Distinguish among leo, meo, heo & gis systems . what type of satellites kennedy space centre is planning to launch in near future
Wireless and mobile communication
Distinguish among LEO, MEO, HEO & GIS
Systems . What type of satellites Kennedy Space
Centre is planning to launch in near future
Submitted to: Sir Madad Ali Shah
By: Niaz Hussain Shaikh
Types of Satellites
Major differences between LEO, MEO & HEO satellite systems……..10
Future Launches At Kennedy Space Center…………………..14
Future of Wireless Telephony in Pakistan……………………………..16
Telecom Jobs for Electrical Graduates in Pakistan and Abroad……….18
Satellite is any object that moves in a curved path around a planet. The moon is Earth's
original, natural satellite, and there are many man-made (artificial) satellites, usually closer to
Earth. The path a satellite follows is an orbit, which sometimes takes the shape of a circle.
To understand why satellites move this way, we must revisit our friend Newton. Newton
proposed that a force -- gravity -- exists between any two objects in the universe. If it weren't for
this force, a satellite in motion near a planet would continue in motion at the same speed and in
the same direction -- a straight line. This straight-line inertial path of a satellite, however, is
balanced by a strong gravitational attraction directed toward the center of the planet.
Sometimes, a satellite's orbit looks like an ellipse, a squashed circle that moves around two
points known as foci. The same basic laws of motion apply, except that the planet is located at
one of the foci. As a result, the net force applied to the satellite isn't uniform all the way around
the orbit, and the speed of the satellite changes constantly.
o It moves fastest when it's closest to the planet -- a point known as perigee
o It moves slowest when it's farthest from the planet -- a point known as apogee.
Satellites come in all shapes and sizes and play a variety of roles.Just as different seats in a
theater provide different perspectives on a performance, different Earth orbits give satellites
varying perspectives, each valuable for different reasons. Some seem to hover over a single spot,
providing a constant view of one face of the Earth, while others circle the planet, zipping over
many different places in a day. Flying hundreds of kilometers above the Earth, the International
Space Station and other orbiting satellites provide a unique perspective on our planet.
Earth and the moon are examples of natural satellites. Thousands of artificial, or man-made,
satellites orbit Earth. Some take pictures of the planet that help meteorologists predict weather
and track hurricanes. Some take pictures of other planets, the sun, black holes, dark matter or
faraway galaxies. These pictures help scientists better understand the solar system and universe.
Still other satellites are used mainly for communications, such as beaming TV signals and phone
calls around the world. A group of more than 20 satellites make up the Global Positioning
System, or GPS. If you have a GPS receiver, these satellites can help figure out your exact
There are essentially three types of Earth orbits: High Earth Orbit (HEO), Medium Earth Orbit
(MEO), and Low Earth Orbit (LEO).
We have many satellites in these three orbits for different purposes, some are given as:
LEO Satellite Systems: Comparison of GPS, GLONASS, Galileo and Compass
(medium earth orbit) satellite navigation system orbits with the International Space
Station, Hubble Space Telescope and Iridium constellation orbits, Geostationary Earth Orbit, and
the nominal size of the Earth. The Moon's orbit is around 9 times larger (in radius and length)
than geostationary orbit.
A low Earth orbit (LEO) is an orbit around Earth with an altitude between 160 kilometers
(99 mi), with an orbital period of about 88 minutes, and 2,000 kilometers (1,200 mi), with an
orbital period of about 127 minutes. Objects below approximately 160 kilometers (99 mi) will
experience very rapid orbital decay and altitude loss. With the exception of the manned lunar
flights of the Apollo program, all human spaceflights have taken place in LEO (or were
suborbital). The altitude record for a human spaceflight in LEO was Gemini 11with an apogee of
1,374.1 kilometers (853.8 mi). All manned space stations to date, as well as the majority of
artificial satellites, have been in LEO.
LEO satellite system used in telecommunications.The satellite’s inclination depends on what the
satellite was launched to monitor. The Tropical Rainfall Measuring Mission (TRMM) satellite
was launched to monitor rainfall in the tropics. Therefore, it has a relatively low inclination (35
degrees), staying near the equator. TRMM’s low orbital inclination—just 35° from the equator—
allows its instruments to concentrate on the tropics. This image shows one half of the
observations TRMM makes in a single day.
Most scientific satellites and many weather satellites are in a nearly circular, low Earth orbit.
LEOs are also used for data communication such as e-mail, paging and videoconferencing.
