Means communication at distance Tele-communication Means communication at distance

Not a New Idea

Early developments for passing messages

The modern era Telegraph started in Europe in 1830s Electronic transmission of morse code Under the Atlantic in Cables Radio transmissions from early 20th Century Usually one way though there were radio phones Use radiowaves Telephone patented 1876 Alexander Graham Bell (but others involved!) Converts sound into electronic messages in mouth piece Message converted back to sound at other end. Used electric cables

The phone

Changes to the phone Changed to optical fibre Became mobile Used satellites for long-distance Now use microwave signals boosted by phone masts

Basic physics Energy Understanding technology Use longer parts of EM Spectrum Understanding Basic grasp of wave behaviour technology Optical fibres Microwave transmissions Digital signals

Transverse: em spectrum Waves Longitudinal: sound Transverse: em spectrum

Key terms 1. When waves interact you get constructive or destructive interference 2. Waves bouncing off things is called reflection 3. Waves passing through materials change speed and therefore direction at boundaries. This is called refraction.

Wave interference

Reflection

Refraction

Total internal reflection

Optical fibre

Why replace copper 1. 2. 3. Fibre bundles much finer Much lighter Carry much more information. Separate messages can pass down same cable simultaneously.

Signals

Satellite transmission

Attenuation Over a distance the energy in a signal is dissipated as it spreads out so the signal at any one point gets weaker. This is why we need phone, tv and radio masts to boost the signals. Imagine as you move away from a light source in the night – its effect gets less. It is just the same with radiowaves and microwaves.

Electromagnetic spectrum

EM spectrum telecommunication 1. light – optical fibres 2. IR remote controls 3 microwaves Telephones, GPS 4 UHF TV 5 Radio waves Radio transmissions

A bit of physics V = λ x f Where v = velocity λ = wavelength f = frequency In the case of em spectrum v is called c as in Einstein´s famous equation E = mc² C = 3 x 108 m/s Rearrange the equation to find the frequency of 15 cm microwaves.

1. 2. 3. This means As wavelength gets longer frequency gets lower High frequency waves attenuate more quickly so need regular boosting 2. This is why we need lots of phone masts But relatively few radio masts. 3.

Types of signal

Practical difference Analogue Digital

Benefits and disadvantages of analogue Allows much greater info. storage Easier to reproduce Easier to send and transport Looses information

Does it matter? Then Our brain perceives the Information to be analogue Why not? Our senses sample information Like a digital signal Digital loses information But does it matter? No!

e.g. film A moving picture is made up of 24 still frames a second Our eyes use this discrete information and our brain perceives it as if we were looking at movement in normal life. Conversely digital allows us now to project many more frames per second giving much greater resolution e.g phantom cameras.

Challenge: A poster Financial and business benefits Timeline of the development of telecommunications Social benefits Financial and business benefits Must include benefits to poor people Environmental costs Social costs Must include an academic article on effects on society or individual Explain a key area of telecommunicational technology

Rubric Marks Timeline Social benefits Social costs Economic benefit Environmentalcosts Example of technology Effort 1 A comment 2 A relevant statement or comment 3 Some elements of task acheived 4 Generally achieved with some omissions or faults. 5 Includes all elements with times to scale Explains how it has changed our lives for the better with before and after examples supported by quotes Explanation of harm to society clearly put and based on a referenced article Clearly explains how people benefit comapred with before and must include example alleviating poverty Identifies pollution issues at all stages of life cycle with examples of types of harm One area of technology explained in detail with diagrams Full effort recorded by teacher and confirmed by team leader.