Sunday, September 27, 2009

***Today lecture***

today lecture we learn about the Introduction To Multimedia. As we know the words 'Multi' means many, while 'Media' means a medium to stored, transmitted, presented or perceived an information.

Wednesday, September 23, 2009

~~RaDio CorPoRaTion AmeRiCa (RCA)~~

One of the largest and most influential electronics companies during the 20th century was the Radio Corporation of America, or RCA. At one time, the breadth of its operations included everything from making vinyl records to building and manufacturing communications satellites.

RCA began life as a joint venture between several different manufacturers of electric equipment. In the early 1900s many companies began manufacturing and selling a new technology called radio. By about 1915 there were several radio stations operating in the U.S, but several of them were foreign owned and nearly all were used exclusively for transmitting Morse Code. When the U.S entered World War I, the federal government seized the foreign stations, and later gave them to the U.S companies General Electric (GE), Westinghouse, the American Telephone and Telegraph Company (AT&T) and United Fruit (an international shipping company). These companies set up a new organization in 1919 to run the stations, and called it the Radio Corporation of America (RCA).

For a time, RCA operated radio stations (still almost entirely used for transmitting Morse Code) and sold radio equipment manufactured by its parent companies. However, many amateur operators were now on the air, and the resulting popularity of radio listening encouraged the parent companies to move in this direction. Westinghouse obtained a license from the U.S government to launch a commercial broadcasting station in 1920 and launched KDKA, the first commercial radio station. By 1926, the success of KDKA led RCA, Westinghouse, and General Electric to create a chain or “network” of radio stations spread across a wide geographic area, all broadcasting content created in central studios in New York. The name of this network was the National Broadcasting Corporation—NBC.

In 1929, RCA purchased photograph manufacturer Victor Talking Machine Company, and renamed its new division RCA-Victor. With Victor’s expertise and facilities, RCA-Victor was able to begin making its own radio receivers (as well as records and phonographs), and quickly became one of the largest consumer electronics manufacturers. While the Great Depression of the 1930s crippled businesses worldwide, RCA-Victor and NBC thrived. NBC became such a big money maker that David Sarnoff, the leader of RCA, moved the headquarters to a huge new skyscraper in New York and created Radio City Music Hall, a large and technologically innovative performance space.

RCA’s major technical accomplishment in the 1930s was the development of the electronic television system that is still used in many parts of the world today (although it may soon be replaced by High Definition Television). Following a ten-year, millions-of-dollars research effort, led by Vladimir Zworykin, TV was demonstrated at the 1939 World’s Fair in New York and briefly sold to the public before it was put aside during World War II.

The huge research effort necessary for television encouraged the company to create a permanent research facility. When World War II came, RCA had a perfect opportunity to do so and opened its new RCA Research Laboratories in Princeton, New Jersey and produced many crucial innovations for the war effort. After the war RCA returned its attention to television, designing inexpensive receivers and sponsoring the creation of a new NBC television network to provide programming. RCA’s original television system, as well as the color television system it announced in the 1950s, would eventually prove to be the company’s most profitable line of products.

The period from the 1950s and 1970s saw both high and low points in RCA’s history. Its research laboratories produced innovative technologies in these years and helped advance computers, integrated circuits, lasers, and other devices. It introduced innovative products like the 45-rpm record and the solid-state television camera. Even some of the company’s minor innovations were very successful, such as the “RCA connector jack” found on many types of audio equipment. However, the company was finding it increasingly difficult to sell its traditional line of products. By the 1970s Asian firms had captured almost all of the consumer electronics market (TVs, radios, etc.). Corporate managers found that is was cheaper to sell foreign-made products in the U.S than to make them at home, so by the 1970s most RCA-branded consumer products were made of Asian parts, or were assembled outside the U.S. By the 1970s, virtually the only U.S-made RCA consumer electronics products were color televisions, and eventually these sales were lost, too.

RCA’s difficulties led to continual changes in its leadership, which negatively impacted business and contributed to RCA’s decline. The company’s inability to “follow through,” for example, led to the failure of its innovative videodisc player, the “Selectavision,” which could have become a competitor to the Betamax and VHS videotape systems. But due to poor management, it was brought to the market too late.

