according to my view, to deal with digital signal is more easy then that of analog. and it also stable so many of the semiconductor circuits run only on dc signals......
i think doubt is clear now....
Digital signals are in general more robust to noise than analog signals, and as a consequence one send more data over a smaller amount of bandwidth than with an analog signal.
Analog signals require higher fidelity than digital signals because digital are either on or off while analog are continuous. A small difference in an analog signal is not detectable while it requires a large difference to turn on into off (digital signal). Error correction is easier with digital signals.
Set top box is basically used to convert the digital signals broadcasted by digital signal broadcasters to analog signals, in case you wish to have your analog tv, but would like to have an access to digital channels. Digital channels definitely have better quality signals than analog and therefore you will have a better picture quality and signal quality even though you have converted the digital signals to analog.
Digital aerials get a better quality of picture than do analog aerials. in addition, digital aerials can get high definition signals over the air,where analog aerials cannot.
Digital phones are more reliable than analog phones. The digital signals are easier to produce and the technology is more reliable than that of analog signal.
Digital signals are capable of carrying more information than analogue signals because digital signals make use of the bandwidth more efficiently by closely approximating the original analogue..
Analogue signals are more vulnerable to error than digital signals. See the related question "Why digital signals are more noise free than analogue signals?" for more details.
You need to make a distinction between analog and digital signals, and analog and digital data. Digital data can be sent on an analog signal by using a modem. Digital data sent on a digital signal is done over a wire using voltage pulses at two or more levels. Digital signals can't travel very far without amplifiers, but analog signals can cover huge distances, such as with satellite communications and even communications with deep space probes.
In the US and Europe they are almost all digital.
Digital signals are "forced" to be either 1 or 0, whereas analog signals are not. This means that a signal of 0.8 will be pushed to 1 in a digital signal and will remain 0.8 in an analog signal, and 0.2 will be 0 digital and 0.2 analog. This means that in order to overwhelm a digital signal the noise must do much more work to be effective. digital signal have only two states analog have infinite states therefore more susceptible to noise
the digital code is binar. so if you get a signal it is absolut. analogue signals can be interfered or altered through interferation.
Bluetooth is a digital communication interface. It tends to be used for audio signals more than other applications so it is often perceived as carrying analog audio. Despite the appearance, it is definitely digital and not analog.
To minimize the distortion of analog signals during transmission Because digital lines transmit signals more efficiently across distances than analog lines Because many telephone networks are moving over to digital interfaces