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## Telecommunication technology fundamental principle

Telecommunication is a technology and it is very very important for our daily life made easy in modern era without this technology our life will stop this is the importance of this technology we will discuss from basic point of telecommunication to advance level in this topic first question is what is telecommunication ?.
Tele - means at a distance, over a distance.
communication - means information transmitted or conveyed a verbal or written message.

Telecommunication means information verbal or written transmitted over a distance or large distance by using the technology is called telecommunication before we go to telecommunication details we need to understand sound wave creation and its characteristics because our voice is sound wave our first question is how sound wave is created ? see the picture below.

From the above picture it is clear that vibration is source of sound and medium required to travel sound without medium sound can't travel from above picture air is medium tiny particle of air medium get vibration and start oscillation back and forth and transfer energy forward to other tiny air particle and continue this energy transfer further and sound wave travel from source to observer ear now this vibration is experience by observer ear and send a signal to mind hence a sound is listen by observer.
air tiny particle does not travel only disturbance that is energy travel from source to observer so this is called sound is a wave hence waves can transport energy through a medium without transporting a medium itself if air particle travel then it is called wind it is important point to remember.
velocity of sound depends upon medium in all medium like air, metal,gas, water velocity of sound is different it is important point.
Sound wave we can't see but we experience and listen only so visual representation of sound wave or parameter involve in sound wave see the picture below.

from above picture it is clear that sound wave travel through air medium like back and forth motion of air molecule generating sine wave and parameter involve amplitude, time period and frequency mentioned above picture.

### if amplitude becomes larger volume of sound increases, frequency is number of oscillation per second f = 1/T Hertz if time period is decreases frequency increases higher node has higher frequency and lower node has lower frequency human can hear lower frequency 20hertz and higher frequency 20,000hertz below and above this range of frequency human can not hear dog can hear above 20,000 to 40,000hz.

wavelength of sound wave when sound travels through air medium air compressed and decompressed the distance between two compressed region or decompressed region is called wavelength of sound wave ⋋ since wavelength is distance it is measured in meter now speed of sound wave is speed of the non compressed air molecules in non humid 20 deg centigrade air speed of sound wave is  343m/s "wave  speed " is NOT molecules speed.
speed of sound is the disturbance moving with speed we called this wave longitudinal because the wave moves parallel to molecules oscillation other wave is transverse wave in this case wave moves perpendicular to the molecules oscillation string and water wave is example of transverse wave.
in longitudinal wave one complete oscillation or time period wave moves length of wavelength hence speed of wave = distance/time  =     ⋋/T = ⋋f hence speed of wave v = ⋋f this formula is valid for all wave not only for sound wave.
now important point for this formula v = ⋋f  if we increase frequency then speed of wave is not increase wavelength is decreases if we increase wavelength then frequency is decreases speed of wave is not increases then what factor speed of wave depend its only depends upon medium like air, gas, metal, liquid medium speed can change after changing properties of medium.
speed of sound depend upon two factor of medium one is stiffness or how rigid is it means stiffer  medium =  faster sound waves second factor is density 𝛒 denser medium = slower sound waves these two factors are taken into account for speed of sound

v = √B/𝛒  where B = Bulk modulus "how hard to compress"
𝛒 = density of medium "how much mass per volume " hence from these factor in iron sound travels 14 times faster than air medium    hence on a railway track if you put your ear to listen train coming sound 14 time faster than a normal person listen sound near you   hence sound speed Vsolid>Vliquid>Vgases.
density play important role in 20deg centigrade speed of sound = 343m/s but in 0deg centigrade speed of sound = 331m/s hence the change the properties of medium can change the speed of sound i hope that you have enjoyed learning basic concept of Telecommunication technology fundamental principle thanks for reading we will continue in next post technology.
dated 25th Aug 2018.