Self-adaptive video twisted-pair wire transmitter

Abstract

The invention relates to a self-adaptive video twisted-pair wire transmitter. In the transmitter, a video coaxial cable signal is input from the bayonet nut connecter (BNC) of a socket Q9; a resistor R1 is a coaxial cable matching resistor; the video coaxial cable signal is coupled to the second pin of an EL5171 video operational amplification chip U4 by a capacitor C1, input into the video operational amplification chip U4 and converted into a differential signal and the differential signal is output; resistors R8 and R9 are U4 feedback resistors and form a video pre-compensation circuit together with resistors R11, R13 and R14 and capacitors C11 and C12; capacitors C4 and C5 are power supply decoupling capacitors; resistors R4, R5, R6 and R7 and suppression diodes V1, V2, V3 and V4 commonly form a two-stage lightning protection circuit; and the differential signal is output to a twisted-pair wire for transmission through a twisted-pair wire interface J2. The power supply for the transmitter is DC12V and can be shared with a front end camera. The self-adaptive video twisted-pair wire transmitter is characterized by long transmission distance, high transmission quality and anti-interference capability, the preservation of the luminance, color and real-time property of the original image, capability of effectively suppressing common-mode interference, and no interference among different signals of pairs of twisted-pair wires in one cable; and the three-stage lightning protection circuit is adopted, so the transmitter is effectively prevented from being damaged by lightning.

Description

technical field [0001] The invention relates to an adaptive video twisted-pair transmitter used in a security / video monitoring system. Background technique [0002] In the entire security / video surveillance system, the transmission of video images is a very important link. The media used to transmit image signals mainly include coaxial cables, optical fibers and twisted pairs. Due to the characteristics of the coaxial cable itself, when the video signal is transmitted in the coaxial cable, the attenuation it receives is related to the transmission distance and the frequency of the signal itself. When the video signal is transmitted in the coaxial cable, not only the overall amplitude of the signal is attenuated, but also the attenuation of each frequency component is very different, especially the attenuation of the color part is the largest, so the coaxial cable is only suitable for the video transmission distance of about 300 meters. Optical fiber is used to solve long-d...

AI Technical Summary

Problems solved by technology

Due to the high price of the overall optical fiber transmission system, special equipment is required for laying and connecting optical fibers, and it is difficult to install and debug, it is difficult to find faults, and it is difficult to repair damage. For short-distance video transmission within 2000 meters, optical fiber is not a very good solution. choose

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