Archive 04/30/2022

Design scheme of power reference power supply based on ON Semiconductor monolithic controller

XDSL modems in home and office applications are usually powered by external AC-DC (AC-DC) adapters. Judging from the usage habits of most people, these adapters have been plugged into the power outlet and continue to consume power from the AC mains power supply. It is estimated that up to 25% of the electrical energy passing through the adapter is consumed during standby (no load). For this reason, the AC-DC adapter must be designed to maintain extremely low energy consumption in standby mode.

XDSL modems in home and office applications are usually powered by external AC-DC (AC-DC) adapters. Judging from the usage habits of most people, these adapters have been plugged into the power outlet and continue to consume power from the AC mains power supply. It is estimated that up to 25% of the electrical energy passing through the adapter is consumed during standby (no load). For this reason, the AC-DC adapter must be designed to maintain extremely low energy consumption in standby mode.

In addition to keeping the standby energy consumption as low as possible, the working efficiency of the AC-DC adapter must be very high. Since the energy consumption of Electronic devices after all occupies a higher proportion (about 75%), higher work efficiency can help save power. In view of this, regulatory agencies around the world continue to publish and implement energy efficiency requirements for external power supplies (EPS) during work and standby, as shown in Table 1.

Design scheme of power reference power supply based on ON Semiconductor monolithic controller
Table 1. Some main energy efficiency specifications for external power supplies

Modem AC-DC adapter design specification requirements

For modem original equipment manufacturers (OEM), AC-DC adapters have become a bulk commercial product. Therefore, they mandate compliance with stringent specifications while also requiring low cost. For AC-DC adapters, the key performance indicators include three items, namely: power density (driven by package size requirements), safety, and low case temperature. The specification requirements of ON semiconductor’s modem AC-DC adapter reference design are as follows:

Input: 90-270 Vac, 50/60 Hz
Output: 12 Vdc±5% at 1.3 A continuous current (power is 16 W); 1.6 A surge current up to 10 s
Voltage stabilization: <2% under combined line and load conditions
Output ripple: less than 200 mV p/p
Steady current: <10% under combined line and load conditions
Average energy efficiency: ≥0.09 * Ln (16) + 0.49 = 74% (in line with “Energy Star” external power supply 1.1 requirements)
Standby (no load) energy consumption: ≤0.3 W
Working temperature: 0 to 50°C
Cooling method: convection
Input protection: 1 A fuse is used to provide 8 Ω surge limit
Output protection: over current protection, over Voltage protection and over temperature protection
Comply with EMI standards: FCC Part 15 conducted EMI (Level B, average profile)

The working principle of the circuit

Figure 1 shows the circuit schematic diagram of this AC-DC adapter. It can be seen from the figure that the adapter power supply is designed based on the flyback converter topology, using a simple Zener device, plus an optocoupler feedback circuit for output voltage sensing and stabilization. The AC input is full-wave rectified by 4 diodes from D1 to D4 and filtered by capacitors C3 and C4 to provide a DC “bulk” bus for the flyback converter section. Resistor R1 provides a surge current limiting function when it is turned on, while capacitors C1, C2 and inductors L1, L2 form common mode and differential mode filtering for conductive electromagnetic interference (EMI).

Design scheme of power reference power supply based on ON Semiconductor monolithic controller
Figure 1. The circuit schematic diagram of ON Semiconductor 16 W Modem AC-DC adapter reference design

The flyback converter is composed of NCP1027 controller (including integrated MOSFET U1), flyback transformer T1, diode D6, capacitors C6 and C7 and other secondary output rectification/filtering parts. The auxiliary winding on T1 and related components such as R15, D7, C10, R9 and C9 provide working bias (VCC) for this control chip, and allow low output power when the power supply is short-circuited, and allow extremely low standby under no-load conditions Energy consumption. Since the voltage generated by the auxiliary winding tracks the main output voltage, this voltage is also used to sense overvoltage conditions when the feedback loop is open.

The overvoltage protection (OVP) trip level can be adjusted by the number of turns of the auxiliary winding and the value of the resistor R9. The main secondary voltage is rectified by Schottky diode D6 and filtered to a relatively normal DC level by main output capacitors C6 and C7. Capacitor C12 provides additional high-frequency noise filtering for the output. The resistor capacitor diode (RCD) buffer composed of R2, R3, C5 and D5 is used to clamp the voltage spike caused by the primary leakage inductance of T1. This snubber network limits the peak voltage and reduces potential EMI emission problems, thereby preventing potential MOSFET drain damage (pin 5).

