Monitoring system outdoor equipment box internal installation specifications

The type of TV monitoring system is mainly composed of front-end equipment and back-end equipment, which can be further divided into the back-end equipment center control equipment and sub-control equipment. Front and back-end equipment has a variety of ways to constitute the link between them (also known as transmission system) can be achieved through cable, fiber optic or microwave and other ways. As shown in Figure 1-1, a television surveillance system consists of four major blocks: a camera section (and sometimes a microphone), a transmission section, a control section, and a display and recording section. In each part, and contains more specific equipment or components.

1. 1 main equipment

1. 1. 1 camera part

The camera part is the front part of the television monitoring system, is the whole system of "eyes". It is arranged in a position to be monitored, so that its field of view can cover the entire monitored parts. Sometimes, the place to be monitored by a larger area, in order to save the number of cameras used, simplify the transmission system and control and display system, the camera on the addition of electric (remote control) variable focal length (zoom) lens, so that the camera can observe the distance farther, clearer; sometimes also installed in the camera on the electric PTZ, through the control console control, you can make the PTZ drive the camera for the horizontal and vertical direction of rotation, so that the camera can cover the whole of the monitored parts. The rotation, so that the camera can cover the angle, the area is larger. In short, the camera is like the eyes of the entire system, the content of its monitoring into an image signal, transmitted to the control center monitor. As the camera part of the system is the most front-end, and the situation of the place to be monitored by it into an image signal transmitted to the control center monitor, so from the whole system, the camera part of the system is the original signal source. Therefore, the quality of the camera part and the image signal it produces will affect the quality of the whole system. From the point of view of the system noise calculation theory, the biggest factor affecting the system noise is the output of the first level of the system (here that is, the camera's image signal output) signal-to-noise ratio of the situation. Therefore, careful selection and processing of the camera part is essential. If the camera output image signal through the transmission part, the control part of the monitor after the arrival, then the arrival of the monitor on the image signal-to-noise ratio will be reduced, this is due to the transmission and control part of the line, amplifier, switcher, and so on, and then the introduction of the cause of the noise.

In addition to the above discussion, for the camera part, in some cases, especially in outdoor applications, in order to dust, rain, high and low temperatures, corrosion resistance, etc., the camera and its lens should also be equipped with a special protective cover, and even the PTZ should have the appropriate protective measures. These will also be discussed in the relevant sections later.

1. 1. 2 transmission part

The transmission part is the image signal path of the system. In general, the transport section refers to the transmission of the image signals alone. However, due to some systems in addition to images, but also to transmit sound signals, at the same time, due to the need to have a control center through the console on the camera, lens, PTZ, shields, etc., and thus in the transmission system also includes the transmission of control signals, so we are talking about the transmission part of the transmission system usually refers to all the signals to be transmitted to form the sum of the transmission system.

As mentioned earlier, the transmission part mainly transmits image signals. Therefore, it is very important to focus on the transmission method of image signals and related problems in transmission. Transmission of image signals, the key requirement is in the image signal after the transmission system, does not produce significant noise, distortion (chromaticity signal and luminance signal do not produce significant distortion), to ensure that the original image signals (image signals from the camera output) of the clarity and grayscale level is not significantly reduced and so on. This requires the transmission system in the attenuation, the introduction of noise, amplitude frequency characteristics and phase frequency characteristics of good performance.

In the transmission mode, the current television monitoring system is mostly used in video baseband transmission. If the camera is far away from the control center, there are also used in the case of radio frequency transmission mode or fiber optic transmission mode. For these different transmission methods, the transmission components and transmission lines used are quite different.

