TV monitoring system overview and features and classification

1. Overview of TV monitoring system

The TV monitoring system in the security field is also called Closed Circuit Television (CCTV) in foreign countries. In order to distinguish CCTV, which is commonly known in China, CCTV is called application TV in China. According to the size of the monitoring area and actual needs, the TV monitoring system can be divided into large, medium and small systems. The general TV monitoring system consists of a front-end device, a transmission system, and a terminal device.

2, TV monitoring system features

(1) CCTV system is different from diffused broadcast TV. It is centralized and generally used for monitoring, control and management.

(2) The information of the CCTV system comes from multiple cameras, and multiple signals are required to be transmitted simultaneously and simultaneously.

(3) The user is concentrated at one or several limited points, and the purpose is to collect or monitor information. The transmission distance is generally short, and is limited to a limited range of several tens of meters to several kilometers.

(4) Generally, closed-circuit transmission is adopted, and open-circuit transmission is rarely used. It can be transmitted by cable within 1km, and it can be transmitted by fiber optic cable for more than 1km.

(5) Generally, video is directly transmitted without radio frequency transmission. Video transmission is also called baseband transmission, that is, it does not undergo any processing such as frequency conversion, and directly transmits video signals output by cameras and other devices.

(6) In addition to transmitting video signals to the receiving end, it also transmits control signals and power to the camera, so it is a two-way multiplex system.

3, TV monitoring system classification

Determine the composition of the system and its equipment configuration according to the technical and functional requirements of the system. The choice of the system's composition is as follows:

(1) Single-head single-tail system Single-head single-tail system is the simplest component. It consists of a camera and a monitor that continuously monitor a fixed target at one location. If some functions are added to the system, such as the length of the focal length of the camera lens, the size of the aperture, and the near and far focus, the remote control modulation can be performed, and the left and right movements of the electric pan/tilt can be remotely controlled and the power of the camera can be turned on. The camera can be operated in a special environment with a special cover. The adjustment of these functions is done by the controller.

(2) Single-head multi-tail system Single-head multi-tail system uses multiple cameras, transmission electric (optical) cable, video distributor, etc. when monitoring the same scattered target in multiple places. It is a camera that delivers image signals to many monitoring points, and the images are viewed simultaneously by monitors at various points.

(3) Multi-head single-tail system Multi-head single-tail system is composed of a camera, transmission electric (optical) cable, switching controller, monitor, etc. when monitoring multiple dispersed targets in one place. In addition to the control functions, it also has the function of switching signals. If there is no motion control requirement in the system, then it is a video signal selector.

(4) Multi-head multi-tail system Multi-head multi-tail system is used to monitor multiple targets in multiple locations, including camera, transmission electric (optical) cable, switching distributor, video distributor and so on.

China's closed-circuit television monitoring system is mainly used in surveillance, scheduling and video conferencing. The functional requirement for such a system is to transmit the image taken by the base observation point to the central control room. The control room can remotely control and adjust the camera, pan/tilt and other equipment at the base layer. CCTV monitoring systems can be divided into the following three categories according to control methods.

(1) Single-stage control Single-stage control has only one control point in the central control room, and all controlled equipment is remotely controlled by the central control room. This type is suitable for small systems.

(2) Do not cross multi-level strings and control non-crossing multi-level strings and control, in addition to the total control center, there are also one or more sub-control centers, and there is no connection between the sub-control centers, that is, the cameras of the sub-control center 1 The output image cannot be transferred to the sub-control center 2.

(3) Cross-multi-level string and control cross-multi-level string and control can realize image exchange between each sub-control center, that is, each control center can call various images of the system as required, and control all cameras or other Controlled device. According to the requirements of the system, the master control center and the sub-control center can be equal or master-slave.