Definition
The loop function and the video distributor are completely two different concepts,
1 points 2 video distributor, is a video input signal Divided into a separate 2-channel video signal output, each output can be connected to a 75 ohm load; all the way or not connected, no effect on the other or the input signal; video distributor input signal There is only one standard, fixed 75 ohm matching resistor, 2 output pickup or no load on input matching, no effect;
"coaxial three-way" or equipment is also a way Video input, 2 channels of video output, but there is essential difference with the dispenser. The 2nd output and input of "Three Command" (loop) are three-port directly parallel relationships, which are not independent. If the 2-way output picks up a 75 ohm load, it is 75 // 75 ohm, which is 37.5 ohms, seriously does not match, the signal is small, reflecting the reaction; for example, the camera signal is used three links The two outputs are output, all the way to the matrix, and give DVR on the way, because the two equipment have a standard 75 ohm load, which is a matching error.
Three-way (loop) Connect the correct use of two devices: Or above, you can install a three-way in the first input of the matrix, the second port input, the third port The cable output is output, gived to the DVR all the way, in order to match, the input impedance of the matrix should be set to "high-resistance", the DVR input is still 75 ohms, and the input signal is "high resistance" "And 75 ohm, or 75 ohms. For devices that do not have software to set an input impedance, you can take the open machine. On the board, the 75 ohm matching power of this road is blocked, and the "high-resistance" state is formed. The problem has not finished, there is a "end matching principle": only 75 ohm matches in the last end of the transmission line. As in the above example, the input of the end DVR is not set to high resistance, and the front matrix is 75 ohms. Because the matrix is said to the matrix, the "open circuit long line" effect is generated, and the broadband matching characteristics are destroyed, and severe frequency distortion is produced. So, if the DVR is convenient in the above example, you can enter the DVR, you can first enter the three-way in the DVR input, and finally the matrix of the end is output to the end, the matrix input is 75 ohms. In the project, "End Matching Principles" can be flexible to grasp the application. The correct use of "Triple" is sometimes saved in the input of the video dispenser.
Some equipment (such as a monitors) are not a three-way structure, which does not receive the load, which does not affect the original signal (independent output). However, it is not enough, this road is not effective enough: the open video voltage is not 2VP-P; there is also a DC level output. Be careful when applied.
Avantoma output
Remove the video signal you enter to other video signals to other video signals.
In the video surveillance, the video signal captured by the front end can be assigned to a spare interface used by the different devices, similar to the video dispenser, but different from the video distributor, actually active video output, isolated Function.