1. 1. 3 control part

The control part is the whole system of the "heart" and "brain", is to realize the whole system function of the command center. Control part of the main console (some systems also have a vice console). The main functions of the main console: video signal amplification and distribution, image signal correction and compensation, image signal switching, image signals (or including sound signals) of the record, the camera and its auxiliary components (such as lenses, PTZ, shields, etc.) of the control (remote control) and so on. In the above parts, the greatest impact on image quality is the amplification and distribution, correction and compensation, image signal switching three parts. In some of the cameras from the control center is very close, or the entire system indicators are not high, in the case of the total console is often not set up and compensation part of the correction. But for some of the farther distance, or due to the requirements of the transmission method and other reasons, correction and compensation is very important. Because the image signal after transmission, often its amplitude-frequency characteristics (due to different frequency components to reach the total console, the attenuation is different, resulting in different frequency components of the image signal amplitude is different, which is called amplitude-frequency characteristics), phase-frequency characteristics (different frequencies of the image signal through the transmission part of the phase shift is different, which is called phase-frequency characteristics) can not be absolutely guaranteed that the target of the requirements, so in the control desk to be Therefore, it is necessary to correct and compensate the amplitude frequency and phase frequency of the transmitted image signal. After correction and compensation of the image signal, and then through the distribution and amplification, into the video switching part, and then sent to the monitor. Another important aspect of the total console is the ability to remote control the camera, lens, PTZ, shield, etc., in order to complete a comprehensive and detailed monitoring or tracking surveillance of the place being monitored. The total console is equipped with a video recorder, you can always be the case of the monitored place of the image recorded, so that after the fact for investigation or as an important basis. At present, some consoles are equipped with one or two high "long delay video recorder", this video recorder can be used for a 60-minute tape length video tape recording up to a few days of image signals, so that you can be some very important places to be monitored by the continuous recording of the image without having to use a large number of videotapes. There is also a total console with a "multi-screen splitter", such as four-screen, nine-screen, sixteen-screen and so on. That is to say, through this device, you can simultaneously display on a monitor four, nine, sixteen cameras to send each of the monitored places of the screen, and a conventional VCR or long-delay VCR for recording. These features are set up according to the requirements of the system, not necessarily all adopted.

The current production of the total console, in the control function, the number of control cameras are often made of building blocks. Can be combined according to requirements. In addition, the total console is also equipped with a time and address character generator, through this device can be the year, month, day, hour, minute, second are displayed, and the address of the place to be monitored, the name of the display. In the video recorder can be recorded, so that the future preparation of the investigation provides a convenient.

The control of the total console on the camera and its auxiliary equipment (such as lenses, PTZ, shields, etc.) is generally used in a bus mode, the control signal to the camera near the "terminal decoder box" in the terminal decoder box will be sent to the total console encoding control signal decoding, become the command signal to control the action, and then to Control of the camera and its auxiliary equipment, a variety of actions (such as lens doubling, PTZ rotation, etc.). In the case of some cameras from the control center is very close, in order to save money, can also be used by the console directly send the command signal to control the action - that is, "on, off" signal. In short, according to the composition of the system and the requirements, can be considered comprehensively, in order to complete the design of the total console requirements or ordering requirements.

1. 1. 4 Display section

The display section generally consists of several or more monitors (or an ordinary TV set with video input). Its function is to display the transmitted images one by one. In the TV monitoring system, especially in the TV monitoring system composed of multiple cameras, generally not a monitor corresponds to a camera to display, but several camera image signal with a monitor to switch the display in turn. This is to save equipment, reduce space occupation; Second, there is no need to correspond to the display. Because the situation of the place being monitored can not happen at the same time accident, so usually as long as the interval of a certain period of time (such as a few seconds, dozen of seconds or dozens of seconds) can be displayed. When a place to be monitored when the situation occurs, you can switch the signal all the way through the switcher will be switched to a monitor has been displayed, and through the console on its remote tracking records. Therefore, in the general system are usually used four to one, eight to one, or even sixteen to one of the camera to monitor the ratio of the number of monitors set the number of monitors. At present, the commonly used camera-to-monitor ratio number of four to one, that is, four cameras correspond to a monitor rotating display, when the number of cameras is a lot of units, and then use eight to one or sixteen to one setup program. In addition, due to the application of "screen splitter", in some of the number of cameras in a large number of systems, the screen splitter to several cameras to send the image signal displayed on a monitor at the same time, that is, in a larger screen monitor, the screen is divided into several equal area of the small screen, each screen display a camera Each screen displays the image sent by one camera. This can greatly save the monitor, and the operator to watch it is also more convenient. However, this program should not be displayed on a monitor at the same time too many split screen, otherwise it will make some details difficult to see clearly, affecting the effect of monitoring. Personally, I believe that four or nine divisions are more appropriate.

