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How far can the transmission distance be when monitoring the installation using POE?
Frequently friends have asked, POE power supply technology issues, what is POE power supply technology? How far is the maximum transmission distance of POE power supply technology? Any professional book on POE in this area has at least a dozen pages of text to describe. After you read it, you will feel that it is still hazy. Today I use the vernacular and everyone to say my own understanding and hope to help everyone.
The POE power supply technology is described in simple terms. In the existing transmission mode of the network cable crystal head, the DC power supply technology is also provided. This is when we install the network camera in the security industry, we do not need to arrange the power cord separately because the power is transmitted in the form of a direct current in the network cable.
Of course, the above statement, you can understand the meaning on the line, is from my own understanding to explain the POE power supply technology, the book is not, the network does not have this definition, just to facilitate understanding of POE technology for a friend who does not understand. Specific power supply process, power supply principle, power supply agreement We do not need to care about the security, just need to know that this technology, for our use, it can be.
To use POE power supply technology, first of all, there will be doubts, what is the maximum distance that POE power supply technology can transmit?
Before answering this question, we just mentioned above that when POE power supply technology is used in twisted-pair transmission, twisted-pair wires not only transmit data signals but also transmit DC power.
Obviously, the simultaneous transmission of data and current, then which transmission distance, it is certainly the maximum transmission distance of POE power supply technology.
Twisted-pair transmission of direct current, although there is loss, but the transmission distance is still far greater than the twisted-pair transmission of data signals! Therefore, the key to POE power transmission distance is the maximum distance of data transmission.
Friends who are familiar with the network know that the twisted pair transmission distance has a 100-meter limit. Regardless of the twisted-pair cable of 100M transmission rate, or the twisted-pair cable of 1000M transmission rate, the farthest effective distance is 100 meters. How to get this distance, do not need to go deeper. Probably to understand that in signal transmission, under the influence of resistance and capacitance, the signal will be attenuated and distorted. Therefore, the authority of the Internet has concluded that the length of the two devices of a twisted pair cannot exceed 100 meters.
In the actual project, the distance is usually the best 80-90 meters, here to explain, because sometimes when we do the actual project, the twisted wire sometimes put 150 to 180 meters, still effective, many Without knowing the reason, people silently remember that the original can be used up to 180 meters.
In fact, there is a precondition for the distance of 100 meters, which is the maximum speed transmission, that is, if the maximum speed is 200M, we usually use 100M to transmit data, so that the distance of 150 meters is not difficult, and at the same time, the quality of the network cable is not too strong. ! Small projects can do this, and major projects do not recommend breaking the distance of 100 meters, because you must consider the issue of future expansion and maintenance!
Therefore, the PoE power transmission distance is not determined by the PoE technology, but is determined by the distance and the distance and the quality of the network cable.