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Analog describes a device or system that represents changing values as continuously variable physical quantities. A typical analog device is a clock in which the hands move continuously around the face. Such a clock is capable of indicating every possible time of day. In contrast, a digital clock is capable of representing only a finite number of times (every tenth of a second, for example). In general, humans experience the world analogically. Vision, for example, is an analog experience because we perceive infinitely smooth gradations of shapes and colors.
When used in reference to data storage and transmission, analog format is that in which information is transmitted by modulating a continuous transmission signal, such as amplifying a signal's strength or varying its frequency to add or take away data. For example, telephones take sound vibrations and turn them into electrical vibrations of the same shape before they are transmitted over traditional telephone lines. Radio wave transmissions work in the same way. Computers, which handle data in digital form, require modems to turn signals from digital to analog before transmitting those signals over communication lines such as telephone lines that carry only analog signals. The signals are turned back into digital form (demodulated) at the receiving end so that the computer can process the data in its digital format.
What is Digital??
Describes any system based on discontinuous data or events. Computers are digital machines because at their most basic level they can distinguish between just two values, 0 and 1, or off and on. There is no simple way to represent all the values in between, such as 0.25. All data that a computer processes must be encoded digitally, as a series of zeroes and ones.
The opposite of digital is analog. A typical analog device is a clock in which the hands move continuously around the face. Such a clock is capable of indicating every possible time of day. In contrast, a digital clock is capable of representing only a finite number of times (every tenth of a second, for example).
In general, humans experience the world analogically. Vision, for example, is an analog experience because we perceive infinitely smooth gradations of shapes and colors. Most analog events, however, can be simulated digitally. Photographs in newspapers, for instance, consist of an array of dots that are either black or white. From afar, the viewer does not see the dots (the digital form), but only lines and shading, which appear to be continuous. Although digital representations are approximations of analog events, they are useful because they are relatively easy to store and manipulate electronically. The trick is in converting from analog to digital, and back again.
This is the principle behind compact discs (CDs). The music itself exists in an analog form, as waves in the air, but these sounds are then translated into a digital form that is encoded onto the disk. When you play a compact disc, the CD player reads the digital data, translates it back into its original analog form, and sends it to the amplifier and eventually the speakers.
Internally, computers are digital because they consist of discrete units called bits that are either on or off. But by combining many bits in complex ways, computers simulate analog events. In one sense, this is what computer science is all about.
â€¢Communication is the process of exchanging information between source and destination(sink)
â€¢Routing of information requires a communication link - Channel to transmit information between source and destination.
â€¢In past ages communication is carried over by runners, torches, pigeons etc. Such mediums are now obsolete in modern communication systems.
â€¢Communication engineering deals with transmitting information through electrical signals, i.e. information or message such as spoken words, photographs, live scenes and sounds are first converted to electrical signals before being transmitted on communication link to receiver or destination.
â€¢Electrical communication is reliable, fast and economical at the same time. Modern communication has applications such as e-banking, e-shopping, teleconferencing etc a possible reality.
Block schematic of basic communication system
Analog Communication is a data transmitting technique in a format that utilizes continuous signals to transmit data including voice, image, video, electrons etc. An analog signal is a variable signal continuous in both time and amplitude which is generally carried by use of modulation.
Analog circuits do not involve quantisation of information unlike the digital circuits and consequently have a primary disadvantage of random variation and signal degradation, particularly resulting in adding noise to the audio or video quality over a distance.
Data is represented by physical quantities that are added or removed to alter data. Analog transmission is inexpensive and enables information to be transmitted from point-to-point or from one point to many. Once the data has arrived at the receiving end, it is converted back into digital form so that it can be processed by the receiving computer.
Advanteges of analog communication
Following are the advantages of Analog Communication:
1)Infinite amount of signal resolution.
2)compare to digital, analog are have high density.
3)Simplify then digital signal.
The primary disadvantage of analog signaling is that any system has noise - i.e., random unwanted variation. As the signal is copied and re-copied, or transmitted over long distances, these apparently random variations become dominant. Electrically, these losses can be diminished by shielding, good connections, and several cable types such as coaxial or twisted pair.
