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Anonymous users2024-02-06Digital communication passes binary**, and the signal waveform is square. Analog communication is a change in the waveform with time, the waveform is the kind of sine wave, and the real-time line is better, such as we play **. The signal will be attenuated during transmission, and it needs to be amplified by a relay device in the middle, but at the same time, some noise will also be amplified together, causing waveform distortion.
Digital signals, on the other hand, use some calibration mechanisms to control errors.
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Anonymous users2024-02-05It's not like that.
Digital communication is to sample, quantize, and code analog signals into digital signals, which are transmitted in the form of pulses. For example, the most common is PCM (Pulse Code Modulation). In other words, after modulation, it is no longer a continuous analog signal!
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Anonymous users2024-02-04There is a problem that the landlord should pay attention to. The purpose of using modem is because the information in the computer is a digital signal composed of "0" and "1", while the transmission on the ** line can only be an analog electrical signal. Therefore, when two computers want to transmit data through the first line, a device is needed to be responsible for the conversion of digital to analog.
Obviously, in this section of the first twisted pair, we are not using digital communication, in the communications industry, we call this very short section of the first line, called the access network.
The entire telecommunication network is divided into three parts according to function: transmission network, switching network and access network. In the "last mile" of the access network, because of the limited conditions, it is not necessarily digital communication, such as twisted pair.
Fiber-to-the-home (FTTH) is the typical access network digital communication.
Finally, the landlord asked, "So the analog signal after modem modulation is the same.""Analog communication"What is the difference between analog signals? Why is it that digital communication has the above advantages while analog communication does not? "Obviously, there is no difference, and the analog signal after modem modulation has to go through an analog-to-digital conversion before it enters the backbone transmission network.
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Anonymous users2024-02-031. The waveform is different.
Digital communication is a rectangular wave, while analog communication is a sine wave.
2. The signal flow is different.
The signal flow is not the same, and the number is a digital signal.
The analog is a sinusoidal signal. Digital signal, low bit error rate, can be said to be lossless compression. Analog signals.
It requires effective identification and is more susceptible to external noise interference. Both signals can be converted into each other.
2. The applicability is different.
Because digital communication transmits digital sampling signals, which can be restored at the receiving end, the signal transmission rate is high. The analog signal is a direct modulation of the signal, multiplying with the carrier, when there is interference in the transmission process, the impact on the system is irreparable, so it causes failure. Comparatively, digital communication is superior to analog communication.
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Anonymous users2024-02-02Category: Electronic Digital >> Other Digital Products.
Problem description: In analog communication, (such as radio and television station analog broadcast communication) the sound signal or image signal is sent out by modulating the amplitude modulation carrier or frequency modulation carrier through the modulation signal, and the receiving end obtains the signal content through frequency selection, detection or frequency selection through the tuning circuit, and frequency discrimination. In digital communication, a very large number of information streams can be transmitted simultaneously on the same communication medium. For example, there are hundreds of mobile phones in the same virtual domain that can play ** at the same time without interfering with each other, so how does the mobile phone identify which information corresponds to the local machine?
What is the signal from the transmitter? What about bandwidth? How to code?
How to modulate? What is the shape of the output waveform? How is the receiver demodulated?
How? In the same medium of communication, will the multitude of digital information flows be superimposed on each other?
Analysis: There are a lot of problems.
An important point: an analog signal is a signal whose size changes over time. The digital signal cavity is transmitting the numbers 0 and 1, in fact, it cannot be said to be the numbers 0 and 1, it should be said to be low and high.
The reception of the broadcast signal is made using the resonance of electromagnetic waves. If the waveforms of two waves are very close to each other, then there will be interference with each other. The digital signal is a series of digital streams that send a combination of 0 and 1, and one of the numbers in a string of numbers is different to mean different meanings, or signals, so they will not interfere with each other.
Both the sending and receiving of a digital stream encode the digital stream, and when it is received, it is reverted to the same digital information as when it was sent.
This is a personal understanding and does not represent the views of any other person or organization.
