With the increasing use of advanced video display products such as large-screen LCDs, back-viewers, and LED curtain walls in video display engineering and home theaters, large display screens require higher resolution and clarity. Ordinary TV/AV composite video signals (interlaced 576I-PAL) have not met the requirements for high-definition video, and the increasing popularity of broadband makes better movie resources easier to obtain, combined with computer VGA-DVI-SVideo video. High-definition, many people have proposed to use the home theater's large-screen LCD to play computer-downloaded movie programs, and watch large movies with high-definition video of computer VGA. Various monitoring, media multimedia information release and other projects have also put forward the requirements for high-definition VGA video transmission. The traditional use of VGA video line transmission often restricts this idea. In order to solve the problem of transmission of VGA signal on the project, the VGA signal amplifier began to appear. It adopts the principle of amplification. With the VGA video cable as the transmission medium, the VGA video signal of the computer can be transmitted hundreds of meters. However, it has been found that there are more and more defects in the use of such transmission. The long-distance VGA cable is thick and hard, which is not only expensive, but also difficult to obtain and needs to be customized at the factory, and the wiring is extremely inconvenient. In addition, the VGA head cannot be routed through the tube, so it has to be connected by one-to-one soldering at the other end of the threading tube. Once the soldering is completed, the terminal device has the defect that the position cannot be changed at will, and the VGA head is also very prone to soldering. The problem, this will bring huge hidden dangers to future engineering maintenance. The non-equilibrium of the VGA cable itself (called single-ended transmission on the circuit) determines its anti-interference difference. As the distance increases, some of the weaker ground loop interference signals can not be ignored in the long-distance wire. Almost all unbalanced amplifiers amplify the video signal along with the interference signal, resulting in some test environments that pass through but the actual project is simply unusable, causing significant losses in rework.
This article refers to the address: http://
In order to solve the problems in these transmissions, one of the methods can adopt the differential balanced transmission mode, so the VGA twisted pair video extender using the ordinary network cable (twisted pair) as the transmission medium has become the new expensive of the current VGA video transmission technology. The transmission method generally adopts a pair of transmitters and receivers. The transmitter re-encodes the RGBHV of the VGA video signal to transmit on the network cable with differential signal technology (and also has a high-fidelity VGA output on the local end) to the far end. The receiver decodes the VGA signal that is restored to one or two high-fidelity allocations. Since the high-frequency attenuation of the five types of twisted pairs is relatively large, the equalization compensation capability of the back-end receiver is important. Line impedance mismatch and under-compensation reduction can cause problems such as poor color reproduction, tailing, ghosting or background noise. Some products use a single potentiometer to control the brightness, but in actual use, the quality of the network cable used by the engineering manufacturer is different (the length of the twisted pair is different), the red, green and blue scattered problems will occur. In severe cases, the image at the far end will appear obvious. The color edge phenomenon. Similarly, there are some products in the market that use DIP switches. However, with the twisted pair wires and the on-site environment, this method cannot achieve the purpose of precise adjustment, and the user is also very troublesome to use.
The differential mode adopted by the VGA video extender itself has strong anti-common-mode interference performance. Because the transmitter uses a highly integrated video integrated circuit, the common mode interference suppression capability (CMRR) is further improved, up to -78dB, and at the same time The ripple rejection capability (PSRR) of the power supply is also excellent. In addition, the VGA twisted pair transmission device is equipped with an ultra-strong anti-ESD and surge protection circuit on the integrated circuit, and can even be considered for application to a harsh electromagnetic environment. Anti-interference is naturally the basic indicator to ensure the quality of the project. The stable and reliable operation of the equipment is an important indicator for the equipment supplier. In addition, our exclusive dispersion adjustment feature allows the product to have perfect chroma recovery.
Twisted pair transmission of VGA video technology is to use the three pairs of lines inside the network cable to transmit RGB video RGB signals, and HV two kinds of signal encoding mixed into RGB transmission. The utility model not only solves the problem of internal crosstalk in long-distance transmission, but also saves a pair of lines to transmit other signals, so that the twisted pair transmission device has more functions and is more widely used. For example, our company's UC04XX series VGA audio extender uses the remaining pair of lines to transmit high-fidelity audio signals, real-time synchronous playback of remote media multimedia information distribution or advertisements, and KVM for transmitting keyboard and mouse signals. Extender or control signal, etc. Of course, the three signals of stereo audio and keyboard and mouse VGA are transmitted at the same time, which is technically more difficult, and requires stronger noise floor, layer transient response, distortion and overall anti-interference of HI-FI audio. Our company has twisted pair and optical fiber transmission technology and solutions for monitoring video, audio, PC-VGA, keyboard, mouse, USB, HDMI/DVI, RS232 interface signals and has always been in the leading position in the industry, thus providing engineering users with Better and more comprehensive products.
It is cheaper to take the wire as the wire, the crystal head is easy to make, and the wiring is convenient. At present, the price difference between VGA twisted pair video extender and VGA signal amplifier is not large. The farther the distance is, the lower the wire cost and the better the anti-interference effect. It can be said that replacing VGA signal amplifiers with VGA video twisted pair extenders over 30 meters is a trend and trend.
High Voltage Dc Contactor,Epoxy Seal Contactor,High Voltage Contactor Relay,Dc Switching Contactor
NanJing QUANNING electric Co.,Ltd , https://www.quanningtrading.com