The effects of noise create signal loss and distortion. This is impossible to recover, since amplifying the signal to recover attenuated parts of the signal amplifies the noise distortion/interference as well. Even if the resolution of an analog signal is higher than a comparable digital signal, the difference can be overshadowed by the noise in the signal.
Most of the analog systems also suffer from generation loss.
What is Digital Communication
Digital Communication is any message passed through digital devices
Digital Communication can be easy and quick to use
Digital Communication can be dangerous if you use it unsafely
Some examples of digital communication are:
- Cell Phones
- Web Kinz
Advantages of digital communication:
1. It is fast and easier.
2. No paper is wasted.
3. The messages can be stored in the device for longer times, without being damaged, unlike paper files that easily get damages or attacked by insects.
4. Digital communication can be done over large distances through internet and other things.
5. It is comparatively cheaper and the work which requires a lot of people can be done simply by one person as folders and other such facilities can be maintained.
6. It removes semantic barriers because the written data can be easily chaned to different languages using software.
7. It provides facilities like video conferencing which save a lot of time, money and effort.
1. It is unreliable as the messages cannot be recognised by signatures. Though software can be developed for this, yet the softwares can be easily hacked.
2. Sometimes, the quickness of digital communication is harmful as messages can be sent with the click of a mouse. The person oes not think and sends the message at an impulse.
3. Digital Communication has completely ignored the human touch. A personal touch cannot be established because all the computers will have the same font!
4. The establishment of Digital Communication causes degradation of the environment in some cases. "Electronic waste" is an example. The vibes given out by the telephone and cell phone towers are so strong that they can kill small birds. Infact the common sparrow has vanished due to so many towers coming up as the vibrations hit them on the head.
5. Digital Communication has made the whole wordl to be an "office." The people carry their work to places where they are supposed to relax. The whole world has been made into an office. Even in the office, digital communication causes problems because personal messages can come on your cell phone, internet, etc.
6. Many people misuse the efficiency of Digital Communicatio. The sending of hoax messages, the usage by people to harm the society, etc cause harm to the society on the whole .... by nishanth kumar vaishnav
Advantages of Digital communication over Analog
1.The first advantage of digital communication against anlog is it's noise immunity.In any transmission path some unwanted voltage or noise is always present which cannot be eliminated fully.when signal is transmitted this noise gets added to the original signal causing the distortion of the signal.However in a digital communication at the receiving end this additive noise can be eliminated to great extent easily
resulting in better recovery of actual signal.Incase of analog communication it's difficult to remove the noise once added to the signal.
2.security is another priority of messaging services in modern days.Digital communication provides better security to messages than the analog communication.It can be achieved through various coding techniques available in digital communication.
3.in a digital communication the signal is digitised to a stream of 0 s
and 1 s.So at the receiver side a simple decision has to me made whether received signal is a 0 or a 1.Accordingly the receiver circuit becomes simpler as compared to the analog receiver circuit.
4.Signal when travelling through it's transmission path gets faded gradually.So on it's path it needs to be reconstructed to it's actual form and re-transmitted many times.For that reason AMPLIFIERS are used for analog communication and REPEATERS are used in digital communication.amplifiers are needed every 2 to 3 Kms apart where as
repeaters are neede every 5 to 6 Kms apart.So definitely digital communication is cheaper.Amplifiers also often add non-linearities that
distort the actual signal.
5.Bandwidth is another scarce resource.Various Digital communication
techniques are available that use the available babdwidth much efficiently than analog communication techniques.
6.when audio and video signals are transmitted digitally an AD(Analog to Digital) converter is needed at tansmitting side and a DA(Digital to Analog) converter is again needed at receiver side.While transmitted in analog communication these devices are not needed.
7.Digital signals are often an approximation of the analog data(like voice
or video) that is obtained through a process called quantisation.The digital representation is never the exact signal but it's most closely approximated digital form.So it's accuracy depends on the degree of approximation taken in quantisation process.
From above discussion we see that analog system are less expensive in many cases than digital ones for the some application.
But digital system offer much more efficiency,beeter performance, and much greater flexibility.Digital communication is easy and quick to use.
But we have to be carefull because digital communication can be dangerous if we use it unsafely.