Security common sense

Security equipment type

Security monitoring equipment includes many aspects, so its equipment types are also relatively complex, basically can be divided into TV monitoring systems, alarm control systems, remote image transmission equipment products, etc., mainly have the following types of monitoring system equipment:

PTZ

In fact, the gimbal is an installation platform composed of two AC motors, which can move horizontally and vertically. However, it should be noted that the gimbal is different from the gimbal in camera equipment. The gimbal of the camera equipment is generally just a tripod, which can only be adjusted by hand; the gimbal described by the monitoring system can control the direction of its rotation and movement remotely through the control system.

There are many types of PTZ:

According to the use environment, it is divided into indoor type and outdoor type. The main difference is that the outdoor type has good sealing performance, waterproof, dustproof, and heavy load.

According to the installation method, it is divided into side installation and ceiling installation, that is, whether to install the gimbal on the ceiling or on the wall.

According to the shape, it is divided into ordinary type and spherical type. The spherical gimbal is placed in a hemispherical and spherical protective cover. In addition to preventing dust from interfering with the image, it is also concealed, beautiful and fast.

When selecting the gimbal, you must consider the installation environment, installation method, working voltage, load size, as well as factors such as cost performance and appearance.

support

If the camera is only fixed to monitor a certain position without turning, then only the camera bracket can meet the requirements. Ordinary camera brackets are simple to install, inexpensive, and have a wide variety. Ordinary brackets are short, long, straight, and curved. Choose different models according to different requirements. The outdoor bracket mainly considers whether the load capacity meets the requirements, and then there is the installation location, because many outdoor cameras in different occasions have special installation locations, some are installed on telephone poles, some are standing on tower cranes, and some are installed on iron frames …… For various reasons, the existing bracket may be difficult to meet the requirements, and additional processing or improvement is needed, so I won't go into details here.

protecting mask

The protective cover is also one of the most commonly used equipment in the monitoring system, mainly divided into indoor and outdoor.

The main difference between indoor protective cover is the size, whether the appearance is beautiful, and whether the surface treatment is qualified. The function is mainly to prevent dust and damage.

The sealing performance of the outdoor protective cover must be good to ensure that rainwater cannot enter the inside of the protective cover to erode the camera. Some outdoor protective covers are also equipped with exhaust fans, heating plates, and rain protectors to better protect the equipment. When the weather is too hot, the exhaust fan works automatically; when it is too cold, the heating plate works automatically; when there is rain on the protective cover glass, the rain protector can be activated through the control system.

When selecting the protective cover, first look at the overall structure. The fewer the mounting holes, the better the waterproofing. Then look at whether the internal wiring is easy to connect. Finally, you need to consider the appearance, mounting seat, weight, etc.

Monitor

The monitor is the standard output of the monitoring system. Only with the monitor can we view the images sent by the front end. The monitor is divided into color and black and white, the size is 9, 10, 12, 14, 15, 17, 21 inches, etc., the commonly used is 14 inches. The monitor also has a resolution, which is expressed by the number of lines as the camera. In actual use, the number of lines of the monitor is generally required to match the camera. In addition, some monitors also have audio input, S-video input, RGB component input, etc. In addition to the audio input monitoring system, the rest of the functions are mostly used for image processing, and will not be described here.

Video Degree Valley Amplifier

When the video transmission distance is relatively long, it is better to use a video cable with a thicker wire diameter. At the same time, a video amplifier can be added to the line to enhance the signal strength to achieve the purpose of long-distance transmission. Video amplifiers can enhance the video's brightness, chrominance, and synchronization signals, but interference signals within the line will also be amplified. In addition, there should not be too many video amplifiers in series in the loop, otherwise saturation will occur, resulting in image distortion.