Design scheme of power reference power supply based on ON Semiconductor monolithic controller
Figure 2. Non-dissipative resonant snubber circuit that can replace RCD snubber circuit

In addition to the above-mentioned RCD snubber circuit, there is an alternative non-dissipative resonant snubber circuit, as shown in Figure 2. According to the properties of the transformer design and related parasitic parameters, this type of buffer can also increase the circuit efficiency by several percentage points. As the output voltage and/or power level of the power supply decreases—depending on specific needs, this increase in energy efficiency may be critical to meeting Energy Star energy efficiency requirements. This non-dissipative buffer circuit uses a resonant tank circuit composed of Lr and Cr. This resonant tank circuit essentially acts as a reactive charge pump, returning the leakage reactance energy of the transformer to (C4 On the input bus instead of venting it on the resistor. This can be achieved by an additional fast recovery diode and a small 1.5 mH Inductor Lr, but it will increase a little cost.

Return to Figure 1. The output voltage regulation is realized by the combination of components such as Z1, R5, R6, R7 and optocoupler U2. When the output voltage increases to about 12 V, the Zener device Z1 conducts, and when enough current flows into R7 to generate the 0.9 V voltage required to turn on the optocoupler diode, the voltage feedback loop is closed and the output will be regulated . The use of resistor R7 forces the Zener current to become a stable part of the device voltage/current (V/I) curve, minimizing the temperature effect of the output voltage. The output voltage will be equal to the rated Zener voltage plus approximately 0.9 V. However, due to the characteristics of the Zener device and the optocoupler and the small negative temperature system of this circuit, there may be some changes in the (actual voltage), but the output voltage (Vout) set point change must not exceed ±5%. The optional resistor R5 supports fine adjustment of the output voltage only in the upward direction.

If the output current exceeds about 1.8 A, the converter duty cycle will be reduced by the peak current sensing of MOSFET U1, and the output voltage will begin to drop. Since the Vcc bias voltage on C10 will decrease with the output voltage, eventually Vcc pin 1 will not have enough voltage to power the controller, and the power supply will enter the start-stop hiccup (hiccup) mode, which will prevent large output currents Enter the overload condition and protect the power supply and load at the same time.

The network of resistors R10 to R12 provides undervoltage protection for the circuit when the AC input voltage (and the DC buck voltage correspondingly) drops below approximately 75 Vac. The level on pin 3 (the chip is turned off at this pin) can be adjusted by R10. C11 provides filtering for this input. In addition, if necessary, optional resistors R8, R13, and R14 can be used to provide optional over-power compensation.

Transformer design

For low-power applications, the size of the transformer needs to be as small as possible; however, as the size of the transformer becomes smaller, the cross-sectional area of ​​the magnetic core also becomes smaller. This requires more primary turns to maintain acceptable magnetic flux density limits, and may cause too many turns to accumulate on the spool, thereby inhibiting effective insulation between the primary and secondary. Too many primary turns will also increase the primary leakage inductance, which does not mention the DC impedance that is usually present on the winding. The E25/10/6 iron core is used in this reference design, and a satisfactory compromise is made for the above-mentioned parameter problems. The transformer design for universal input is shown in Figure 3.

There is also a design specifically for 230 Vac input conditions (Europe), which can provide higher energy efficiency and increase the continuous power output to 20 W (1.65 A). Regardless of the design, the primary is divided into two layers, and the secondary and Vcc windings are sandwiched in between. This configuration has lower leakage inductance and therefore provides a lower voltage spike when the MOSFET is turned off. This three-winding 12 V secondary is suitable for minimizing AC and DC losses in the windings. The exact pin output will depend on the specific wiring, but the core selection, wiring harness size, inductance value and turns ratio should be suitable for proper operation. This special flyback transformer is designed for 100 kHz discontinuous conduction mode (DCM) operation, so the slope compensation feature provided by pin 2 of NCP1027 is not necessary.

Design scheme of power reference power supply based on ON Semiconductor monolithic controller
Figure 3. Transformer design for universal input conditions (90-270 Vac)

Test Results

1) Work efficiency.

Table 2 shows the energy efficiency test results at 25%, 50%, 75% and 100% load under 120 and 230 Vac input conditions. The left table shows the energy efficiency data of the reference design using the RCD snubber circuit, and the right table shows the relatively higher energy efficiency data of the reference design using the resonant snubber circuit. It is worth mentioning that the average energy efficiency in these two cases easily meets the requirements of the CEC and Energy Star EPS specifications (version 1.1) for their power level ranges. Under the 230 Vac input condition, the energy efficiency will be slightly reduced at light load, mainly because the switching loss of the MOSFET is higher at this input level.

Design scheme of power reference power supply based on ON Semiconductor monolithic controller
Table 2, The average energy efficiency of ON Semiconductor 16 W Modem AC-DC adapter reference design

2) Standby (no load) energy consumption

The no-load energy consumption of the reference design using the traditional RCD snubber circuit is:

290 mW @ 120 Vac
210 mW @ 240 Vac

No-load energy of the reference design with non-dissipative resonant buffer circuit:

240 mW @ 120 Vac
200 mW @ 240 Vac

These no-load energy consumption data not only meet the requirements of CEC and “Energy Star” version 1.1, but also meet the latest “Energy Star” version 2.0 requirements.

