HDMI

High Definition Multimedia Interface (English: High Definition Multimedia Interface, HDMI) is a digital video/audio interface technology. It is a dedicated digital interface suitable for video transmission. It can transmit audio and video signals at the same time. The maximum data transmission speed is 18Gbps. . At the same time, there is no need for digital/analog or analog/digital conversion before signal transmission. HDMI can be combined with Broadband Digital Content Protection (HDCP) to prevent unauthorized copying of copyrighted audio and video content. The extra space provided by HDMI can be used in future upgraded audio and video formats. And because a 1080p video and an 8-channel audio signal requires less than 4Gbps, HDMI has a lot of headroom. This allows it to connect the DVD player, receiver and PRR separately with a single cable.

HDMI can not only meet the resolution of 1080P (the 1.3 version is basically at 5760*3240 resolution), but also support digital audio formats such as DVD Audio, support eight-channel 96kHz or stereo 192kHz digital audio transmission, and can transmit uncompressed audio signals and video signals. HDMI can be used in set-top boxes, DVD players, personal computers, video games, integrated amplifiers, digital audio and televisions. HDMI can transmit audio and video signals at the same time.

HDMI supports EDID and DDC2B, so the device with HDMI has the characteristics of "plug and play". The signal source and the display device will automatically "negotiate" to automatically select the most suitable video/audio format.

Compared with DVI, the HDMI interface is smaller in size, and the optimum cable length of HDMI/DVI is no more than 8 meters. Only one HDMI cable can replace up to 13 analog transmission lines, which can effectively solve the problem of messy and tangled wiring behind the home entertainment system.

DVI

 DVI (Digital Visual Interface), the digital video interface. It was launched in 1999 by Silicon Image, Intel (Intel), Compaq (Compaq), IBM, HP (HP), NEC, Fujitsu (Fujitsu) and other companies to form DDWG (Digital Display Working Group, Digital Display Working Group). interface standard.

Taking into account compatibility issues, the graphics card generally uses a DVI-I interface, which can be connected to a common VGA interface through a conversion connector. A monitor with a DVI interface generally uses a DVI-D interface, because such a monitor generally also has a VGA interface, so a DVI-I interface with an analog signal is not required. Of course, there are a few exceptions, some monitors only have a DVI-I interface and no VGA interface. Display equipment using DVI interface has the following major advantages:

One is fast

DVI transmits digital signals, and the digital image information will be directly transmitted to the display device without any conversion, thus reducing the cumbersome conversion process of digital → analog → digital, which greatly saves time, so it is faster. , effectively eliminate the smear phenomenon, and use DVI for data transmission, the signal is not attenuated, the color is purer and more realistic.

Second picture is clear

The internal transmission of the computer is a binary digital signal. If you use the VGA interface to connect the liquid crystal display, you need to convert the signal into R, G, B three primary color signals and line and field synchronization through the D/A (digital/analog) converter in the graphics card. Signals, these signals are transmitted to the inside of the liquid crystal through the analog signal line, and the corresponding A/D (analog/digital) converter is required to convert the analog signal to a high-definition video high-definition video (generally speaking, a single-channel DVI interface, the maximum refresh rate Only 1920*1080*60hz or 1600*1200*60hz) can be converted into digital signals to display the image on the LCD. In the above-mentioned D/A, A/D conversion and signal transmission process, signal loss and interference will inevitably occur, resulting in image distortion or even display error, and DVI interface does not need to perform these conversions, avoiding signal loss and making The sharpness and detail of the image have been greatly improved.

Three supports HDCP protocol

The DVI interface can support the HDCP protocol, laying the foundation for viewing high-definition video with copyright in the future. However, in order to make the graphics card support HDCP, it is not enough to have a DVI interface. It needs to install a dedicated chip and pay a lot of HDCP certification fees. Therefore, there are not many graphics cards that really support the HDCP protocol.

The interface form, pin definition, and data format of HDCP signal are the same as DVI, but the data is encrypted in consideration of confidentiality reasons, which must meet the protocol requirements of HDCP. Considering that this is only a protocol-level difference, we can consider the two equally.

The DVI interface is different from the VGA interface. There are many standards for the DVI interface. You must understand it when using the monitor. DVI is divided into five standards. Among them, DVI-D and DVI-I are divided into two types: "dual-channel" and "single-channel". We usually see the single-channel version. The cost of the dual-channel version is very high, so only some professional equipment has it. , it is difficult for ordinary consumers to see.

