Wireless technology. Electromagnetic waves Transmission of radio-waves and microwaves Transmission of infrared waves Radio wave-based networking.

Wireless technology

Wireless technology

Electromagnetic waves

Transmission of radio-waves and microwaves

Transmission of infrared waves

Radio wave-based networking

Electromagnetic waves

• Electromagnetic waves:

• Transmit data across the atmosphere.

• Are categorized according to frequency ranges.

• Frequency ranges are based on repeating patterns of a waveform.

• One complete waveform is called a cycle.

• Frequency is the number of times a cycle occurs in one second.

• Include:

• Radio waves

• Microwaves

• Infrared waves

Crest

Trough

One cycle

Electromagnetic spectrum WavelengthMore

Wavelength

• The length of a wave is the distance between two crests or two troughs.

• The frequency of a wave is the number of times a cycle occurs in one second.

• The Greek letter, lambda (λ) is used to indicate wavelength.

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Wave Frequency

Radio waves 3 Hz - 300 GHz

Microwaves 300 MHz - 300 GHz

Infrared waves 300 GHz – 405 THz

Wave frequencies

Transmission of radio- and microwaves

• Works on the principle of producing a carrier wave.

• A carrier wave is a set frequency that is used to carry data.

• A carrier wave is mixed with the data signal. This process is called modulation.

• A carrier wave must be at a higher frequency than the digital data signal.

• The frequency range occupied by a modulated carrier wave is called the bandwidth.

• A carrier wave with a width of 200 kHz has a bandwidth of 200 kHz.

• The bandwidth of the carrier wave is referred to as a channel.

Carrier wave

Signal wave

Frequency modulated wave

Carrier wave

Signal wave

Amplitude modulated wave

Transmission of radio- and microwaves

• Modulation takes place during radio broadcasting. A transmitter generates the carrier wave and modulates information into the carrier wave.

• A receiver receives the modulated wave and demodulates it.

Transmission of infrared waves

• Infrared waves lies in between visible light spectrum and microwaves. It has wavelength of 700 nm to 1 mm and frequency ranges from 300 GHz to 430 THz.

• Infrared waves is transmitted as a series of digital light pulses.

• Infrared waves are used for very short range communication purposes such as television and it’s remote.

• Infrared travels in a straight line so they are directional by nature.

Radio wave-based networking

There are three basic types of radio wave-based networking.

• Wi-Fi:

• Wi-Fi means wireless fidelity.

• Wi-Fi operates on a higher frequency (2.4 GHz – 5 GHz) than cell phones.

• Uses radio-waves to transmit information to and from the Internet or computer.

• An access points act as a central transmitter and receiver of wireless radio signals.

• Most computers and other devices contain built-in access points.

USB type wireless access point

• Information from the access point is send to a wireless router.

• The router converts it to radio-waves and beams it to a computer.

• The computer interprets the radio-waves with the help of hardware (Access point) and software.

Radio wave-based networking

Wireless router Mobile wireless router

• Bluetooth:

• The name ’Bluetooth’ reflects the Scandinavian origins of the technology. It is named after a 10th century Danish viking, King Harald Blåtand (translating as 'Bluetooth' in English).

• Bluetooth is a short range wireless system designed for limited distances.

• The frequency ranges from 2.4 GHz – 2.585 GHz.

• A Bluetooth network is referred to as a piconet or Personal Area Network (PAN).

Radio wave-based networking

A piconet Two piconets linked

How does Bluetooth work?Bluetooth in medicineBluetooth and toys

• Cellular technology:

• A cellular network or mobile network is a wireless network distributed over land areas called cells, each served by at least one fixed-location transceiver, known as a cell site or base station.

• Radio-waves connect to designated areas referred to as cells.

• A remote device (e.g. Mobile phone) connects to a radio transceiver within a cell.

Radio wave-based networking

Transceiver (base station)Cell

How does a cell phone work

Electromagnetic spectrum

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