Because LEOs are not fixed in space in relation to the rotation of the earth, they move at very
high speeds and therefore data being transmitted via LEOs must be handed off from one satellite
to the next as the satellites move in and out of range of the earth-bound transmitting stations that
are sending the signals into space. Because of the low orbit, the transmitting stations do not have
to be as powerful as those that transmit to satellites orbiting at greater distances from the earth's
surface. LEO telecommunication systems are a promising technology because they provide the
ability for underdeveloped territories to acquire satellite telephone service in areas where it is
either too costly or not geographically possible to lay land lines.
Other uses of LEO
Although the Earth's pull due to gravity in LEO is not much less than on the surface of the Earth,
people and objects in orbit experience weightlessness because they are in free fall.
A low earth orbit is simplest and most cost effective for a satellite placement and provides high
bandwidth and low communication latency.
Earth observation satellites and spy satellites use LEO as they are able to see the surface of
the Earth more clearly as they are not so far away. They are also able to traverse the surface
of the Earth. A majority of artificial satellites are placed in LEO, making one complete
revolution around the Earth in about 90 minutes
The International Space Station is in a LEO about 400 km (250 mi) above the Earth's
surface, Since it requires less energy to place a satellite into a LEO and the LEO satellite
needs less powerful amplifiers for successful transmission, LEO is still used for many
communication applications. Because these LEO orbits are not geostationary, a network (or
"constellation") of satellites is required to provide continuous coverage. (Many
communication satellites require geostationary orbits, and move at the same angular velocity
as the Earth. Some communications satellites including the Iridium phone system use LEO.)
Lower orbits also aid remote sensing satellites because of the added detail that can be gained.
Remote sensing satellites can also take advantage of sun-synchronous LEO orbits at an
altitude of about 800 km (500 mi) and near polar inclination. ENVISAT is one example of an
Earth observation satellite that makes use of this particular type of LEO.
Medium Earth orbit (MEO), sometimes called intermediate circular
orbit(ICO), is the region of space around the Earth above low Earth orbit (altitude of 2,000
kilometres (1,243 mi)) and below geostationary orbit (altitude of 35,786 kilometres (22,236 mi)).
The most common use for satellites in this region is for navigation, communication,
and geodetic/space environment science. The most common altitude is approximately 20,200
kilometres (12,552 mi)), which yields an orbital period of 12 hours, as used, for example, by
the Global Positioning System(GPS). Other satellites in Medium Earth Orbit
include Glonass (with an altitude of 19,100 kilometres (11,868 mi)) and Galileo (with an altitude
of 23,222 kilometres (14,429 mi)) constellations. Communications satellites that cover the North
and South Pole are also put in MEO.
The orbital periods of MEO satellites range from about 2 to nearly 24 hours.Telstar 1, an
experimental satellite launched in 1962, orbits in MEO.
The orbit is home to a number of satellites. They have a larger capacity than LEOs. This enables
them more flexibility in satisfying shifting market demands for voice or data services.
A fleet of several MEO satellites, with orbits properly coordinated, can provide global wireless
communication coverage. Because MEO satellites are closer to the earth than geostationary
satellites, earth-based transmitters with relatively low power and modest-sized antennas can
access the system. Because MEO satellites orbit at higher altitudes than LEO satellites, the useful
footprint (coverage area on the earth's surface) is greater for each satellite. Thus a global-
coverage fleet of MEO satellites can have fewer members than a global-coverage fleet of LEO
In 1962, the first communications satellite, Telstar, was launched. It was a medium earth orbit
satellite designed to help facilitate high-speed telephone signals, but scientists soon learned what
some of the problematic aspects were of a single MEO in space. It only provided transatlantic
telephone signals for 20 minutes of each approximately 2.5 hours orbit. It was apparent that
multiple MEOs needed to be used in order to provide continuous coverage.
MEO’s are Communications satellites allow telephone and data conversations to be relayed
through the satellite. Typical communications satellites include Telstar and Intelsat. The most
important feature of a communications satellite is the transponder -- a radio that receives a
conversation at one frequency and then amplifies it and retransmits it back to Earth on another
frequency. A satellite normally contains hundreds or thousands of transponders.
Communications satellites are usually geosynchronous (more on that later).
MEO Broadcast satellites broadcast television signals from one point to another (similar to
MEO Navigational satellites help ships and planes navigate. The most famous are the GPS
A highly elliptical orbit (HEO) is an elliptic orbit with a low-altitude (often under 1,000
kilometres (540 miles)) perigee and a high-altitude (often over 35,786 kilometers (19,323 miles))
apogee The 'highly elliptical' term refers to the shape of the ellipse, and to the eccentricity e of
the orbit, not to the high apogee altitude.
