Basic knowledge of security monitoring

A brief overview of basic knowledge of security monitoring (suitable for beginners)

1. Lens Analysis

1. Lens types (classified by application)

Wide Angle Lens: The viewing angle is more than 90 degrees, viewing distance is long, and near image is distorted.

Standard lens: The viewing angle is about 30 degrees, and it can be used in a wide range.

Telephoto: The angle of view is within 20 degrees, and focal length can reach tens of millimeters or hundreds of millimeters.

Zoom lens: The focal length of lens is continuously adjustable, and focal length can be changed from wide-angle to telephoto. The longer focal length, larger image.

Pinhole Lens: Used for covert surveillance, often mounted in places such as ceilings or walls.

2. Relationship between object size, distance and focal length

Suppose width and height of object are w.h respectively, distance between object and lens is l, and focal length of lens is f.

3. relative aperture

To control amount of light passing through lens, an aperture is set at back of lens. Assuming that effective aperture of aperture is d, due to relationship between refraction of light, actual effective effective aperture of specular light is d, which is larger than d, and ratio of d to focal length f is defined as relative aperture a, that is, a=d/ f, relative aperture of lens. The aperture determines illumination of camera, and reciprocal of illumination of image and relative aperture of lens is size of lens. aperture. The smaller f-number and larger aperture, more light flux reaches CCD chip. Therefore, for same focal length f, smaller f value, better lens.

4. Lens focal length

1) Fixed focal length: The focal length is fixed and can be divided into two types: with iris and without iris.

With aperture: The aperture size of lens can be adjusted. According to change in ambient light, you need to adjust size of aperture accordingly. The aperture size can be adjusted manually or automatically. If aperture is adjusted manually, it is called manual aperture. The lens has its own micromotor for automatic iris adjustment, which is called auto iris.

No aperture: i.e. fixed aperture, amount of light passing through it is fixed. It is mainly used when light source is constant or camera has an electronic shutter.

2) Zoom: The focal length can be adjusted as needed to enlarge or reduce image of subject. Commonly used zoom lenses are 6x and 10x.

Three and two variable lenses

Three adjustable lenses: adjustable focusclose distance, adjustable focus, adjustable aperture.

Two adjustable lenses: adjustable focus, adjustable focus, auto iris.

5. The principle of selecting lenses in first place

To get camera effect you expect, there are six main elements to consider when choosing a lens:

a) Item Size

b) Detailed item size

c) Object distance

d) Focal length

e) CCD camera target size

f) Lens and camera system resolution

Operation steps:

* Remove anti-tip device and attach lens.

* If you are using a cs lens, lower c (5mm) ring and fix cs lens unit.

* The c-type lens can be installed and used directly.

* Connect video output (bnc) to a monitor or other device.

* Connect DC 12V/AC 220V power supply * Check if indicator is on.

* If image is blurry, adjust lens focus.

2. Introduction to monitoring system equipment

①Cloud

In previous introduction, we often mentioned pan/tilt, but some people have no idea about it. In fact, pan/tilt is an installation platform composed of two variable streams that can move horizontally and vertically. The cloud platform we are talking about is different from cloud platform in photography equipment. Generally speaking, cloud platform of photography equipment is just a tripod, and orientation can only be adjusted manually, while cloud platform mentioned by monitoring system is controlled by remote control system, can control direction of rotation. There are many types of hangers: according to use environment, they can be divided into indoor and outdoor. The main difference is that outdoor types have good sealing performance, waterproof, dustproof and heavy load. According to installation method, it is divided into side installation and lifting installation, that is, whether tiltrotator is installed on ceiling or on wall. According to shape, it can be divided into ordinary type and spherical type. The ball type head is placed in a hemispherical or spherical protective cover. In addition to fact that dust does not interfere with image, it is also hidden, beautiful and fast. When choosing a pan/tilt, consider installation environment, installation method, operating voltage and load size, as well as price-performance ratio and beautiful appearance.

②Shackle

If camera is fixed only to observe a certain position and does not need to be rotated, then only camera bracket can meet requirements. Conventional camera mounts are easy to install, inexpensive, and available in a wide range. Common brackets come in short, long, straight and curved, and different models can be selected according to different requirements. The outdoor bracket mainly considers whether load capacity meets requirements, and then installation location, because we found out from practice that many outdoor cameras are installed in special places, some are installed on poles, some are on tower cranes, and some are installed on iron on shelf. .. For various reasons, existing bracket may not meet requirements, and additional processing or refinement is required, so I will not say more here.