DVI-A is an analog transmission standard seen in late large-screen professional CRTs. However, because there is no essential difference with VGA, and the performance is not high, DVI-A has actually been abandoned. As for the DFP interface, this is an early digital specification that has been abandoned.

VGA

VGA (Video Graphics Array) is a video transmission standard introduced by IBM with PS/2 in 1987. It has the advantages of high resolution, fast display rate and rich colors, and has been widely used in the field of color displays.

VGA data cable is a cable used to connect VGA interface devices. The length of the finished cable is 1.5 meters, 2 meters, 3 meters, 5 meters, 10 meters, 15 meters, etc. Generally, there are no finished cables exceeding 15 meters, because When the signal transmission distance exceeds 15 meters, the VGA signal quality will be seriously degraded. If you need to transmit the VGA signal generated by the graphics card to a distance of more than 15 meters, if the distance is not too long, you can solder a VGA cable to test the effect. If the distance is too far, you should directly use a VGA-CAT5 converter.

BNC

BNC connector is a kind of connector for coaxial cable, the full name is Bayonet Nut Connector (snap fit connector, this name vividly describes the shape of this connector), also known as British Naval Connector.

BNC connectors are used for the transmission of radio frequency signals, including the transmission of analog or digital video signals, the connection of amateur radio equipment antennas, the connection of avionics and other electronic test equipment. In the field of consumer electronics, BNC connectors for video signal transmission have been replaced by RCA terminals. With a simple adapter, RCA terminals can be used on devices that only have BNC connectors. BNC terminals have been widely used in 10base2 Ethernet. Since coaxial cables are replaced by twisted pairs, it is difficult to see network cards with BNC terminals. Some ARCNET networks make coaxial cables terminated with BNC terminals.

 BNC connectors are available in 50 ohm and 75 ohm versions. There is less chance of transmission errors when connecting 50 ohm connectors with other impedance cables. Different versions of the connector are compatible with each other[1], but if the impedance of the cable is different, the signal may be reflected. Usually BNC connectors can be used at 4GHz or 2GHz.

75 ohm connectors are used for video and DS3 connections to the telephone company central office, while 50 ohm connectors are used for data and RF transmission. A 50-ohm plug incorrectly connected to a 75-ohm outlet can damage the outlet. 75 ohm connectors are used in VHF applications.

1080P, 4K, 2160P and 8.3MP are often used to represent the resolution of the video, but so many names are often confusing and confusing, so let's make the video resolution clear today.

'P'

720P, 1080P, etc., means "the total number of lines of video pixels". For example, 720P means that the video has 720 lines of pixels, while 1080P means that the video has a total of 1080 lines of pixels. The 1080P resolution camera usually has 1920 pixels* 1080. "P" itself stands for "progressive scan", which is the abbreviation of Progressive, as opposed to interlaced scan (Interlaced).

'K'

2K, 4K, etc., means "the total number of columns of video pixels", such as 4K, means that the video has 4000 columns of pixels, specifically 3840 or 4096 columns. 4K resolution cameras usually have 3840*2160 or 4096*2160 pixels.

'MP'

MP is the total number of pixels, that is, the result of multiplying the number of rows (P) and columns (K) of pixels (megapixels). For example, a 1080P camera is 1920 pixels multiplied by 1080 pixels, resulting in a total of 2MP (megapixels) of pixels.

Which expression is better:

"P" makes the worst sense, because "P" expresses the "vertical" pixel measurement, which is not very applicable in the video surveillance industry. Because, the commonly used "pixel density" calculation (PPF/PPM) is measured in the "horizontal direction". In this way, the expression of "K" is relatively more meaningful, because the pixel measurement in the horizontal direction is directly given, which is very convenient for the calculation and comparison of PPF.

Liquid crystal is based on the principle that liquid crystals are deflected under the action of voltage. The liquid crystals that make up the screen can display the three primary colors of red, green and blue at the same point, or a point of the liquid crystal is superimposed by three points, which are arranged in a certain order, and stimulate these liquid crystals by voltage, Different colors can be presented, and the combination of different proportions can present ever-changing colors. The liquid crystal itself does not emit light, it relies on the backlight tube to emit light, so the LCD screen depends on the backlight tube. Because the liquid crystal adopts point imaging, the more points formed on the screen, the finer the imaging effect, and the number of vertical and horizontal points constitutes the resolution of the LCD TV. The higher the resolution, the better the effect.

