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What are the differences between several common intelligent building intercom systems

Looking at the intelligent industry, there are almost no real intelligent communities. The reason is that although we understand that intelligence is the trend of The Times and imperative, we are keen to look at the "model", "scale", on "qualification", on "price", and avoid talking about the essence of intelligent construction, that is, the fundamental basis of whether intelligence can be realized - highly comprehensive system integration technology across a variety of technology industries.

For a time, smart building has become a trade, as if anyone can do it. And the result? The "hodgepodge" type intelligent system of the community, not only loses the great intelligent function and effect, but also wastes the precious resources of the developer and the society. Especially because the technology has intellectual property rights and inheritance reasons, many systems cannot be effectively turned because they cannot get the corresponding technical support and after-sales service, and can not upgrade and expand the system, which becomes an undiluted "decoration" and baggage, directly leading to a small number of people who do not know the truth about the misunderstanding of intelligent technology and doubts about intelligent community life.

Looking at the intelligent industry, there are almost no real intelligent communities. The reason is that although we understand that intelligence is the trend of The Times and imperative, we are keen to look at the "model", "scale", on "qualification", on "price", and avoid talking about the essence of intelligent construction, that is, the fundamental basis of whether intelligence can be realized - highly comprehensive system integration technology across a variety of technology industries.

For a time, smart building has become a trade, as if anyone can do it. And the result? The "hodgepodge" type intelligent system of the community, not only loses the great intelligent function and effect, but also wastes the precious resources of the developer and the society. Especially because the technology has intellectual property rights and inheritance reasons, many systems cannot be effectively turned because they cannot get the corresponding technical support and after-sales service, and can not upgrade and expand the system, which becomes an undiluted "decoration" and baggage, directly leading to a small number of people who do not know the truth about the misunderstanding of intelligent technology and doubts about intelligent community life.

(A) audio transmission mode, usually divided into three

First, the audio does not make any changes in the baseband transmission mode;
The second, through frequency modulation or amplitude modulation transmission;
The third is the digital transmission of audio signals that convert audio signals into digital signals.

1, audio does not make any changes in the baseband transmission mode

Since the audio signal does not need to be converted to other transmission methods, the circuit of the audio signal is simple, the manufacturing cost is low, and it is widely used in the building intercom system now, but its disadvantages are: the transmission distance is short, once it is affected by external interference and is not easy to eliminate, and an independent audio signal transmission line is required.

2, through the frequency modulation or amplitude modulation to convert the audio signal into radio frequency signal transmission

This method is widely used in radio and television audio signal transmission, its characteristics are: audio signal transmission distance, the use of frequency modulation transmission of audio signal anti-interference ability, small distortion, clear sound quality. The disadvantage is that in the transmitting and receiving equipment, the modulation and demodulation circuits are added respectively, and the price is relatively higher than the first way, but the multi-modulated audio signal can be transmitted at the same time.

3, the digital transmission of audio signals into digital signals

This transmission method is to completely convert the audio signal into a digital signal, the quality of the audio signal depends on the acquisition accuracy of the audio signal, the higher the acquisition accuracy, the greater the amount of data, the higher the cost of the signal acquisition and restoration circuit, but the digital signal in the transmission process, there will not be any loss, this audio signal transmission method, widely used in the digital program control switch, However, in practical application, due to the relatively small amount of digital audio signal data, multiple digital voice signals can be transmitted in a line, or other data or image signals can be transmitted at the same time.

(2) Video signal transmission methods, usually divided into the following types

The first is baseband transmission of video signal;
Second, the video signal is modulated into a radio frequency signal transmission mode;
The third is the transmission method of converting video signals into digital signals.

1. Baseband transmission of video signal

This video transmission method does not do any processing on the image of the camera, directly through the coaxial cable transmission, its characteristics are: The video signal does not make any changes, omits the video signal conversion circuit, reduces the production cost of related equipment, the disadvantage is that the signal transmission distance is short, although amplified, but the transmission distance is generally not more than 1KM, once the baseband transmission of the video signal is interfered with, it is difficult to eliminate; This transmission mode is widely used by the building intercom system.

2, the video signal is modulated into a radio frequency signal transmission mode

This transmission method converts the video signal into a radio frequency signal, after amplification, the use of coaxial cable up to 5KM, but its transmission equipment requires the relevant modulation and demodulation circuit, the cost is high, this method is widely used in the transmission of TV signals.

3, video signal conversion into digital signal transmission mode

This video transmission method is the digital transmission of video signals, but because the video signal is converted to digital signals, the amount of data is too large, the cost of related conversion equipment is too high, in the ordinary civil system, generally do not use this way.

(3) Control signal transmission, usually control signal transmission methods, RS422, RS485, RS232 several commonly used data transmission methods

RS422 is a full-duplex data transmission mode, and its transmission data line is generally a separate five-core signal line, which is only used in a few induction card access control systems due to the large number of lines.
RS485 is a half-duplex data transmission mode, with fewer lines, the transmission distance is generally not more than 1.2KM, the access equipment is generally not more than 50, such as more equipment, must be divided into multiple interface management, generally use two cores, but the protocol is more complex, this transmission mode in the building intercom induction card, access control, meter reading, alarm and other systems are used more commonly.
RS232 is generally used in the communication of intelligent equipment and computers in the community, which is characterized by short signal transmission distance, in general, the data transmission line does not exceed 10 meters, but it is widely used when connecting intelligent equipment and computers in the community.

In the past two years, due to the extensive promotion of LONWORKS signal control technology, it has gradually been adopted by some intelligent manufacturers in the community, but the price of its special control chip is high, the network itself can only transmit data signals, audio and video signals can not be transmitted on it, limiting its use in the intelligent system in the community. In particular, it restricts its use in building intercom and monitoring system.

1, ordinary building intercom usually used signal transmission mode

In the current building intercom system, due to production costs and technical reasons, audio and video is commonly used baseband transmission, data signals are usually transmitted by RS485, so the general building intercom system, usually at least four cores (an audio line, two signal lines, a ground line) plus a video line transmission mode. This signal transmission method uses many lines, complex wiring, short signal transmission distance, high cost, wiring and debugging difficulties. The series networking method increases the transmission distance of the line and increases the probability of the above problems.

Once the network fails, it takes at least half a day, and more than a few days to repair the system under the cooperation and guidance of the manufacturer. Residential property management personnel, the maintenance of the intelligent system is too dependent on manufacturers, once the manufacturer service can not keep up, it will bring a lot of negative impact on the property management of the community, according to the "China Property market Report", the current intelligent community in three to five years, about 35% of the system is paralyzed, and 30% of the system is not working properly. Just over 20 percent of the systems are working.

2, the multi-wire building intercom system usually uses the wiring method

One is the screw crimping method for overloading signal lines, which has the advantage that the crimping wiring is more reliable. However, there are many wires, it is easy to connect the wrong line, especially the installation, debugging and maintenance of the system bring a lot of trouble. The other is the connection method using the air to connect the joint. Although the installation and removal of equipment is fast, conducive to debugging and equipment maintenance, repair, but high temperature and humidity areas, not suitable for use, because when the temperature and humidity are high, air docking metal joints, easy oxidation, mold, resulting in poor contact, so that the system failure rate increased, many engineering examples prove, In some high temperature, high humidity areas, fast is half a year, slow is one to two years, the above faults will multiply.

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