Summarize

This article introduces a fully constructed and tested GreenPointTM solution used by ON Semiconductor for xDSL modem AC-DC adapters. This power reference design is intended for low-altitude offline applications that require good output regulation. In addition to xDSL modems, this reference design is also suitable for printers, routers, hubs, and/or similar consumer audio and video applications that require a single output voltage in the range of 10 to 20 W.

This power reference power supply design is based on ON Semiconductor’s NCP1027 monolithic controller integrated with 700 V MOSFETs. It constructs a power supply with an output capacity of 12 V and 1.3 A. It has a surge capability of more than 1.6 A and is in line with “Energy Star”, etc. Standardize the work energy efficiency and standby energy consumption requirements of the organization, as well as other safety regulations. It is worth mentioning that only need to reconfigure the transformer ratio and voltage reference Zener device, this reference design can be modified for output voltage of a few volts up to 28 V (or higher), power is about 20 Application of W.

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Allwinner’s first RISC-V application processor released, based on the Pingtou Ge Xuantie 906 core

On April 15th, Allwinner Technology announced today the launch of the world’s first mass-produced application processor equipped with the Flathead Black Iron 906 RISC-V, which is also the world’s first application processor based on the RISC-V architecture. D1″.

  

According to reports, Allwinner’s “D1” chip cooperates closely with Pingtou Ge Xuantie 906, combined with the company’s in-depth accumulation in high-definition video processing and system architecture, and integrates the self-developed on-chip high-speed interconnect bus NSI and rich application interfaces, which can provide High-performance heterogeneous multi-core computing processing and excellent graphics acceleration capabilities. Its strong product performance is highly compatible with the massive scene needs of the AIoT era in terms of underlying performance and specification design, and can be widely used in many fields such as smart cities, smart cars, smart commercial displays, smart home appliances, and smart office.

Allwinner’s “D1” open source, open and efficient features provide stable technical support and sustainability for the birth of various differentiated applications of AIoT, and meet users’ long-term needs for independent and reliable technology supply chain. AIoT-like fragmented customized products show their talents.

At present, the global RISC-V camp is growing rapidly. Relying on Allwinner’s long-term practical experience in technology implementation and customer service, Allwinner’s “D1” rich ecosystem can also help users to quickly design, migrate, and Application and perfect service will comprehensively solve all kinds of problems encountered by users in the practice process. While providing chips, Allwinner will also provide customers with the self-developed Tina software system and the open source Fedora system.

Allwinner Technology said that with the release of the “D1” application processor, Allwinner Technology is actively cooperating with many innovative developers and core ecological partners to give full play to RISC-V features and product system performance to achieve more AIoT application scenarios. of mass production. In the future, Allwinner will continue to adhere to open innovation and provide more reliable paths for users to achieve value growth.

  

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Extremely tiny but powerful, what the heck is a chip?

Suppose that a hundred years or a few hundred years later, looking back on the relationship between major powers from 2018 to 2019, people in the future may invent a new word, which may be called chip war. Although this kind of war has not yet heard the sound of guns and smoke, but the far-reaching impact on the future world pattern may be no less than a sub-level world war. This is because the trading volume around the international commodity such as chips is several times the total global crude oil trading market today. There have been more than one battles over oil, and the fierce battle over chips will also reconstruct the basic world pattern in the first half of the 21st century.So now everyone

Suppose that a hundred years or a few hundred years later, looking back on the relationship between major powers from 2018 to 2019, people in the future may invent a new word, which may be called chip war. Although this kind of war has not yet heard the sound of guns and smoke, but the far-reaching impact on the future world pattern may be no less than a sub-level world war. This is because the trading volume around the international commodity such as chips is several times the total global crude oil trading market today. There have been more than one battles over oil, and the fierce battle over chips will also reconstruct the basic world pattern in the first half of the 21st century. So now everyone hears the word chip almost every day. So what exactly is a chip, and why the design and production of chips has become a high-tech, for most people, I am afraid that they are half-understood, or pretend to understand, which is also a basic attitude. After all, a chip is actually a microcircuit. So what is a circuit? Open the computer case, or the inside of any kind of programmed appliance, and you’ll see the circuit board. A chip is an extremely tiny but powerful miniature logic circuit.

