Optical fiber is the most common type of signal transmission device in surveillance systems. In the case of near-distance cable transmission, cables are generally used to transmit signals. In environments where the transmission distance is relatively long, cable transmission attenuation will be large. In this case, optical fibers are generally used to transmit signals. Not only can be used to transmit analog signals and digital signals, but also to meet the needs of video transmission. Optical fiber transmission is generally carried out using fiber optic cables. The data transmission rate of a single optical fiber can reach several Gbps, and the transmission distance can reach several tens of kilometers without using a repeater. However, in some environments where it is not convenient to deploy optical fibers and cables, we use a combination of wired and wireless to transmit video signals. How do optical fibers connect to wireless monitoring devices and wireless bridges? The following is a brief description by Shenzhen Leian Technology Xiaobian:
1, optical fiber usually has SC, ST, FC and other types of interface, and we simulate the wireless monitoring device is the AV interface, if the two are to communicate with each other is not direct communication, the signal must be converted, this time It is necessary to use analog optical transceivers to convert optical signals to analog signals.
A video optical transceiver is a device that converts one to multiple analog video signals through various encodings into optical signals through optical fiber media. The analog optical transceiver adopts the PFM modulation technology to transmit the image signal in real time. The transmit end first performs the PFM modulation on the analog video signal, and then performs the electro-optical conversion. After the optical signal is transmitted to the receiving end, the optical-electrical conversion is performed, and then the PFM demodulation is performed to recover the video signal. Due to the use of PFM modulation technology, the transmission distance can reach 50KM or more. Through the use of wavelength division multiplexing technology, it is also possible to realize bidirectional transmission of image and data signals on a single optical fiber to meet the actual needs of the monitoring project.
2. If the optical fiber wants to communicate with a wireless bridge, and the wireless bridge is an RJ45 interface, then we just need to use a digital optical transceiver to convert the front-end fiber signal into an RJ45 signal, and then transmit the signal through a wireless bridge.
Since digital technology has obvious advantages in many respects compared with traditional analog technologies, digital technology has just replaced analog technology in many fields. The digitalization of optical transceivers is also an inevitable trend. There are mainly two kinds of digital video optical transceivers: one is an MPEG11 video compression digital optical transceiver, and the other is a digital non-compressed video optical transceiver.
The image compression digital optical transceiver generally adopts MPEG11 image compression technology. It can compress moving images into N*2Mbps data streams and transmit them through a standard telecommunication interface or directly through optical fiber. Due to the use of image compression technology, it can greatly reduce the signal. Transmission bandwidth.
The all-digital uncompressed video optical transceiver adopts all-digital non-compression technology, so it can support any high-resolution active, still-image distortion-free transmission; overcome the conventional analog FM, phase modulation, and amplitude modulation. , Disadvantages of environmental interference, poor transmission quality, and low stability in long-term operation. And support audio two-way, data bidirectional, switch bidirectional, Ethernet, telephone and other signals in parallel transmission, convenient field wiring, plug and play.
Optical transceivers can be divided into 2 optical transceivers, 4 optical transceivers, 6 optical transceivers, 8 optical transceivers, 16 optical transceivers, and even more (32, 64, 128) optical transceivers. Specifically how to choose according to your specific project situation.
Wireless bridge and optical fiber connection diagram:
Shenzhen Leian Technology mainly produces wireless monitoring equipment and wireless bridges. The wireless monitoring equipment produced by our company has a very stable and mature wireless technology, and has a very strong technical and sales team, and we can provide 24-hour after-sales service System allows you to worry about after sales. We can also design various wireless monitoring solutions for you. Welcome to inquire!
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