③Protective cover

The protective cover is also one of most commonly used devices in monitoring system, mainly divided into indoor and outdoor. The main difference between internal protective coatings is size, beautiful appearance and quality surface treatment. The main function is to prevent dust and vandalism. The tightness of outer protective cover must be good so that rain water cannot get inside protective skin.ha and damage camera. Some outdoor enclosures also have exhaust fans, heating plates, and windshield wipers that can better protect equipment. When weather is too hot, exhaust fan works automatically, when it is too cold, heating plate works automatically, when rain falls on protective glass, wiper can be activated through control system. When choosing a protective cover, first look at overall design. The smaller mounting holes, better waterproofing. Then check whether internal wiring can be easily connected. Finally, consider appearance, weight, mounting base, etc.

④Monitor

Monitor is standard output of monitoring system. Only with help of monitor can we view images sent from external interface. Monitors are divided into color and black and white, and sizes are 9, 10, 12, 14, 15, 17, 21 inches, etc., and most commonly used is 14 inches. The monitor also has a resolution, which is represented by number of lines, just like a camera. In real use, number of lines of a monitor is usually required to match camera. In addition, some monitors also have audio input, s-video input, rgb component input, etc. With exception of audio input monitoring system, most of other functions are used for image processing, so we will not introduce them here.

⑤Video Amplifier

When video transmission distance is relatively long, it is better to use a larger diameter video cable. At same time, a video amplifier can be added to line to enhance signal level to achieve purpose of long-term remote transmission. The video amplifier can amplify luminance, chrominance and synchronous signal of video, but noise signal in line will also be amplified. In addition, too many video amplifiers cannot be connected in series in a loop, otherwise saturation will occur and image will be distorted.

⑥Video Splitter

One video signal corresponds to one monitor or DVR. If you want to send image from one camera to several managers, it is better to choose a video splitter. Due to large attenuation of parallel video signal, after being sent to multiple output devices, image will be seriously distorted and line will be unstable due to reasons such as impedance mismatch. In addition to impedance matching, video splitter also has video amplification so video signal can be sent to multiple output devices at same time without any interference

⑦Video Switcher

Need to send multiple channels of video signal to same monitoring location. One channel of video can correspond to one monitor, but monitor takes up a large area and is expensive. If you do not need constant monitoring, you can add a switcher in monitoring room, connect camera signal to input end of switch, and output end toswitcher to monitor channels, and can also switch sound at same time (depending on model). The switch has two modes of operation: manual switching and automatic switching. In manual mode, switch switches to any channel you want to see; In automatic mode, delay will switch preset videos in order, and switching time can be adjusted with knob. Usually 1 second to 35 seconds. The price of switch is low (usually only three to five hundred yuan), connection is simple and operation is convenient, but only one input image can be viewed at a time. To view images from multiple cameras at same time on same monitor, a screen divider is required.

⑧Screen Splitter

Screen dividers are available in 4, 9 and 16 splits. They can display images from 4, 9 or 16 cameras at same time on one monitor or send them to a VCR for recording. Quad Split is one of most commonly used devices, and its performance-price ratio is also good, and image quality and continuity can meet most requirements. Nine and sixteen division is more expensive, and resolution and continuity of each image after division is reduced, and video recording effect is not good. In addition, there are devices with six, eight and double four partitions, but aspect ratio, image clarity and continuity are not ideal, and market utilization rate is even less. In addition to displaying images at same time, most splitters can also display a single image, overlay time and characters, set automatic switching, and connect to security equipment.

⑨VCR

The most commonly used recorders in surveillance systems are civilian DVRs and long life DVRs because they are easy to learn and video cassettes are easy to store and buy. Unlike home DVRs, time-lapse DVRs can work for a long time, can record images for 24 hours (on ordinary VHS tapes) or even hundreds of hours, can connect to a burglar alarm, automatically start recording when a signal is received. alarm, can overlay time and date, and can also edit VCR's automatic recording program, select recording speed, automatically stop or rewind after end of video tape... it's outstanding, it's expensive, and current resolution is not very high, and image is too large in slow-motion recording time, some of it will be lost and playback image will jump from one meal to another.< /p>

Third, choosing a hard disk DVR

At present, it can be said that it has entered Spring and Autumn periods and Warring States of digital monitoring hosts. Objectively speaking, since digital products keep pace with rapid development of computer technology, they have outstanding performance in hard disk recording, network communication, video alarm, work schedule, multi-screen display, etc., and have won favor of many people. , Monitoring, cashier monitoring, civil monitoring and many other areas are gradually taking their place. Due to rapid development of this field, no national or industry standard has been released so far. This article introduces some precautions and skills when choosing and evaluating digital products. I hope that choosing a digital monitoring host will be useful to everyone.

