on videoo How does your mobile phone work?



How does your mobile phone work?
For most of us, a mobile phone is a part of our lives, but I am sure your curious minds have always been struck by such questions as how a mobile phone makes a call, and why there are different generations of mobile communications. Let's learn the technology behind mobile communications. Starting with the walkie talkie vs mobile phone.

Walkie talkie v/s mobile phone
To understand the sophistication of the cell phone let's compare it with a walkie talkie. Walkie talkies are half duplex devices that mean when 2 people communicate; use the samefrequency. So the only one person can talk at a time. Whereas a cellphone is a full duplex device that means you can use one frequency for talking and a second frequency for listening. So both people can talk on the call at once.

How is your voice converted into electromagnetic signals?
Let's take an example, when you speak on your phone, your voice is picked up by your phone's microphone. The microphone turns your voice into a digital signal with the help of an MEMS sensor and IC (refer Fig 1a). The digital signal contains your voice in the form of 0s and 1s. An antenna inside the phone, receives these 0s and 1s and transmits them in the form of electromagnetic waves (refer Fig. 1b). Electromagnetic waves transmit the 0s and 1s by altering the wave characteristics such as the amplitude, frequency, phase or combinations of these. For example, in the case of frequency, 0 and 1 are transmitted by using low and high frequencies respectively.

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