Advantages: high resolution, thin thickness, light weight, low energy consumption, long life, no radiation.

Cons: The seam is slightly larger. The technical advantages of LCD splicing large screen wall in the field of splicing:

Compared with DLP products and PDP products, LCD products have their own advantages and characteristics in terms of use effect and technical parameters. Let us focus on the two major advantages of LCD splicing curtain walls in the field of large-screen splicing. 1. Combination of size and size, more flexible use

Liquid crystals are available in various sizes and sizes are optional. For LCD splicing curtain wall, in addition to the arbitrary selection of the number of splices [row (m) × column (n)], the size of the screen also has a variety of choices, and can be mixed and spliced, which meets the needs of different places of use.

We know that the splicing curtain wall not only needs to realize the full-screen large-screen display, but also realize the multi-channel small-screen display. For example, the splicing curtain wall of a traffic monitoring center is more often required to view the pictures of all monitoring points at the same time. When an abnormal situation occurs at a monitoring point, it can be quickly enlarged to a full screen for everyone in the monitoring center to watch at the same time. This requires that in practical application, the splicing curtain wall should achieve a good display effect in both large and small pictures.

DLP rear projection and PDP plasma splicing curtain wall, the unit size is large, some can reach 100 inches or even 150 inches, although a certain program reduces the splicing seam when displaying a large screen, but due to its low resolution, if The use of a screen splitter to achieve the purpose of displaying multi-channel images is not ideal, and the cost and stability of the system are greatly affected due to the addition of equipment. The result is that the DLP splicing curtain wall can only be used to display a large picture, and the small pictures of many monitoring points still need to be displayed by LCD monitors or other monitors, and the signal switching is frequent, and the effect is very unsatisfactory.

LCD splicing curtain wall, there is no such problem. We know that the liquid crystal display unit is relatively small in size, but the resolution is the highest, and it can be mixed in size and size, which is beneficial for users to reasonably arrange the splicing scheme according to the actual use needs, so as to achieve the size matching, each Appropriate effect. 2. Long stable life and low maintenance cost

Compared with DLP and PDP, the service life of liquid crystal is very long, and the power is low, the heat generation is not large, and the failure rate is very low. PDP plasma is prone to plasma burn, and its dynamic display life may reach tens of thousands of hours, but when displaying high-brightness static images, screen burns may occur after 5,000 hours; while DLP's lamp life is only 3,000 to 10,000 hours. Five thousand hours, 4 hours of continuous use of the security monitoring large-screen splicing curtain wall selection, should try to consider the choice of LCD splicing curtain wall, in order to improve the use efficiency, reduce the cost of use and maintenance costs. Summary of large LCD screen:

1) In terms of function: the volume and weight of rear-projection technology are too large, and the key technical indicators are far less than that of plasma and liquid crystal, and it works continuously for a long time, which accelerates the aging of the backlight. With four hours of operation, the backlight needs to be replaced every few months. Plasma is not suitable for displaying static monitoring images for a long time due to the large power consumption and heat generation, and serious burns. After being used for splicing, the whole machine heats up even higher, which makes the equipment easy to burn. Liquid crystal stands out in the flat panel display technology. Its advantages such as thin thickness, light weight, low energy consumption, long life, no radiation, and excellent performance of various key performance indicators have made it the mainstream of development with promising prospects.

2) In terms of price: Considering the economy of the system, it is necessary to mention the cost-effectiveness. Only under the premise of high performance and high quality, the economy of the system is meaningful. At present, there are plasma (PDP) splicing curtain walls on the market, but their prices are relatively high. Generally, the price of one square meter is as high as hundreds of thousands, and due to the problem of plasma branding, it is not suitable for displaying static images in some (security, road traffic, Ports and wharfs, etc.), the overall cost performance is low. Although the price of DLP video wall is relatively low, the replacement cost of light bulbs is as high as several thousand yuan a year.

LCD large screen splicing curtain wall has been widely welcomed at home and abroad for its excellent performance and reasonable price. With a service life of up to 50,000 hours, stable quality and low maintenance costs, it is a wise choice.

