
Three varieties of the differential technique are explained in more detail:
Satellite Based Augmentation System
A Satellite Based Augmentation System (SBAS) is a system that supports wide-area or regional
augmentation through the use of additional satellite-broadcast messages. Such systems are commonly
composed of multiple ground stations, located at accurately-surveyed points. The ground stations take
measurements of one or more of the GNSS satellites, the satellite signals, or other environmental factors
which may impact the signal received by the users. Using these measurements, information messages are
created and sent to one or more satellites for broadcast to the end users.
While SBAS designs and implementations may vary widely, with SBAS being a general term referring to
any such satellite-based augmentation system, under the International Civil Aviation Organization (ICAO)
rules a SBAS must transmit a specific message format and frequency which matches the design of the
United States' Wide Area Augmentation System
EGNOS is the European SBAS. This system uses 30 reference stations spread over Europe to build up
differential corrections. These corrections are broadcast via geostationary satellites covering the European
region. Using EGNOS an accuracy of 3-5 meter is reached.
Besides differential data, integrity data is also included in the signal. This tells the receiver which navigation
satellite malfunctions so the receiver can ignore it. Similar systems are operational in the USA (WAAS), and
Asia (MSAS). The use of these systems is free of charge, but special receivers are needed. There are also
three commercial SBAS systems: VERIPOS, StarFire and OmniSTAR.
Ground Based Augmentation
Each of the terms Ground Based Augmentation System (GBAS) and Ground-based Regional
Augmentation System (GRAS) describe a system that supports augmentation through the use of
terrestrial radio messages. As with the satellite based augmentation systems detailed above, ground based
augmentation systems are commonly composed of one or more accurately surveyed ground stations,
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which take measurements concerning the GNSS, and one or more radio transmitters, which transmit the
information directly to the end user.
The term Differential GPS can refer to both the general differential technique, as well as specific
implementations of it. It is often used to refer specifically to systems that re-broadcast the corrections from
ground-based transmitters of shorter range. For instance, the United States Coast Guard runs one such
system in the US and Canada on the radio frequencies between 285 kHz and 325 kHz. These frequencies
are commonly used for marine radio, and are broadcast near major waterways and harbours. Similar
systems are globally available at the coast. The International Association of Lighthouse Authorities (IALA)
organises the global availability of MF radio beacons.
The accuracy of the system depends on the distance of the user to the reference station. For radio-DGPS a
typical accuracy of 2 meters is used. Although an accuracy of sub-meters can be achieved.
Figure 2-2: DGPS reference station providing differential correction data
Several commercial providers make use of GSM or internet to supply users with differential data. 06-GPS
and Globalcom provide full coverage of the Netherlands. Due to the fine grid sub-meter accuracy is
achieved.
Virtual Reference Station
The Virtual Reference Station (VRS) method extends the use of DGPS to a whole area of a reference station
network. Operational reliability and the accuracies to be achieved depend on the density and capabilities of
the reference station network. For all locations the differential corrections are interpolated from the closest
reference stations. 06-GPS claims an accuracy of 20 cm horizontally and 30 cm vertically. It provides the
differential data through the internet. A contract is needed to access the data.
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In the Netherlands a network of reference stations providing the VRS method is available through NETPOS
(RTK), 06-GPS and LNR Globalcom. Similar networks are available in our neighbouring countries: SAPOS
(Germany), FLEPOS (Belgium).
Real Time Kinematic
Real Time Kinematic (RTK) satellite navigation is a technique used in land survey. RTK is based on the use
of carrier phase measurements of the GPS, GLONASS and in future Galileo signals, where a single reference
station provides real-time corrections resulting in a centimetre level of accuracy. When referring to GPS in
particular, the system is also commonly referred to as Carrier-Phase Enhancement, CPGPS.
In practice, RTK systems use a single base station receiver and a number of mobile units. The base station
re-broadcasts the phase of the carrier that it measured, and the mobile units compare their phase
measurements with the ones received from the base station. This allows the units to calculate their relative
position to millimetres, although their absolute position is accurate only to the same accuracy as the
position of the base station. The typical nominal accuracy for these dual-frequency systems is 2 centimetres
horizontally and 3 centimetres vertically.
Although this limits the usefulness of the RTK technique in terms of general navigation, it is perfectly suited
to roles like surveying. In this case, the base station is located at a known surveyed location, often a
benchmark, and the mobile units can then produce a highly accurate map by taking fixes relative to that
point. RTK has also found uses in autodrive/autopilot systems, precision farming and similar roles.
Like with DGPS, the RTK system can also use a network of reference stations. NETPOS (government), 06GPS and LNR-Globalcom (commercial) provide these systems. NETPOS broadcasts the RTK-differential data
short-range radio frequencies and 06-GPS offers the data over a GSM/GPRS connection.
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Figure 2-3: Network of Reference Stations as deployed by 06 - GPS in the Netherlands
2.2.3.2
Assisted GPS
Assisted GPS or AGPS provides the receiver with almanac and ephemeris data. Normally this is downloaded
from the GPS satellite. This satellite data stream has a very slow rate of 50bits/second, which is the reason
why it often takes several minutes for conventional GPS receivers to download the required data from the
satellite before computing its own location (cold start). The AGPS server can provide the data via a cell
tower through GSM/GPRS techniques, but also through the internet.
In some systems the AGPS receivers send the raw GPS signal to the AGPS server. This server has high
processing power available to compute the position, which is returned to the receiver. An advantage here is
the low power consumption of the receiver. Various AGPS services provide next to the almanac data also
differential data and satellite integrity data.
2.3
Position Errors
The position calculated by a receiver is influenced by several error sources. In the table below the most
important effects are outlined, with descriptions following.
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Source
Effect
Ionospheric effects
± 5 meter
Ephemeris errors
± 2.5 meter
Satellite clock errors
± 2 meter
Multi-path distortion
± 1 meter
Tropospheric effects
± 0.5 meter
Numerical errors
± 1 meter
Table 2-1: Sources of Errors
When adding up all error sources GPS is typically accurate to about 15 meters.
2.3.1
Atmospheric Effects
The largest error is due to time delay, caused by the slowing down of the signal (time delay) by the
atmosphere. Receivers use an internal mathematical model to apply an estimated correction for the error,
which reduces the error to around 5 meters. Additionally, military and expensive survey-grade civilian
receivers can compare the difference in delay between the L1 and L2 frequencies to measure this
atmospheric delay and apply precise corrections. This is possible because the ionosphere has a frequency
dependent effect on the speed of radio waves.
2.3.2
Multipath Effects
GPS signals can also be affected by multi-path issues, where the radio signals reflect off surrounding
terrain; buildings, canyon walls, hard ground, etc. This delay in reaching the receiver causes inaccuracy. A
variety of receiver techniques have been developed to mitigate multi-path errors. For long delay multi-path,
the receiver itself can recognize the wayward signal and discard it. To address shorter delay multi-path from
the signal reflecting off the ground, specialized antennas may be used. This form of multi-path is harder to
filter out since it is only slightly delayed as compared to the direct signal, causing effects almost
indistinguishable from routine fluctuations in atmospheric delay.
Multi-path effects are much less severe in dynamic applications such as cars and planes. When the GPS
antenna is moving, the false solutions using reflected signals quickly fail to converge and only the direct
signals result in stable solutions.
