2019年6月12日星期三

Modulation World: Deep Learning about the Difference between Analog and Digital Modulation | Soukacatv.com


Analog Modulation vs. Digital Modulation
Modulation is the process of modifying one signal based on another, and it is used mostly in the transmission of data from one point to another. Although there are many types of modulation, there are two basic types: analog modulation and digital modulation. The main difference between analogmodulation and digital modulation is in the manner that they transmit data. With analog modulation, the input needs to be in the analog format, while digital modulation needs the data in a digital format.
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Because of the differences in the input signal, the output signal is also quite different. In analog modulation, any value between the maximum and minimum is considered to be valid. It is not so with digital modulation as only two values are considered valid; one value to represent “1” and another to represent “0.” All other values are considered noise and are rejected.
Because most signals that we transmit are analog in nature, like one’s voice, it is far simpler to do analog modulation than digital. If you want to transmit a voice using digital modulation, you’d need to pass it through an analog-to-digital converter before transmission and a digital-to-analog converter at the receiver to recover the original signal. The additional stages needed for transmitting digital modulation increases both the cost and complexity of the transmitter and receiver.
The major advantage that digital modulation has over analog transmission is how it achieves greater fidelity. With analog modulation, any noise or interference that falls in the given frequency bandwidth gets mixed with the actual signal. Although there are a number of ways to mitigate noise, it will still cause some amount of degradation. Because digital modulation only recognizes 0’s and 1’s, any noise is virtually eliminated once the receiver discerns whether a “0” or a “1” was transmitted. Unless the signal is very badly distorted, the output signal will be literally identical to what was transmitted.
Under both analog modulation and digital modulation, there are a number of other modulation techniques each with its own strengths and weaknesses. But each technique has its basic commonalities of transmitting either a digital or analog signal.
Summary:
1. Analog modulation takes an analog signal while digital modulation takes a digital signal.