In order to save money, for non-special requirements of the TV monitoring system, the monitor can be used with video input terminals of the ordinary TV, rather than using a more expensive special monitors. Monitor (or TV) screen size should be used between 14 inches and 18 inches, if the use of "screen splitter", you can choose a larger screen monitor.

Placement of the monitor should be suitable for the operator viewing distance, angle and height. Generally in the rear of the main console, set up a special monitoring shelf, the monitor placed on the shelf.

The choice of monitor should meet the requirements of the total system functions and total technical indicators, in particular, should meet the requirements of long-time continuous work. As the monitor or TV has been molded products, we are all very familiar with, and will not go into detail here.

System design:

1. 2 small and medium-sized television monitoring system

The usual television monitoring system is not large in scale, the function is relatively simple, but its scope of application is very wide. The object of monitoring is not limited to think of people, commodities, goods or vehicles, some applications also involve such as natural gas tanks, high oil ink melon furnace monitoring, and some other applications need to factory chimneys and sewage pipes for song monitoring. Television monitoring system can be self-contained system, can also be combined with burglar alarm system or access control system, constitute a comprehensive security monitoring system. Generally speaking, the typical small and medium-sized television monitoring system camera monitoring points not more than 32 points, the cost of most of the tens of thousands of dollars to hundreds of thousands of dollars.

1. 2. 1 simple fixed-point monitoring system

The simplest fixed-point monitoring system is to monitor the site to place a fixed-point camera (the camera is equipped with a fixed-focus lens), through the coaxial cable will be the video signal transmission to the monitor room monitor. For example, in the small factory gate placed a video camera, and through the coaxial cable will be transmitted to the factory office of the video signal monitor (or TV), the management can see which people work late or leave early, leave the factory whether to carry the factory's goods. If the configuration of a video recorder, you can also monitor the picture recorded for future retrieval and verification.

This simple fixed-point surveillance system is suitable for a variety of applications. When the number of cameras is large, it can be monitored by a multi-channel switcher, a screen splitter or a system host. A famous foreign company headquarters, for example, the headquarters has repeatedly lost high-grade laptop computers, and then all 12 exits on each floor of the installation of fixed-point cameras, and equipped with three four-screen splitter and 24-hour real-time video recorders, effectively eliminating the phenomenon of the above theft.

A guest house also uses this simple fixed-point surveillance system. This is in the 1 ~ 6-floor guest room channel at each end of the installation of a fixed-point black and white cameras, plus the entrance, foyer, back door, parking lot and other four monitoring points *** count 16 cameras, and then configure a 16-screen splitter, a 29-inch color TV and a 24-hour VCR constitutes a complete monitoring system.

When the number of points to monitor the increase will make the system larger, but if there is no other additional equipment and requirements, this type of monitoring system can still be attributed to a simple fixed-point system, a supermarket CCTV monitoring system, for example, due to the supermarket's business area is large (up and down the two floors totaling about 16,000 square meters), shelves are more, a total of *** installed 48 fixed-point black-and-white cameras. The 48 camera signals are divided into three groups, respectively, received the corresponding 16 screen splitter, 17-inch black and white monitor and 24-hour VCR (the supermarket's actual project in addition to the increase in the anti-theft alarm system and public **** broadcast / background music system, omitted here). Figure 1-2 shows the composition of the supermarket TV monitoring system.

