Technologies Associated With DAB And FM Radio Computer Science

Essay add: 28-10-2015, 15:43   /   Views: 230

A radio receiver generally will only receive those radio frequencies which are modulated either by FM or AM however, Frequency modulation (FM) yet still quite common and popular way of listening to radio all around the world, its better reception and less interference sound quality makes it an ideal way to listen radio with features no where near found on Amplitude modulation (AM).For radio transmission to be broadcast on FM mode very high frequency use (V.H..F) Between 30MHZ-300MHZ where as AM requires just 30 KHZ-30 MHZ.

Digital audio broadcasting (DAB) is another and yet quite new way of broadcasting programs over the air digitally, its all together different way of broadcasting programs as compared to FM or AM, more then 80% of the UK inhabitants is covered by DAB transmission .DAB uses multiplexing so that many frequencies can be combined into one. DAB in comparison with FM got more choice of stations, clear crystal sound quality, digital display and many other features.

Digital audio broadcasting

DAB is not the recent invention; BBC (British Broadcasting Corporation) in fact broadcast DAB radio in UK in 1995, with commercial stations appearing some what four years later. There are two main technologies which gives Dab an edge over Fm, the first one is MUSICAM which helps reducing the vast amount of digital information required to be broadcast it eliminates very quite sounds which are covered by other, louder sounds, and efficiently deliver together the remaining information .The second most important technology a DAB uses is COFDM(coded orthogonal Frequency division multiplex) this technology basically helps delivering signals reliably and robustly ,even in the most diverse prone interference, which normally cause wide disruption in fm signals. Here are some of the features of DAB in details.


Dab brings lot more stations as compared to FM, which can be even record as well as pause and rewind.


Dab gives crystal clear sound quality as compared to Fm, where as Fm analogue transmission is affected by multipath disturbance which get interference from the signals bouncing off hills and buildings, but as DAB uses digital transmission it eliminates the chances of signals getting interfere by those natural resort.


Dab gives chance to its users by scrolling name of the station rather then by frequency, so no hustle of remembering frequencies any more.


Dab radios have an LCD display, which let its users know which track as well as station or artist is on.


Despite all the big factors which distinguish DAB from Fm such as clear sound still Fm is the most popular way of listening radio in almost every country .It works on very simple rule which requires a carrier to transmit information and a receiver to catch it. It uses very high frequency which helps spreading signals more widely, However, radio waves from a FM transmitting aerial travels in space wave which is very suitable for Ultra high frequencies such as requires in radar, satellites and many others. Space wave travels more or less straight line from transmitter to receiver, it can deliver wave at range of about 150km on Earth if transmitting aerial is high above the ground. An FM transmitter is same as that for AM but the difference is in Radio frequency carrier which is changed by audio frequency signal in Fm. However, receiver is more or less same as for AM and both works on super heterodyne principles which offer both great selectivity as well as great sensitivity. There are two main components apart from receiver and transmitter which play a vital role in both Fm or Am receiver the first one A.G.C. (Automatic gain control) and the other is A.F.C (Automatic frequency control) A.G.C helps avoiding adjusting the volume every time when there is change in station or signal, where as A.F.C helps restoring distorted audio frequency out put. Here are some of the common features of a FM radio.


Fm radio signals are generally quite stronger than as of DAB OR AM although Dab got good sound quality .Fm signals can be easily found almost any where.


Despite of having extra channel choices in Dab still Fm has some what more good station sound quality than Dab because in Dab channels are compressed so that more channels can be squeezed into available bandwidth.


Fortunately now days a FM radio would be easily available for as less as one pound, which shows the popularity as well as ease through which it can be created .on the other hand Dab is relatively expansive where a Dab radio would typically cast around 30 pounds but however, prices are seems to be dropping now.


Every communication system requires some sort of way to send signals to those outside, it can be either via cable in telecommunication or radio waves in broadcasting media .In radio or TV generally audio frequency signals can be send directly via cable but however in general it is now done by a carrier such as FM, AM or Digital satellite.







Diagram above illustrate the typical process of sending and receiving audio broadcasting, First of all source sends information signals which then modulated by the process of modulation and send it by transmitter then at the end aerial of radio receives that signals and demodulate it to make it in useful form and at the end we can listen to that information by speaker or headphones.

In order to listen to FM broadcasting on radio sets radio broadcaster requires a transmitting antenna to send audio wave once they modulated and a receiver at the other end to receive it, however in FM radio it self there are several main components which plays an important role and these components are.




Fm Transmitter

A fm transmitter is important part of any audio device, a fm transmitter basically use where one has to convert its audio signal to fm signal and then broadcast to their FM radio, A fm transmitter is though same as Am transmitter but the frequency of the radio frequency (R.F) carrier in Am is changed by the Audio frequency signal in Fm. Diagram below illustrate about how Fm transmitter works.


Audio signal

Amplified Audio signal Modulated R.f Carrier








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