The emergence of network surveillance cameras has brought greater convenience to integrated security systems. Even more complicated is the problem of independent device cabling in integrated systems. In surveillance systems, surveillance cameras and storage systems are often talked about. In fact, the transmission part is also very important.

Video transmission is very important in the security system. Through the physical connection of various network devices in the security system, good transmission facilities allow the entire system to be optimized, which saves installation costs and reduces operating costs. However, this is easier said than done. Although test integrators have a lot of experience, they still need precise design for different monitoring projects. Precise transmission ensures that it can handle the operating environment, as well as future expansion requirements that may be met, and is suitable for end-user budgets.

There are three common transmission modes: PoE Power Over Ethernet, EoC Ethernet Coaxial Cable Transmission, and PLC Power Line Carrier Communication. The following is a detailed explanation of the three communication methods.

PoE Power over Ethernet

Power over Ethernet is a great invention. More and more network surveillance cameras first use PoE as the largest. In the fourth quarter of 2012, the global Ethernet switch market reached 570 million U.S. dollars, which is an increase of 7% over the same period of last year. The Ethernet switch market has the most outstanding market competitiveness in the Asia-Pacific region, accounting for 15.5%, except for Japan. The same period last year increased by 13.8%, and Latin America accounted for 12%, followed by the Middle East and Africa.

PoE is a secure power transmission technology that enables a two-in-one function together with Ethernet data transmission. Connected to the monitoring device and the Internet through a network cable. This technology is mainly based on the IEEE802.3af and IEEE802.3at standards. PoE devices classified as PSEs and PDs. PSE power includes network switches, media converters, and power supplies. On the other hand, the PD can provide backup assistance for network cameras, control devices, and so on.

In PoE technology, such as the surveillance camera PD connected to the PoE switch cable via Ethernet. The standard cable has four pairs of twisted pairs, only two of which are for 10BASE-T and 100BASE-T data transmission. Power transmissions can occur in "data pair" or "spare pair", but they cannot be used at the same time.

The rise of network cameras has largely affected the popularity of surveillance cameras. One of the reasons for this is the PoE technology, which eliminates local supply voltage or additional installed cable equipment and saves installation costs.

Ethernet coaxial cable transmission

It is in an analog-network monitoring and monitoring system and is no stranger to Ethernet coaxial cable. The emergence of this technology can be inherited from existing coaxial cable network cameras. Since most of the users installed the analog system using the coaxial cable output, this method allows the user to directly upgrade to the network monitoring system without rewiring.

EoC allows the transmission of the coaxial cable to be upgraded to a monitoring system that supports PoE without the need for rewiring. This approach speeds installation time, saves transmission investment, and reduces the possibility of failure rates. This is the biggest advantage of analog-digital retrofit.

The EoC transmission is adapted to the length of the existing coaxial cable, which may be two kilometers. There are several ways to implement EoC. Coaxial Cable Security Link (SLOC), a single coaxial cable composite video designed for digital IP video transmission, is a technology that transmits Ethernet signals over digital subscriber lines. The medium can be A copper twisted pair or coaxial cable. The frequency of use is 30 MHz to provide downlink and uplink data transmission rates of 100 Mbps. Compared to home ADSL broadband Internet access, its advantages are not only in terms of bandwidth, but also a blessing of transmission distance.

SLOC is a form of EoC transmission and can be integrated directly into monitoring equipment. SLOC overcomes the limitations of distance. From standard definition video to megapixel network cameras using existing coaxial cables, the transmission medium can only explain one of the reasons, and more importantly, the interpretation of the final effect.

Power Line Carrier Communication

PLC is a technology for data transmission over power lines and can be extended to coaxial cables. The technology provides a simple solution for home monitoring, office and building monitoring systems without the need to install any additional wires. PLCs use a modulated carrier signal in the cabling system, and different types of PLCs work in different frequency bands.

This technique is designed to have a very high frequency at ac power transmission frequencies of 50 or 60 Hz, and similar power line circuits. Taking the HomePlug technology as an example, it can connect devices inside and outside the building and connect PCs and other network-needed products through bridges or adapter power cables.

With the PLC interface, digital signals are encoded and transmitted to the back-end via the existing power-line network cameras, and the PLC interface is connected to the Ethernet switch. The transmitted data is connected to a digital video recorder via an Ethernet cable, presented through a liquid crystal display, and remotely monitored by an IP client site or a VMS server.

As everyone thinks, PLC transmission is through the existing PLC infrastructure and determines the transmission distance.

Is there a globally accepted outgoing standard? In fact, this is not only the limitations of transmission media, transmission distance, or transmission technology. The key is to know what the end user's transmission needs are. What kind of solution is chosen to meet their standards? There is no perfect solution, only a more suitable solution. .

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