2.3.3
Ephemeris Errors
The navigation message from a satellite is sent out every 12.5 minutes. However, the data contained in
these messages tends to be "out of date" up to 5 hours. Consider the case when a GPS satellite is boosted
back into a proper orbit; for some time following the manoeuvre, the receiver’s calculation of the satellite's
position will be incorrect until it receives another ephemeris update.
2.3.4
Clock Errors
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Further, while it is true that the onboard clocks are extremely accurate, they do suffer from clock drift. This
problem tends to be very small, but may add up to 2 meters of inaccuracy.
Ephemeris and clock errors are more "stable" than ionospheric effects and tend to change on the order of
days or weeks, as opposed to minutes. This makes correcting for these errors fairly simple by sending out a
more accurate almanac on a separate channel (Assisted-GPS).
2.4
GNSS System of Systems
2.4.1
Overview
Figure 2-4 provides an overview of the current GNSS augmentation systems.
Figure 2-4: Overview of GNSS satellite and augmentation systems
2.4.2
Global Positioning System
The Global Positioning System, usually called GPS, is the only fully-functional satellite navigation system. A
constellation of more than 24 GPS satellites broadcasts precise timing signals by radio waves to GPS
receivers, allowing them to accurately determine their location (longitude, latitude and altitude) in any
weather, day or night, anywhere on earth.
The United States Department of Defense developed the system, officially named NAVSTAR GPS
(Navigation Signal Timing And Ranging GPS), and launched the first experimental satellite in 1978. The
satellite constellation is managed by the 50th Space Wing. Although the costs of maintaining the system are
approximately US$400 million per year, including the replacement of aging satellites, GPS is available for
free use in civilian applications.
In late 2005, the first in a series of next-generation GPS satellites was added to the constellation, offering
several new capabilities, including a second civilian GPS signal called L2C for enhanced accuracy and
reliability. In the coming years, additional next-generation satellites will increase coverage of L2C and add a
third and fourth civilian signal to the system, as well as advanced military capabilities.
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One of the issues with GPS is that the system is a military system. The US-army can decide to decrease the
accuracy because of war or political issues.
2.4.3
GLONASS
GLONASS (ГЛОНАСС) is the Russian counterpart to the United States' GPS system. This satellite navigation
system is operated for the Russian government by the Russian Space Forces.
The system is designed to consist of 24 satellites, 21 operating and three on-orbit 'spares' and placed in
three orbital planes at an altitude of 19,100 km, which is slightly lower than that of the GPS satellites. Each
satellite completes an orbit in approximately 11 hours, 15 minutes.
The system was intended to be operational in 1991 but the constellation was not completed until December
1995. However, due to the economic situation in Russia there were only eight satellites in operation in April
2002 rendering it almost useless as a global navigation aid.
At present 18 satellites are operational, and a full system is expected this year. GLONASS is likely to be
important for Russia, Belarus and other countries in the Russian sphere of influence.
Additionally, following a joint venture deal with the Indian Government it was proposed to have the system
fully operational again by 2008 with 18 satellites, providing full coverage of Russian territory and by 2010 a
global coverage with all 24 satellites.
2.4.4
Galileo
Galileo will be Europe’s own global navigation satellite system, providing a highly accurate, guaranteed
global positioning service under civilian control.
The Galileo system is planned to be fully operational in 2014 and consists of 30 satellites, 27 operational + 3
active spares, positioned in three circular planes at 23 222 km altitude at an inclination of 56 degrees. Once
this is achieved, the Galileo navigation signals will provide good coverage even at latitudes up to 75 degrees
north, which corresponds to the North Cape, and beyond. Compared to GPS this will be a major
improvement to the coverage in the countries in northern Europe, such as Norway and Sweden.
There are several more advantages of Galileo compared to GPS and GLONASS:
• The Galileo satellites will broadcast integrity data, which informs users within seconds of mall
functioning of any satellite. This will make Galileo suitable for applications where safety is crucial,
such as running trains, guided cars and landing aircrafts. The integrity data will be composed at 20
Galileo Sensor Stations spread over Europe.
• Galileo supplies a subscription in which it will guarantee availability of the service. The availability of
GPS can be reduced by the US-army, like they did during the war in Iraq.
• Galileo’s open service is like GPS available free of charge to the public. Additionally, Galileo offers
within the open service the so-called dual-frequency service. With a dual-frequency supporting
receiver the accuracy improves from around 20 meters to 5 meters. In the coming years, additional
next-generation GPS satellites will also include a second civilian signal (L2C). All systems are
planning to add a third and fourth civilian signal to the system in the future.
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• Galileo is under civilian control and there for independent of war or political issues. This in contrary to
the military GPS and GLONASS systems.
One of the main advantages is in de growth of the number of positioning satellites Galileo will be interoperable with GPS and GLONASS. This means that when all systems are fully operational about 80
navigation satellites will be available. With receivers able to receive more systems, accuracy will increase
and effects due to atmosphere and multipath will be reduced.
As a further feature, Galileo will provide a global Search and Rescue (SAR) function, based on the
operational Cospas-Sarsat system. To do so, each satellite will be equipped with a transponder, which is
able to transfer the distress signals from the user transmitters to the Rescue Coordination Centre, which will
then initiate the rescue operation. At the same time, the system will provide a signal to the user, informing
him that his situation has been detected and that help is under way. This latter feature is new and is
considered a major upgrade compared to the existing system, which does not provide a feedback to the
user.
2.5
Architecture of GNSS based applications and services
2.5.1
Overall Architecture
Figure 2-5 provides an overview of service provision architecture of a GNSS based application and service.
Figure 2-5: Service provision architecture of GNSS based applications and services
2.5.2
Receiver types and performance
The accuracy of the estimated location depends among others on the techniques used in the receiver. The
receiver can use mono or dual-frequency, combined with code-phase or carrier-phase. This section gives a
short explanation of these methods.
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2.5.2.1
Global Navigation Satellite Systems
Single/Dual Frequency
The GPS signal is transmitted over two different carrier frequencies called L1 and L2.
The single-frequency receivers only use the L1 band. These are the most commonly used low-cost
receivers, which are implemented in all mass navigation applications. These receivers reach an accuracy of
around 20 meters.
Dual frequency means that the receiver, besides the standard L1 signal also receives the L2 frequency. By
comparing the delays of these two signals a correction is made for the ionospheric delay, which results in a
more accurate position with an accuracy around 5 meter. In the past only the US-military and its NATO
members had access to the signals on the L2 carrier. Nowadays, with the modernisation of GPS the L2
carrier is made available for the public. However global coverage is not reached because of delay in the
replacement of the satellites. The uncertainty on the date of global availability is the reason of the lack of
mass-production of low-cost dual-receivers. Dual-frequency requires a very sophisticated and thus
expensive receiver.
In Galileo the two different carrier frequencies will both be available within the open signal. This makes the
dual-frequency technique available to the public for free. At the moment, the designers of Galileo are
examining the option to add a third civilian frequency to the system.
2.5.2.2
Code-Phase
Standard GPS receivers make use of a pseudo-random code, which is modulated in the carrier frequency L1
(1.57 GHz). This code is repeated every millisecond and compared to an identical code generated by the
receiver. From this comparison the receiver calculates the travel time of the signal.
Figure 2-6: Standard receivers use de pseudo-random code to determine the travel
time of the signal (source: www.trimble.com)
This technique is very sensitive for positioning errors and has a theoretic error of around 300m, but with the
use of smart receivers the error is reduced to 3-6 meters. The most common and low-cost receivers make
use of the code-phase technique. This receiver error is just a part of the position error, errors due to
ionospheric delay and a time error need to be added. The total error with a low cost single-frequency
receiver in a GPS-only system is 10-20m.
