Inspection Method

1. Check the braided mesh of the shielding layer: Is the number of braids enough? The copper mesh is woven to check the solderability, and the tinned copper computer wire is scraped to see if it is copper wire. The hardness of the aluminum-magnesium alloy wire is obviously greater than that of the copper wire; Poor cable; use a lighter to burn the core wire, if it is copper-clad aluminum, it is easy to see that the inner color is different from the outer copper; peel off the outer skin and see the braiding angle of the shielding layer, if it basically stands up, then the basic It can be seen from the above that the weaving angle is large, which is a product that cuts corners;

2. PVC sheath: On the surface, you can see the regular "unevenness" of the woven mesh inside the compression, indicating that the processing technology is good, there will be no relative sliding, and it is a good cable. The appearance is smooth, and the "unevenness" of the compressed braided net cannot be seen. There is a loose feeling when pinching the sheath by hand, which is a poor cable;

3. Check the adhesion between the core wire and the insulating layer: cut the insulating layer obliquely, pull the core wire in the peeling direction, and see if the core wire and the insulating layer have adhesion process materials; good cables have larger adhesion force, poor The cable is not adhered;

4. Check the core wire: diameter - SYV cable is 0.78-0.8mm, SYWV cable is 1.0mm; recently there has been a SYV75-5 cable with a core wire diameter of 1.0mm, the characteristic impedance of this cable is definitely not 75 Ohm, do not apply to 75 ohm transmission system; check the diameter of the inner core of the cable with a vernier caliper;

5. Longitudinal tensile test: Take one meter of security cable, peel off the core wire, insulating layer, shielding layer, and outdoor jacket in layers, each with a length of 10 cm. The method is: hold the adjacent two layers of the cable with two hands and pull them in opposite directions; good cables cannot be pulled with general force, but poor cables can be easily pulled out without much effort.

6. Open a coil of wire to measure the length, or use a weighing method to roughly judge;

  solution

If you buy the above unqualified cables and have problems, here are several recommended solutions:

1. If the transmission distance is more than 800 meters, use the SYV-75-5 cable, and it turns out that there is no image or the image is beating, you can use the video amplification anti-jamming device, which adopts the video segment amplification method, which can amplify the video signal 10 times , so that the transmission distance can be effectively extended (a simple amplifier cannot be used, otherwise the signal loss will be very large);

2. If several cables interfere with each other, multi-signal multiplexing equipment can be used, and 8 channels of video images and control signals can be simultaneously transmitted in one video cable;

3. If you encounter the problem of cable welding, it is recommended to buy pure tin welding wire, and use a high-power soldering iron for rapid welding, and must not slowly tin;

4. Finally, if you are not very confident about the video cable, you can also use the radio frequency cable to transmit multi-channel video signal equipment. One radio frequency cable can transmit 20 channels of image and control signals at the same time. The transmission range can reach 3 kilometers, so the cost will be more cost-effective.