Such extremely elongated orbits have the advantage of long dwell times at a point in the sky
during the approach to, and descent from, apogee. Visibility near apogee can exceed twelve
hours of dwell at apogee with a much shorter and faster-moving perigee phase. Bodies moving
through the long apogee dwell can appear still in the sky to the ground when the orbit is at the
right inclination, where the angular velocity of the orbit in the equatorial plane closely matches
the rotation of the surface beneath. This makes these elliptical orbits useful for communications
While circular orbits may be the obvious solution for many satellites, elliptical orbits have many
advantages for certain applications.
As a result of this many satellites are placed in elliptical orbits, especially where certain
attributes are required. For example it does not require the orbits to be equatorial like the
geostationary orbit. This means that polar and high latitude areas can be covered with highly
elliptical orbits, HEO.
With the highly elliptical orbit described above, the satellite has long dwell time over one area,
but at certain times when the satellite is on the high speed portion of the orbit, there is no
coverage over the desired area. To solve this problem we could have two satellites on similar
orbits, but timed to be on opposite sides of the orbit at any given time. In this way, there will
always be one satellite over the desired coverage area at all times.
If we want continuous coverage over the entire planet at all times, such as the Department of
Defense's Global Positioning System (GPS), then we must have a constellation of satellites with
orbits that are both different in location and time.
In this way, there is a satellite over every part of the Earth at any given time. In the case of the
GPS system, there are three or more satellites covering any location on the planet.
The satellite elliptical orbit gives a number of coverage options that are not available when
circular orbits are used.
Highly elliptical orbit, HEO, applications
The highly elliptical satellite orbit can be used to provide coverage over any point on the globe.
The HEO is not limited to equatorial orbits like the geostationary orbit and the resulting lack of
high latitude and polar coverage.
As a result it ability to provide high latitude and polar coverage, countries such as Russia which
need coverage over polar and near polar areas make significant use of highly elliptical orbits,
Sirius Satellite Radio uses HEO orbits to keep two satellites positioned above North America
while another satellite quickly sweeps through the southern part of its 24-hour orbit. The
longitude above which the satellites dwell at apogee in the small loop remains relatively constant
as the earth rotates. The three separate orbits are spaced equally around the Earth, but share a
common ground track.
Examples of HEO orbits offering visibility over Earth's Polar Regions, which most
geosynchronous satellites lack, are:
Molniya orbits, named after the Molniya Soviet communication satellites which used
Much of Russia is at high latitude, so geostationary orbit does not provide full coverage of the
region. These Soviet HEO orbits include polar coverage
Major differences between LEO, MEO & HEO satellite systems:
Parameter LEO MEO HEO
Satellite Height 500-1500 km 5000-12000 km 35,800 km
Orbital Period 10-40 minutes 2-8 hours 24 hours
Number of Satellites 40-80 8-20 3
Satellite Life Short Long Long
Number of Handoffs High Low Least(none)
Expensive Expensive Cheap
Propagation Loss Least High Highest
GIS: A geographic information system (GIS) is a computer system for capturing, storing,
checking, and displaying data related to positions on Earth’s surface. GIS can show many
different kinds of data on one map. This enables people to more easily see, analyze, and
understand patterns and relationships.
With GIS technology, people can compare the locations of different things in order to discover
how they relate to each other. For example, using GIS, the same map could include sites that
produce pollution, such as gas stations, and sites that are sensitive to pollution, such as wetlands.
Such a map would help people determine which wetlands are most at risk.
GIS can use any information that includes location. The location can be expressed in many
different ways, such as latitude and longitude, address, or ZIP code. Many different types of
information can be compared and contrasted using GIS. The system can include data about
people, such as population, income, or education level. It can include information about the land,
such as the location of streams, different kinds of vegetation, and different kinds of soil. It can
include information about the sites of factories, farms, and schools, or storm drains, roads, and
electric power lines
Data and GIS
Data in many different forms can be entered into GIS.
Spatial data: Describes the absolute and relative location of geographic features.
Data that are already in map form can be included in GIS. This includes such information as the
location of rivers and roads, hills and valleys.
