3. Radio Communication Compared to the relatively new mobile phone technology, radio has been used for communication for over a hundred years. Marconi made the very first radio transmission in 1895. 30 years later two-way radio communication was being used by the military and the police. Today, over 100 years later, 60% of the UK population (approx 40 million people) use mobile phones.
4. What are Radio Waves? Mobile phones and their base stations transmit and receive signals using electromagnetic waves (radio waves), which are emitted by both natural and man-made sources. We are warmed by the electromagnetic emissions of the sun and we see using the part of the electromagnetic spectrum that our eyes detect as visible light. All electromagnetic radiation consists of oscillating electric and magnetic fields and the frequency (which is the number of times per second at which the wave oscillates) determines their properties and the use that can be made of them.
5. What are Radio Waves? Frequencies are measured in hertz or Hz, where 1 Hz is one oscillation per second, 1 kHz a thousand, 1 MHz is a million, and 1 GHz, is a thousand million. Frequencies 30 kHz - 300 GHz are used for telecommunication (including radio and TV), and also comprise the radio frequency band. AM radio uses frequencies 180 kHz - 1.6 MHz / FM radio ranges from 88 - 108 MHz / TV ranges from 470 - 854 MHz/ Cellular mobile services operate within ranges 872-960 MHz, 1710-1875 MHz and 1920 - 2170 MHz. Waves at higher frequencies are referred to as microwaves and are used for radar, telecommunication links, satellite communications, weather observation and medical diathermy.
6. How Radio Communication Works A radio frequency wave is referred to as a carrier wave. To convey information, such as speech, via radio wave the information has to be added in a process known as modulation. For AM (amplitude modulation) transmission, the electrical signal from a microphone produced by speech or music is used to vary the amplitude of the carrier wave, so is it proportional to the electrical modulating signal. Other modulations include Frequency (FM) and Digital, which are used for radio broadcasting and mobile phones
8. Mobile Phone Networks Today, over 100 years later, 60% of the UK population (approx 40 million people) use mobile phones. A mobile phone sends and receives information by radio communication. Radio frequency signals are transmitted from the phone to the nearest base station and incoming signals are sent from the base station to the phone at a slightly different frequency. Once the signal reaches a base station it can be transmitted to the main telephone network.
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10. Base stations are connected to one another by central switching centres. Without sufficient base stations in the right locations, mobile phones will not work.
11. Base stations are typically spaced about 0.2-0.5 km in towns and 2-5 km apart in the countryside.