1. View interface selection

Most digital monitoring hosts choose an industrial control chassis as their shell. Appearance, workmanship and printing should be exquisite and beautiful. The style of locking floppy drive and power switch with a mechanical lock helps reduce human error. If you can open cover, pay attention to which fan and power supply you are using. The dedicated fan MTBF on Pentium III processor is more than 3 years, and general fan time may not be accurate. This is a hidden danger for digital monitoring host, which is always on. In addition, pay attention to ensure that connection method of interface in back row is safe and convenient.

For best user experience, interface should be in Chinese, and main functions should be clearly displayed on main interface. It is recommended that you choose an interface that looks professional, beautiful, and intuitive. It is best to work with menus as with windows.

The function is highly expandable. The main functions are divided into monitoring function, video recording function, alarm function, control function, network function, identification function and schedule function. If there is a matrix, it is best to use full duplex intercom. Two points is much harder to do. Let's make an introduction accordingly.

2. Diversification of functions

(1), monitoring function

The monitoring function is one of most important functions of matrix host and digital host. The monitoring function is nothing more than viewing entire scene and seeing scene clearly. If necessary, there should be sound, and pay attention to whether video and audio are synchronized. The monitoring effect is mainly determined by resolution, screen degree, and real-time display form. Unlike TV display, monitoring effect of different graphics cards and data acquisition cards is different. As with measuring sharpness of a CCD camera, it is recommended to select a professional graphica hard test card and a camera with a large number of lines, and accurately read horizontal and vertical resolution that can be observed, as basis for monitoring. sharpness. Typically an image per second. When it exceeds 17 frames, it looks like a relative real-time image to naked eye, and cash register system and some special observation places require images to reach 25 frames per second or higher. Usually, some quick hand movements can be used to observe this function. such as quick data counting, hand clapping, etc., this effect should be recorded as a video playback recording. The display shapes usually include 1, 4, 7, 9, 10, 16 and other screen division shapes, and screen can also be cut to full screen. Brightness, contrast, color, saturation and other parameters of each channel must be smoothly adjusted, otherwise it cannot be seen well due to uneven lighting with multiple screens. In this, digital hosts are superior to conventional screen splitters. When viewed in full screen mode, it can accurately reflect image quality, video recording speed, and graphics card quality.

(2), video:

The video recording effect is core and vitality of digital host. A clear real-time image can be seen on monitor, but playback effect may not be very good after recording. The most important thing for forensics is video recording effect As a general rule, video recording effects are more important than monitoring effects.

The observation methods and effects of observation are similar in clarity and degree of real time. The memory used for video recording per unit of time and memory of one frame are also most important parameters for reflecting effect of video recording. The memory occupied by video recording per unit of time and space occupied by one frame have a decisive influence on how long same hard disk can be recorded and on image transfer speed on Internet. Generally, standard mpeg format needs to record 600m per hour and each channel, while mjpeg format records 16 channels of images at same time and occupies 150m under standard conditions (image quality) and graphic format. How much memory a dynamic image takes depends on size of image and how much image is compressed, format of image, and whether image changes and how fast it changes. I once tested a digital host using mjpeg format and set image size to 800 × 600. 3 KB , 180 bytes when not in motion. In addition, some security monitoring hosts must have a pre-installed alarm recording function, which can filter out non-alarm information and greatly reduce storage capacity requirements. Some hosts also have a function to automatically increase number of recorded frames after an alarm. This is also veryIt is useful for storing reliable information.

Special reminder: The same image with same quality may cover a large area (70-550m/channel/hour). Currently you cannot see display of machine monitoring interface and you can only check file size in operating system (such as windows, nt, unix...) to be accurate.

(3), alarm function:

The alarm function mainly refers to detector input alarm and image and video frame measurement alarm. After alarm, system will automatically turn on recording function and turn on corresponding spotlight, alarm and network output through alarm output function.

Image and video frame detection and alarm is a unique digital surveillance function that can easily set video trigger area and sensitivity, and can also play role of a detector in a certain sense.