Attribute data: describes characteristics of the spatial features. These characteristics can be
quantitative and/or qualitative in nature. Attribute data is often referred to as tabular data,
Digital, or computerized, data can also be entered into GIS. An example of this kind of
information is data collected by satellites that show land use—the location of farms, towns, or
forests. GIS can also include data in table form, such as population information. GIS technology
allows all these different types of information, no matter their source or original format, to be
overlaid on top of one another on a single map.
o One of GIS's practical applications is street network control. Finding the right
location when given an address is important to the postal service, police and fire
departments, and it can be used to schedule vehicle-routing for transportation
departments. It's also vital for developers in its capacity for site selection and
analysis, as it provides relevant information about the quality of the site and
geographical features that may, or may not, be desirable for builders. Street
networks can also be employed in security-related activities when preparing
o GIS is employed in the natural resource management of rivers, recreational
grounds, flooded areas, wetlands, farming lands, woodlands, and wildlife. It is
used in Environmental Impact Analysis, scrutinizing the effect of various projects
on the environment. GIS is involved in analyzing the hazards of toxins to land or
groundwater. Water quality management is yet another GIS application, used to
control wildlife habitats and to foresee the migration routes of animals.
o GIS is employed in land management, as a tool for preparing zoning and land
subdivision plans, and in mapping. Individuals, businesses and corporations can
utilize GIS for examining the features of land lots. As GIS has direct access to
information about land ownership, accuracy in land title transfers is also realized
with this system.
o GIS proves helpful in facilities management, as well as utility and construction
companies, because of its ability to access the location of cables and pipes. Utility
companies also use GIS to track energy use and to plan for improvements, and
commercial property owners can use GIS to plan the maintenance of their
o Crime mapping is used by analysts in law enforcement agencies to map,
visualize, and analyze crime incident patterns.
Other applications include the use of GIS techniques for Water, Wastewater and Storm water
systems, and in Solid Waste management, Networking, Transportation Engineering.
Future Launches At Kennedy Space Center:
Date: June 6
Mission: SpaceX-4 Commercial Resupply Services flight with ISS-RapidScat
Launch Vehicle: Falcon 9
Launch Site: Cape Canaveral Air Force Station, Fla.
Launch Pad: Space Launch Complex 40
Description: SpaceX-4 will deliver cargo and crew supplies to the International Space Station. It
will also carry the ISS-RapidScat instrument, a replacement for NASA's QuikScat Earth satellite
to monitor ocean winds for climate research, weather predictions, and hurricane monitoring.
Mission: Orbiting Carbon Observatory-2 (OCO-2)
Launch Vehicle: Delta II 7320
Launch Site: Vandenberg Air Force Base, Calif.
Launch Pad: Complex 2
Launch Window: 2:56 a.m. PDT, 1-second window
Description: OCO-2 is an Earth satellite mission to study carbon dioxide in the atmosphere and
provide scientists with a better idea of the chemical compound's impacts on climate change.
Date: Sept. 12
Mission: SpaceX-5 Commercial Resupply Services flight with Cloud-Aerosol Transport
Launch Vehicle: Falcon 9
Launch Site: Cape Canaveral Air Force Station, Fla.
Launch Pad: Space Launch Complex 40
Description: SpaceX-5 will deliver cargo and crew supplies to the International Space Station. It
will also carry CATS, a laser instrument to measure clouds and the location and distribution of
pollution, dust, smoke, and other particulates in the atmosphere.
Date: Dec. 5
Mission: SpaceX-6 Commercial Resupply Services flight
Launch Vehicle: Falcon 9
Launch Site: Cape Canaveral Air Force Station, Fla.
Launch Pad: Space Launch Complex 40
Description: SpaceX-6 will deliver cargo and crew supplies to the International Space Station.
What is the future of wireless telephony in Pakistan? What types of
opportunities are available for entrepreneurs to invest money in wireless
telephone industry? Give a comprehensive account of telecommunication jobs
for telecom graduates in Pakistan and abroad?
Future of Wireless Telephony in Pakistan
The newly deregulated telecom sector in Pakistan took off and has elevated the national
economy. From 2.1 phones per 100 Pakistanis in 1999, the number of fixed lines has crept up to
3 per 100 today. Share of telecom sector in Gross Domestic product (GDP) has also touched 1.9
per cent mark last year as compared to 1.6 per cent in 2001. Cellular subscribers in Pakistan
reached 132,333,853 at the end of November 2013, as per stats made available by Pakistan
Currently in Pakistan the mobile companies are providing 2G(GSM) and 2.5G(GPRS, EDGE)
services. After many years of investment and growth, the telecommunication industry is facing
economic challenges, price wars and flat revenues. With nearly 100 million subscribers.
