In this assignment I will be talking about the different kinds of broadcast technology. The four types of broadcasting methods are :
- Satellite
- Cable TV
- Analogue Terrestrial
- Digital TV
Satellite
A satellite is an object that has been place into orbit by humans. Also known as Artificial satellites. Satellites are used for cell phones,navigation, radio and communication.
Satellites receive and transmit all kinds of information from radios and other sources. The data may be pinpointed to specific reception points for additional distribution or it may also be received by individual users on specialised equipment such as satellite dishes. Satellites are very useful as they can tell us about the weather, climatic shifts, geophysical changes and give us general information about our world. Satellites are also used by the military.
The first satellite was used for television signal, in 1962, which relayed from Europe to the Telstar satellite over North America. The first geosynchronous communication satellite was then launched a year later in 1963. Two years later the worlds first commercial communication satellite was launched into orbit on April 6th, 1965. This satellite was called Intelsat also know as Early Bird.
A satellite dish, found on most peoples houses works by reflecting the signal from the satellite in orbit, to the dish’s focal point.
This a diagram showing the process of satellite TV. They are sent out from a powerful antenna at the uplink station as radio waves which are converted into streams of digital data. The data is compressed using specific digital file formats such as MPEG-2 to send the greatest amount of data within the allowed bandwidth. The waves travel only in a straight line, so broadcasters direct the transmissions toward satellites that have been launched into orbit, which redirect the signals toward the earth.
The advantages of satellites are that they are used for mobile communication, they can provide details about the earth and the weather, high bandwidth, large area of coverage and can normally be cheaper over long distances.
The disadvantages of satellites are that they are very expensive to build and place into orbit, somewhat unreliable signal, expensive to repair and they are susceptible to noise and interference.
Cable TV
Cable TV is a good method of broadcasting where the programme information is broadcasted via cables, instead of through the air like analogue.
Cable TV works by a head-end facility that processes the programs. Then the head-end transmits the programs down a large coax cable. The coax cable then runs through the middle of a city or town. Next feeder cables split off the trunk and takes the signal into a neighbourhood. The drop cables come off the feeder cables. Then the signal is carried directly into the customers homes. And the final stage is the drop cables travel into a cable modem, which processes the signal, which is then sent to the TV along a video connector.
This is a diagram of how cable TV works once inside someones house.
The advantages of cable Tv are can offer customers free local channels, for some people can be the most convenient solution and can be cheaper for most people who have more than one TV in their home.
The disadvantages of cable TV are that customers receive less channels that satellite TV customers, can be expensive, if the cable goes down, so does the customers internet and home phone and cable companies can be slow at fixing any problems that occur.
Analogue Terrestrial
Analogue terrestrial is a form of broadcasting which means TV signal that is sent to the viewer via electromagnetic waves.
Analogue terrestrial TV works by first transmitting antennae broadcast the programme information over radio waves. The attena then catches and carries the signal through a wire and to the TV. And finally the TV then tunes the channels and is set according to their frequency.
The advantages of analogue terrestrial TV are its very cost efficient, can easily serve local and national audiences, quality doesn’t vary or differ with the size of the audience.
The disadvantages of analogue terrestrial TV is that the image quality can become distorted and the image can suffer from ghosting. Also analogue terrestrial takes up alot of airspace than newer broadcasting methods and finally there is a lack of interactivity.
Digital TV
Digital TV is the transmission of video and audio by digital signals in the air, in contrast to the analogue signals used by analogue TV. During 2010 and 2012 the old analogue signal is finally being switched off and is being replaced with digital. This is called the digital switchover.
Compared to the old analogue signal, digital signals take up less bandwidth than analogue signals. This means there is more room to transmit other information. The way in which the signal is packaged, it should also mean that it isn’t as lossy as an analogue signal can be.
Before the Digital TV, transition was in place, standard analog TV signals were transmitted in a similar manner to radio.
VOD
VOD stands for video on demand. VOD allows users to download or stream vidoes to a computer or device and watch them in real time.
Advantages of VOD
- Easily provides enough bandwidth to carry full motion video
- Leaves room for expansion
- Puts the user in control of what and when they want to watch something
- Mostly free
Disadvantages of VOD
- Bandwidth relatively low compared to fiber/coax
- Wiring each home up with fiber optic cable
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