The automatic arming and disarming function according to time period, preset alarm recording function, and automatic addition of a frame to alarm recording are functions that traditional alarm systems do not have.

The alarm output time should be adjustable, and various alarm results should be clearly recorded in computer.

(4), control function:

Mainly refers to control of pan/tilt and lens of omnidirectional camera through host, which is usually done with a special decoder, mainly to observe flexibility and reliability of operation.

(5), network function:

Dial-up Internet access via LAN and simple identity recognition allows you to perform various video monitoring and control operations on host

4. A Brief Introduction to Ultra-Low Light Camera and Infrared

Ultra-Low Light Camera is a popular monitoring product that has emerged in recent years due to development of semiconductor technology. At present, it is widely used in finance, cultural museums, hotels, office buildings, residential property management and other fields. Since it is difficult for traditional cameras to meet needs of 24/7 continuous surveillance (because it is impossible to turn on light 24 hours a day in any place), ultra-low light cameras based on new technologies have seized this opportunity and developed rapidly. .

Most conventional ultra-low light cameras use exview technology. Cameras using exview CCDs greatly improve sensitivity to ambient light. In near infrared region, its sensitivity can be increased by 4 times compared to conventional cameras. cameras such as (Fig. 1). Thus, even in very dark conditions, this type of camera can usually see objects that are invisible to human eye. The advent of this technology is welcomed by video surveillance market, and it can show best results in various lighting conditions, especially when using special infrared lighting equipment, black and white can be obtained. high-definition white images and zero-light monitoring (in case of total darkness). In near infrared region of 760-1100 mm, sharp black and white images can be obtained when combined with infrared illumination of a suitable wavelength.

Similarly, low-light imaging method is to increase illumination of CCD in a single-frame image by accumulating charges in a single frame, thereby increasing camera's sensitivity to a single-frame image. This method also allows you to get a lower illuminance index, but it should reduce image coherence, so when choosing this type of camera, pay attention not to use it with PTZ as often as possible, otherwise it will cause image loss phenomenon. There are other ways to get an image in low light, but none of them can fundamentally solve problem of illumination.

In addition, there are a few things to keep in mind when choosing cameras for low light and infrared light sources.

First, you need to choose right lens. To improve sensitivity of camera to infrared light and scene, you should choose a lens with as much light as possible, and you should pay attention to value of large aperture movement level when using auto iris or electric variable lens. Because usually as focal length of lens increases, amount of light passing through it will relatively decrease. When choosing an infrared lamp, you need to leave some margin and pay attention to nominalinfrared lamp index.

Secondly, additional power supply of infrared lamp should be as close as possible to minimum required electric power, and irradiation distance is often insufficient.

Thirdly, consider degree of reflection of scene being shot. Since infrared rays have same characteristics as visible light, such as reflection and refraction, in absence of a good reflective environment (such as buildings, walls, signs) around target scene, a certain margin of distance should be considered

Five, Yongtai

Pan/Tilt is an auxiliary device for installing and fixing camera. It is divided into two types: fixed and electric pan/tilt.

Fixed pan/tilt is suitable for situation where monitoring range is short. After setting camera to fixed pan/tilt, you can adjust horizontal and tilt angles of camera. After reaching best working position, you only need to lock adjustment mechanism.

Motorized pan/tilt is suitable for scanning and monitoring a large area, and can expand camera's viewing range. The high-speed position of electric pan/tilt is carried out by two actuator motors, and motors receive signals from controller for precise operation and positioning. Under action of a control signal, camera on PTZ device can not only automatically scan surveillance area, but also track surveillance object under control of duty personnel in surveillance center.

According to rotation characteristics, gimbal can be divided into horizontal rotary, which can only rotate left and right, and omnidirectional, which can rotate both left and right, as well as up and down. Generally speaking, horizontal rotation angle is 0°～350°, and vertical rotation angle is +90°. The horizontal rotation speed of constant speed head is generally 3°～10°/s, and vertical speed is about 4°/s. The horizontal rotation speed of variable speed head is generally 0°～32°/s, and vertical rotation speed is about 0°～16°/s. In some high speed cameras, horizontal pan/tilt speed is up to 480°/s and vertical speed is over 120°/s.

6. DVR Features:

The main function of hard disk video recorder is to convert analog audio and video signals to mpeg digital signals and store them on hard disk drive (hdd), and provide related functions for recording, playback and program management.

