how data is transferred over the air

The science behind how data is transferred over the air

Communication

Have you ever wondered how data is transferred over the air? The reason why its possible to download your favorite song on WiFi or send your loved ones a Whatsapp message yet they so far away? Well this is what we are going to discuss today. Its not so complicated after you understand the basic concepts that make this possible.

Before i can explain how data is transferred over the air you need to know what communication is. Communication can be defined as the imparting or exchanging of information by speaking, writing, or using some other medium. Imagine that 2 people A & B are standing on opposite sides of the road “A” is holding a torch and the other one “B” is waiting for a signal. Lets say they agree that if the torch is flashed twice it mean that person “B” can cross the road if not he/she should just stand there. There has been no physical contact but they have successfully communicated because “B” understands the message being sent.

In this scenario they used light to carry the information. Communication on radio works in a similar way and the carrier of the information are electromagnetic waves.

How data is transferred over the air

 

how data is transferred over the air

The important characteristics of a wave we need to know for now are the Amplitude, Phase, Period & its reciprocal Frequency. Radio is the transmission of signals by the modulation of electromagnetic waves.

  • Amplitude is the maximum displacement of points on a wave, which you can think of as the degree or intensity of change.
  • Phase is a particular point in time on the cycle of a waveform, measured as an angle in degrees. A complete cycle is 360°.

  • Period (denoted by ‘T’ ) is the time needed for one complete cycle of vibration to pass in a given point.
  • Frequency is the inverse of the period (1/T).

Modulation is a process through which audio, video, image or text information is added to an electrical or optical carrier signal to be transmitted over a telecommunication or electronic medium.

Modulation enables the transfer of information on an electrical signal to a receiving device. The receiver then demodulates the signal to extract the information. Modulation has three different types and It’s achieved by altering the periodic waveform or the carrier. The types are Amplitude, Frequency and Phase modulationdata transmission methods

If you change the amplitude as a function of the information you want to send, you’ve got Amplitude Modulation(AM). If you change the frequency to be a bit faster/slower according to what you want to send, you’ve got Frequency Modulation(FM). There are also other methods like Phase Modulation that are a bit more complicated. And some things use a combination of modulation techniques together, such as AM and PM.

fm

Wrapping it up

As long as the sender and receiver both understand the code, you can transmit information. I do hope this will help you appreciate the Physics behind this concept. Now that you know how data is transferred over the air, do like our Facebook Page and follow me on Linked-in.

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3 Comments

  • This write up is explanatory but didn’t tell us what to do to alter either amplitude to get Amplitude modulation, AM, or frequency to get frequency modulation, FM. That’s list of activities that must be carried out to cause a modulation or alteration. Thanks

    • Dale says:

      Thank you Emughuphel for the question. Firstly, yes the article is introductory because i was trying to keep things simple for those without a Physics or Electrical/Electronic engineering background. However, since you have asked:

      AM modulation can be achieved by passing the RF carrier and the modulating signal into an electronic mixer. FM modulation is done by feeding message into input of voltage controlled oscillator.

      An electronic mixer is a device that combines two or more electrical or electronic signals into one or two composite output signals while an oscillator is a circuit which produces a continuous, repeated, alternating waveform without any input.

      • Thank you for the clarification. I have learnt a new thing today. I am not an Engineer or a Physicstist but did physics at secondary School and loved it. I believe in practicals and not grammar. thanks once again.

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