Video isolation amplifier instruction manual
GA01 video isolation amplifier can realize the isolation transmission of analog video signal.
GA01 contains DC / DC isolated power supply, video isolation circuit, video drive circuit, etc., which realizes the isolation between power input, video input and video output.
GA01 is suitable for CCTV monitoring system, optical transceiver, instrumentation, etc.
The main characteristics of GA01 are shown in the table below:
Item description Power supply voltage 12-15V, typical value 12V. The current is about 100mA.
The video input voltage amplitude is 1Vpp. Impedance 75Ω.
The video output voltage amplitude is 1Vpp (with 75Ω load) or 2Vpp (no load). Impedance 75Ω.
Transmission bandwidth 25Hz-2.5MHz (± 3dB)
Isolation voltage 1KV
The warm-up time is due to capacitor charging, and the image may appear distorted or color abnormality immediately after power-on. It will enter the normal state after about 10 seconds.
Circuit board size 37x50mm
Please see the figure below for the physical appearance and mechanical dimensions of GA01.
GA01 uses a standard 10-pin IDC pin plug (the pin of the square pad is pin 1), and the pin definitions are as follows.
Pin number description
1 Video output location
2 Video output
3 Video input location
4 Video input
5, 6 Power negative
7, 8 Positive power supply
9, 10 empty feet (not connected internally)
Taking CCTV surveillance system as an example, the component equipment usually includes: camera, monitor, pickup head, video matrix, multi-picture splitter, PTZ lens controller, codec, computer, etc., which includes video, audio, RS485 For signals such as communication, their ground wires are connected in parallel at multiple points to form a complex mesh topology. Because the ground wires have a resistance of a few ohms to tens of ohms, the currents of these signals on the ground are superimposed on each other, forming a "common ground" interference, resulting The image is abnormal, typical phenomena such as: image distortion, image ghosting, image scrolling, image texture, image loss of color, image tearing, etc. In severe cases, the image is almost unrecognizable. The key to solving this problem is to eliminate all "co-locations". The recommended methods are: 1. Add a ground wire to the system. A copper core wire with a cross-sectional area greater than 4 square millimeters is used, one end is connected to the ground (a copper or iron rod can be buried as a ground wire at a meter below the ground), and the other end is connected to the chassis of all computers, video matrices, monitors, etc Or AC power ground. 2. All audio signals are isolated by transformer. 3. If the camera adopts switching power supply or centralized power supply, it will be changed to a separate transformer power supply. 4. The video signals of all cameras are connected to GA01 at the end of the control center (before entering the video matrix, monitor or computer). Note: All video signals must be connected to GA01, not just those with interference. Theoretical analysis shows that when more than two video signals share a common ground, there may be interference. If 8 video signals share the same ground, then at least 7 of them must be serially connected with a video isolator.
Even if 6 channels are connected in series, the interference may not be eliminated.
Questions and answers (1) Is there a shell for the product I bought?
A: The actual product delivered is the same as the previous physical picture, with no shell. Because when applied to products, GA01 is generally installed inside the product (such as an optical transceiver), and no shell is required. When used in engineering, usually dozens of GA01 are used at the same time, and they are generally installed in a standard rack-type chassis, and the outer shell is not easy to install.
(2) Can I use a switching power supply to power GA01?
Answer: Yes. But be careful not to use inferior switching power supplies to avoid interference.
(3) Can I use one power supply to power all GA01 in parallel?
Answer: Yes.
(4) There is a high-power motor near my camera. When the motor starts, there is snowflake interference on the monitor. Can it be eliminated with GA01?
Answer: No. Analyzed in principle, video isolation can only eliminate common ground interference and has no effect on radio frequency interference caused by electric sparks.
(5) Can GA01 be used to drive a 100-meter cable?
Answer: No. GA01 is mainly used for isolation, not a driver. If your video cable is very long, you can put GA01
Place at the end of the cable.
(6) I did a CCTV surveillance project, which has 32 cameras, almost every channel has interference, I want to try
GA01, but do n’t want to buy 32, what is the solution?
Answer: You can buy 2 GA01 first for the test. First, you need to disconnect the camera from the surveillance center, and only keep 2 channels.
Note: You can't just turn off the power of the camera, because even if the power is turned off, the common site still exists, so you must disconnect it completely. At this time, interference should still be visible on the monitor. Then, you string GA01 into it. If the interference is eliminated, it proves to be a common ground interference, and you can use GA01 to eliminate it.
(7) I have 8 cameras, and only 2 of them have interference. I only install GA01 in these 2 channels, okay?
Answer: No. Install at least 7 channels, preferably all, otherwise the interference cannot be eliminated reliably.
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