Its outstanding features are reflected in following aspects

1. Realize digital high-quality storage of analog programs. It can record and store widely distributed and personally assembled analog audio and video programs in digitally enhanced form. After repeated recording and playback, quality will not suffer. .reject.

2. Comprehensive input and output interfaces Provides antenna/TV cable, AV terminal, S-terminal input interface, and AV terminal, S-terminal output interface. It can record almost all TV programs and signals from other players and cameras and can be easily connected to other audiovisual equipment.

3. Various additional image recording levels. There are three picture-recording quality levels for same program source: high, medium, and low. When highest level is selected, quality of recorded image is closer to that of a DVD.

4. Large-capacity, long-term program storage, highly scalable Users can choose between 20.4 GB, 40 GB or more hard disk for program storage. Based on a capacity of 20.4 GB, ratio between recordable program time at selected bit rate is shown in following table:

Baud rate (Mbps) Program recording time (hour)

6 7

4 10

2 20

1.15 38

5. With advanced timeshifting function. When a TV program needs to be interrupted, user only needs to press timeshift key, and program from moment of interruption will be automatically saved. After that, you can continue watching program from interrupted position without feeling a pause.

6. Ideal function for scheduled recording/playback of programs. Users can freely set parameters such as start time and duration of recording/playback of programs. By editing and combining scheduled program list, various intermittent TV programs including TV series can be systematically recorded.

7. Powerful Network Information Center for Home Appliances Users will be able to get extensive online information through network communication interface using a web browser configured by dvr and equipped with appropriate network resources.

8. Provide a convenient way to manage recorded programs. Users can organize and categorize recorded programs by recording time, program type, etc., and bookmark their favorite places.

9. Provide free play mode Thanks to fastm and random hard disk storage characteristics, when watching a recorded program and a program being recorded, it can be played in different ways and with more flexibility than current DVD player. images in fast playback and higher resolution in slow playback.

Seventh, skills of choosing optical transceivers in safety engineering

Multichannel digital video optical transceivers currently on market use a wide range of technical indicators, and most engineering companies and users also lack appropriate means to evaluate rationality and validity of technical indicators, so it is easy to get lost when choosing a product. This article describes two technical indicators that are relatively key and easy to verify in a project, and focuses on reliability and practicality, and analyzes how to select multi-channel digital video optical transceivers in security monitoring projects.

1. Spec Features

Multichannel digital video optical transceivers can have multiple functions, and each type of function has corresponding performance requirements such as video index, audio index, asynchronous data index, Ethernet index, etc. For specific performance specifications, manufacturers may be required to provision of third-party test certificates. Before purchasing equipment, qualified contractors must re-test in accordance with indicators provided by manufacturer to verify actual technical performance of equipment and integrity of manufacturer. Here we will briefly explain following two video indicators from an engineering point of view.

A video bandwidth of 1.1 3dB is sufficient

Video bandwidth is a perennial issue. If video bandwidth is insufficient, details of monitor image will not be clear enough, horizontal resolution will be poor, and even serious distortion or loss of color will occur. It is precisely because of importance of video bandwidth to image quality that some unscrupulous manufacturers intentionally inflate video bandwidth of their products in order to deceive buyers. A manufacturer's multi-channel digital video optical transceiver claims to have a video bandwidth of 8m, but claims a video sampling rate of 12.5m. According to Nyquist's sampling law, sampling frequency must be at least twice frequency of signal to truly reconstruct signal. Therefore, theoretical video bandwidth of this manufacturer's optical transceiver cannot exceed 6.25m anyway. Obviously, this is a lie about exaggerating performance to deceive customers, so manufacturers without a commercial reputation should not be considered for purchase. But not all buyers can accurately identify manufacturer's lies, and engineering companies and users can roughly judge device's video throughput by observing image details.

A range of 1.2 pl is wide enough

apl, that is, average level of image, many engineering companies do not pay much attention to this indicatormania or not familiar. However, if we talk about such a problem that occurs in some projects: when transmitting a video signal through an optical transceiver, when there is a large area of ​​white color in picture (for example, when camera is illuminated with strong light), picture on monitor will shake horizontally, so Engineers should be not strangers. This is because APL range of video optical transceivers produced by some manufacturers is too narrow. When there is a large white area in image signal, DC component in each line of image signal will increase, and APL will increase, resulting in a decrease in amplitude of horizontal sync signal or If it is lost, monitor cannot detect horizontal sync and picture is shaky.