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2.5.2.3
Global Navigation Satellite Systems
Carrier-Phase
The carrier-phase technique is a highly sophisticated technique and is only used in expensive receivers.
These receivers start with the pseudo random code, like with code-phase, but now move on to
measurements based on the carrier frequency. This frequency is much higher so its pulses are much closer
together and therefore more accurate, see Figure 2-7. Expensive code-phase receivers in combination with
augmented systems can reach a very high accuracy around centimetres.
Figure 2-7: The carrier-phase technique uses the carrier signal to determine the
signals travel time (source: www.trimble.com)
2.5.2.4
Additional augmentations of the signal
As indicated in Figure 2-4, additional techniques are available to improve the position accuracy, time to first
fix, and reliability:
• Differential Global Positioning System (DGPS) is an enhancement to Global Positioning System that
uses a network of fixed, ground-based reference stations to determine and broadcast the difference
between the positions indicated by the satellite systems and the known fixed positions. This
difference can be forwarded to the receiver, either via a dedicated network, or available networks
such a cellular networks or WLAN. Generally, GBAS (Ground Based Augmentation System) networks
are considered localized, supporting receivers within 20km, and transmitting in the Very High
Frequency (VHF) or Ultra High Frequency (UHF) bands. GRAS (Ground-based Regional
Augmentation System) is applied to systems that support a larger, regional area, and also transmit
in the VHF bands.
• Wide Area Augmentation System (WAAS) uses a network of ground-based reference stations to
measure small variations in the GPS satellites' signals. Measurements from the reference stations are
routed to master stations, which queue the received Deviation Correction (DC) and send the
correction messages to geostationary WAAS satellites in a timely manner. Those satellites broadcast
the correction messages back to Earth, where WAAS-enabled GPS receivers use the corrections
while computing their positions to improve accuracy. An example of a WAAS is the EGNOS service.
• Mapmatching is the functionality where a measured position is linked to the nearest road. Based on
subsequent measurements, driving direction can be determined. This technology is e.g. applicable in
route navigation.
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• Relative Kinematic Positioning (RKP) is another approach for a precise GPS-based positioning
system. In this approach, determination of range signal can be resolved to a precision of less than
10 centimetres (4 inches). This is done by resolving the number of cycles in which the signal is
transmitted and received by the receiver. This can be accomplished by using a combination of
differential GPS (DGPS) correction data, transmitting GPS signal phase information and ambiguity
resolution techniques via statistical tests—possibly with processing in real-time (real-time kinematic
positioning, RTK).
• RAIM is the abbreviation for Receiver Autonomous Integrity Monitoring, a technology developed to
assess the integrity of GPS signals in a GPS receiver system. It is of special importance in safetycritical GPS applications, such as in aviation or marine navigation. RAIM detects faults with
redundant GPS pseudorange measurements. That is, when more satellites are available than needed
to produce a position fix, the extra pseudoranges should all be consistent with the computed
position. A pseudorange that differs significantly from the expected value (i.e. an outlier) may
indicate a fault of the associated satellite or another signal integrity problem (e.g. ionospheric
dispersion).
• An Inertial Navigation System (INS) is a navigation aid that uses motion sensors (accelerometers)
and rotation sensors (gyroscopes) to continuously calculate the position, orientation, and velocity
(direction and speed of movement) of a moving object without the need for external references,
based on its measured acceleration and rotation. It is used on vehicles such as ships, aircraft,
submarines, guided missiles, and spacecraft. It is used in GNSS receiver in case of loss of signal, to
provide continuity of position and speed. Furthermore, it can be used to improve the determination
of position.
• Assisted GPS, generally abbreviated as A-GPS, is a system which can improve the startup
performance of a GPS satellite-based positioning system. It is used extensively with GPS-capable
cellular phones.
2.5.2.5
Selection criteria for receivers
Figure 2-8 provides a qualitative relation between accuracy and costs of the GNSS receivers. The trend will
be that the overall price of the GNSS receivers will go down.
Selection criteria for the GNSS receiver are indicated and very much depend on the type of application
which needs to be realised:
• For LBS, in most cases the mass markets is addressed, and with mobile phones power consumption
needs to be very low. As such, low price, low accuracy (15 m) receivers will be selected. With the
availability and interoperability of Galileo with GPS, improved accuracy will be possible.
• For mission and safety critical applications, reliability of the positioning and availability of the signal is
key, so receivers fit for this purpose will be selected, which are more expensive. In the case of an
increase in accuracy and a switch to dual band receiver, prices go up.
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• For mobile phones, and also for GPS receivers in for example watches etc. dimensions are very
small. Miniaturisation at this moment will increase the price. However, with the addressable market
in mobile phones, in-car units and GPS enabled gadgets, prices are expected to drop soon.
Figure 2-8: Pricing vs. Accuracy of GNSS Receivers, and a first cut overview of
selection criteria
2.5.3
Mobile Phones
With the growth of mobile phones including a GNSS receiver, the potential for offering LBS grows rapidly,
see Figure 2-8.
Figure 2-9: Growth in GNSS enabled mobile phones, key in LOBS
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The challenge for the developers of mobile phone LBS is to provide and maintain the applications for several
available mobile phone platforms; iPhone, Symbian, Google Andriod and Mobile Windows. Several
developers offer GNSS based applications for these platforms. The challenge, however, is that for
professional services providers, and commercial operations, the applications need to be developed for all the
platforms, imposing additional effort to develop them. As a consequence, an increasing number of service
providers choose to develop web based applications for mobile phones, served by the mobile internet.
2.5.4
Communications
In order to provide the end user with information based on their location, time and personal preferences,
two options are available for the services provision architecture:
• All information necessary for the LBS is present on the mobile device. Advantages are the
independence from availability of communication, quick access to data, and security. Disadvantages
are that information is less dynamic, and information is limited due to the storage capability of the
mobile phone. Also, the LBS is limited to the user of the mobile phone - there is no link with other
mobile users, e.g. for social network (friend finder). The communication link is often used to update
the information off-line at regular intervals. This can be performed via a wireless link or through
connection to the internet via a host computer.
• All information is stored in a back office, and is retracted based on user profile, time and location
through a communication link. In this case, and for the update of local information, several
communication means are available, as indicated in Figure 2-10.
Figure 2-10: Overview of communication means for location based services,
presenting characteristics and an overview of the selection criteria.
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2.5.5
Global Navigation Satellite Systems
Back Office
The back office of the service provider is typically an ICT infrastructure, based on a GEO ICT system or
service. The back office holds the information and allows access to the user mobile device. Location
information and user profiles are typically maintained in the back office, either by service providers or by the
users.
The back office also includes the communication functionality to receive locations from the users and submit
the location based information, based on subscription. In addition, the back office may include the security
infrastructure, customer relations applications, invoicing system, and possibly web portals for users to
configure their services.
2.6
Value chain for GNSS based applications and services
2.6.1
Value chain
Figure 2-11 presents a typical value chain in the provision of GNSS based applications and services, and
introduces a first overview of their business model. Two streams can be identified:
• The realisation of the necessary infrastructure to provide GNSS based applications and services or
“products”. This provision includes the development of the platform, e.g. the receiver terminal and
back office, usually the products which are independent of the actual service.
• The realisation, provision and maintenance of the actual services or “services”, which are the service
specific element, e.g. content, communication and the actual service provider.
