The military space program is a significant but largely unseen aspect of space operations.Military space operations are divided into five main areas: reconnaissance and surveillance, signals intelligence, communications, navigation, and meteorology. Around the world, military operations are increasingly using commercial satellites to accomplish their missions. Commercial communications satellites are particularly useful and cheap. In addition, commercial reconnaissance satellites are finding many military uses, enabling countries that cannot afford their own satellites to buy photos of their adversaries.

Satellites are not required for many local military operations. But if a country is operating far from its borders or has global interests, they are a necessity. Only a few countries are willing to pay the expense of operating military space systems, but that number is growing.

Untill and unless a strict step is not taken it could really be a threat to the existence of world.

Satellite broadcasting consists of two parts satellite television and satellite radio. Satellite television is a system of delivering television programming using signals relayed from communication satellites. The signals are received via an outdoor parabolic reflector antenna usually referred to as a satellite dish and a low block down converter(LNB). The direct broadcast satellite television signals were earlier analog signals and later digital signals, both of which require a compatible receiver. Digital signals may include high definition television (HDTV). There are three primary types of satellite television usage: reception direct by the viewer, reception by local television affiliates, or reception by head ends for distribution across terrestrial cable systems. Direct to the viewer reception includes direct broadcast satellite(or DBS) and television receive only (or TVRO), both used for homes and businesses including hotels, among other properties. Satellite radio is a radio broadcasting service from satellites. The satellite's signals are broadcast nationwide, across a much wider geographical area than terrestrial radio stations, and the service is primarily intended for the occupants of motor vechile .The satellite television industry developed first in the US from the cable television industry as communication satellites were being used to distribute television programming to remote cable television head ends.Home box office (HBO), Turner broadcasting systems (TBS), and Christian broadcasting network (CBN, later The family channel) were among the first to use satellite television to deliver programming.

A satellite navigation or satnav system is a system of sattelites that provide autonomous geo-spatial positioning with global coverage. It allows small electronic receivers to determine their location (longitude, latitude, and elevation) to high precision (within a few metres) using time signals transmitted along a line of

sight by radio from satellites.

The United States Department of Defense is developing a new generation of navi- gation satellites known as the Navstar Global Positioning System or GPS.

The concept for the first navigation satellite dates back to the launch of Sputnik I in 1957.

Advances in technology and new demands on the existing system have now led to efforts to modernize the GPS and implement the next generation of GPS Block IIIA satellites and Next Generation Operational Control System (OCX). Announcements from Vice President AI Gore and the White House in 1998 initiated these changes. In 2000, the U.S authorized the modernization effort, GPS III.

Navstar will greatly improve the efficiency of mine sweeping operations. A minesweeper that knows exactly  where it is and where it has been will be able to sweep a given area more quickly.

Maritime navigation is another obvious application for Navstar, not only on oceanic voyages but also in coastal and inland waterways and in approaches to harbours. It would also be a boon to oceanography and to exploration for offshore resources.

Navigation satellites were one of the first practical applications of space systems. The second generation of navigation satellites now under development will provide a truly global positioning system, which will provide opportunities for many new and important applications; some of these have been mentioned. No doubt other innovative uses will emerge when Navstar is fully developed and its capabilities and costs become known to potential users.

Satellite communication,in telecommunication , the use of artificial satellites to provide communication links between various points on Earth. Satellite communications play a vital role in the global telecommunications system. Approximately 2,000 artificial satellites orbiting Earth relay analog and digital signals carrying voice, video, and data to and from one or many locations worldwide.

Satellite communication has two main components: the ground segment, which consists of fixed or mobile transmission, reception, and ancillary equipment, and the space segment, which primarily is the satellite itself. A typical satellite link involves the transmission or uplinking of a signal from an Earth station to a satellite. The satellite then receives and amplifies the signal and retransmits it back to Earth, where it is received and reamplified by Earth stations and terminals. Satellite receivers on the ground include direct-to-home (DTH) satellite equipment, mobile reception equipment in aircraft, satellite telephones, and handheld devices.

1  http://www.webopedia.com/TERM/S/satellite_radio.html

2 http://www.satellitesuperstore.com/advice.htm

3  http://www.cinemasource.com/articles/TOP10%20QaboutSat-TV.htm

4 https://www.youtube.com/watch?v=TgeGYd3ujdo

5  https://www.youtube.com/watch?v=BPByy9RpmXk

6 http://www.wisegeek.com/what-is-satellite-tv.htm

7 http://www.actionantenna.com/funfacts.htm

1 LNB 

Low noise block

2 ADC

Analog to digital

converter

3 ASI

Asynchronous serial interface:A streaming data format which often carries an MPEG transport system.