Figure 1-2 The composition of the supermarket TV monitoring system

1. 2. 2 Simple omni-directional monitoring system

The omni-directional monitoring system is the fixed-focus lens in the aforementioned fixed-point monitoring system into a motorized zoom lens, and increase the full range of up and down the left and right movement of the PTZ (PTZ has two motors), so that the camera can be carried out for each point of surveillance, up and down the left and right sweep. Sweep up and down, left and right, the focal length of the lens can also be changed within a certain range (monitoring the scene can be farther away or advance). Obviously, the action of the head and motorized lens needs to be controlled by the controller or decoder with the system host to control.

The simplest omni-directional monitoring system and the simplest fixed-point monitoring system, compared with the front-end increase of an omni-directional pan-tilt and motorized zoom lens, in the control room to increase the number of controllers, such as SP3801, in addition to the front-end to the control room needs to be more than the deployment of a multi-core (10-core or 12-core) control cable. A small garment factory monitoring system, for example, in its garment workshop installed two omni-directional camera, in the factory director's office configured with an ordinary TV, a switcher and two controllers, when the factory director needs to understand the situation of the workshop, just through the switcher to select a camera screen, and through the operation of the controller so that the camera to the entire monitoring site for sweeping, but also for a localized The camera can also be used to monitor a localized area.

In practice, it is not necessary to make each monitoring point according to the full range of configurations, usually only in the whole monitoring system in a few special monitoring point is equipped with a full range of equipment. For example, in the aforementioned hospitality fixed-point monitoring system, can also consider monitoring the parking lot of the fixed-point camera into a full range of cameras (replace the motorized zoom lens and increase the full range of PTZ), and then in the control room to increase a controller, so that the parking lot can be expanded to monitor the scope of the parking lot, not only the entire parking lot can be swept, but also a local monitoring. Especially when advancing the lens, you can also see the license plate number. Figure 1-3 shows the system structure of adding an omni-directional monitoring point in the fixed-point monitoring system.

Figure 1-3 System structure for adding an omni-directional monitoring point to a fixed-point monitoring system

1. 2. 3 Low-cost omni-directional monitoring system

In this system (shown in Figure 1-4), the PTZ lens controller is replaced by a split-control keypad, SP8050, so that the system's connecting wires appear to be relatively simple.
The SP8050 is also capable of remotely controlling the switch (SP2000 series) and the screen. (SP2000 series) and screen splitter. Switcher also has an alarm function, when there is an alarm, can automatically switch out the alarm scene camera, and record. In terms of cost, it is lower than the use of the system host / matrix switcher system.

1. 2. 4 Surveillance system with a small host

How large the system needs to be equipped with a system host and there is no strict limit. Generally speaking, when the monitoring system in the full range of the number of cameras to reach more than 3 ~ 4, you can consider using a small system host. Although more than one single-channel controller or a multi-channel (such as 4 or 6-way) controller can also realize the full range of camera control, but the number of control cables required (at least one 10-core cable each way), and the length of the cable will be too long (long resistance caused by the voltage drop may lead to the pan-tilt head and the motorized lens slow action or even inaction), the whole system will also appear to be fragmented.

In general, the use of the system host will increase the cost of the entire monitoring system, this is because the cost of the system host is higher than the average switcher, and the price of the front-end decoder with the matching is also higher than the average single-channel controller. However, from the wiring considerations, the decoder and the system host is connected to the bus, so the number of cables in the system is not much (only need a two-core communication cable). In addition, most of the integrated system hosts have alarm detector interfaces, which can easily integrate the burglar alarm system with the TV monitoring system. When a detector alarm occurs, the host can also automatically switch the main monitor screen to the screen captured by the on-site camera where the alarm occurred. FIGS. 1-5 illustrate the structure of a small TV monitoring system using the system's mainframe.

