New technologies

The wired transmission consist of the use of a physical support for transmission. It is used when you need a high quality of transmission or when the environmental accidents or the weather are extreme, makes more difficult the transmission of electromagnetic waves. One of the first supports as used was wire cable.

Advantages

Disadvantages

cheaper

reliability

Very fast

The installation is difficult

Physical access

Difficulty and expansion

expectations

Conventional cable:It is a copper wire, protected by an insulating cover.

Transmitting the converted electromagnetic signal

into electrical current, or a series of specific

impulses.

Often used in wireline systems

Coaxial cable:-This cable is a moderately immne to outside electromagnetic interference compared to conventional cable.

-It is also well suited for broadband applications.

-Expensible and inflesible

Optic fibre cable:-Has much grta transmission than the other tipes of cables.

-It is inmmune to outside interferences.

-It is used in the higher rate communications places.

The routing of signals is based on the transmission of light signals

through a canal inside which the total reflection occurs.

Inside the core of the fibre are transmitted beams of light that are

reflected and continue extending.

USE OPTICAL FIBER

The core formed by high transparency materials so that losses are lower.

AdvantagePossibility of sending of a same fiber up to 100 light beams and high speeds are achieved

DisvantageFiberglass is fragile and difficult to repair, connections with it are difficult and is a expensive than other cable

The signals in the form of light must also become electrical signals to be used by devices that are connected through optical fiber.

Is applied in the field of communication when necessary is a great transmission.

Analogical telecommunications

It is a transmission systems of electromagnetic signals.

Very fast

Characterics Electromagnetic waves

Intensity and frecuency controlled

TelephoneThe operation is based on the conversation of sound waves in electromagnetic waves. These are transmitted by cable or waves radiated. It is an alternation between the emitter and receptor that allows a real-time conversation

Fundamental objects Microphones

• There are a lot of types of microphones (coal, dynamic, ribbon). But all of these are based in the same process: waves vibrate a membrane is used to modify and modulate an electric current.

Headphones

• They do the opposite that microphone, they transform electric current into sound waves. For do this they used the electromagnet.

THE HISTORY OF THE TELEPHONE

1854: Antonio Meucci invent an electromagnetic for the transmision of voice.

1876: Alexander Graham Bell he develops an operating telephone.

1887: First telephone lines in Germany.

1889: Automated telephone system.

1891: First telephone cable service in the USA and in France.

1947: First movil phone. The sistem expanded since 1893.

1952:First Telecomunication satellite, it can recibed and transmited waves of radio and television.

Nowadays: All the telephones are avanced a lot, and we have very modern movil phones.

THE RADIOFUNCTIONING

It turns the sound in electrical impulses

The sounds are caught by the microphones

The sound comes to the antenna

There takes place an electrical variation, which finally comes to your house

The recipients of your radio transform the sign into sound

COMPONENTS System of emission (station of radio)

System of transmission (high or clear places)

System of receipt (every radio set)

Modulation in frequiency (FM):

variable frequiency - Carrying wave constant extent

- Reduces not wished noise interferences distorsions on the sound

- Quality of de trasmission is improved

- Minor scope

FREQUENCY

Modulation in extent (AM):

constant frequency - Carrying wave variable extent

- Typical of issures of short, average and long wave

- Great scope

HISTORY

TELEVISION

- Telecommunication medium - Transmitting and receiving moving color images and sound - Uses a broadcasting mechanism - Recipient : television - Transmission can be made by

-Radio waves

-Networks cable television

- Satellite television

To realize a television broadcast we need: camera to recive the images and a system to record the sound.

TREATMENT OF THE IMAGE

Images in color 3 faeces of electrons

Red

Green

Blue

London

In 1911 the physicist russian Zworykin realizes the first experimental transmission of a static image.

On 25 December 1926, Kenjiro Takayanagi demonstrated a TV system with a 40-line resolution.

Eperiments of Guillermo González Camarena began in 1931 and led to a patent for the color television in 1940.

In 1950 takes place the invention of the system of three cannons for the television in color.

In 1972 are formed the first commercial nets of television by cable, in EEUU.

In 1979 is invented the first recipient of television with a flat screen of liquid crystal.

The World Day of the Television is celebrated on November

21 in commemoration of the date in which the first World Forum

of Television was celebrated in 1996 in the United Nations.

THE END Cristina Céspedes

Laura Fernández

Paloma González

Lourdes Sevilla

Julia Soubrier