Analog and Digital Communication...!

The essence of communication is an exchange of information. From the very dawn of human civilizations it has been an endless effort to find means and ways of sharing thoughts, ideas, expressions and messages conveying much value. Language was the first means of communication, be it Arabic or Latin; which was gradually enriched to make the mode of communication more effective. This made possible the exchange of written messages or documented information that could not only be sent to distant locations but could also be handed down the generations and preserved for posterity. Many other modes of sending messages evolved from the early days of human interaction. Tireless endeavors at finding ways and means of conveying information effectively evolved gradually into many time-tested communication techniques.

 The History...

Unfortunately, all primitive modes of communication were restrictive in nature. They were inefficient as far as speed and range of communication were concerned. The main breakthrough came in the late nineteenth century with the discovery of electricity (electronically) when messages were converted into electrical signals by electrical means. There was an unprecedented enhancement of speed of transmission and large distances were covered in very short time. With the invention of telegraph by Morse in 1844, messages started to be sent through cables. Messages were encoded by dots and dashes and sent over cables as electrical pulses of different duration's representing the dots and dashes. The transatlantic telegraph cables were used successfully in 1866. A.G. Bell invented the telephone network in 1876, about forty years after the invention of telegraph. Later, with the discovery of radio wave propagation by Jagadish Chandra Bose, followed by the demonstration of wireless telegraphy by Marconi in 1895, the radio spectrum came to be used for carrying messages or signals. The message was in the form of an electronic signal, which was either carried by cables or beamed into space as electromagnetic waves. Thus, began the era of electronic communication.

Analog or Digital?? 

Lets start off with the definitions:

Analog: 

   An Analog signal is any continuous signal for which the time varying feature (variable) of the signal is a      representation of some other time varying quantity, i.e., analogous to another time varying signal.

                                                                   or

               Analog signal is a continuous signal which represents physical measurements.

Digital :

   Digital signals are discrete time signals generated by digital modulation.

The most important difference for ECE engineers!

                 Difference between Analog and Digital
  

	Analog	Digital
Signal	Analog signal is a continuous signal which represents physical measurements.	Digital signals are discrete time signals generated by digital modulation.
Waves	Denoted by sine waves	Denoted by square waves
Representation	Uses continuous range of values to represent information	Uses discrete or discontinuous values to represent information
Example	Human voice in air, analog electronic devices.	Computers, CDs, DVDs, and other digital electronic devices.
Technology	Analog technology records waveforms as they are.	Samples analog waveforms into a limited set of numbers and records them.
Data transmissions	Subjected to deterioration by noise during transmission and write/read cycle.	Can be noise-immune without deterioration during transmission and write/read cycle.
Response to Noise	More likely to get affected reducing accuracy	Less affected since noise response are analog in nature
Flexibility	Analog hardware is not flexible.	Digital hardware is flexible in implementation.
Uses	Can be used in analog devices only. Best suited for audio and video transmission.	Best suited for Computing and digital electronics.
Applications	Thermometer	PCs, PDAs
Bandwidth	Analog signal processing can be done in real time and consumes less bandwidth.	There is no guarantee that digital signal processing can be done in real time and consumes more bandwidth to carry out the same information.
Memory	Stored in the form of wave signal	Stored in the form of binary bit
Power	Analog instrument draws large power	Digital instrument draws only negligible power
Cost	Low cost and portable	Cost is high and not easily portable
Impedance	Low	High order of 100 megaohm
Errors	Analog instruments usually have a scale which is cramped at lower end and give considerable observational errors.	Digital instruments are free from observational errors like parallax and approximation errors.

   

For any state-of-art technology the main objective is to produce better than the one i.e already existing. The transition from analog to digital was also for this very purpose!
Analog communication had various error and privacy problems and to overcome that the digital media was brought into picture. With digital media storage and transfer is much more easier now! All the pics that we upload on facebook or twitter can be very conveniently transferred and shared with friends and family, thanks to digitization of everything!