Figure 1-5 shows the structure of a small TV monitoring system using a system host

1. 2. 5 Monitoring system with sound monitoring

TV monitoring systems often need to listen to the sound of the scene (for example: bank teller monitoring system), so from the system structure, the entire TV monitoring system consists of two parts: image and sound. Due to the increase in sound signal acquisition and transmission, in a sense, the size of the system is equivalent to a pure fixed-point image monitoring system doubled, and in the transmission process should also ensure that the image and sound signal synchronization.

For a simple one-to-one structure (camera - VCR - monitor), as long as the increase in the monitor head and audio transmission line, you can display the video and audio signals together, listening and recording. For the switching monitoring system, you need to configure the video and audio synchronization switcher, which can switch from multiple input video and audio signals and output the selected video and corresponding audio signals.

1. 3 Large and medium-sized television monitoring system

Large and medium-sized television monitoring system to monitor the increase in the number of points, in addition to including a large number of full-spectrum monitoring points, but also often integrated with the burglar alarm system. As a result of the collection of video and audio signals in the central control room, often requiring a variety of video and audio equipment for the combination of many systems also need more than one sub-control center (or sub-control point), so the system is relatively large.

1. 3. 1 Large and medium-sized television monitoring system definition

In principle, large and medium-sized television monitoring system and the aforementioned small and medium-sized television monitoring system is the same. Here the so-called "large and medium-sized" can have two meanings: one refers to the size of the system, such as the number of front-end cameras and the number of equipment at the center of the console are a lot of central control room is also a huge scene, there is often a huge wall of monitors, can be displayed at the same time, varying in size dozens or even dozens of real-time monitoring of the scene, but also in many related departments. Picture, but also in many related departments with sub-control systems, and sometimes with burglar alarm systems or access control card system linkage; Secondly, the complexity of the system is high, the operation is difficult, the transmission conditions are poor, so that more than a dozen points of the monitoring system than ordinary supermarkets or office buildings with the same ten or even hundreds of points of the monitoring system of the construction and commissioning of the system is still difficult.

1. 3. 2 multi-host multi-level TV monitoring system

Conventional TV monitoring system is generally only a host, even for medium and large systems, but also to increase the number of cameras and increase the number of sub-control system. But for some special applications, this single host plus a number of sub-controllers to achieve the method is unable to meet the needs of users. A large factory monitoring system, for example, the user requires a relatively independent plant in each of its installation of a set of closed-circuit television monitoring system, the plant has an independent monitoring room, managers can be any operation of the system control. The whole factory also want to establish a large-scale monitoring system, the subsystems of the plant together, and set up a large TV monitoring center, in the center can look at a plant in a factory in the image of a camera, and the camera's PTZ and motorized zoom lens for control. This puts forward by the plant's multiple hosts *** with the composition of large-scale television monitoring system requirements.

As the internal structure and working principle of each host is the same, therefore, relative to the ordinary matrix host, this multi-host system of each host has increased the address identification code, can be selected by the upper host, the image of each camera is selected through the secondary or tertiary switching to the main center control room monitor.

The front-end equipment of the television monitoring system

The front-end equipment of the television monitoring system usually consists of cameras, manual or motorized lenses, heads, shields, monitors, alarm detectors and multi-functional decoders and other components, which have their own responsibilities, and through wired, wireless or fiber-optic transmission media and the center of the control system of the various devices to establish the corresponding links (transmission of video/audio signals and control, alarm signals). and control, alarm signals). In the actual TV monitoring system, these front-end devices are not necessarily used at the same time, but the realization of the monitoring site image acquisition cameras and lenses are essential.

2. 1 camera

The camera is the front-end equipment to obtain images of the monitoring site, it is a surface array CCD image sensor as the core components, plus synchronized signal generation circuit, video signal processing circuit and power supply. In recent years, the new low-cost MOS image sensor has a more rapid development, based on the MOS image sensor camera has begun to be applied to the image quality requirements of the video phone or conference TV system is not high. Due to the MOS image sensor resolution and low illumination and other major indicators such as the temporary is not comparable to the CCD image sensor, therefore, in the television monitoring system using the camera is still a CCD camera.