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2. Analog modulation has a range of valid values while digital modulation only has two.
3. Analog modulation is cheaper to implement than digital modulation.
4. Digital modulation produces more accurate output than analog modulation.
Difference between Analog and Digital Signals
Analog vs. Digital Signals
There are two types of signals that carry information – analog and digital signals. The difference between analog and digital signals is that analog is a continuous electrical signal, whereas digital is a non-continuous electrical signal.
Analog Signals vary in time, and the variations follow that of the non-electric signal. When compared to analog signals, digital signals change in individual steps and consist of pulses or digits. Analog signals are a model of the real quantity and the voice intensification that causes electric current variations. Digital signals have discrete levels, and the specified value of the pulse remains constant until the change in the next digit. There are two amplitude levels, which are called nodes, which are based on 1 or 0, true or false, and high or low.
Digital signals, similar to Morse code, are sent to a computer which interprets these into words. A digital signal, a 0 or 1, is sent through the phone line. For example, when you type the letter A into your computer, it converts it into 01000001. This 01000001 goes to other computer, which interprets it as A. A series of eight 0’s and 1’s is called a byte, whereas each 0 or 1 is called a bit.
The difference between digital and analog signals can also be understood by observing various examples of different waves, and how they work. In the 1800’s, analog waveforms were used in conjunction with copper to relay or transmit conversations. Since they have the tendency to catch distorting electromagnetic waves, or noise which drops the quality of the signal, they soon became troublesome and difficult to maintain. Soon the change from analog to digital occurred, because digital signals were easier to transmit and were more reliable compared to analog signals.
A signal is the transmission of data that we constantly deal with during our daily routine life. From telephones to cellular devices, and music to computers, signals are very important. With the advent of modern technology, telephone and computers etc. have become a necessity, and the cost of analog signal transmission has become not only expensive, but troublesome. Digital signals soon replaced analog because they are simply different and uniformed, and not severely altered by noise or distortion. Almost all electronic devices use digital signals, because they remain accurate in shape and amplitude. Digital signals provide better continuous delivery, and are preferred over analog signals.
Summary:
1. Analog signals can be converted into digital signals by using a modem.
2. Digital signals use binary values to send and receive data between computers.
3. Digital signals are easier and more reliable to transmit with fewer errors.
4. Analog signal are replicas of sound waves that can be distorted with noise and drop the quality of transmission.
5. Digital data has a faster rate of transmission when compared to analog, and gives better productivity.
Difference between Analog and Digital Transmission
Analog vs. Digital Transmission
Analog transmission is a method of conveying voice, data, image, signal, or video information. It uses a continuous signal varying in amplitude, phase, or another property that is in proportion to a specific characteristic of a variable. Analog transmission could mean that the transmission is a transfer of an analog source signal which uses an analog modulation method (or a variance of one or more properties of high frequency periodic waveform, also known as a carrier signal). FM and AM are examples of such a modulation. The transmission could also use no modulation at all. It is most notably an information signal that is constantly varying.
Data transmission (also known as digital transmission or digital communications) is a literal transfer of data over a point to point (or point to multipoint) transmission medium –such as copper wires, optical fibers, wireless communications media, or storage media. The data that is to be transferred is often represented as an electro-magnetic signal (such as a microwave). Digital transmission transfers messages discretely. These messages are represented by a sequence of pulses via a line code. However, these messages can also be represented by a limited set of wave forms that always vary. Either way, they are represented using a digital modulation method.
Analog transmission is capable of being conveyed in a no fewer than four ways: through a twisted pair or coax cable, through a fiber optic cable, through the air, or through water. There are, however, only two basic types of analog transmission. The first is known as amplitude modulation (or AM). This is a technique used in electronic communication and works by alternating the strength of a transmitted signal in relation to the information that is being sent. The second is known as frequency modulation (or FM). This type of communication conveys information over a carrier wave, just as AM transmission. However, FM communication alternates the frequency of the transmitted signal.
Data that is transmitted via digital transmission may be digital messages that have origins for a data source (a computer or a keyboard, for example). However, this transmitted data may also be from an analog signal (a phone call or a video signal, for example). It may then be digitized into a bit stream using pulse code modulation (or PCM) –or even more advanced source coding schemes. The coding of the data is carried out using codec equipment.
Summary:
1. Analog transmission conveys voice, data, image, signal, or video information using an information signal that is continuously varying; digital transmission transfers data over a transmission medium discretely.
2. Analog transmission can be conveyed in four ways: a twisted pair or coax cable, a fiber optic cable, the air, or water; digital transmission may be transmitted via an electro-magnetic signal, such as a microwave.
Difference between Analog and Digital
Analog vs. Digital
Technologically speaking analog and digital are two kinds of processes used for the transmission of any  electric signals. A  Usually the information which transformed into electric signal is either audio or video. This is done via the translation of any information into different types of electric signals. For the analog format, the translation of data is in electric pulses  which varies in amplitude while for the digital format, the translation of data is in the binary format with two distinct amplitudes represent each bit.
Devices come with built-in ‘translation’ facilities so you have equipment like analog or digital phones, fax machines, modems, clocks, watches etc. A microphone and speaker are good examples for analog devices.
Analog technology is older and has been used for decades. It is cheap too but the problem with analog signals is that there is a limitation on the size of the data that can be transmitted at any given point of time.
Digital technology has changed how most of our equipment works. It changes all data into binary code at the point of transmission and this binary code is reassembled back into data as original at the reception point of the transmission. Since digital signals can be manipulated by software, it gives you way more options than an analog one. In telecommunication, as compared to analog signals since digital signals have an original blueprint that has to be replicated at the conclusion point of the transmission, it is more accurate and clear.
However, another difference between the digital and analog technology is that of quality. Since digital devices are translating and reassembling data, the quality is not that good.  But advancement in computing technology allows to artificially remove possible errors and disturbances in  any digital signals. Digital is still quite expensive as compared to the analog one. Global technology giants are working on reducing the price though.
The most efficient use of the digital technology has been realized in the cellular phone industry with analog becoming redundant though the sound quality is better in the latter. It can be said that all natural signals are analog. For instance when human speech is transformed directly to electric signals it is an analog signal. But converting it to digital format opens up an endless possibility of usage,  like a simple act of saving that in a computer.
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