Figure 2-11: Overview of the Value Chain for GNSS based applications and services
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The following product provision value chain players can be identified:
• U-Blox, Motorola are examples of companies developing GNSS chipsets, organisations like NXP will
develop these chipsets into e.g. microcontroller stacks for mobile phones and car systems.
• These stacks are used by Garmin, Mio, TomTom, Navigon, Magellan etc. to develop the navigation
systems, and Nokia, HTC, SonyEricsson, Apple (iPhone) etc. for development of GNSS enabled
smart phones.
• For some of the platforms, additional technologies will be added to improve the performance. For
example for car platforms, inertial platform and mapmatching is included.
• For the back office, more traditional ICT solutions, manufacturers and service providers are available.
One of the most recent technologies for LBS is LAYAR (layar.com), for augmented reality. With the
increase of services to be provided to a mobile phone, cloud computing is a technology under
consideration to solve the challenges for channelling of many information resources.
For the service provision, the following players can be identified in the value chain:
• Map developers, of which TeleAtlas (owned by TomTom) and Navteq (owned by Nokia) are well
known. AND is a still independent map supplier, and many open source initiative like Open
Streetmap allow for tailoring the maps to specific needs. GEO solutions will be used to link the map
to specific service information.
• For communication means, the alternative technologies as presented in section 2.5.4 are available.
For use of cellular networks, local communication providers are available.
• For service providers, the list is very long, and depending on the type of service provided. In the
examples section, some of the possible services are identified.
2.6.2
Business Model
It is very challenging to provide a single reference business model, as factors vary between GNSS services.
For illustration purposes, Figure 2-12 introduces a possible service from the Tallinn tourist information office.
On a smart phone (PDA), either your own or rented from the tourist office, a user will obtain tourist
information based on his/her position. For this, a tourist can subscribe to this service for a selected period
and pay the tourist office for this service. As such, the tourist office will generate revenue from the service.
The operator of the cellular network will generate revenue from the data traffic to and from the smart
phone. This can be seen as independent, or the tourist office can prepare a contractual arrangement with
preferred operators. Once the tourist office has an infrastructure in place, it can contact shops, restaurants,
accommodation, and offer the service to provide information to the tourist based on time and location, e.g.
special offerings, marketing messages. By charging these businesses, the tourist office may decide to
reduce charges to the tourist.
Charging either the tourist of the advertising entities can be on different business models as identified in
Figure 2-12. This is an example. Many other business models are possible, even in this specific case.
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Figure 2-12: An example of a business model for a GNSS enabled service
2.7
Examples of Applications
2.7.1
Route-Navigation
Route-Navigation is a well known application of satellite navigation systems. More and more people around
the world use it to navigate to their desired location. It is used in cars, airplanes, and ships. Personal
navigation devices such as hand-held GPS systems are used by mountain climbers and hikers.
The more expensive automobile navigation systems use data from sensors attached to the drive train and a
gyroscope for greater reliability as GPS signal loss and/or multi-path errors can occur due to urban canyons
or tunnels. This augmentation of sensor information in navigations devices is called Dead Reckoning. There
are numerous examples of Route-Navigation systems, such as TomTom, Navman, etc.
GPS Navigation also has applications in the fishing sector, an example of which
is illustrated opposite. The location is used with background maps, which
include navigation aids and wrecks and obstructions in coastal and Great Lakes
waters. Eagle Electronics combines sonar-instruments and GPS-navigation
systems.
2.7.2
Tracking and Tracing
In the technique of tracking and tracing a vehicle, person or asset the receiver determines its position on a
regular basis, which is transmitted via a connection with a back office. The data is processed or monitored
by the back office. Location business rules can be added to the monitoring system to give an alarm
notification when the receiver enters a restricted area. This principle is called Geo-fencing.
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Some example applications using this technique are:
• Tracking and tracing the transport of hazardous materials: The transport vehicles are equipped with
a tracking device, which determines its position and communicates this position to a monitoring back
office. The following figure shows an example of the system architecture.
Figure 2-13: System architecture for tracking & tracing [Source: ARMAS III]
• Recovery of stolen valuable assets: Position of stolen property can be recovered by simply calling the
tracing device, which returns its position to the owner. Car insurance companies already obligate the
use of this technique for expensive cars.
• Fleet management: All transport businesses can have extreme logistic advantages if the company
knows where its vehicles are.
• Tracking and monitoring delinquents on leave.
2.7.3
Surveying
Surveying
is
the
technique
and
science
of
accurately
determining the terrestrial or three-dimensional space position
of points and the distances and angles between them. These
points are usually, but not exclusively, associated with positions
on the surface of the Earth, and are often used to establish land
maps and boundaries for ownership or governmental purposes.
In land survey the RTK technique is used to achieve centimetre
accuracy.
Some example applications of surveying are:
• Cadastral surveys: map ownership boundaries for purposes of land valuation and taxation.
• Building and construction measurement
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• Mapping and Geographic Information Services-applications (GIS)
2.7.4
Location Based Services
Location Based Services (LBS) are services enabling users to request information based on their location.
This information is shown on a personal mobile device, such as a mobile phone.
One example of a location-based service might be to allow the subscriber to find the nearest business of
interest, such as an Italian restaurant. The ability of the restaurant to send an invitation to passing people
has also been mentioned, even though this might be regarded as unsolicited commercial email or
spamming. The latter is only allowed when users subscribe to this service.
These services were launched in the late 1990s, and the development in this area seems to be driven by
technical ability rather than by user need.
2.7.5
Automated/Guided Systems
The farming sector is a business area where the use of navigation systems is increasing. Very precise
navigation techniques are used for preparing, planting, and cultivating fields, which are critical operations
that must be performed within minimal times at the right moment (weather conditions can vary quickly)
and very accurately to maximize the land's productivity.
Factory installed automated steering systems are available on tractors and combine harvesters. Such a
system combined with a DGPS or RTK-GPS receiver creates an autopilot capable of working the land via a
fully automated process.
A recently project called “Future Farming Flevoland” has progressed successfully. The tractors are driven
and manoeuvred automatically, using RTK-GPS with an accuracy of 2 cm in straight lines over the land.
2.7.6
Location based games
The availability of hand-held low-cost GPS receivers (approximately €80) has led to recreational applications
including location based games such as the popular game Geocaching. Geocaching involves using a handheld GPS unit to travel to a specific longitude and latitude to search for objects hidden by other geocachers.
This popular activity often includes walking or hiking to natural locations providing family orientated
activities for all ages. Other location based games are played controversially by two or more teams on the
streets of a city, but most of these are still in the stage of research rather than a commercial success.
2.7.7
Precise time reference
Many systems that have to be accurately synchronized use GPS as a source of accurate time. For instance,
GPS can be used as a reference clock for time code generators or NTP clocks. Also, when deploying sensors,
for seismology or other monitoring applications, GPS may be used to provide each recording apparatus with
a precise time source, so that the times of events may be recorded accurately. Communication networks
often rely on this precise timing to synchronize RF generating equipment, network equipment, and
multiplexers.
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3
SATELLITE TELECOMUNICATION
3.1
Introduction
Satellite Telecomunication
The telecommunications segment represents the largest and the most mature downstream segment of the
space sector. It comprises two main components: telecommunications and broadcasting, with an additional
distinction being made between fixed and mobile services. Evolution of digital technologies over the last
years have lead to convergence of the satellite telecommunications services sector, with growing
requirements in terms of flexibility and bandwidth. The most promising growth applications in satellite
telecommunications are expected to be mobile and fixed broadband internet access, machine to machine
(M2M) applications, emergency and security service applications and multimedia entertainment.