Others argue that the country offers a lot more potential for information and telecommunication
services. So new technologies and services will grab more and more subscriber towards wireless
Today, most of the telecom revenue comes from voice and to a small extent from value
added services such as SMS and ringtone songs and news . Other data services such as mobile
financial services, mobile web browsing, mobile social networking etc have not become popular
in Pakistan and in other developing countries. Compare that with the rapid adoption of
applications in EU and US on smart phones such as iPhone and BlackBerry and how that results
in productivity, higher revenues and innovation.
Analysts agree that unless the conditions are right, consumers will not use the data services.
Factors which impact the adoption of such services include: availability of high speed wireless
networks, monthly cost, and availability of compatible handsets at affordable prices, availability
of useful and interesting applications and content (preferably in local languages), literacy and
One of the discussion points from above is the lack of 3G networks in Pakistan. In simple
terms, 3G is a network technology which allows for high speed wireless data services. It requires
a certain frequency spectrum, which is managed by Pakistan Telecom Authority (PTA). It is
usual for mobile companies to bid for the right to use the spectrum. The decision to offer 3G
spectrums for auction rests with the Ministry of IT and Telecom.
The dilemma is that 3G services come with a high infrastructure and spectrum acquisition
cost. The mobile telecom companies in Pakistan contend that there are very few potential
customers for this new technology and most of them are concentrated in a few large urban cities.
This point came up at a telecom conference in Lahore where stakeholders from industry,
government and public presented their point of views. It was clear from the discussion that 3G
have less to do with technology, more with adoption.
However, there are a number of improvements, which are possible with the existing 2G
networks. EasyPaisais one of the examples where it solves a huge problem for a large section of
the population. Telenor plans to offer advanced services including in the coming months expect
more of such services from other telecom companies and allows the mobile applications which
are being developed in Pakistan have good potential for both the local and international market.
There’s also the need to support Urdu and other local languages, which has been ignored till
So if simply we summarize the above whole discussion then we can say that in Pakistan right
now we cannot deploy the 3G wireless mobile networks due to the cost, lack of awareness in
people, costly handset etc. People usually use wireless mobile phone services in Pakistan for
voice calls (mostly in late night very low rate packages) and sms. People don’t use wireless
mobile phones for browsing purposes for this they prefer the Internet services on laptops or
computers which are very cheep in price and fast as well. So in future as per my research after 10
to 15 years the deployment of 3G networks can be thought. Currently all companies should
provide services using existing 2G and 2.5G networks which should be easily adoptable by a
common wireless mobile phone user in Pakistan.
Opportunities for Entrepreneurs to Invest Money in Wireless Telephone Industry of
Telecom sector exhibited stability in the 2011 and invested $495.8 million with cellular mobile
sector being the leading contributor.In addition, Universal Services Fund (USF) also invested Rs
3.5 billion in unserved areas.Besides this, telecom and Information Technology sector in the country is
also looking for potential opportunities with the possible emergence of Third Generation (3G) technology
in Pakistan in 2012.Hence The entrepreneurs are investing money by seeing the big opportunity in
Following are the opportunities available:
1) They can invest money in telecom service providing companies that are expected to introduce 3G in
Pakistan such as Ufone and Zong.
2) They can invest money in hardware vendors in Pakistan such as Huawei, Ericsson Pakistan.
Simply investment is possible in those network service providing companies which are moving
towards 3G (investment should be long term because it will take some time to establish 3G in
Pakistan if it is launched). Investment in current 2G or 2.5G mobile networks will not be more
profitable and fruitful.
Telecom Jobs for Electrical Graduates in Pakistan and Abroad
1) Electrical Engineer III (Telecom) (HDQ)
2) VoIP Telecommunication Engineer
3) 2G/3G RF Optimization Engineers
4) 2G/3G Drive Test Engineers
5) O&M Engineers
6) RNO Experts
7) Network Deployment Engineers
8) Transmission Engineers
9) Wireless Performance Engineers
10) Wireless Performance Engineers
11) Core Performance Engineers
12) Voice Network Engineers
13) Telephony System Engineers
14) Cisco Analyst
15) Network Integration Engineers
Most jobs are being offered by new network solution providing companies such as
Netkom,Telenor, Zumbeel & Mobiserve etc.
In abroad specially in middle east the telecom engineers jobs are mostly offered by Huawie and Alcatel.