PDP (Plasma Display Panel), that is, a large plasma screen. PDP is a display technology that utilizes gas discharge, and its working principle is very similar to that of fluorescent lamps. It uses a plasma tube as a light-emitting element. Each plasma tube on the screen corresponds to a pixel. The screen uses glass as a substrate. The substrates are spaced at a certain distance. Mixed inert gases such as xenon are used as working medium, and metal oxide conductive films are coated on the inner sides of two glass substrates as excitation electrodes. When a voltage is added to the electrode, the mixed gas in the discharge space will have a plasma discharge phenomenon, also known as the plasma effect. The gas plasma discharge produces ultraviolet rays, which excite a phosphor screen coated with red, green and blue phosphors, and the phosphor screen emits visible light to display images. When each color unit achieves 256 grayscales and then performs color mixing, color display is realized.

The technical principle is that since the light-emitting plasma tubes in the PDP are evenly distributed in the plane, the center and edge of the displayed image are exactly the same, and there will be no distortion, realizing a true pure plane without any image distortion. Since there is no electron beam movement in the display process, it does not need to rely on an electromagnetic field, so the external electromagnetic field will not interfere with it, and it has better environmental adaptability. PDP is a self-illuminating display technology that does not require a background light source, so there are no viewing angle and brightness uniformity issues. The design of three-color phosphors sharing the same plasma tube also avoids focusing and convergence problems, and can achieve very clear images. Plasma has high voltage and high power consumption, large energy consumption, and inherently short lifespan. After 5,000 to 10,000 hours of use, the screen brightness will be attenuated by half, and it is difficult to work normally at altitudes above 2,500 meters.

PDP plasma works

Plasma (PDP) is a display technology that utilizes a gas discharge that works much like a fluorescent lamp. It uses a plasma tube as a light-emitting element, each plasma tube on the screen corresponds to a pixel, the screen uses glass as a substrate, the substrates are separated by a certain distance, and the surrounding areas are air-tightly sealed to form discharge spaces. The discharge space is filled with mixed inert gas such as neon and xenon as the working medium. Metal oxide conductive films are coated on the inner surfaces of the two glass substrates as excitation electrodes. When a voltage is applied to the electrode, the mixed gas in the discharge space will generate a plasma discharge phenomenon. The gas plasma discharge produces ultraviolet rays, which excite the phosphor screen, which emits visible light to display images. When using a phosphor screen coated with three primary colors (also called three primary colors) phosphors, ultraviolet light excites the phosphor screen, and the light emitted by the phosphor screen is in the three primary colors of red, green, and blue. When each primary color unit achieves 256 grayscales and then performs color mixing, color display is realized. Plasma display technology can be divided into two categories according to its working mode: DC-type PDPs in which electrodes are in direct contact with gas and AC-type PDPs in which electrodes are covered with a dielectric layer. There are mainly three types of color PDPs currently researched and developed: single-substrate type (also known as surface discharge type) AC PDP, dual-type (also known as opposite discharge type) AC PDP and pulse storage DC PDP.

PDP plasma features

Plasma (PDP) is a self-illuminating display technology that does not require a background light source, so it does not have the viewing angle and brightness uniformity issues of LCD displays, and achieves higher brightness and contrast. The design of the three primary colors sharing the same plasma tube also avoids the problem of focusing and convergence, and can achieve very clear images. Compared to CRT and LCD display technologies, the larger the screen of the plasma, the higher the color depth and fidelity of the image. In addition to the brightness, contrast and viewing angle advantages, plasma technology avoids the response time problems of LCD technology, which are critical factors in dynamic video displays. Therefore, from the current technical level, the advantages of plasma display technology in the field of dynamic video display are more obvious, and it is more suitable for use as a home theater and a display terminal. The plasma display has no scanning lines, so the image is clear and stable without flickering and will not cause eye fatigue. Plasma is also free of X-ray radiation. Due to these outstanding features, plasma can be called a true green environmental protection display product, and is an ideal product to replace traditional CRT color TVs.

customer service

A. Pre-sales service:

In the pre-sale, after years of development, STONBEL has a first-class pre-sales program design engineer in the industry. STONBEL has always adhered to the principle of customer first and performed every perfect design of STONBEL. Through careful analysis and research on the needs of large-screen display systems, on the premise of meeting customer needs, combined with the advancement of system technology, reliability, cost performance, upgrade and expansion performance and other factors, to provide you with high-resolution Large-screen display system, network video transmission system as the main design scheme. To provide you with the most applicable large-screen display system engineering solutions and quotations. STONBEL will also provide you with the necessary technical support for STONBEL's products, such as the model specifications of the equipment, the realization of the control module, the precautions for use and so on. Before the equipment leaves the factory, the quality control department of STONBEL will conduct quality inspection on each product, and attach the quality assurance letter of STONBEL to ensure that each product meets the quality standards.