2. Available denaturation options

In a security monitoring design, equipment variability should be considered first. Equipment variability must be taken into account by equipment manufacturers when designing products, however some manufacturers may not want or know how to do this work for some reason. Here we briefly discuss following issues from an engineering point of view.

2.1 Convenient power supply, wide range of power supply

Power is a major factor to consider when providing variability in digital video optical transceivers. It is not possible to guarantee that power supply will be variable and reasonable. Talking about variability of digital video optical transceivers is like catching moon in water. A video optical transceiver powered by 220V is more convenient for power supply, and variability is also high. In a project, an optical transceiver powered by 220V should be chosen as much as possible according to situation. At present, there are mainly two power supply methods for this optical transceiver, one is an external power supply, and other is a built-in power supply type, that is, power supply and optical transceiver are integrated. In terms of engineering applications, built-in power supply is not only easy to install, but also highly reliable, which is why most modern multi-channel digital video optical transceivers use an integrated power supply.

Based on situation of domestic power grid and actual situation of project site, a multi-channel digital video optical transceiver with a wide input power range should be selected as much as possible. As a general rule, you should try to choose an optical transceiver that uses a switching power supply. Compared with linear power supply, switching power supply not only has high efficiency, but also has a wide input voltage range, which in principle can guarantee normal operation in range of 160-265V AC, and its output voltage will not change with input voltage. so it has no effectno to optical transceiver. The performance and specifications will not cause optical transceiver to restart due to instability of mains, interrupting transmission of video and audio surveillance signals.

2.2 Strong adaptability to temperature and humidity

In some security monitoring projects, optical transceiver environment is relatively harsh, with a wide temperature range and high humidity. Some field monitoring sites experience power outages from time to time, and optical transceiver generates heat during operation, and condensation forms when equipment cools down when power is turned off. All this requires more attention to temperature and humidity range of multi-channel digital video optical transceivers in order to ensure their stable operation in harsh environments and meet needs of security monitoring.

3.1 The appearance is generous and structure is reasonable

The multi-channel digital video optical transceiver is of high technical content, and its appearance should be small and exquisite, beautiful and generous, and overall structure should be as close as possible to requirements of engineering installation. In addition to using 19 cabinets for common indoor multi-channel digital video optical transceivers, it is also necessary to place optical transceiver on a desktop or wall during a project. In addition, digital video multi-channel optical transceiver must also have good heat dissipation performance and electrical contacts.

3.2 Rich interfaces and smart layout

In addition to a sufficient number of video interfaces for multi-channel digital video optical transceivers, other multifunctional interfaces may also be required or may be required in future, such as high-quality audio interfaces, conventional telephone interfaces, asynchronous data interfaces, Ethernet interfaces. , switch interface, etc., which requires selected multi-channel digital video optical transceiver to be able to upgrade system, so as not to completely replace equipment due to network upgrades or system function changes to protect user. initial investment.

Multichannel digital video optical transceivers have many types and numbers of interfaces, and there may be some mode dials corresponding to these interfaces. The user interface, which consists of all these elements, must have a reasonable layout, and a large working space between interfaces, to facilitate engineering installation and maintenance. For example, if video interfaces are too dense, there will be an awkward situation where other conventional video interfaces must be disabled in order to support a particular video interface in practical applications.

3.3The meaning of indicator light is clear, which is convenient for opening and maintaining project

The multi-channel digital video optical transceiver should be marked with a clear indicator light to facilitate project opening and maintenance. In addition to power indicator light, multichannel digital video optical transceivers must have video presence or absence indicators to indicate whether corresponding video channel has a video input or output. opening and maintenance situations, find location of fault and eliminate possible problems as soon as possible.

In addition, appropriate indicators should also be provided for audio and data parts. An easy way is to refer to practice of telecommunications equipment and provide a synchronization indicator light and a loop indicator. Based on this, engineering personnel and equipment manufacturers can judge whether equipment system is faulty or part of interface is faulty in order to make right answer.

The Ethernet interface must provide a link/activity indicator, a full duplex/half duplex indicator, and a 10m/100m indicator in accordance with general requirements for data transmission equipment.

Multichannel digital video optical transceivers must also have system indicators that indicate health of transmitting equipment and health of receiving equipment, so that engineers can distinguish whether this is a hardware failure or a fiber optic link failure.

Summing up, when choosing equipment, users can consider technical performance, variability and practicality of equipment, make more comparisons according to above methods, and draw up a suitable plan according to actual situation of project. the best multi-channel digital video optical transceiver for you.