Telecommunication is the transmission of signals, signs, messages or information of any nature by wire or radio

Cell phones

  • A microchip inside a cell phone takes the vibrations of your voice into a tiny microphone which turns it to strings of numbers (encoding) that are transmitted in form of radio waves by means of the phone’s antenna to the nearest cell phone mast.
  • The mast works in the same way as the tiny antenna in the phone, transmitting the radio waves across to the next phone mast and the next, until it reaches the one closest to the person you are trying to phone.
  • From that mast it is transmitted to the other person’s phone where the encoded digital message is decoded back into electrical pulses that get the speaker of the receiver vibrating to produce sound waves.
  • The signal is analogue at first and the cell phone digitalises it before sending it off to a mast. The signal quality is very good i.e. there is very little loss of energy and sound quality
  • The signal is converted back to analogue by the other cell phone and into sound waves for the other person to hear.


  • The internet works similar to cell phones and regular phones, converting information into a string of numbers and transmitting these through a combination of radio waves through antennas, electrical pulse through phone lines and pulses of lights through fibre optics. In order to make this possible, the computer chips in the computer break up information into smaller, addressed packets.



  • Transmits vibrations created by a person’s vocal cords through a wire to a receiver. – The signal is analogue from sender to receiver.
  • When speaking in the mouth piece, the voice makes the diaphragm in the microphone inside vibrate converting sound energy into electrical energy. The electrical energy travels from the phone through exchanges to another phone where the diaphragm in the loud speaker inside the ear piece of the receiving phone converting the incoming electrical energy back to sound energy.


Signal transmission

– There are two types of signals are used in telecommunications i.e.

  1. Analogue signals is made up of a continuous wave that varies over time in both amplitude and frequency. The wave contains the message that is being transmitted.
  2. Digital signal is an electrical signal that has been chopped into bits which are in form of pulses that can only take two values either 1 or 0. Therefore a digital signal is made up of series of ones (on) and zeros (off).


Media for signal transmission

– Signal carry the message and is transmitted in two ways i.e.

  1. Guided media in cables e.g. optic fibre, coaxial cables and sheathed pair cables
  2. Wireless media e.g. Wi-Fi

Transmission in cables

  • Optic fibre sends information coded in a beam of light down a glass pipe in modes. The light that carries the signal cannot leave the cable but continue to totally internally reflect off the edges of the glass until it reaches its destination
  • Sheathed cables and coaxial cables all have copper wires through which electrical signal travels.
  • The signal is analogue from talker to listener. The signal travels by electrical pulses through copper wires or by light through optic cables.
  • The signals via copper cables tend to attenuate (lose energy) along the way. This is why amplifiers (signal boosters) are needed along the way. However there is less attenuation in optic cables and the signal speed is very fast sent via light. Optic fibre can also carry far more data than copper cables


Wireless signal transmission

  • A wireless network uses radio waves
  • Wireless signals are electromagnetic waves travelling through a pathway from a transmitter, into space and finally receiver. The space of the pathway is unguided, so waves generally transmit in all directions and any appropriated antenna can receive the signal.
  • A computer’s wireless adapter translates data into a radio signal and transmits it using an antenna and waves are formed around the antenna which can travel some distance depending on the strength of that energy. A wireless router receives the signal and decodes it. The router sends the information to the internet thus the router relay connections to and from the internet.
  • When a device sends out a wireless signal, it is called a transmitter
  • When another device picks up that wireless signal and understands the information, it is called a receiver
  • Wi-Fi is essentially two radios communicating back and forth that use lower power and broad cast over much shorter distances. Wi-Fi is a method of linking wireless devices to the internet through a shared connection point (router) which typically makes a wired connection to a telephone or cable line.

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