By 1986 RCA was so weak that its rival (and former co-owner) GE bought the company and dismantled it, selling off most of its parts, including the RCA name and the consumer electronics business. Today, the RCA name is owned by Thomson, a French company, while the German conglomerate, Bertelsmann, owns the RCA record division. The corporate headquarters was moved to Indianapolis, where RCA had once operated a large manufacturing facility. Today, Thomson manufactures consumer electronics in a variety of countries and sells them under the RCA and GE names.


Sunday, September 13, 2009

Sunday: 13 September 2009

today in miss Azura class, we learn about the video production and multimedia networks which is in Chapter 7. Here, this topic consist of a video communication, analog tv srandards, digital tv (DTV) and high-defination tv (HDTV), multimedia standards, video and multimedia prospects. lastly, before miss Azura diamiss us, she remind us about the third assignment which we have to submit it by today..;D..

Thursday, September 3, 2009

RAZAKSAT SATELLITE


Malaysia’s innovation pride, the RazakSAT satellite, is all set for a lift-off as scheduled on Tuesday from Kwajalein Atoll in the Marshall Islands.

Science, Technology and Innovation Minister Datuk Dr Maximus Ongkili, the ministry’s deputy secretary-general (Policy) Datuk Dr Sharifah Zarah Syed Ahmad and senior officials arrived in Guam today to witness the historical launch via live webcasting, a statement from the Ministry of Science, Technology and Innovation (Mosti) said today.

It said upon arrival, the minister and his delegates were briefed on the readiness of the launch by Astronautic Technology (M) Sdn Bhd chief executive officer Datuk Dr Ahmad Sabirin Arshad.

The minister was also informed that the satellite and launch vehicle, the Falcon 1, which is operated by United States’s Space Exploration Technologies (SpaceX), have now been erected on the launch pad at Omelek Island, the launch site for Falcon 1.

The 180kg remote sensing satellite was designed, developed, built and tested locally and it will also be the first remote sensing satellite to orbit the Equator.

Named after Malaysia’s second prime minister Tun Abdul Razak Hussein, it will orbit the Near Equator Orbit (NEqO) at a nominal altitude of 685km.

The orbital location will allow increased frequency in the image observation of the Earth’s surface and environment.

RazakSAT will carry a high resolution camera which can capture images from space for differnt applications such as precision farming, landscape mapping, disaster mitigation, urban and road network planning, which will not only benefit Malaysia but also other countries along the equatorial region.

The images could also be used to study various meteorological phenomena.

According to the statement, prior to this, the launch if the Low Equatorial Orbit (LEO) satellite was delayed due to vibration problems on the launch vehicle.

However it said all issues related to the problem had been rectified with upgrading carried out by SpaceX.

“I am satisfied with the preparations and necessary steps taken by ATSB and SpaceX to ensure a smooth launch. We hope all Malaysians will pray for the successful launch of RazakSAT,” Ongkili said.

During the visit to Guam, Ongkili and his delegation are also scheduled to visit a marine laboratory and marine heritage and oceanography centre at the University of Guam

Tuesday, September 1, 2009

...MESH TOPOLOGY AND TREE TOPOLOGY...


MESH TOPOLOGY

Mesh Network is a network where all the nodes are connected to each other and is a complete network. In a Mesh Network every node is connected to other nodes on the network through hops. Some are connected through single hops and some may be connected with more than one hope.

While the data is traveling on the Mesh Network it is automatically configured to reach the destination by taking the shortest route which means the least number of hops. Data travels by hopping from one node to another and then reaches the destination node in a Mesh Topology Network.

An example of a Mesh Network is the Mobile Adhoc Network or MANet. The entire Mesh Network is continuously connected. Being completely connected does not mean that Mesh Network is dependant on each and every node of the network. Even if one node fails in the Mesh Network the network finds an alternate route to transfer the data. It is called the self healing technology where it receives data one way or the other.

The Mesh Network is based on a very sensible concept and has lesser chances of a network breakdown. There are so many possible combinations of routes and hops a data transfer can take that it will reach the destination one way or the other. It is highly unlikely that all the nodes in a single Mesh Network will break down at any given point of time.