Video splitter

One video signal corresponds to one monitor or video recorder. If you want to send the image of one camera to multiple managers, it is best to choose a video distributor. Because of the large attenuation of the parallel video signal, the image will be severely distorted due to impedance mismatch and other reasons after being sent to multiple output devices, and the line is also unstable. In addition to impedance matching, the video splitter also has video gain so that the video signal can be sent to multiple output devices simultaneously without being affected. Video switcher
Multi-channel video signals must be sent to the same place for monitoring. One channel of video corresponds to one monitor, but the monitor occupies a large area and is expensive. If you do not require constant monitoring, you can add a switcher in the monitoring room The output signal is connected to the input terminal of the switch, the output terminal of the switch is connected to the monitor, the input terminal of the switch is divided into 2, 4, 6, 8, 12, 16 channels, and the output terminal is divided into single and double channels, and You can also switch audio simultaneously (depending on the model).

The switcher has two working modes: manual switching and automatic switching. The manual mode is to switch the switch to the desired way; the automatic mode is to delay the preset video in sequence, and the switching time can be adjusted by a knob. Generally between 1 second and 35 seconds. The price of the switch is cheap (generally only three to five hundred yuan), the connection is simple, and the operation is convenient, but only one image in the input can be seen in a period of time. To view multiple camera images on one monitor at the same time, you need to use a picture splitter.

Screen splitter

There are four kinds of screen splitter, nine-segment and sixteen-segment. It can display the images of 4, 9, 16 cameras on one monitor at the same time, and can also be sent to the recorder to record. Quad-segmentation is one of the most commonly used equipment, its performance and price ratio is also good, and the quality and continuity of the image can meet most of the requirements. Nine-segmentation and sixteen-segmentation are more expensive, and the resolution and continuity of each image will be reduced after the division, and the recording effect is not good. In addition, there are six-segment, eight-segment, and double-four-segment devices, but the image ratio, sharpness, and continuity are not ideal, and the market utilization rate is very small. In addition to displaying images at the same time, most splitters can also display a single picture, can superimpose time and characters, set automatic switching, and even alarm equipment.

VCR

The most commonly used recording devices in surveillance systems are civilian video recorders and longer-latency video recorders. Because their operation is simple and easy to learn, video tapes are also easy to save and purchase. It should be noted that unlike a home video recorder, a delayed video recorder can work for a long time, and can record images for 24 hours (using ordinary VHS video tapes) or even hundreds of hours. It can be connected to alarm equipment and automatically start recording when an alarm signal is received. Time and date can be superimposed. You can compile the automatic recording program of the recorder, choose the recording speed, whether the tape will automatically stop or rewind after the tape reaches the end, etc. Although the performance of the time-lapse video recorder is outstanding, it is expensive, and the current resolution is not very high. A part of the image will be lost when the time-lapse video is recorded, and the playback image is skipped.

Video input

In computer video, the red, green, blue and sync signals are separate electrical signals. In VHS video, the red, green, blue, and sync signals are a single electrical signal. In S-VHS video, the red, green, blue and sync signals are separated. The video input here mainly refers to the process that the external recorder or camera records the monitored area and then inputs it to the monitor. Because there are multiple recorders or cameras, there may be multiple inputs. According to the above splitter, there are 4 Channel, 9 channel, 16 channel input, etc.

Video output

For the output of the security monitoring system, the monitor is the standard output of the monitoring system. Only with the monitor can we view the image sent by the front end. The monitor is divided into color and black and white. The video input on the camera and video recorder must be finally input to the monitor for monitoring.

Audio input
Audio input refers to the process that the sound of the monitored area is collected and sent to the monitoring center. Because there may be multiple places in the monitored area, there will be multiple audio inputs. The simplest example is the prison system monitoring system of the prison system. The collection of sounds in each cell is a typical multiple audio input system.

Audio output

Audio output refers to the process that the collected sound of the monitored area is output in the audio device. Because some monitoring systems do not require sound output, no output device is required. However, some security monitoring systems require audio output. Website promotion even requires multiple audio outputs.

Communication Interface

The communication interface in the security monitoring system is mainly for the input and output of video and audio. Therefore, the communication interfaces generally have the following types: RS-232, RS-485, and general-purpose network interfaces, which can support various networking environments of PSTN, ISDN, and LAN. The entrance examination has a USB2.0 ultra-high-speed data interface, which is connected to the computer for important image data. Backup, optional with progressive scan VGA output interface, etc.