4  DBS

Direct Broadcast-satellite: Television and radio programs distributed by satellite for reception via a dish at the receiver's property.

5  Encryption

The scrambling of a signal to allow reception via a decoder only be specific viewers, e.g. after the payment of a fee

6 Transponder

A physical part of a satellite that broadcasts the signal. In colloquial use, the satellite equivalent of the "channel" a television station is broadcast on (e.g. "broadcasting from Transponder 2C of the satellite").

7  Public information film(PIF)

A government-produced commercial, usually shown for free, giving safety information or advice.

8  Hammocking

Placing a new or poorly-performing program between two established popular programs in order to boost viewing figures.

9  Bandwith

The available space between two given points on the electromagnetic spectrum and, the amount of information that can be squeezed into that space.

Satellite broadcasting can be put to number of uses

1 Satellite television

2 Satellite radio

3 Satellite internet acess

4 Satellite ground stations

Could a communication satellite that fails to reach GEO be repurposed?

Possibly, but not likely. Geo satellites are made to work at that constant orbit, and getting it to work without being at the GEO orbit can cause a lot of problems. The radiation isn't the concern, but the various sensors on the spacecraft are meant to work at GEO altitude. Thermal issues are also of concern, as are the batteries.
How do polar satellites disrupt communications between GEO satellites and ground control?

Satellites in LEO travel at around 7000 m/s. This means that a 1 m sized LEO satellite will take around 150 us (microseconds) to cross a given line between a GEO satellite and a ground antenna.

So it is a very short event, and all satellite communications are protected against error bursts (especially from interference) by using FEC (forward error correction codes) and other diversity methods.

What is a satellite image?

It is a pictorial representation measuring the electromagnetic energy recorded by a sensor, not by photography. A photograph is normally taken within a certain spectral range (visible light). Satellites take images outside this limited range.

What are the advantages of Geostationary Satellites for remote imaging?

As they are positioned at such a high altitude the spatial resolution (i.e. amount of detail shown) of their images (typically 2.5 Km per pixel) tends to be not as good as some polar orbiting satellites (typically 1 Km to 50m per pixel), which are much closer to the earth. However the advantage of their great height is that they can view the whole earth disk below them, rather than a small subsection, and they can scan the same area very frequently (typically every 30 minutes). This makes them ideal for meteorological applications.

1.  Deterrence-the inhibition of criminal behavior by fear especially of punishment.

2.  Reconnaissance-military observation of a region to locate an enemy or ascertain strategic features.

3.  Deception-the action of deceiving someone

4.  

Concealment-the action of hiding something or preventing it from being known

5.  Clandestine-kept secret or done secretively, especially because illicit.

6.  Ceasefire-a temporary suspension of fighting; a truce.

7.  RPVs -remotely-piloted vehicles

8.  Ballistic missiles-a missile with a high, arching trajectory, which is initially powered and guided but falls under gravity on to its target.

1.  http://www.losangeles.af.mil/library/factsheets/factsheet.asp?id=5309

2.  http://www.aerospace.org/crosslinkmag/spring-2010/military-satellite-communications-then-and-now/

3.  http://www.defenseone.com/technology/2013/09/why-military-needs-commercial-satellite-technology/70836/

4. 

https://www.youtube.com/watch?v=M66gsTm4xhQ

5. 

https://www.youtube.com/watch?v=ndmwmrl1hLw

6.  http://www.jstor.org/stable/40724676?Search=yes&resultItemClick=true&searchText=SATELLITES&searchUri=%2Faction%2FdoBasicSearch%3FQuery%3DSATELLITES%26amp%3Bacc%3Doff%26amp%3Bwc%3Don%26amp%3Bfc%3Doff%26amp%3Bgroup%3Dnone

7.  http://science.howstuffworks.com/question529.htm

Antenna Gain: It is the ratio (in dB) of the power radiated in the direction of interest to the power that would be radiated in the same direction by an isotropic antenna. By definition, an isotropic antenna has 0dBi gain. Expressed in dBi (dB's relative to the gain of an isotropic antenna). The gain figure is only applicable to a particular direction and frequency. 