The modern integrated circuit was invented by Kilby in 1958. Therefore, he won the Nobel Prize in Physics in 2000. The inventor of the practical integrated circuit was Noyce, who was unable to win the prize at the same time due to his early death. All Nobel prizes are only awarded to living people. Integrated circuits can integrate a large number of microtransistors onto a small sheet of pure silicon, which is a huge advance. Integrated circuits have two main advantages over discrete transistors: cost and performance. The low cost is due to the fact that the chip prints all components through photolithography as a unit, rather than making just one transistor at a time. The high performance is due to the fast switching of the components, which consumes less energy because the components are small and close to each other. Now it has entered the nanoscale. For example, a 7-nanometer chip can integrate 6.4 billion micro-components in one square centimeter, which is close to the limit of the laws of physics. If you get closer, electrons may directly penetrate the circuit. The space between them is naturally isolated, resulting in the natural failure of the chip circuit. This is the role of Moore’s Law in the field of microelectronics.

Advanced integrated circuits are the heart of microprocessors, or multi-core processors, that control everything from computers to cell phones. Although the cost of designing and developing a complex integrated circuit is very high, the cost per integrated circuit is minimized when spread over products, often in the hundreds of millions. In the end, the profit is lucrative enough.

The basic material for making chips is a thin slice of monocrystalline silicon. Monocrystalline silicon is considered to be the most suitable semiconductor material for large-scale production of integrated circuits after many trials in the early years. Become the grassroots of the mainstream of integrated circuits. Silicon has a high content in the earth’s crust. For example, sand cement contains a large amount of silicon, but it can use monocrystalline silicon with extremely high purity, that is, to extract silicon crystals that do not contain 1/100 millionth of impurities. For crystals, the thicker the diameter, the better. The larger the crystal, the thinner the disc with the larger diameter can be, and more small rectangular chips can be printed on this sheet. The production diameter of a single crystal silicon disc is the first technical indicator of a chip processing company. It took decades to develop defect-free pure single-crystal silicon crystals in the past. In addition to using single-crystal silicon as the substrate for making chips, there are also III-V materials, such as gallium arsenide.

The complete process of manufacturing a single-crystal silicon chip in an assembly line now includes several links such as chip design, wafer fabrication, packaging fabrication, and testing, among which the wafer fabrication process is particularly complex. The first is the chip design, the “pattern” generated according to the needs of the design. The raw material for making chips is wafers. The composition of the wafer is pure silicon, the silicon is refined from quartz sand, and the wafer is silicon purified by 99.9999999%, and then these pure silicon are made into silicon crystal rods, which become the quartz semiconductors for the manufacture of integrated circuits. The material, which is sliced, is the wafer that is specifically required for chip fabrication. The thinner the wafer and the larger the diameter, the lower the production cost, but the higher the process requirements.

Then, the wafer is coated with a film, which can resist oxidation and temperature resistance, and its material is a kind of photoresist. Then there is the lithography development and etching of the wafer. The basic flow of photolithography process. The first is to apply a layer of photoresist to the surface of the wafer or substrate and dry it. The dried wafers are transferred to the lithography machine. The light passes through a mask, and the pattern on the mask is projected on the photoresist on the surface of the wafer to achieve exposure and stimulate the photochemical reaction. A second bake is performed on the exposed wafer, the so-called post-exposure bake, which makes the photochemical reaction more sufficient. Finally, the developer is sprayed onto the photoresist on the wafer surface to develop the exposed pattern. After development, the pattern on the mask is left on the photoresist. If you don’t understand this, you can think of the wafer as the development process of an old-fashioned film camera.

Gluing, baking, and developing are all done in a dispenser, and exposure is done in a lithography machine. Dispensing machines and lithography machines are generally operated online, and wafers are transferred between units and machines by robotic arms. The entire exposure and development system is closed, and the wafer is not directly exposed to the surrounding environment to reduce the impact of harmful components in the environment on the photoresist and photochemical reactions.

This complex process uses chemicals that are sensitive to UV light, which softens when exposed to UV light. The shape of the chip can be obtained by controlling the position of the shade. A photoresist is applied to the silicon wafer so that it dissolves when exposed to UV light. At this time, the first part of the shade can be used, so that the part that is directly exposed to the ultraviolet light is dissolved, and the dissolved part can then be washed away with a solvent. This way the rest is the same shape as the shade, and this effect is exactly what is desired.

The next step is to add impurities and implant ions into the wafer to generate corresponding P and N semiconductors. The specific process is to start from the exposed area on the silicon wafer and put it into a chemical ion mixture. After the above several processes, lattice-shaped grains are formed on the wafer. The electrical characteristics of each die are tested by needle testing. Fix the manufactured wafer, bind the pins, and make various packaging forms according to the needs. After the above process flow, the chip production has been completed, and the final step is to test the chip, remove defective products, and finally package and market.

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Three-quarters of the world’s mobile phones are produced in China. Which brand of mobile phone do you use?

Recently, the Global System for Mobile Communications (GSMA) information organization released a report “Future of Devices” at the Consumer Electronics Show in Las Vegas, USA. The report shows that three-quarters of the world’s mobile phones are produced in China.

