Common failure phenomena of the monitoring system and their solutions (reposted)

After a monitoring system enters the commissioning stage, trial operation stage and delivery, there may be such and other failure phenomena, such as: can not operate normally, the system can not meet the technical requirements of the design requirements, the overall performance and quality is not ideal, that is Some "soft problems". These problems are inevitable for a monitoring engineering project, especially for a complex and large-scale monitoring engineering project.

1. Equipment failure caused by incorrect power supply. Incorrect power supply generally has the following possibilities: the power supply line or the power supply voltage is incorrect, the power is not enough (or the diameter of a power supply line is not enough, the voltage drop is too large, etc.), the transmission line of the power supply system has a short circuit, open circuit, or transient Press and wait. In particular, damage to the equipment due to power supply errors or transient overvoltages has occurred. Therefore, in system debugging, before power supply, it must be carefully and strictly checked and checked, and should never be taken lightly.

2. Because there are many connections for some devices (such as cameras with three variable lenses and gimbal), if the processing is not good, especially the lines connected to the device are not processed well, there will be open circuit, short circuit, line Problems such as poor insulation and incorrect wiring cause equipment damage and performance degradation. In this case, it is necessary to calmly analyze according to the fault phenomenon and determine which lines have the faulty connection on several lines. This will reduce the scope of the problem. It is particularly worth noting that due to the omnidirectional movement of the camera with the gimbal, it takes a long time to cause the connection to fall off and break. Therefore, pay special attention to the connection between the equipment and various lines in this case should meet the requirements of long-term operation.

3. The quality of the equipment or component itself. In theory, all kinds of equipment and components are likely to have quality problems. However, from an empirical point of view, it is purely a quality problem of the product itself, which mostly occurs in devices such as decoders, electric pan-tilts, transmission parts and so on. It is worth pointing out that some devices may not be unusable in terms of quality as a whole, but some technical indicators can not reach the indicators given in the product manual. Therefore, the necessary samples must be tested for the selected products. When it is indeed a product quality problem, the best way is to replace the product, rather than dismantling and repairing it.

In addition, the most common problems are due to improper adjustments to the equipment. For example, the adjustment of the camera's back intercept is a very delicate and precise task. If the adjustment is not carried out carefully, problems such as poor focusing or defocusing during various operations of the three variable lens will occur. In addition, whether the positions of some switches and adjustment knobs on the camera are correct, whether they meet the technical requirements of the system, whether the decoder coding switch or other adjustable parts are set correctly will directly affect the normal use of the device itself or the normal performance of the entire system .

4. The problem caused by the incorrect connection between the device (or component) and the device (or component) will generally occur in the following aspects:

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⑵ The communication interface or communication method does not correspond. This situation mostly occurs between the control host and the decoder or control keyboard and other devices with communication control relationships, that is, the selected control host and decoder or control keyboard are not caused by a manufacturer's product. Therefore, the products of the same manufacturer should be selected for the host, decoder, control keyboard, etc.
⑶ The driving capacity is not enough or exceeds the specified number of device connections. For example, some picture splitters have an alarm input interface. In their product manuals, the system host connected to the alarm probe, long delay recorder, etc. is connected to form a system. If the alarm probe is connected to the alarm of the picture splitter At the input, the alarm signal of the probe will drive both the alarm host and the picture splitter. In this case, the problem of insufficient driving capacity often occurs. The phenomenon shown is that although the picture splitter can alarm, the input alarm signal is weak and the work is stable, resulting in the image of the camera corresponding to the alarm signal being converted to a full-screen image on the monitor. But it is lost (cannot be kept), and the image on the monitor is still the multi-screen before the alarm.

One of the methods to solve the above-mentioned problems is to connect the signal of the alarm probe to the picture splitter or the video switching host through the dedicated alarm interface box. Or drive equipment.

The problems mentioned above sometimes appear in the output and distribution of video signals.

1. Failure of the gimbal. A pan / tilt does not work well or cannot rotate at all soon after use, which is a common malfunction of pan / tilt. In addition to the factors of product quality, this situation is generally caused by the following reasons:

(1) Only the pan / tilt head where the camera is installed is allowed, and the method of lifting is used when it is used. In this case, the hoisting method leads to increased operating load of the gimbal, so the transmission mechanism of the gimbal will be damaged soon after use, and even the motor will be burned.

⑵ The total weight of the camera and its protective cover exceeds the load-bearing capacity of the gimbal. Especially for the gimbal used outdoors, the weight of the protective cover is often too large, and the problem that the gimbal cannot rotate (especially in the vertical direction) often occurs.

⑶ The outdoor gimbal has malfunctioned or even damaged due to the high ambient temperature, low temperature, poor waterproof and anti-freezing measures.

2. When the distance is too far, the operation keyboard cannot remotely control the camera (including the lens) and the gimbal through the decoder. This is mainly because the control signal attenuation is too large when the distance is too far, and the control signal received by the decoder is too weak. At this time, a relay box should be installed at a certain distance to amplify the shaping control signal.

3. The image contrast of the monitor is too small and the image is light. If this phenomenon is not a problem of the control host and the monitor itself, or the transmission distance is too far or the video transmission line is too attenuated. In this case, a device for line amplification and compensation should be added.

4. The image clarity is not high, the details are lost, and in severe cases, the color signal will be lost or the color saturation will be too small. This is because the loss of the high-frequency end of the image signal is too large, and the signal with a frequency above 3MHz is basically lost. In this case, the transmission distance is too far, and there is no amplification compensation device in the middle; or the distributed capacitance of the video transmission cable is too large; or the concentrated equivalent capacitance is distributed between the core of the transmission line and the shielded line in the transmission link Caused.

5. Tonal distortion. This is a failure phenomenon that is easy to occur in the long-distance video baseband transmission mode. The main reason is that the high-frequency phase shift of the signal caused by the transmission line is too large. In this case, a phase compensator should be added.

6. The operation keyboard fails. This phenomenon can basically be determined to be caused by the "crash" of the operation keyboard when there is no problem in checking the connection. On the operation instructions of the keyboard, there are generally methods to solve the "death", such as "whole reset" and other methods, which can be solved by this method. If the problem cannot be solved, the keyboard itself may be damaged.

7. The host's switching of images is not clean. The performance of this kind of fault phenomenon is that the screen after the selection and cutting is superimposed with the interference of other screens or the interference of the line sync signal of other images. This is due to the poor quality of the main mechanism matrix switch and the requirement to achieve isolation between images.

If a radio frequency transmission system is used, it may also be caused by excessive crosstalk modulation and intermodulation of the system.

A large-scale TV monitoring system that operates in conjunction with anti-theft alarms is a highly technical and complex system. Although various failure phenomena may occur, as long as the quality of the selected equipment and equipment is properly controlled and the construction is strictly in accordance with the standards and specifications, there will generally be no major problems. Even if it appears, as long as you calmly analyze and think, and do not blindly dismantle and dismantle, you will solve the problem quickly.