The need for availability of wide-band communication in all remote areas will drive the next generation of
satellite communication networks. Related services, like tele-medicine, remote control and navigation of the
unmanned vehicles etc., are already used for the military purposes. With the growth of economic potential
of developing countries, the need for video-on-demand services will multiply the capacity requirements of
telecommunication satellites in the near future. In Estonia, the wide use and development of terrestrial
infrastructure for communication services has led to high penetration of the IT services, resulting in almost
100 % coverage of mobile and fixed networks. Extensive use of the satellite communication infrastructure is
not foreseen in the near future except in the field of direct-to-home television broadcasting, which is a
moderately priced and high-quality service, competitive mostly in the rural areas of Estonia (Towards an
Estonian space policy & strategy, July 2008, p. 29).
3.2
Satellite Communications Network and its Functioning
Whist there are many variations depending on the service being provided and the chosen type of satellite
system, the majority of satellite communications adopt the basic architecture shown in Figure 3-1 below.
The following elements are depicted in the figure:
• Satellite: A single satellite or constellation of satellites receiving radio signals from satellite terminals
on the ground and retransmitting them back down to receiving ground terminals. Most importantly
the vast majority of satellite payloads are transparent, i.e. the radio signals transmitted by the
satellite are essentially the same as those received (apart from being amplified and translated in
frequency): this ensures that, once launched, the satellite is flexible to changing service
requirements and technology advances on the ground. Satellites also provide a number of beams for
connecting different coverage areas on the earth, and means for switching channel capacity between
beams. Satellite operators own and generally operate the satellites, through a satellite control or
operations centre (SCC / SOC – responsible for satellite station keeping and monitoring).
The majority of satellite operators still wholesale most of their satellite capacity to a network of
satellite service providers, who then sell the services onto consumers or business / governmental
customers. This situation is changing however, with operators extending their reach in the value
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chain towards the end customers, or service providers starting to procure and operate their own
satellites.
Application and
Content Providers
Service Providers
Satellite Operators
Retail
RetailBusiness
Business
Systems
Systems
Wholesale
Wholesale/ /Retail
Retail
Business
BusinessSystems
Systems
Wholesale
Wholesale
Business
BusinessSystems
Systems
Content
Content
Service
ServiceCentre
Centre
Satellite
SatelliteControl
Control
Centre
Centre(SCC)
(SCC)
Network
NetworkControl
Control
Centre
Centre(NCC)
(NCC)
Applications
Applications
Mobile
Mobile
Applications
Applications
Public terrestrial
networks
Satellite
Ground Network
Private terrestrial
networks
Network
Gateways
Ground
Stations
Fixed
Fixed
Applications
Applications
Figure 3-1: Generalised architecture of a satellite communications network
• Satellite terminals: Users of the satellite service can be connected through a wide variety of
terminals, for instance handheld, vehicle-mounted, airborne, shipborne or fixed installations. The
satellite terminals may themselves provide a gateway to local networks (home or office LAN, campus
networks, local wireless networks) supporting multiple users through a single terminal installation.
• Ground stations: The majority of satellite communications links are established between large
ground stations and the satellite terminals, either as a one-way broadcast network or a hubbed
network providing two-way communications. The ground stations are either owned by the satellite
operator on behalf of their service provider community, or owned and operated by the service
provider directly. Interconnection is made through a satellite ground network and network gateways
into external terrestrial networks (for example public and private telephone networks, the internet,
corporate VPN, governmental networks). Management of the satellite network and ground network
is undertaken by a network control or operations centre (NCC / NOC) by the operator or service
provider; the gateways can be under separate control of the service provider.
The ground station controls allocation of network resources depending on type of service and
satellite terminal demand. In some instances the satellite connection and bandwidth allocation is
fixed (e.g. long-term lease arrangement), in others bandwidth is dynamically allocated and charged
according to the traffic demand (i.e. per voice call or per unit data).
• Service Centre: Some service providers do little more than just connect end users into external
public and/or private networks: in this model, users have a direct relationship with the external
application and content providers (e.g. consumer services over the web, or business applications on
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the corporate network), and the satellite service provider acts merely as a ‘bit pipe’ for access to
these services. For other service providers, for example satellite TV companies, their business
concerns the delivery of complete services to end users: in this case the service provider will operate
the necessary platforms, applications etc to deliver the service (e.g. TV playout facilities) and retail
business systems to manage the relationship with the end customers (billing, customer care etc).
Some service providers do both, i.e. provide access services but also support value-add services,
applications and content through a service centre. VoIP, messaging / email services, broadcast /
multicast content delivery are examples of these. Specialist applications are normally within the end
user community domain.
The satellites themselves can operate in a variety of orbits depending on the regions of the earth to be
covered and the specific requirements of services and applications using the satellite connection. The two
most common, Geostationary Earth Orbit (GEO) and Low Earth Orbit (LEO), are depicted below.
Low Earth Orbit (LEO)
• 500 – 1400km altitude
• Period ~100 mins
• Range of inclinations
(polar orbit shown)
Geostationary Earth Orbit (GEO)
• 36000km altitude
• Period 24 hours
• Equatorial plane
(inclined orbits sometimes used)
Figure 3-2: Satellite orbits predominantly used
A comparison of LEO and GEO systems is provided in Table 3-1. Because of their relative network simplicity,
GEO systems (e.g. operated by SES, Intelsat, Eutelsat and Telesat) support by far the most satellite
communications traffic, carrying the vast majority of the world’s satellite TV services and communications to
and from fixed satellite terminals. GEO systems also support mobile applications (e.g. Inmarsat), but this is
also an area where LEO-based systems have captured some of the market for both handheld and low rate
data SCADA applications (e.g. Iridium, Globalstar, Orbcomm).
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GEO
Satellite Telecomunication
LEO
• Appears stationary in the sky
• Ground stations do not need
to track
• Satellite travels across sky from horizon to horizon in 5 15 minutes => handoff between satellites may be
required
• Earth stations must track satellite or have omnidirectional
• 3 satellites can cover the
antennas
earth (120° apart)
• Relatively high latency (240270ms, ground-spaceground)
• Large constellation of satellites is needed for continuous
communication
• Requires complex architecture
• Polar regions cannot be seen
• Relatively low latency (~10ms) but currently only supports
low data rates
Table 3-1: Comparison of GEO and LEO systems
Satellite communications services are also classified into Mobile Satellite Services (MSS) and Fixed
Satellite Services (FSS), which principally governs the radio frequency bands that the satellite terminals
use but also broadly describes the types of user and how the satellite communications service is used. (Note
however there are fixed satellite services that are used to support connectivity to vehicles, ships and
aircraft.)
The range of frequency bands used by satellite communications systems and examples of the types of
terminals used within each frequency band are shown below.
Mobile Satellite Services (MSS)
Commercial
Commercial
Commercial
Fixed Satellite Services (FSS)
Commercial
Military
Commercial
Commercial
Military
VHF/UHF
L-band
S-band
C-band
X-band
Ku-band
Ka-band
sub 1GHz
~1.5GHz
~2GHz
~6GHz up
~4GHz dn
~8GHz up
~7GHz dn
~14GHz up
~10-12GHz dn
~30GHz up
~20GHz dn
Figure 3-3: Principal satellite frequency bands and example satellite terminal types
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3.3
Satellite Telecomunication
Advantages of Satellite Communication
There is a strong and established market for satellite services, generating an estimated €54bn worldwide in
2005 (not including satellite terminal supply). Satellite has positioned itself as a competitive (and sometimes
only) means for providing communications in a number of key market sectors, most obviously TV
broadcasting, but also maritime, aeronautical, media, military and multinational corporate applications. The
costs of launching and operating a satellite system can compare favourably with terrestrial equivalents,
especially in cases where significant new terrestrial infrastructure needs to be rolled out.
