HDMI Encoder Modulator,16in1 Digital Headend,HD RF Modulator at Soukacatv.com: 五月 2019

2019年5月30日星期四

Modulation: Difference between Analog Modulation and Digital Modulation | Soukacatv.com

Analog 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 analog modulation 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.
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.

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Dingshengwei Electronics Co., Ltd

Company Address: Buliding A,the first industry park of Guanlong,Xili Town,Nanshan,Shenzhen,Guangdong,China

Tel : +86 0755 26909863

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Source: difference between

Modulation -- concept, advantages, classification, analog & digital modulation | Soukacatv.com

What is modulation?

· Operation of varying amplitude, frequency or phase of carrier signal accordingly with the instantaneous amplitude of the message signal is called modulation.

· Modulation= Adding information to a carrier signal

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Need for Modulation:

Baseband signals are incompatible for direct transmission. For such a signal, to travel longer distances, its strength has to be increased by modulating with a high frequency carrier wave, which doesn’t affect the parameters of the modulating signal.

Advantages of Modulation

The antenna used for transmission, had to be very large, if modulation was not introduced. The range of communication gets limited as the wave cannot travel a distance without getting distorted.

Following are some of the advantages for implementing modulation in the communication systems.

· Reduction of antenna size

· No signal mixing

· Increased communication range

· Multiplexing of signals

· Possibility of bandwidth adjustments

· Improved reception quality

Signals in the Modulation Process

Following are the three types of signals in the modulation process.

Message or Modulating Signal

The signal which contains a message to be transmitted is called as a message signal. It is a baseband signal, which has to undergo the process of modulation, to get transmitted. Hence, it is also called as the modulating signal.

Carrier Signal

The high frequency signal, which has a certain amplitude, frequency and phase but contains no information, is called as a carrier signal. It is an empty signal and is used to carry the signal to the receiver after modulation.

Modulated Signal

The resultant signal after the process of modulation is called as a modulated signal. This signal is a combination of modulating signal and carrier signal.

Types of Modulation

There are many types of modulations. Depending upon the modulation techniques used, they are classified as shown in the following figure.

Continuous-wave Modulation

In continuous-wave modulation, a high frequency sine wave is used as a carrier wave. This is further divided into amplitude and angle modulation.

· If the amplitude of the high frequency carrier wave is varied in accordance with the instantaneous amplitude of the modulating signal, then such a technique is called as Amplitude Modulation.

· If the angle of the carrier wave is varied, in accordance with the instantaneous value of the modulating signal, then such a technique is called as Angle Modulation. Angle modulation is further divided into frequency modulation and phase modulation. If the frequency of the carrier wave is varied, in accordance with the instantaneous value of the modulating signal, then such a technique is called as Frequency Modulation.

If the phase of the high frequency carrier wave is varied in accordance with the instantaneous value of the modulating signal, then such a technique is called as Phase Modulation.

Pulse Modulation

In Pulse modulation, a periodic sequence of rectangular pulses is used as a carrier wave. This is further divided into analog and digital modulation.

In analog modulation technique, if the amplitude or duration or position of a pulse is varied in accordance with the instantaneous values of the baseband modulating signal, then such a technique is called as Pulse Amplitude Modulation (PAM) or Pulse Duration/Width Modulation (PDM/PWM), or Pulse Position Modulation (PPM).

In digital modulation, the modulation technique used is Pulse Code Modulation (PCM) where the analog signal is converted into digital form of 1s and 0s. As the resultant is a coded pulse train, this is called as PCM. This is further developed as Delta Modulation (DM). These digital modulation techniques are discussed in our Digital Communications tutorial

Another way

· Analogmodulation:

If the variation in the parameter of the carrier is continuous in accordance to the input analog signal the modulation technique is termed as analog modulation scheme. It is classified as:

1. Amplitude Modulation

2. Frequency Modulation

3. Phase Modulation

· DigitalModulation:

If the variation in the parameter of the carrier is discrete then it is termed as digital modulation technique.it is classified as:

1. Amplitude Shift Keying

2. Frequency Shift Keying

3. Phase shift keying

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DingShengwei Electronics Co., Ltd

Company Address: Building A, the first industry park of Guan long, Xili Town, Nan Shan, Shenzhen, Guangdong, China

Tel: +86 0755 26909863

Fax: +86 0755 26984949

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Source: eceacademy

Top 5 Advantages of Digital Communication System and the Disadvantages | Soukacatv.com

In this post, we will discuss the advantages and disadvantages of a digital communication system briefly:

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Advantages:

1. The digital communication systems are simpler and cheaper compared to analog communication systems because of the advances made in the IC technologies.

2. In digital communication, the speech, video and other data may be merged and transmitted over a common channel using multiplexing.

3. Using data encryption, only permitted receivers may be allowed to detect the transmitted data. This property is of its most importance in military applications.

4. Since the transmission is digital and the channel encoding is used, therefore the noise does not accumulate from repeater to repeater in long distance communications.

5. Since the transmitted signal is digital in nature, therefore, a large amount of noise interference may be tolerated.

6. Since in digital communication, channel coding is used, therefore, the errors may be detected and corrected in the receivers.

7. Digital communication is adaptive to other advanced branches of data processing such as digital signal processing, image processing and data compression, etc.

Disadvantages

1. Due to analog to digital conversion, the data rate becomes high. therefore more transmission bandwidth is required for digital communication.

2. Digital communication needs synchronization in case of synchronous modulation.

However, the advantages of digital communication system outweigh its disadvantages.