It is reported that the survey data for the report comes from more than 38,000 users in 36 countries.

GSMA also said that with the development of 5G technology, the recovery of the mobile phone industry is in sight. Users in China, South Korea and countries in the Middle East are likely to choose to buy a 5G phone. Nearly half of Chinese consumers said they would buy 5G mobile phones as soon as they were put on the market. Another 20% admit to buying, but the timing is uncertain. Given China’s huge population base, that means China will be ahead of any other country in the first few years of 5G technology rollout.

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Maxim Integrated Releases Trinamic Servo Controller/Driver Module

TRINAMIC Motion Control GmbH & Co. KG, now part of Maxim Integrated Products, Inc (NASDAQ: MXIM), today announced the industry’s smallest, lowest power, single-axis servo controller/drive module with integrated motion control. The new TMCM-1321 servo controller/driver module is used to support the operation of two-phase bipolar stepper motors in robotics and automation equipment, optimizing speed control and synchronization of each axis, and reducing power consumption by 75% while increasing production. Modules feature onboard magnetic encoders and digital inputs for optical encoders to simplify servo control, enabling advanced feedback and diagnostics; 3X smaller size compared to similar stepper motor solutions.

Maxim Integrated Releases Trinamic Servo Controller/Driver Module

The TMCM-1321 module uses linear ramp function control, known as Trinamic SixPoint™ ramp function, and advanced S-shaped ramp function control to speed up effective transfer time. Trinamic’s closed-loop control technology uses direct feedback to automatically reduce power consumption by 75%. With the RS-485 interface and Trinamic’s integrated development environment, the TMCM-1321 module can simplify the design and reduce the size of the stepper motor by more than 3 times.

main advantage

Reduced power consumption: Compared to similar stepper motor solutions, Trinamic closed-loop control technology offers the best energy savings in the industry.

Increase productivity: Improve effective transit time by implementing a ramp function profile that matches application requirements.

Small size solution: The TMCM-1321 module cooperates with the magnetic encoder and digital ABN input to provide the smallest size single axis servo controller/driver solution, occupying an area of ​​only 784 mm2.

evaluate

“When choosing an energy-efficient drive, engineers tend to gravitate towards servo drives. However, stepper motors have much higher torque at low speeds than servo motors of comparable size,” said Jonas Proeger, business director at Trinamic. The motor, combined with closed-loop control technology, can get rid of expensive and inefficient gearboxes without sacrificing positioning accuracy to get the efficiency of a servo motor at the cost of a stepper motor.”

Availability and Price

The TMCM-1321 module is available now for $119.40 through authorized Trinamic dealers.

All trademark rights belong to their owners.

The Links:   BSM300GA12DA11S SKM400GAL124D

Realization of video image display of monitoring system based on WEB server

Overview of Network Video Surveillance System Based on Embedded WEB Technology At present, network-based digital video surveillance system is the mainstream of video surveillance system development. With the advancement of microprocessor technology and computer network technology, embedded WEB-based network The video surveillance system has gradually attracted widespread attention. The main principle is that the embedded video server adopts an embedded real-time operating system and has a built-in embedded WEB server. After the video signal sent from the camera is compressed by the high-efficiency compression chip, it is transmitted through the internal bus to the built-in WEB server.The user can watch the web server directly through the browser on the monitoring terminal

1. Overview of network video surveillance system based on embedded WEB technology At present, network-based digital video surveillance system is the mainstream of video surveillance system development, and with the progress of microprocessor technology and computer network technology, embedded WEB-based digital video surveillance system is the mainstream of video surveillance system development. The network video surveillance system has gradually attracted widespread attention. The main principle is: the embedded video server adopts an embedded real-time operating system, and a built-in embedded WEB server. The bus is sent to the built-in WEB server. On the monitoring terminal, the user can directly view the video image of the camera on the WEB server through the browser, and the authorized user can also control the action of the PTZ lens of the camera. The schematic diagram of the monitoring system described in this paper is shown in Figure 1.
 

Realization of video image display of monitoring system based on WEB server

The system consists of cameras, embedded WEB server, transmission network and monitoring terminal. Cameras are used to capture video of the surveillance site. The embedded WEB server is the core of the whole monitoring system. It has two parts: hardware and software. The detailed structure will be introduced separately below. Its main functions include: providing a WEB access page for the monitoring terminal; checking the validity and security of the access of the monitoring terminal; responding to the request of the monitoring terminal, providing the required video image for the monitoring terminal; receiving the control information of the monitoring terminal, through software and hardware conversion Then control the camera. Each server has its own IP address, and the monitoring terminal can access the server through the browser interface. The function of the monitoring terminal is to Display the live video, and send video requests and control signals to the camera to the server as needed.