B. In-sale service:

After signing the contract, STONBEL will work with you to formulate corresponding project implementation plans for different projects and according to the characteristics of the project. According to the requirements of customers, the company cooperates closely with customers, sends experienced technicians and construction personnel to the site for installation and commissioning, and organizes supervision to complete the project smoothly. Achieve your satisfaction with the highest efficiency. STONBEL will send special engineering and technical personnel to the site to carry out installation and commissioning work in strict accordance with the project implementation plan. In case of special circumstances that make it difficult to carry out the construction as scheduled, the project leader must negotiate with you, and the construction plan can be modified only after obtaining your consent. After all equipments are installed and debugged, the system will continue to operate normally and both parties will carry out acceptance tests. When all the basic functions and technical performance of the equipment meet the requirements of the site, sign the equipment acceptance certificate. After the acceptance is completed, the technicians of STONBEL will conduct systematic operation training for your technicians, so that users can operate and maintain the large-screen projection display system independently, and master the installation, operation adjustment, fault judgment and simple maintenance technology of the projector. , Master the installation, use and simple maintenance of the control system and the application technology of the control system software.

C. After-sales service:

The after-sales service of engineering projects is an important part of the quality of engineering projects. With the development of the IT industry, the improvement of quality and the improvement of engineering quantity, STONBEL has also accumulated a lot of experience in after-sales service. Provide thoughtful and satisfactory service, handle customer complaints in a timely and efficient manner, and meet customer requirements to the greatest extent." This is the consistent service tenet of STONBEL. STONBEL companies wholeheartedly provide customers with fast and high-quality after-sales service, so that all systems and equipment of customers can maintain normal operation. To this end, the specialized technical after-sales service department of STONBEL will provide prompt and timely post-service for the entire project, which will truly relieve users from worries. Once the equipment fails, the user on duty should immediately notify the user service center designated by STONBEL, who will respond within 30 minutes after receiving the notification, and rush to the site to provide maintenance in the fastest way according to the actual vehicle and traffic conditions Service (the longest time is not more than 4 hours), and the equipment failure can be eliminated within 24 hours. If the failure cannot be eliminated within 24 hours, STONBEL will provide users with backup equipment services, which will not affect the user's use. During the free maintenance period , When the key components fail, the replacement time is not more than one week.

STONBEL arranges designated engineering after-sales service personnel and coordinates with various partners, keeps in touch with users on a regular basis, and is responsible for maintaining technical contacts and after-sales service departments between users and hardware equipment partners for a long time. Regularly understand the operating status of the system from users and pay attention to the further needs of users in a timely manner. Long-term assistance to the user's system management personnel in the management of the entire system application, and timely exchange of the latest technology and development trends of various business applications in the command center with the user.

The after-sales service process is as follows:

After-sales service requirements

STONBEL's requirements for after-sales service personnel: strong technical skills, high comprehensive quality, strong sense of responsibility, and correct attitude, so as to satisfy customers and maintain the company's image and interests as the standard.

Scope of after-sales service

STONBEL solemnly promises:

The free warranty period for all hardware equipment and software quality provided by STONBEL is three years (from the date of passing the initial inspection), and the lifetime warranty is only charged for man-made damage, and the rest is free, and software upgrade services are provided in time. .

STONBEL guarantees that the operating equipment meets the user's technical requirements;

Lifetime free answers to users' technical inquiries;

Emergency on-site or remote rescue for major or special faults;

STONBEL guarantees the consistency of the software and hardware of the operating equipment;

During the warranty period, if there are problems in system design, production, and process, STONBEL will be responsible for timely handling free of charge;

Hardware and software failures of the device will be replaced free of charge.

After disposal or replacement, the warranty period for the system or equipment is extended for 12 months from the date of repair.

Product quality assurance during the warranty period.

After the warranty period, spare parts will be provided at the contract price.

Other necessary technical services.

