Composition of security monitoring system - security monitoring system is an emerging specialty that people pay more and more attention to. In terms of current development, its application is more and more popular and its scientific and technological content is higher and higher. Almost all high and new technologies can promote its development, especially the advent of the information age, which provides an opportunity for the development of the major. However, as far as the monitoring industry is concerned, the system composition has not been clearly divided, which makes it very inconvenient for engineers and users to communicate about the security monitoring system.

For the security monitoring system, according to the different functions of each part of the system, we divide the whole security monitoring system into seven layers - presentation layer, control layer, processing layer, transmission layer, execution layer, support layer and acquisition layer. Of course, due to the increasing integration of devices, for some systems, some devices may exist in the system as multiple layers at the same time.

1、 Presentation layer

The performance city is the most intuitively felt by us. It shows the quality of the whole security monitoring system. Such as monitoring TV wall, monitor, tweeter alarm horn, alarm automatic connection telephone, etc. all belong to this layer.

2、 Control layer

The control layer is the core of the whole security monitoring system, and it is the clearest embodiment of the scientific and technological level of the system. Usually we have two control modes - analog control and digital control. Analog control is an early control mode. Its console is usually composed of controller or analog control matrix. It is suitable for small local security monitoring system. This control mode has low cost and low failure rate. However, for medium and large-scale security monitoring systems, this method is complex and has no price advantage. At this time, our wiser choice should be digital control. Digital control takes the industrial control computer as the control core of the monitoring system. It changes the complex analog control operation into simple mouse click operation, reduces the huge analog controller stack to an industrial control computer, and changes the complex and large number of control cables into a serial telephone line. It turns medium and remote monitoring into reality and provides possibility for Internet remote monitoring. However, the digital control is not so perfect. The price of the control host is very expensive, the module is wasted, the system may collapse across the board, the control is lagging behind and so on.

3、 Processing layer

The processing layer may be called the audio and video processing layer. It distributes, amplifies and divides the audio and video signals sent from the transmission layer, and organically connects the presentation layer with the control layer. Audio and video distributors, audio and video amplifiers, video dividers, audio and video switchers and other equipment all belong to this layer.

4、 Transport layer
The transport layer is equivalent to the blood of the security monitoring system. In the small security monitoring system, our most common transmission layer equipment is video line and audio line. For the medium and remote monitoring system, we often use RF line and microwave. For the remote monitoring system, we usually use the cheap carrier of Internet. It is worth mentioning that the emerging transmission layer medium - network cable / optical fiber. Most people have a misunderstanding about digital security monitoring. They think that the digital security monitoring system used by the control layer is the digital security monitoring system, but it is not. The transmission medium of pure digital security monitoring system must be network cable or optical fiber. When the signal comes out of the acquisition layer, it has been modulated into a digital signal. The digital signal runs on the mature network and has no attenuation in theory, which ensures the loss free display of remote monitoring images, which is unmatched by analog transmission. Of course, high-performance return also requires high-cost investment, which is one of the most important reasons why pure digital security monitoring system can not be popularized.

5、 Executive layer

The execution layer is the command object of our control instructions. In some cases, it is not completely separated from the support layer and acquisition layer. We think that the controlled object is the execution layer device. For example: pan tilt, lens, decoder, ball, etc.

6、 Support layer

As the name suggests, the support layer is used to support back-end devices, protect and support acquisition layer and execution layer devices. It includes support, protective cover and other auxiliary equipment.

7、 Acquisition layer
The acquisition layer is the key factor for the quality of the whole security monitoring system, and it is also the place with the largest system cost. It includes lens, camera, alarm sensor and so on.