2. The hardware structure of the embedded WEB server

The hardware structure of the embedded WEB server is shown in Figure 2. It is mainly composed of CPU chip, MPEG-4 audio and video coding chip, Flash chip, SDRAM memory, Ethernet network interface, and large-capacity hard disk. Among them, the CPU adopts PowerPC series embedded communication processor MPC8250 of MOTOROLA Company. The MPEG-4 audio and video encoding chip completes the compression and encoding of the video data transmitted from the camera. According to the network bandwidth, topological structure and the requirements for image quality, this system selects the hierarchical scalable coding scheme based on MPEG-4 standard. The compressed video data can be stored in a large-capacity hard disk or transmitted over an Ethernet network as required. In order to realize the video storage function, a large-capacity hard disk is required.
  

Realization of video image display of monitoring system based on WEB server

Figure 2 Hardware structure of embedded WEB server

3. Software system of embedded WEB server

The software design and realization of the embedded WEB server is one of the keys to the realization of the system, including the embedded operating system and application software.

3.1 Embedded operating system

Embedded operating system is an operating system software that supports embedded system applications. The system adopts the embedded LINUX operating system, which is realized on the basis of miniaturizing and real-time cutting the LINUX operating system according to the needs of the system. The advantages of using LINUX are: the source code of its operating system is open and can be customized according to needs; the system kernel is small, so the hardware requirements are relatively low; it supports multi-tasking and multi-process, and can provide better real-time performance.

3.2 Application software

The application software structure of the server is shown in Figure 3. It is mainly composed of several important parts such as WEB server, CGI program, embedded database mSQL, video scheduling and transmission module, storage management and scheduling module, and camera control module.

3.2.1 WEB server and CGI program

The WEB server exchanges information with the monitoring terminal browser software through the HTTP protocol, and provides interfaces for other application modules, video data browsing interface and camera control interface. In addition, it also controls the access rights of the monitoring terminal, filters the request and control information of the monitoring terminal, and handles the synchronization and priority issues of the requests and controls of multiple monitoring terminals. This system chooses the Boa WEB server which is suitable for the embedded system. Boa is a single-task HTTP server that supports CGI technology that can realize dynamic WEB technology, with open source code and high performance. At the same time, the server program itself occupies a small space, so it is very suitable for embedded systems. At the same time, the system adopts CGI (Common Gateway Interface) to realize dynamic WEB technology. CGI specifies the interface protocol standard for the WEB server to call other executable programs (CGI programs). The WEB server realizes the interaction with the browser by calling the CGI program, that is, the CGI program accepts the information sent by the browser to the WEB server, processes it, and sends the response result back to the WEB server and the browser. Principle CGI programs can be written in any programming language, but CGI programs written in C language have the characteristics of high execution speed and high security.
  

Realization of video image display of monitoring system based on WEB server

Figure 3 Application software structure of embedded WEB server

3.2.2 Embedded database mSQL

In this system, the storage of user information, the user’s login and logout, the storage and query of video equipment parameters, and the storage and query of video files all require an embedded database. Comprehensive consideration, this system uses mSQL (MiniSQL) as the background database of this system. mSQL is an excellent embedded database with a compact architecture and less system resources. It is especially suitable for use in embedded Linux systems. At the same time, mSQL provides special API functions, so that CGI programs written in C language can communicate with the database engine of mSQL.

3.2.3 Video scheduling and transmission module

The video scheduling and transmission module provides the required real-time video information for the monitoring terminal, and is the most important module in the server application software. This module establishes a connection with the monitoring terminal according to the adopted network transmission and control protocol, and monitors the monitoring terminal’s request; at the same time, according to different service types, it adopts the corresponding scheduling strategy to create a video stream, and then groups and packages the video data and sends it to the monitoring terminal. , and perform error processing and congestion control according to the network status information fed back by routers and monitoring terminals.

The transmission of video data generally adopts the UDP network communication protocol, and the IP transmission methods of UDP are three kinds of on-demand, broadcast and multicast. The multicast is that the server only sends a data packet to a specific user group, and each user in the group can This packet is shared, but users outside the group cannot receive it. This system adopts IP multicast mode, and the advantages of using multicast technology are as follows: the server can bear the video data broadcast requirements of a large number of clients; due to the small number of data packets copied and the sending destination address, the data transmitted in the network is greatly reduced. In order to ensure a higher quality of service; reduce the bandwidth occupation of video data stream transmission, reduce the burden on the server.

The network transmission protocol adopted by this system uses the RTP/UDP/IP model. The RTP protocol is a protocol that provides end-to-end real-time media transmission services. It consists of two parts: the real-time transmission protocol RTP and the real-time transmission control protocol RTCP. RTP is used for the transmission of real-time video data, while RTCP is used to monitor the transmission of real-time video data. The RTP/UDP/IP method takes into account the real-time performance and QoS guarantee of video transmission. At the same time, certain congestion control and error control strategies can be adopted for the uncertainty of the transmission network condition.

