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## Student portal for Physics and technology

This website is Student portal for Physics and Technology learning free education in technology section we will learn complete information about Telecommunication because today Telecommunication has became our life without this technology our life is dead like mobile,TV, internet to understand telecom technology and its principle we have to study basic communication principle and parameter so today our topic is about Sound wave complete information we have already study in previous post some basic and important point about sound wave and its parameter involved in sound wave you can refer that post to understand here in this post we will learn more details about wave there are three types of waves

1 Mechanical wave (the disturbance of medium particle is transported material medium is required example water waves, sound waves )
2 Electromagnetic wave (the disturbance of electric and magnetic field is transported there is no requirement of material medium it is electric and magnetic field which travel in free space or vaccume example light, heat, radio waves )
3 Matter waves (A complex wave linked with moving particle)
Communication system:
communication is the act of sharing or exchange of information with someone or any entity for example speaking, by writing or sending radio signals.
As we have study sound wave is mechanical wave sound wave is longitudinal wave tinny air particle is medium as it propagate from one point to other point its amplitude decreases due to friction this phenomenon is called damping due to which volume is decreases and it can be up to certain distance only audible but we want that this voice to be transmitted to a long distance hence we required Telecom technology  see picture below.

See in first picture one person is speaking and other is listening means first person is communicating with other person when first person is speaking his vocal cord is generating vibration and due to this vibration air molecules start vibration and transferring to other person ear sensation here it is simple communication by speaking as usually we talk with any person.

In second case you have seen children made telephone with using machise box with string one speak and other listen they communicate over string now our main concern is for long distance communication like 20km, 100km or more your voice can't reach by simple speaking in this situation you have to use tools like mobile or telephone to send your voice this sound voice is converted into electrical signal this electrical signal convert into electromagnetic signal and reaches to the other person in form of electromagnetic wave other person mobile catch this signal and convert back to sound wave signal hence other person listen this sound this is the way of long distance communication system this is called wireless communication system only mobile communication is not wireless communication system there are many wireless communication like TV, Radio remote all are wireless communication system TV center broadcast program using electromagnetic wave to satellite and D2H connection at your home antenna catches signal from satellite and send it to TV and you watch the program on TV screen similarly for radio may be tower between them using  radio signals see in picture number 3 here medium is free space or medium is also called channel see below in block diagram equipment use in communication system.

From the above picture when we speak something in microphone this signal becomes electrical from microphone and goes to modulator a high carrier frequency signal is modulated with original electrical signal because our voice signal frequency is low to send it through space need to modulate and amplify means bust the signal to travel long distance and then finally transmitted through antenna as electromagnetic wave in free space on other side receiving antenna is there in mobile receive the electromagnetic wave from space and demodulate high carrier frequency and send original electrical signal to amplifier bust this signal because this signal is weak and send to loudspeaker which convert this electrical signal to voice signal then we hear original voice signal or sound wave signal here channel is free space now i hope that you have enjoyed to learn Student portal for Physics and technology thanks for reading.
Dated 1 Sep 2018