Top 5 Advantages of Digital Communication System

Good Reasons to Choose Digital Communication System

1. The digital communication system has high noise immunity. High noise immunity means the digital communication system is more immune to noise as compared to the analog communication system. In an analog communication system, the system has less noise immunity compared to a digital system. The noise produced in an analog communication system is very high compared to the digital communication system. Therefore, the digital communication system is preferred for better noise immunity.

2. It has many advantages in storing and processing various data and information. The data and information stored or retrieved in a digital communication system can be achieved in any format like audio or video, etc. But in an analog communication system, the information processed is hard to obtain in any desirable format. It can't achieve in the format demanded by the user. Therefore, the digital communication system is preferred for a better output format.

3. The digital communication system is best in the view of the economy point. For analog or digital communication system, the economic factor plays an important role in mass production. When installing any communication system whether analog or digital, economic factor plays a vital role.

The communication system is installed according to the economic budget. That is what type of system can be installed and is best in the invested budget.

Therefore, the digital communication system is cheap as compared to the analog communication system. As per economic view, the digital communication system is preferred rather than the analog communication system.

4. It has the advantage of signal regeneration. It means that various signals that are processed in a digital communication channel can be regenerated into the original input form as per a user's demand. But if you look in the case of an analog communication system you can't easily regenerate the required signal after it is processed.

Hence, the digital communication system is best in the case of the signal regeneration process.

5. Also, for security purposes, the digital communication system is used nowadays. It has better security options than an analog communication system. Nowadays, the security problem is a hot issue in the case of any communication system. One only chooses the communication system where better security is used. It is so to prevent signal theft, data loss, system hack, and many other important functions. Therefore, the digital communication system has a better advantage for security purposes. It is so because of the encryption and decryption algorithm used in the digital communication system.

Disadvantages of a digital communication system

It has just a few disadvantages as compared to an analog communication system. In a digital communication system, the signals of high bandwidth are passed. Therefore, to pass such high bandwidth signals obviously the high bandwidth communication channel is used as compared to the analog communication channel. The high bandwidth communication channel is costly than the low bandwidth communication channel.

Also, there are many complex operations carried out in the digital communication channel as compared to analog one. The few examples of such complex operations are encoding and quantization of input signals. In other words, we can say that various quantization operations are carried out for the signals passed through the digital communication channel which is a little bit complex to deal with.

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Dingshengwei Electronics Co., Ltd

Company Address: Buliding A,the first industry park of Guanlong,Xili Town,Nanshan,Shenzhen,Guangdong,China

Tel : +86 0755 26909863

Fax : +86 0755 26984949

Phone: +86 13410066011

Email:ken@soukacatv.com

Skype: soukaken

Source：electronicspost & mannparyo

Question: Explain the need for modulation and advantages of modulation | Soukacatv.com

Need for Modulation:

The baseband signals can be transmitted directly, but the baseband transmission has many limitations which can be overcome using modulation.
In the process of modulation, the baseband signal is translated i.e. shifted from low frequency to high frequency.
This frequency shift is proportional to the frequency of carrier.
The modulation process has the following advantages:

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Advantages of modulation:

- Reduction in the height of antenna:

When the transmission occurs over free pace, the antennae radiate the signal out and receiver receives it. In order to operate efficiently, antennae need to be in order of the magnitude of wavelength of the transmitted signal.
For the transmission of radio signals, the antenna height must be a multiple of (λ/4).Here λ is the wavelength. Λ =c/f where c is velocity of light and f is the frequency of the signal to be transmitted.
The minimum antenna height required to transmit a baseband signal of f=10 kHz is calculated as follows:

Minimum antenna height= λ/4 = c/4f= (3* 108108)/(410103103 )=7500meters i.e. 7.5 km

It is impossible to build antennae this big.

Now consider a modulated signal at f= 1MHz.The minimum antenna height is given by,

Minimum antenna height= λ/4 = c/4f=(3108108)/(410*106106 )=75 meter

This length of the antenna can be built easily and this example clearly shows us how hugely the process of modulation is enabling communication systems.

-Avoids mixing of signals:

This is a point from the practical side of things. Suppose you are transmitting the baseband signal as it is to a receiver, say your friends phone. Just like you , there will be thousands of people of people in the city using their mobile phones.
There is no way to tell such signals apart and they will interfere with each other leading to a lot of noise in the system and a very bad output.
By using a carrier wave of high frequencies and allotting a band of frequencies to each message, there is no mixing up of signals and the received signals are absolutely perfect.

-Increase the range of communication:

By using modulation to transmit the signals through space to long distances, we have removed the need for wires in the communication systems.
The technique of modulation helped humans to use wireless equipment in a bug way in their lives.

-Multiplexing is possible:

Multiplexing is a process in which two or more signals can be transmitted over the same communication channel simultaneously. This is possible only with modulation.
The Multiplexing allows the same channel to be used by many signals.

-Improves quality of reception:

With frequency modulation (FM), and the digital communication techniques like PCM, the effect of noise is reduced to a great extent. This improves quality of reception.

For more, please access to https://www.soukacatv.com.

Dingshengwei Electronics Co., Ltd

Company Address: Buliding A,the first industry park of Guanlong,Xili Town,Nanshan,Shenzhen,Guangdong,China

Tel : +86 0755 26909863

Fax : +86 0755 26984949

Phone: +86 13410066011

Email:ken@soukacatv.com

Skype: soukaken

Source: ques10

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