3.2.4 Storage Management and Scheduling Module

The main function of the storage management module is to store the compressed and encoded video information in a specific area of ​​the disk according to a certain strategy, and store the video file information in the embedded database for retrieval and playback, and respond to video scheduling and The request of the transmission module reads video data from the disk to the memory buffer according to a certain disk scheduling policy and priority order. For storage management, the system adopts the equal-length grouping storage strategy, that is, the video information is divided into several data units according to the time sequence relationship, these data units are called groups, and each group is stored in a fixed-size storage unit.

3.2.5 Camera Control Module

The camera control module mainly realizes the control of the camera. On the monitoring side, the user sends the camera control command to the WEB server through the browser. After the control command is accepted and processed by the WEB server, it is sent to the camera control module through the CGI program, and then converted into the corresponding hardware operation instructions for camera control. , so as to realize the remote control of the camera pan/tilt lens.

4. Monitoring terminal browsing

The system uses a browser at the monitoring end to monitor the monitoring site. The platform that the browser runs is independent of the platform that the embedded WEB server runs, and no third-party software is required to browse the remote video, thus realizing cross-platform. The interface of using this system to browse video on the monitoring terminal is shown in Figure 4.

Realization of video image Display of monitoring system based on WEB server

Figure 4 Surveillance end browsing video interface

5. Conclusion

This paper introduces the design and implementation of a network video surveillance system based on embedded WEB technology. Compared with the traditional network video surveillance system, the main features of this system are: the design of the server is based on embedded WEB technology; it supports dynamic IP, can Directly connected to the Ethernet, it can be plugged and viewed; users can watch only with a browser without using special software; at the same time, the system adopts the advanced MPEG-4 encoding standard, which greatly reduces the amount of data while improving the video quality. . It is believed that with the popularity of network video surveillance, the network video surveillance system based on embedded WEB will have a good development prospect.

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The concept of metaverse is hot, which “meta-skill” talents are hot?

With the layout and investment of a large number of technology companies, the discussion and voice of the Metaverse have become more and more high, and it has become one of the hottest topics on the Internet.

With the layout and investment of a large number of technology companies, the discussion and voice of the metaverse are getting higher and higher, and the year 2021 that has just passed is even called the “first year of the metaverse”.

The concept of metaverse is hot, which &#8220;meta-skill&#8221; talents are hot?

Metaverse consists of two roots, Meta and Verse. Meta means “transcendence” and “meta”, and verse means “universe”. Since the world envisioned by the Metaverse involves a variety of technologies, the skill requirements for talent are also very diverse. It is understood that from VR/AR, blockchain, artificial intelligence and other “infrastructure” technologies equipped with infrastructure, to “creator” skills such as application development, graphic art, 3D modeling, game design and virtual human design, all It is an essential core ability for the Metaverse to land.

Meta-skill 1: VR/AR

Known as the entrance to the “metaverse”, the demand for talents ranks second in the world

According to the current general view, the metaverse has six characteristics: immersion, sociality, openness, sustainability, rich content production, and a complete economic system. And these six characteristics, if boiled down to one point, is “highly realistic”.

Without virtual reality, there is no sense of existence, let alone a high degree of realism. Therefore, VR has become a key technology for the existence of the metaverse. To put it simply, virtual technologies such as VR are the entrance for real users to enter the virtual world of the metaverse. By wearing the corresponding equipment, the user’s virtual avatar can enter the metaverse.

In this context, many VR jobs will be created, such as VR panoramic shooting, VR application design, and 3D modeler. Especially in the metaverse era, the technical requirements for 3D modeling will be higher. In addition to the traditional beauty promotion, original painting, games, film and television animation, figure and other industries, 3D modelers have a new choice – virtual person.

However, at present, the number of VR talents in China only accounts for 2% of the world. From the perspective of VR job demand, China accounts for about 18%, and the demand for VR talents in China ranks second in the world.

Meta-skill 2: Blockchain

To create trust for the virtual world, compound talents are in short supply

Blockchain is an open, censorship-resistant database model secured by encryption and decentralization. Blockchain records information in blocks on a shared ledger and stores synchronized copies of that ledger across all systems participating in the network, ensuring its immutability.

Applied to the Metaverse, blockchain can store user data on a tamper-proof shared ledger, ensuring user immutability. Since the blockchain ledger is publicly verifiable, this will create more trust in these emerging virtual environments. Blockchain-based metaverse projects have emerged, of which “sandbox (a security mechanism in the field of computer security)” and “decentralized zone” are the most popular. Both virtual worlds are built on Ethereum, leveraging its open infrastructure to create a trusted data environment.