Wireless Mesh Networks

Wireless Mesh Networks work based on the radio frequencies and was originally developed by the army to be able to communicate. The reliability factor is high in any kind of Mesh Network. There are three types of wireless Mesh Topologies.

• Fixed Wireless Connections
Peer to Peer or Adhoc Networks
• Node to Node

Fixed Mesh Networks

The fixed Mesh Networks will work only in the specified location and they are not mobile networks. They are meant to be used in a limited surrounding with boundaries. The location of nodes in affixed Mesh Network is all pre determined and they are not interchangeable.

The fixed Mesh Network does not work on line of sight like the other types of Mesh Networks. The total number of hops in a fixed Mesh Network is usually fixed and also short. There may not be many nodes as this kind of Mesh Networks exist within an office or building. More often than not the data travels ion a specific direction.

Peer to Peer Mobile Networks

In a peer to peer mobile network the individual devices connect to each other using the Mesh Network. The peer does not require connecting to the main node and they can still communicate from one device to another device by taking the shortest possible data transfer route. However many experts believe that in the peer to peer Mesh Networks the problems with scalability in terms of time taken for data transfer is questionable. The device has to know to transmit the dat

a in the most optimal path and the entire data transfer or depends on this single factor. If the device is incapable then the whole purpose of using it in a peer to peer connection is lost.

Node-To-Node Network

A Node-To-Node network is a combination of fixed Mesh Network and the mobile Mesh Network. In the node to node network a network cloud is introduced and all the nodes are configured to use the network cloud to connect to each other. So this feature makes it mobile and also the network is fixed because all the nodes of the same network connect to one single network cloud.


TREE TOPOLOGY

Tree topology is a combination of the bus and the star topology. The

tree like structure allows you to have many servers on the network and you can branch out the network in many ways. This is particularly helpful for colleges, universities and schools so that each of the branches can identify the relevant systems in their own network and yet connect to the big network in some way.

A tree structure suits best when the networks is widely spread and vastly divide into many branches. Like any others topologies, the tree topology has its advantages and disadvantages, A tree network may not suit small networks and it may be a waste of cable to use it for small networks. Tree topology has some limitations and the configuration should suit those limitations.

The tree topology follows a hierarchical pattern where each level is connected to the next higher level in a symmetrical pattern. each level in the hierarchy follows a certain pattern in connecting the nodes. Like the top most level might have only one node or two nodes and the following level in the hierarchy might have few more nodes which work on the point connectivity and the third level also has asymmetrical node to node pattern and each of these levels are connected to the root level in the hierarchy. Think of the tree that branches out in various directions and all these branches need the roots and the tree trunk to survive. A tree structured networks is very similar to this and that is why it is called the tree topology.

ADVANTAGES AND DISADVANTAGES; COAXIAL CABLE, FIBER OPTIC CABLE & TWISTED PAIR

COAXIAL CABLE
- advantages
  • sufficient frequency range to support multiple channel, which allows for much greater throughput.
  • lower error rates. because the inner conductor is in a Faraday shield, noise immunity is improved, and coax has a lower error rates and therefore slightly better performance than twisted pair.
  • greater spacing between amplifiers coax's cable shielding reduces noise and crosstalk, which means amplifiers can be spaced farther apart than with twisted pair.
- disadvantages
  • more expensive to install compare to twisted pair cable.
  • the thicker the cable, the more difficult to work with.
FIBER OPTIC CABLE
- advantages
  • system performance
  • greatly increased bandwidth and capacity
  • lower signal attenuation (loss)
  • immunity to electrical noise
  • immune to noise (electromagnetic interference and radio frequency interference)
  • less restrictive in harsh environments
  • overall system economy
- disadvantages
  • fiber optic component are expensive
  • fiber optic transmitters and receivers are still relatively expensive compared to electrical interfaces
  • the lack of standardization in the industry has also limited the acceptance of fiber optics.
TWISTED PAIR CABLE
- advantages
  • using telephone wires are their relative low cost and their availability
  • handled a data flow of up to approximately one megabit per second (Mbps) over several hundred feet
  • small local area network with a limited number of users, twisted pair is an ideal choice because it is both inexpensive and easy to install.
- disadvantages
  • susceptibility to signal distortion errors and the relatively low transmission rates they provide over long distances.