The following are the key advantages that satellite communications provides:
• Wide coverage: The most obvious advantage of satellite communications is the ability to cover
large areas with minimal infrastructure roll-out. This enables communications to be provided in areas
difficult or impossible to reach effectively by terrestrial means (maritime, aeronautical and remote
land applications), and also means a single system can be used internationally without incurring
roaming charges, or problems due to system incompatibility or drop outs in terrestrial coverage
(important for example in road transportation, and international emergency applications).
Satellite has to date been used predominantly as an independent service, but the increasing
availability of dual-mode or even multi-mode terminals (i.e. able to connect to both satellite and a
range of terrestrial services, e.g. 3G, WiFi, WiMax etc) opens a range of new opportunities where
satellite augments and extends terrestrial network coverage rather than competes with it. Here the
coverage advantages of satellite are readily evident, with satellite services providing connectivity in
areas where it would be expensive to roll-out adequate terrestrial infrastructure. Significant advances
in the data rates supportable to satellite handheld terminals helps ensure that the user experience is
comparable whether connected via satellite or terrestrial means.
• Broadcast capability: Coupled with its ability to cover large areas is satellite’s natural advantage in
being able to broadcast services to large numbers of users in a bandwidth efficient and hence
extremely cost effective way. This is most evident in the success of analogue and digital satellite TV
services, with significant market penetration in a number of countries worldwide.
An area currently underexploited is the ability of satellite to broadcast content other than live TV or
radio, for example digital files containing films, music, videos or games in consumer markets or
application-specific content (e.g. product information, stock information, weather charts) in business
and governmental markets, potentially taking advantage of quiet periods on the satellite network.
The broadcasted content can be stored and accessed locally whenever the user(s) wish to use it,
either directly or sideloaded into another device (e.g. laptop, mobile phone, portable media players,
portable gaming devices). IP multicasting is key network enabling technology for delivery such
content over satellite broadcast systems.
• Flexibility: As mentioned earlier the transparent nature of most satellite communications systems
means that the satellite infrastructure itself does not need to change if there are changes to the mix
of services provided or upgrades to the radio network. This ensures a good level of future proofing,
allowing the ground stations and terminals to take advantage of technology advances and providing
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the satellite operator or service provider flexibility to introduce new services (within the capability of
the satellite itself). Naturally, successive generations of satellites themselves provide a step change
in the overall capacity provided.
Modern satellite payloads also provide significant flexibility in how the satellite capacity (in terms of
available RF power and bandwidth) is utilised, allowing resources to be utilised according to current
user demands in different parts of the world. This is a key advantage for applications requiring
capacity to be provided on a short-term or potentially longer-term basis in particular parts of the
world (disaster relief, military operations), but also allows satellite operators to optimise resources
according to daily variations in usage.
• Network independence: Satellite communications can provide a vital role in providing connectivity
In situations where terrestrial connectivity is compromised or overloaded, e.g. following natural
disasters (e.g. the 2004 Indian Ocean tsunami) or terrorist activity (e.g. the 9/11 attacks). The near
complete independence of satellite networks from local communications infrastructure is a strong
driver for adoption by disaster relief organisations (e.g. UN, ICRC/IFRC) and by the military and
other governmental organisations. The UN cites satellite as essential in being able to quickly deploy
aid workers anywhere in the world.
Satellite networks also are seeing an increasing role in providing back up communications capability
for corporate and governmental applications, enabling business continuity when the primary
terrestrial network fails. The independence of satellite from local terrestrial infrastructure is again a
key advantage: satellite service offerings are now becoming available to allow this back up facility to
be procured at low cost and enable seamless switching between satellite and terrestrial links in event
of failure.
3.4
Major Service Categories and Promising Applications
The figure below shows the breakdown in revenues from satellite services according to market sector and
application:
3B€
0.2B€
47B€
SATELLITE
NETWORKS
CONSUMER
BROADBAND
VIDEO
DISTRIBUTION
1.55B€
1.23B€
0.16B€
Corp.
Networks
Defense &
Security
Internet
direct access
0.21B€
Rural
Com.
46.3B€
2.2B€
1B€
0.8B€
VIDEO
CONTRIBUTION
MOBILE
COMS
MOBILE
ENTERTAINMENT
0.78B€
0.62B€
1.58B€
DTH TV
HITS
Sat. news
gathering
Content
Mgt
na
0.01B€
na
Telemedecine
Digital
Cinema
Teleeducation
1B€
na
0.8B€
na
Pro. coms
Asset
tracking
DAB
DMB
In-flight
na
Business
TV
Figure 3-4: Satellite service revenues by market sector and application (2005)
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These applications are described below, broken down into the FSS and MSS marketplaces.
3.4.1
Current FSS Services and Applications
The Fixed Satellite Service is dominated by four players, which account for 80% of the revenue generated
by satellite operators in this market. These satellite operators provide a very similar mix of services,
covering media, broadband access and internet backbone services, enterprise / governmental services and
transportation applications, as shown below.
Company
Fleet
Service offerings
Revenue
SES Global
40
DTH, cable head-end, HDTV, iTV, SNG
€1.6
Home satellite broadband access
(2007)
(Luxembourg)
bn
IP backbone
Enterprise IP, VSAT
Cellular Backhaul
Mobile broadband (maritime, train)
Governmental services
Intelsat
56
DTH, cable head-end, HDTV, SNG, IPTV
$2.2
bn
(Bermuda/
IP backbone
(2007)
US)
Enterprise IP, VSAT
Cellular Backhaul
Mobile broadband (maritime)
Governmental services
Eutelsat
26
(France)
DTH, Cable / DTT head-ends, HDTV, iTV, IPTV, SNG, €877m
Business TV
(FY 2007-
Home / business satellite broadband access
2008)
IP backbone
Enterprise IP, VSAT
Cellular Backhaul
Mobile broadband (Euteltracs, maritime, train, business jet)
Governmental services
TeleSat
13
(Canada)
DTH, Cable / DTT head-ends, HDTV, SNG, Business TV
$653m
Home / business satellite broadband access
(2007)
IP backbone
incl
Enterprise IP, VSAT
Skynet
Loral
Mobile broadband
Governmental services
Table 3-2: Service offering of the major players providing a Fixed Satellite Service
As can be readily seen from Figure 3-4 the market is dominated by Direct to Home (DTH) TV Services, a
position which is unlikely to change in the near term, with roll-out of satellite HDTV services already
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underway and expectation of the first 3DTV services by 2012. The largest player in Europe (third in the
world) is Sky (UK) – revenues ~£9M – with CanalSat (France), Sky Italia and Direct+ (Spain) also strong
players, all enjoying a virtual monopoly on satellite TV services in each of their respective countries.
Media in a broader sense also accounts for a considerable portion of remaining FSS revenues with satellite
providing Satellite News Gathering (SNG) backhaul and other video contribution services; supporting cable
TV / DTT head-ends (including so-called “head end in the sky” - HITS – services, where a single satellite
supports a multiplex of TV channels from different providers); and distributing digital cinema and business
TV services.
