Radio Communication and the Mobile Phone

TECH 1002 Directed Study Task Week 16 Andy Heard

RadioFor over a hundred years, radio has been used as a means of communication. It is argued Gugliemo Marconi was responsible for the very first radio transmission in 1895. However, Alexander Popov publicly demonstrated the transmission of radio waves several months before Marconi, but failed to register a Patent.

Both men arguably contributed significantly to the invention of radio communication.

Gugliemo Marconi

Alexander Popov

Because of these men’s foresight 60% of the UK population enjoy the benefits of mobilephone use today.

What is a radio wave?

Radio waves are a type of electromagnetic radiation with wavelengths in the electromagnetic spectrum. Naturally-occurring radio waves are made by lightning, or by astronomical objects. Artificially-generated radio waves are used for fixed and mobile radio communication, broadcasting, radar and other navigation systems, satellite communication, computer networks and countless other applications

Radio communication using Amplitude Modulation (AM)

A radio frequency wave used for radio communication is called a ‘carrier wave’. If the radio wave is to contain more information, such as speech, this needs to be added to the carrier wave; a process known as ‘modulation’. For AM transmission an electrical signal from a source is used to vary the amplitude (height and strength) of the carrier wave.

This is so the amplitude of the radio frequency carrier wave is made proportional to the size of the electrical modulating signal.

FrequenciesAn advantage of radio waves is the wide range of frequencies available. So thus many applications can use radio waves.

In the UK, AM radio uses frequencies between around 180kHz and 1.6 MHz. Television ranges from around 470 to 854 MHz. Cellular mobile services (a mobile phone works via a cell) operate within frequency ranges 872-960 MHz, 1710-1875 MHz and 1920-2170MHz.

Mobile Phone Networks 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. Base stations link mobile phones to the rest of the mobile and fixed phone network.

After reaching a base station it is then transmitted to the main telephone network.

The huge amount of base stations is required because base stations can only carry a limited number of calls at any one time. This is because the amount of radio spectrum allocated to each mobile phone operator is limited.

Cellular Radio Each base station provides radio

coverage to a geographical area, a cell. As a caller moves from one cell to another the base stations transfer them through central switching centres which connect base stations to one another.

To make sure a mobile phone user always remains within range of the base station the individual cells overlap at the edges. Mobile phone communication would not work without sufficient base stations in the right locations.

Types of Mobile Phone Technology

Global system for Mobile Communications (GSM)

Universal Mobile Telecommunication System (UMTS)

Within the UK Cellular radio networks operate in one of 3 bands; 900 MHz, 1800 MHz and 2.2 GHz using 2 different technologies, GSM and UMTS. GSM: The international, pan-European operating standard for the current generation of digital cellular mobile communications. Enables mobile phones to be used across national boundaries. In the UK is operating in the900 and 1800 MHz frequency bands.UMTS: The next generation of mobile phone technology, expected to result in widespread use of video phonesand access to multimedia information. In the UK is operating in the 2 GHz region.

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