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Anonymous users2024-02-01The differences between digital communication and analog communication are as follows:
1. Different anti-interference ability: digital communication has obvious advantages compared with analog communication. It has strong anti-thousand disturbance ability, the communication quality is not affected by distance, can adapt to the requirements of various communication services, is convenient for the use of large-scale integrated circuits, and is convenient for the realization of confidential communication and computer management.
The disadvantage is that the channel frequency band occupied is wider. The anti-interference ability of analog communication is weak.
2. The system is different: compared with digital communication, analog communication system has simple equipment and narrow occupied frequency band, but the communication quality, anti-interference ability and confidentiality performance are not as good as digital communication. In the long run, analog communication will gradually be replaced by digital communication.
The analog communication system is mainly composed of user equipment, terminal equipment and transmission equipment. Analog communication systems for digital communication are relatively complex.
3. Confidentiality is different: Compared with analog signals, digital signals are easy to encrypt and decrypt. As a result, digital communications are confidential.
Poor confidentiality of analog communications. Analog communications, especially microwave communications and wired open-wire communications, can be easily eavesdropped. As long as you receive a signal from a foolish mind, it is easy to get the content of the communication.
Definitions:
Analog communication: refers to the way in which information is transmitted through analog signals. In analog communication, the signal is continuous, and different frequency amplitudes and phases can be used to represent the band-based information. Analog communication is often used to transmit audio and signals, such as radio and television, etc.
Digital communication: refers to the way in which information is transmitted through digital signals. In digital communication, the signal is discrete and represented by a series of numbers.
Digital communication can be encoded and decoded by BICO to ensure the accuracy and completeness of information. Digital communication is often used to transmit data and image signals, such as the Internet, digital television, etc.
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Anonymous users2024-01-31First, the anti-interference ability is different.
Digital communication is stronger than analog communication anti-interference ability, digital communication signal quality is not affected by distance and weakened, this feature makes it able to adapt to the requirements of communication business, its signal characteristics are convenient for the use of large-scale integrated circuits, can realize the confidentiality and computer control of Sun Xiao communication.
Second, the use of different systems.
The analog communication system is simple in equipment and occupies a narrow frequency band, and the system is mainly composed of user equipment, terminal equipment and transmission equipment, etc., and its communication quality is poor and the anti-interference ability is weak. Digital communication is mainly composed of sources, modulators, demodulators, etc., which have strong anti-interference ability and excellent communication.
3. Confidentiality is different.
Since digital communication is transmitted in digital form, it is easy to encrypt and decrypt it, so its confidentiality effect is very good. Since analog communication uses microwave or wired and open-wire communication, as long as the analog signal can be intercepted, the communication content can be obtained with the containment, and the confidentiality is very poor.
What we usually call ** signal, often refers to the analog ** signal, its recording method is generally analog tape recording, considering the signal attenuation of the video tape itself, with the increase of playback or copying, its image quality will also be irreparably degraded.
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I was admitted to Xidian Communication and Information System in 10 years, I am also a bachelor in Xidian Communication Institute, Xidian 10 years of communication and information system major applied for more than 1350 people, academic admission of 380 people, re-examination line 330 45 45 90 90, don't look at 330, but the final examination is less than 350 is quite few, you know, 400 above 51 people, 350+ is also ranked about 400, the main re-examination 250 points, the final result is the initial examination and the re-examination directly added, according to the ranking of admission, So it's stable, it's hard to say, some of the initial examination of more than 330 or on and is a second-class scholarship, some of the initial examination of 370 after the re-examination fell to 380 outside, and then the employment of the institute, the employment of graduate students of the Xidian Institute is very good, the average salary when it first came out was about 6500, note that this is average, mainly many people have entered state-owned enterprises, you also know that the salary of entering state-owned enterprises to telecommunications and mobile Unicom is not particularly high, but the treatment is quite good, easy, and there are many foreign companies and private enterprises. A large piece of salary 7k8k, mainly depends on the recent mix, Xidian this year's first-class ratio is about 60%, or very high, Wuhan University's communication does not know much, Xidian's communication ranks second in the country, the communication is very famous is Tsinghua Xidian North Post handed over to Southeast Chengdian, other school communications and these 6 are not in a grade.