The other most successful sector is that of VSAT services providing broadband connectivity for businesses
and government organisations, typically through 1-2m diameter dishes. Depending on customer’s utilisation
of the system, VSAT networks can provide fixed bandwidth serial communications (usually on lease
arrangement) or increasingly on-demand IP-based services, where users can be charged by data volume.
In many cases, VSAT is deployed as the primary communications network, but there is also an increasing
trend for VSAT to be used as a back up system which is only pressed into action when terrestrial
connectivity is cut or heavily congested. The near independence of satellites from the local terrestrial
infrastructure makes this an attractive option for business continuity. A potential large future market for
VSAT services also lies in home broadband services – this is covered in greater detail in section 3.4.3 .
FSS services also have reasonable penetration in transportation applications, competing head-on with MSS
providers in these markets. Vehicle tracking systems such as OmniTRACS and EutelTRACS have been
successful in providing low-rate messaged based services to long-distance road haulage and container
fleets, supplying over 500,000 units worldwide. VSAT systems are also showing increased adoption in
maritime applications, especially ocean going container vessels and passenger ships; to a lesser extent
VSAT is also finding application on trains (to support local WiFi hotspots for passengers) and emergency
services communications.
3.4.2
Current MSS Services and Applications
Commercial MSS operators split into two predominant categories: those supporting mobile broadcast
services (TV and radio) to personal and vehicle devices, and those supporting two-way mobile
communications services to a variety of mobile platforms, including handheld, in-vehicle, maritime and
aeronautical.
The leading MSS operators in this sector are shown in the table below.
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Operator
Inmarsat
Based
UK
Satellite Telecomunication
Satellite Principal market Coverage
orbit
sectors
GEO
Maritime,
Land
Services
Aero, Near global
Voice,
mobile,
SMS,
SCADA
Thuraya
UAE
GEO
Land
US
LEO
Land
Aero,
IP
data,
messaging
mobile, Europe,
Maritime
Iridium
ISDN,
Africa, Voice,
Middle East
mobile, Global
Maritime,
SMS,
IP
data
Voice, Short Data
Service, IP data
SCADA
Globalstar
US
LEO
Land
mobile. Near global
Maritime, SCADA
Orbcomm
US
LEO
SCADA
Voice,
SMS,
IP
data
Global
Store
and
forward
messaging
Skyterra
US
GEO
Land
mobile, North America
maritime, SCADA
XM Sirius
US
GEO
/ Satellite Radio
Voice, PTT Voice,
SMS
North America
HEO
In-vehicle
radio
and
entertainment
Table 3-3: Major MSS operators and services
The principal market sectors and applications currently served are as follows:
• Land users: A variety of mobile satellite terminals are available to support communications in remote
areas to individuals (handheld or portable capability), vehicles and deployed offices. Capabilities are
generally governed by the size of the terminal: handheld communications and small vehicular
terminals are currently limited to voice, SMS and low rate data services (though see future trends);
portable and larger vehicular terminals can support broadband data speeds (currently up to
~500kbps) enabling potentially many users to connect e.g. via Ethernet or WiFi through the same
terminal.
Current usage typically includes voice communications, standard mobile office applications (e.g.
email, web access, corporate intranet access) and low rate data messaging applications including
location reporting (particularly vehicle tracking). Media organisations also use the higher rate
capabilities of portable terminals to upload recorded video and support live video links for news
reporting. The increased need for content uploading and distribution over mobile satellite services is
seen as one of the major drivers for future services (see future trends).
• Maritime: Satellite communications form a critical part of the Global Maritime Distress and Safety
System (GMDSS), supported for example by the Cospas-Sarsat Emergency Position-Indicating Radio
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Beacon (EPIRB) system for search and rescue operations and the Inmarsat-C SafetyNET service
providing two-way ship-shore messaging communications and a broadcast safety information
service. Inmarsat-C also supports the Long Range Identification and Tracking (LRIT) System, for
tracking passenger and cargo vessels on international voyages.
Satellite communications can also provide a key means for non-safety related communications to
the shore, with relatively inexpensive omnidirectional terminals serving smaller vessels and leisure
craft (Iridium, Globalstar, Inmarsat-C), and progressively larger terminals such as the Inmarsat
FleetBroadband range serving ocean-going yachts, passenger vessels and merchant shipping.
Depending on the terminal type a variety of services / applications are supported including voice
communications, real-time chart and weather updates, web / intranet access, email / SMS and
videoconferencing.
Services are also starting to be extended to the crew (to enable voice / SMS / email communication
with friends and family, e.g. through specially installed phones in the crew quarters), and for
passenger ships GSM services through locally installed base stations and internet access. Note that
fixed satellite services are also being used for some of these applications.
• Aeronautical: Satellite communications is an established means for supporting cockpit-ground
communications for air traffic control (ATC) and aeronautical operational control (AOC) services,
through two-way voice and low rate data messaging. Though currently used predominantly in ocean
regions, satellite potentially will be an integral component of the European SESAR programme
aiming to provide a new harmonised Air Traffic Management (ATM) infrastructure for managing
Europe’ airspace by 2020: ESA is funding studies into how satellite should support this vision through
their IRIS programme.
SatComs is also set to play a significant role in enabling new cabin services on passenger aircraft,
notably supporting use of GSM phones for voice, SMS and eventually GPRS data services during the
flight. Regulatory approval has been given in some regions to operate GSM picocells onboard
aircraft, with services already provided by AeroMobile on Emirates and Malaysia airlines, and being
trialled by a number of European airlines through the OnAir service.
• SCADA / M2M applications: Satellite communications also has an established market in supporting
automatic monitoring and control of remote assets, historically described as Supervisory Control and
Data Acquisition (SCADA) applications but increasingly referred to under the more general banner of
machine-to-machine (M2M) applications. Depending on the application, communications here do not
necessarily need to be supported in real-time, enabling store and forward messaging services to be
used as supported by market-specific players (e.g. Orbcomm).
Principals users of M2M services are the transportation and distribution sector (e.g. vehicle and
goods tracking, maritime safety services) as already described, but satellite also has an established
role in remote monitoring and control of high value assets in the oil and gas (oil and gas extraction,
pipelines, storage facilities) and utility industries (power lines, water monitoring). There are however
a wealth of emerging M2M applications driven in particular by the green agenda and homeland
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security concerns all of which could potentially be supported by satellite (see future trends – section
3.4.3 ).
• Media broadcast: Significant media coverage has been given to the use of satellite broadcasting to
support mobile TV and radio services to mobile handsets and in-vehicle entertainment systems.
Whilst there have been some qualified success stories, notably the XM-Sirius satellite radio service in
North America (reaching approximately 20 million), and to a lesser extent the satellite mobile TV
service in South Korea, the business case for widespread mobile TV roll out remains to be proven
whether supported by satellite or terrestrial means. The major hurdle for satellite mobile
broadcasters lies in getting good service availability in towns and cities: an ancillary terrestrial
component (ATC) comprising a network of ground repeaters is required to provide the necessary
reception, significantly increasing the cost of such ventures.
3.4.3
Future trends
Increasingly sophisticated spacecraft with flexible switching of capacity to beams and highly directive
onboard antennas able to form multiple small spot beams on the earth’s surface, have enabled the GEObased operators to introduce increasingly capable services to their users. The LEO-based MSS operators
have also announced their next generation of systems which will increase their capabilities.