Antenna Noise Temperature: It is the measure of all the external noise collected by a receiving antenna. Measured in Kelvin (K). It varies with antenna diameter, elevation angle and antenna polarisation. The larger the antenna, the lower the noise temperature. Major noise sources are cosmic noise (caused due to sun, moon and starts) and ground noise; caused due to noise energy radiated from the soil. 

EIRP: Used to indicate the power transmitted from an antenna.EIRP=Power +Antenna Gain, Both EIRP and Power is expressed in dBW and Gain in dBi.

LNA Noise Temperature: It is the measure of the amount of noise generated by the LNA. It is measured in Kelvin-the lower the better. Typical performance can be achieved for 30K to 70K. LNA noise performance is sometimes specified in terms of Noise Figure which is measured in dB.

Working of a communication satellite:

1.http://history.nasa.gov/satcomhistory.html

2.

3.https://www.youtube.com/watch?v=hXa3bTcIGPU

4.http://www.williamcraigcook.com/satellite/work.html

5.http://infofavour.blogspot.com/2013/06/satellite-communication-with-its.html

6.https://edupediapublications.org/journals/index.php/ijr/article/view/768

7.https://www.youtube.com/watch?v=BPByy9RpmXk

• Long distance education.
• Entertainment - Broadcasting via satellite offers a variety of programming to the avid viewer including local and foreign programs.
• Do serve civilians in rural area where terrestrial communication network does not exist by providing telephony service.
• In military sector, providing robust and sophisticated secure communications network
• provides communication when the terrestrial systems fail due to disaster such as earthquake, volcanic eruption  floods, drought, cyclones, landslides and epidemics.

Most radio signals can only travel about 30 or 40 miles (48 to 64 kilometers) from their source. Satellite radio are generally used in automobiles as it offers better sound quality and more no of stations over traditional AM and FM radio.

1. A satellite receiver.
2. A dish kit consisting of a dish, an LNB (low noise block) and a wall mount.
3. Cable and connectors that connect between the dish and receiver.
4. Some satellite systems may also need methods of decoding scrambled channels.

Broadcasting Satellite Services
Broadcasting Satellite system is the services for distribution of video and audio streams through satellite.

Fixed Satellite Services
The services implement Point to Point communication and network via satellite between fixed Stations.

Mobile Satellite Services
The Services implement Point to Point communication and network via satellite between mobile stations.  Services are available to the maritime users and land users in any locations that require long distance portable telephony, fast and instantaneous communications setup. Satellite phone is a type of mobile phone that connects to orbiting satellites instead of terrestrial cell sites. Depending on the architecture of a particular system, coverage may include the entire Earth, or only specific regions. 

Satellite TV offers a very wide variety of programming to the avid viewer .You can see a lot of programming without commercials. You can see foreign programs. You can watch all the sports you’ll ever want. You can see raw news footage, without the reporters.

An LNB is the box of electronics on the end of the dish boom arm. It acts like a aerial masthead amplifier. The signal (microwaves) reflect off the dish and into the feedhorn to the LNB. It pulls in the signal better. The signal is then sent down the coaxial cable to the satellite receiver.

FUTURE PROSPECTS

1.  Inter-Satellite Links- Inter-satellite links (or cross-links) may be used to extend the coverage area of a geostationary system, eliminating the need for intermediate anchor stations or as links between low orbiting and geostationary or super synchronous satellites.

2. 

 Optical Communication- While optical SATCOM is particularly appropriate for inter-satellite links (where performance would seem to be comparable to EHF system), there is also scope for space-to-ground communications subject to the obvious problems of cloud and rain. Such a system might operate around 1.3 micron wavelength most likely.

Survivable Satellite Networks -The military satellite communication networks of future will be more flexible, more cost-effective and most importantly capable of functioning under any scenario from peace through protracted nuclear war. This goal will be achieved by ensuring inter-operability of links handling communications, mission data, or satellite tracking, telemetry and command for different types of future Defense satellite communication systems.

4.

Enhanced Processing On-Board- There will be FH uplink~ from small terminals andhaving multiple accesses in FDMA mode. This will bepossible as wide bandwidth at EHF will be available.Therefore, protection against jamming for large numberof tactical terminals is anticipated. Other features ofon-board processing such as the Demodulation tobaseband and data routing on-board is also envisaged.