SDK development kit is provided free of charge to support re-development.

Quality assurance service during the warranty period

If the equipment and products provided by STONBEL are faulty due to quality problems, the equipment and products with quality problems will be replaced free of charge;

If the project fails, it is guaranteed to provide effective response services within 2 hours, and troubleshoot in the shortest possible time;

If there is a failure due to equipment and product problems in the project, STONBEL is responsible for contacting the manufacturer for warranty and maintenance;

For the equipment and products used in the project, if the warranty period provided by the manufacturer is less than one year, the warranty and maintenance within the short period of time shall be the responsibility of STONBEL.

If the damage is caused by other factors, STONBEL can also provide paid maintenance.

When the software version is upgraded, if no new functions or analog sound are added, STONBEL will update and upgrade the software version free of charge, and provide relevant information such as the corresponding new version software function manual and modification manual.

If the failure is caused by the following conditions, it is not covered by the warranty:

Malfunctions caused by not being used as required (misoperation);

Failures due to falls, collisions;

Failure caused by self-disassembly and repair;

Failures caused by natural disasters such as water, electricity, lightning, and earthquakes;

Failure due to abnormal voltage, damping of equipment and other external factors.

In order to ensure the normal operation of the system, it is recommended that the user send trained personnel to perform maintenance operations on the system equipment.

During the warranty period, the following services are chargeable services:

Add hardware equipment;

Reinstallation and debugging; for failures caused by wrong operation, unauthorized repair or maintenance by users, STONBEL will replace or repair the faulty parts after receiving them, and install them to the installation site. However, the user shall bear all the expenses arising therefrom;

When the system failure is due to other non-product quality reasons not mentioned.

Quality assurance service after the warranty period

After the warranty period, STONBEL will be responsible for life-long maintenance (repair), and only the cost of repair will be charged within 10 years; technical service fees will be charged appropriately after 10 years.

STONBEL guarantees that it will continue to provide repairs and maintenance for the equipment, and the costs arising therefrom shall be borne by the user.

STONBEL guarantees at least 10 years of spare parts supply for all system equipment.

STONBEL still promises to be responsible for the improvement and upgrade of the software free of charge.

Within four years after the warranty period, STONBEL guarantees to carry out regular maintenance and repairs to users, among which the maintenance and elimination of failures without replacement parts are free; The cost of relevant parts and travel expenses of maintenance personnel will be charged as appropriate.  

After the warranty period expires, STONBEL promises to renew the relevant maintenance service agreement and provide spare parts at the preferential price of the contract.

fault response

When the system is normal, STONBEL is responsible for assisting the user to formulate a system fault emergency plan to ensure the safe and reliable operation of the entire system. After receiving the user's fault repair information, assign an engineer to assist the user to further identify the fault condition.

The fault response time does not exceed 30 minutes, and the troubleshooting time does not exceed 24 hours. If the fault is a product quality problem, the user is responsible for the overall replacement of damaged parts within the warranty period; if the maintenance personnel cannot eliminate the fault within 24 hours, STONBEL provides spare equipment services for users and guarantees that it will not affect the use of users.

Troubleshooting Time When encountering difficult problems but not jeopardizing the operation of the system, STONBEL will give a reply within 1 day. In the process of on-site fault repair, if STONBEL needs to use the user's on-site equipment, the user should cooperate with it. After the expiry of the warranty period, if the damaged plate cannot be repaired, STONBEL will offer a discount for spare parts.

Technical support method:

During each period of system installation and commissioning, test acceptance, operation and maintenance, we provide users with technical support and consultation, including: telephone technical service, on-site technical service, regular inspection service, technical upgrade service, etc.

According to actual needs, STONBEL can provide users with two technical support methods: remote communication maintenance (by telephone guidance or remote maintenance terminal) and on-site fault repair.

STONBEL has a remote support center at the headquarters. If users have any questions, they can contact them at any time, and they can get satisfactory answers. With the consent of users, they can be connected to the on-site system through MODEM. Real-time operation and maintenance of equipment

As a key user of STONBEL, STONBEL will track and record the operation and maintenance of the equipment and store it in the key user files. During the operation of the system equipment, the engineer of the user service center will visit the user regularly to inquire about the operation of the equipment. condition. According to the specific situation, when necessary, the engineers of STONBELfang User Service Center will come to the site to guide the maintenance work.