Of particular interest within the MSS community currently are the new services to be offered by GEO
systems at S-band, with the potential of providing medium-high rate communications to handheld and
vehicle-mounted terminals. Terrastar (US) launched its S-band satellite in 2009, with services expected to
be rolled out in H1 2010. The satellite, one of the largest commercial spacecraft ever launched, will support
500 spot beams covering North America enabling services approaching those of terrestrial 2.5 and 3G
systems (noting that terrestrial repeaters are required for high service availability in cities). Licences for
pan-European S-band spectrum were awarded to Inmarsat and Solaris Mobile also in 2009, with the
requirement to launch by 2011.
With C-band and Ku-band becoming increasingly saturated significant focus is now being placed within the
FSS community on Ka-band systems, operating at 30/20 GHz. Substantial amounts of spectrum are
available making it particular attractive for the TV, business and home broadband market. Technical
challenges in particular the high rain fade experience at these high frequencies have until recently hindered
the move to Ka, but systems are already providing service particularly in North America, with European
service already provided by SES and within 2010 by Eutelsat and Avanti.
The figure below shows what we believe are some of the key growth applications which will be supported
through future MSS and FSS systems.
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High speed data, VoIP,
IPTV, IP Multicast
Satellite Telecomunication
High speed data, Netted voice,
Messaging, IP Multicast
High speed data, Messaging,
IP Multicast
Low rate data,
Messaging
Satellite home broadband
Emergency & security services
Intelligent Transport Systems
Machine to Machine (M2M)
Two-way services, 10Mbps+
Broadcast IPTV
Media distribution services
Gaming, entertainment
GIS systems, situational awareness
Database checks, image recognition
Image / video upload, CCTV
Medical records / telemedicine
WiFI
Direct to
Home
Congestion avoidance
Driver information services
Road user charging
Automated accident reporting
Asset tracking
Remote monitoring and
maintenance
Environmental regulation
Figure 3-5: Important growth applications and services in satellite communications
We believe the main areas for satcoms growth are in the following:
• Emergency and security service communications: The availability of next
generation mobile satellite services will provide national and international
emergency, civil protection and military organisations with new capabilities
to keep field units better informed on operational progress and improve
overall situational awareness. Satellite will act as an overlay service,
providing a high rate data services capability to complement existing voice services supported by
terrestrial networks such as TETRA, TETRAPOL and P25.
The Terrastar service (US) promises delivery of high rate services to multimode devices (above),
incorporating satcom, 2G, 3G and WiFi into a single PDA-sized device: similar services are projected
to be delivered over Europe in a two-three year timeframe, potentially having TETRA network
connectivity also integrated into the handset. Improvements will also been seen to vehicle-mounted
satcoms giving true broadband two-way communications on the move (COTM) from relatively
small antenna units. Vehicles can then act as wireless relays to allow personnel to connect using
smartphones, PDAs, laptops etc at the scene.
The
availability
of
high
rate
bidirectional
IP
data
communications is seen of critical importance to future
emergency and security service operations. In the upstream
direction, this would support uploading of photos, other
images, sensor data, video, CCTV back to the operational
HQ or data processing centre. In the downstream direction,
processed content (e.g. GIS systems showing locations
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and status of operational staff, potentially augmented satellite EO images) would be
disseminated back out to the operational staff. This aids greater situational awareness (right) in the
field and improved operational effectiveness. Allied to this is the increasing need to support one-way
and two-way real-time video communications from the field, for example for telemedicine, remote
monitoring and surveillance applications. Availability of video communications also provides nonoperational benefits in terms of engaging with the media and promoting support from fund-donating
organisations.
• Intelligent transport systems: Satellite is also well positioned to support future transport systems,
with vehicle-mounted terminals enabling a range of private and commercial vehicle applications,
either using satellite only systems or, more likely, using multimode capability as above. Applications
include road user charging, automatic accident reporting, congestion detection and
avoidance, vehicle health and fuel consumption monitoring and driver information
services. The latter is particularly suited to satellite given its ability to cost-effectively broadcast
information over a wide coverage area; indeed a variety of in-vehicle systems could benefit from
data and software updates broadcasted via satellite.
• M2M: The market growth in machine to machine communications (M2M) over the next 5-10 years is
expected to be significant even by the most conservative of estimates, with both government policy
(e.g. environmental monitoring, GHG regulation) and private sector needs (e.g. remote
equipment monitoring and maintenance, asset tracking, automated payment systems)
driving the demand. It is predicted that existing terrestrial networks will be unable to serve the
demand and/or provide sufficient coverage, leading to a number of key new opportunities for
satellite communications either as a standalone network or as a satellite-terrestrial hybrid. Existing
MSS systems are already in a position to target some of these new applications with no new
requirements on infrastructure.
• Satellite broadband: An estimated 70m European homes are currently unable to receive a basic
2Mbps broadband service, creating the so-called “Digital Divide”. Initiatives are underway at a
national (e.g. the Digital Britain programme) and European level (e.g. EU plans to subsidise rural
broadband access by up to €1.8bn).to help bridge this gap and provide universal access to all.
However it is a situation that is likely to reappear and worsen as Next Generation Access (e.g.
through fibre communications) are started to be rolled out – for instance in the UK it is estimated
that only two-thirds of the population will be reached by the NGA market forces alone. Satellite
broadband has significant potential to support both universal access at 2Mbps and, ultimately, NGA
services to rural areas, repeating the success of US satellite broadband services which currently
support over 1 million subscribers. The particular advantages of satcom could be exploited to provide
a range of cost-effective value add services such as broadcast IPTV and mass content distribution.
Costs of terminals and services are also continually reducing in this sector.
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Abbreviations
ABBREVIATIONS
Acronym
Definition
AGPS
Assisted GPS
DTH
Direct to Home
EC
European Commission
EEA
European Environment Authority
EO
Earth Observation
ESA
European Space Agency
GBAS
Ground Based Augmentation System
GCM
GMES Contributory Mission
GEO
Geostationary Earth Orbit
GMES
Global Monitoring for Environment and Security
GRAS
Ground-based Regional Augmentation System
GSCDA
GMES Space Component Data Access
HITS
“head end in the sky”
INS
Inertial Navigation System
LEO
Low Earth Orbit
MSS
Mobile Satellite Services
FSS
Fixed Satellite Services
NAVSTAR GPS
Navigation Signal Timing And Ranging GPS
NCC
Network Control Centre
NOC
Network Operations Centre
RAIM
Receiver Autonomous Integrity Monitoring
RTK
Real Time Kinematic
SatCom
Satellite Communications
SatNav
Satellite Navigation
SAR
Search and Rescue
SAR
Synthetic Aperture Radar
SBAS
Satellite Based Augmentation System
SCC
Satellite Control Centre
SNG
Satellite News Gathering
SOC
Satellite Operations Centre
VRS
Virtual Reference Station
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Glossary
GLOSSARY
Term
Definition
Earth Observation
The acquisition and exploitation of data from aerial or satellite-based
observations of the Earth.
Acquisition
Collecting data from aerial or satellite-based observations, putting it
into a usable format, and making it accessible to the users of the
data
Exploitation
Putting the data to use, e.g. in weather forecasting, flood damage
assessment, or selling posters of famous landmarks seen from space.
Satellite Based
A system that supports wide-area or regional augmentation through
Augmentation System
the use of additional satellite-broadcast messages.
Ground Based
a system that supports augmentation through the use of terrestrial
Augmentation System
radio messages
and Ground-based
Regional Augmentation
System
Differential GPS
Can refer to both the general differential technique, as well as
specific implementations of it
Multi-path
Radio signals reflect off surrounding terrain; buildings, canyon walls,
hard ground, etc.
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