The camera has a black-and-white and color points, due to the black-and-white camera has a high resolution, low illumination and other advantages, in particular, it can be in the infrared light imaging, so in the television monitoring system, black-and-white CCD cameras still have a high market share. Incidentally, the business list of CCTV surveillance equipment in the list of cameras are usually not with a lens (except integrated cameras), so in practice, according to the actual environment of the monitoring site and the user requirements, the camera with a suitable lens (see section 2-2 of this chapter).

2. 1. 1 The main parameters of the black and white CCD camera

In the television monitoring system to choose the camera, generally look at a few major parameters, that is, the resolution, the minimum illumination and signal-to-noise ratio, etc., in addition to considering the camera's incidental features and price and future service and other factors. The following is an introduction to several major parameters of the camera.

A, CCD size and number of pixels

CCD size refers to the diagonal size of the light-sensitive surface of the CCD image sensor, the early CCD size is relatively large, for lin, 2/3in and 1/2in and so on a few, and thus in recent years used for television surveillance cameras CCD size to 1/3in for the mainstream.

The number of pixels refers to the maximum number of pixels of the camera CCD sensor, some give the number of pixels in the horizontal and vertical directions, such as 500H * 582V, and some grouped out of the product of the first two values, such as 300,000 pixels. For a certain size of CCD chip, the more pixels means the smaller the area of each pixel unit, and thus the higher the resolution of the camera formed by the chip. For example, some of the CCD sensors used in TV surveillance cameras have pixels of up to 480,000 pixels.

B, resolution

Resolution is an important parameter to measure the merits of the camera, it refers to when the camera ingests the black and white stripes arranged at equal intervals, in the monitor (which should be higher than the resolution of the camera) on the ability to see the maximum number of lines. When more than the number of lines, the screen can only see a gray piece and can no longer identify the black and white lines.

Industrial surveillance cameras typically have a resolution of 380 to 460 lines, while broadcast-quality cameras can have a resolution of about 700 lines.

C, low illumination

Low illumination refers to the scene when the brightness of the scene being photographed to a certain extent and make the camera output video signal level is low to a specified value of the scene brightness value. Determination of this parameter should also specify the maximum relative aperture of the lens. For example, the use of F1. 2 lens, when the brightness of the scene is low to 0. 04lx, the camera output video signal amplitude for the largest value of 50%, that is, up to 350mV (the standard video signal maximum up to 700mV), it is said that the camera's minimum illumination of 0. 04lx / F1. 2. The photographed scene of the luminance of the value of the low, the camera to output the amplitude of the video signal It is not up to 350mV, reflected in the monitor screen, will be a screen is difficult to distinguish the level of gray images.

D, signal-to-noise ratio and gamma correction factor

Signal-to-noise ratio is also a major parameter of the camera. Its basic definition is the signal to noise ratio multiplied by 20log, the general camera to give the signal-to-noise ratio are in the AGC (Automatic Gain Control) off the value, because when the AGC is turned on, it will be on the small signal to enhance the noise level is also increased accordingly. CCD camera signal-to-noise ratio of the typical value of the general 45 ~ 55dB. Measurement of the signal-to-noise ratio parameter should be used when the video clutter When measuring the SNR parameter, you should use a video clutter meter directly connected to the video output terminal of the camera.

The gamma correction coefficient is the γ value mentioned earlier, and its typical value is γ=0. 45. Most of the current cameras use a fixed γ value.

2. 1. 2 black and white CCD camera incidental functions

In addition to the basic parameters described above, most of the brands of cameras also have some incidental functions, such as automatic aperture interface, electronic shutter, automatic gain control, backlight compensation, line-locked synchronization and external synchronization, etc., the following briefly.

A, motorized aperture interface

Currently on the market to see most of the standard CCD camera with a drive to choose (such as JETCOM's JC series of cameras), but also by the camera cover the video processing board on the location of the different sockets to choose, and set up a way to set up a way to do so before the factory