1. A television (TV) transmission is an example of which type of transmission?

  a) Simplex

  b) Half duplex

  c) Full duplex 

2  INTELSAT stands?

(a)International Telecommunications satellite

(b)India Telecommunications Satellite

(c) Inter Telecommunications Satellite

3 Mention the different services of satellite

systems.

(a)Broadcasting satellite services

(b)Signal transmission

(c)Information transmission

(d)None of the above

4 Define

Polar orbiting Satellites.

(a) Polar orbiting Satellites orbit the earth in such a way as to cover the north & south polar regions

(b)Orbiting Satellites orbit the earth in such a way as to cover the east & west Polar Regions .

(c) Either (a) & (b)

Inter Satellite Links will be great step towards advancement of SATELLITES, and will definitely help next generation as intermediate stations will be eliminated. There are many weather disturbances caused which ma block signals and affect communication.Communication could be either by EHF at 60 GHz or optically. Calculations suggest that excessive powers are not required, and the main problems lie in the antenna/aperture acquisition and tracking.

How does the Global Positioning System work?

Who supplies DGPS receivers?

How can DGPS help maritime transport?

Is DGPS provided elsewhere?

Satellite Cell : Satellite cells are precursors to skeletal muscle cells, able to give rise to satellite cells or differentiated skeletal muscle cells. They have the potential to provide additional myonuclei to their parent muscle fiber, or return to a quiescent state.

Satellite Dish Aerial : Directional antenna consisting of a parabolic reflector for microwave or radio frequency radiation.

Satellite DNA : Satellite DNA consists of very large arrays of tandemly repeating, non-coding DNA. Satellite DNA is the main component of functional centromeres, and form the main structural constituent of heterochromatin.

Satellite Chromosome : A satellite chromosome or SAT chromosome has a chromosome segment that is separated from the main body of the chromosome by such a secondary constriction. The term is due to Sergei Navashin, in 1912.

What are the advantage of SPEC method over DSI method?

a). The SPEC method over DSI method is that freez-out does not occur during overload conditions.

(b). The SPEC method over DSI method is that freez-out does occur during overload conditions.

(c) a&b 

(d) None of above

What is meant by burst position acquisition & burst position synchronization? 

(a). A station just entering ,or reentering after a long delay to

acquire its correct slot position.

(b). A station just entering , or reentering after a long delay to acquire its un-correct slot position.

(c) a & b 

(d) None of these

 With reference to satellite communication, the anti-jamming technique preferred is

a) key leverage

b) Frequency hopping 

c) Once-only key

d) Frequency-spectrum modulation

1 BROADBAND DIGITAL COMMUNICATIONS

2 DIRECT BROADCAST SERVICES

3 ENVIORNMENTAL MONITORING

4 FIXED SATELLITE SERVICES

5 GOVERNMENT

5 MOBILE SATELLITE SERVICES

The Galileo, Glonass and Compass constellations will improve satellite navigation for everybody - if the receivers can be made to work.

Satellite navigation systems take their location cues from 30 GPS satellites that circle the Earth twice a day transmitting status, date and time, and orbital information. Soon there will be around 100 satellites to lock on to as GPS is joined by global constellations from Europe (Galileo), Russia (GLONASS), and China (Compass).

• Location-Based Services

A Location-Based Service, or LBS in short, is a mobile application that providesinformation services to users based on their geographical location. These services can range from finding popular landmarks such as gas stations, banks, etc. to locating specific people or places.

• Real-Time Tracking

One of the original uses of GNSS technology in the field was to provide real time tracking, which allowed vehicles to periodically report their location over a wide area wireless network.

  • Turn-by-Turn Navigation

One of the most popular applications of GNSS technology is the ability to receive “turn-by-turn” driving directions in real time. In-vehicle navigation systems use GNSS to calculate the user’s current position then use navigation algorithms to compute the best route for the user’s planned destination.

http://www.jstor.org/stable/37386

http://eandt.theiet.org/magazine/2010/06/future-of-sat-nav.cfm

http://linxtechnologies.com/blog/beginners-guide-satellite-navigation-systems/

www.trinityhouse.co.uk 

A)3600 B)1800 c)7200 d)none

2)When did the U.S. Department of Defense stop intentionally degrading civilian-use GPS (Global Positioning System) signals?

A)2000 B)Never c)1984

3) Europe is developing its own satellite-navigation system, which should be fully operational by 2020. What is it called?

A)Big Brother B)L'il GPSC)Galileo