[ Huaqiang Security Network News ] The use of monitors has brought indelible contributions to the society. However, there are sometimes some faults, image distortion, distortion, unsynchronized behavior, and even no input signal failures. 1. The potential difference between the front-end device, the control host device and the terminal device may also interfere with the video signal, causing distortion of the image signal or the image appearing in the raceway. If the entire system is powered on (ie, the front-end device, the master control) When the device and the terminal device are both connected to the front and rear devices of the BNC head when they are powered on, the ground potential may be caused by the potential difference between the ground wire of the front and rear devices (actually the shielding layer of the transmission cable). Fire, this severe fire will destroy the components at the input or the ground level wire in the PCB casserole. The input is open and the input has no image failure. Therefore, the construction of the monitoring system project should be designed and constructed in strict accordance with the specifications. The grounding busbar shall be made of copper conductor with sufficient cross-sectional area to ensure that the ground-to-ground resistance of the front and rear ends is <1Ω. The grounding wire shall not form a closed loop and shall not be short-circuited or mixed with the neutral line of the strong power grid.
2. The industry standard for monitors specifies that the input signal amplitude of a professional monitor is 1Vp-P±3dB (about 0.7Vp-P-1.4Vp-p) and the input impedance is 75 ohms. Therefore, if the input signal is not standardized due to cable attenuation, impedance mismatch or BNC head of the transmission cable, the input signal amplitude is much lower than 0.7pp; or because the output of the camera is not standardized or some irregularities are accessed. When the access device (such as a distributor, amplifier, etc.) causes the input signal amplitude to be much larger than 1.4Vp-p, the image distortion and the line field may be unsynchronized.
3. Due to the wide frequency range of video, video signals are more susceptible to interference during transmission (including 50Hz power supply interference, electromagnetic wave interference, etc.), thus affecting image quality. Serious interference may result in image distortion, distortion, raceway, and field synchronization. Therefore, during the installation of the monitoring system, the video line must be kept away from electromagnetic interference sources.
When the monitor is used as the monitor terminal of the matrix control system, why is there a period of unsynchronization when switching images in the matrix controller?
In the monitoring system, if there is a phase difference in the field sync signal in the image signal outputted by each front-end device (such as a camera), when the matrix controller switches each image signal, the monitor will be out of sync for a period of time. The larger the phase difference, the longer the time of unsynchronization. Therefore, it is recommended to use a front-end device with external synchronization (GEN-LOOK) input when constructing the monitoring system, and all front-end devices use the external synchronization mode, that is, the synchronization of each image signal is controlled by the same synchronization signal. Causes the monitor screen to display synchronization.
2. The industry standard for monitors specifies that the input signal amplitude of a professional monitor is 1Vp-P±3dB (about 0.7Vp-P-1.4Vp-p) and the input impedance is 75 ohms. Therefore, if the input signal is not standardized due to cable attenuation, impedance mismatch or BNC head of the transmission cable, the input signal amplitude is much lower than 0.7pp; or because the output of the camera is not standardized or some irregularities are accessed. When the access device (such as a distributor, amplifier, etc.) causes the input signal amplitude to be much larger than 1.4Vp-p, the image distortion and the line field may be unsynchronized.
3. Due to the wide frequency range of video, video signals are more susceptible to interference during transmission (including 50Hz power supply interference, electromagnetic wave interference, etc.), thus affecting image quality. Serious interference may result in image distortion, distortion, raceway, and field synchronization. Therefore, during the installation of the monitoring system, the video line must be kept away from electromagnetic interference sources.
When the monitor is used as the monitor terminal of the matrix control system, why is there a period of unsynchronization when switching images in the matrix controller?
In the monitoring system, if there is a phase difference in the field sync signal in the image signal outputted by each front-end device (such as a camera), when the matrix controller switches each image signal, the monitor will be out of sync for a period of time. The larger the phase difference, the longer the time of unsynchronization. Therefore, it is recommended to use a front-end device with external synchronization (GEN-LOOK) input when constructing the monitoring system, and all front-end devices use the external synchronization mode, that is, the synchronization of each image signal is controlled by the same synchronization signal. Causes the monitor screen to display synchronization.
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