The demand for blockchain talents in the metaverse era will focus on blockchain application development, blockchain algorithm, blockchain platform development, etc., and will involve industries including finance, management, public services, medical care, education and employment, etc. knowledge. “Chaoyang Technology” naturally spawns “Chaoyang Employment”. However, according to data from a recruitment platform, based on existing industries and positions, blockchain talents, especially “blockchain + industry” compound talents are facing serious challenges. In short supply situation.

Meta Skill 3: Artificial Intelligence

Connecting virtual and reality, relevant talents become the key to the landing of the Metaverse

Artificial intelligence technology can provide technical support for a large number of scenarios in the metaverse. As we all know, data, algorithms and computing power are the three core elements of artificial intelligence. Data is the cornerstone and foundation of the development of artificial intelligence. Algorithms are an important engine and driving force for the development of artificial intelligence. Computing power is an important guarantee for the realization of artificial intelligence technology. . Before heading to the “metaverse”, it is necessary to create an infrastructure that realizes the combination of virtual and real. Obviously, artificial intelligence is the “key” that connects the virtual world with the real world.

AI technology also needs to play many different roles in the metaverse. The metaverse can be said to be a multiverse, it can be a comic in the second dimension or a certain game, so there are destined to have some staff-like roles in this world. At this time, artificial intelligence is needed to exert force, such as Robots that can communicate freely with humans without barriers are needed.

At the same time, the Metaverse needs a powerful computing power to efficiently process the operation of the virtual world, because the Metaverse can be regarded as a microcosm of the real world, and users in the real world will have a virtual clone to enter this world. . Therefore, the number of users in the metaverse and the number of people online at the same time will be very large, so the requirements for computing power are more stringent. For example, when the metaverse comes, but the computing power is not efficient enough, then the user is faced with the infinite circle of pictures when the network is not good in real life, just one word is – card.

Therefore, talents who master the core skills of artificial intelligence, such as big data, cloud computing, machine learning, computer vision, and biometrics, will become indispensable talents in the metaverse era. However, a report released by the Ministry of Human Resources and Social Security in July 2021 revealed a worrying fact: at present, the supply and demand ratio of artificial intelligence talents in my country is only 1:10. If the training is not strengthened, there will be a talent gap in 2025. will reach 10 million. If we don’t pay attention to talent cultivation, I am afraid that the quantity and quality of AI talent cultivation will become a key factor restricting the implementation of the Metaverse.

Meta Skill 4: Digital Twin

Copying a virtual world is difficult to cultivate talents

What is a digital twin? In simple terms, it is to digitize things in the physical world and generate a digital entity corresponding to it.

The ideal state of the metaverse is to replicate a real world as a virtual state. In this virtual world, there are real characters, real social forms, and economic systems. The development of digital twin technology can speed up the arrival of the metaverse, because the most powerful capability of digital twin technology lies in deduction. By establishing corresponding digital scenarios and then performing corresponding deductions through programs, many failures can be avoided.

Digital twin technology involves multiple skills, including big data, edge computing, artificial intelligence, etc., and requires a large number of talents in application development, design, and management of related technologies. At the same time, the foundation of digital twin technology is the Internet of Things. Some industry insiders believe that the potential space of the overall Internet of Things market exceeds 10 trillion yuan, and the potential for industry-driven applications is huge, including navigation, smart buildings, and smart cities.

Industry drives employment. In recent years, with the accelerating process of social digitization, the market demand for IoT professionals has been showing an upward trend. It is understood that in addition to learning computer knowledge, this major also needs to master communication technology, modern sensor technology, wireless network sensing, etc., and also involves software development. It belongs to high-skilled compound talents, so it is more difficult to cultivate talents.

Meta Skill 5: semiconductor Design and Manufacturing

Metaverse infrastructure, talent shortage will be the new normal in the next 10 years

The infrastructure communication technology in the Metaverse world mainly refers to the full popularization of 5G, because the Metaverse is a world composed of numbers and has relatively high requirements for the network. If there is no stable and high-speed network, users may even walk in it. questions, let alone making friends and exploring. At the same time, the Metaverse has extremely high requirements for data transmission capabilities, which is reflected in the magnitude, speed, and stability of data transmission.

It can be said that communication technology is an important infrastructure for the development of the Metaverse, and once the Metaverse enters the “infrastructure era”, the chip industry is expected to benefit first. In fact, the talent shortage in the semiconductor industry will begin to emerge in 2021. Some experts even pointed out that the shortage of semiconductor talents will be the norm in the next 10 years.

The Links:   LQ057Q3DC01 1MBI400NA-120

IPO Radar | Ninety percent of revenue has not been recovered, and Xinke Mobile, which has doubts about its ability to continue operations, plans to raise 4 billion yuan to compete with Huawei and ZTE?

The renewal and iteration of each generation of mobile communication systems has stimulated the rise of a large number of industrial chains and brought significant economic benefits.

In the 2G era, Ericsson and Nokia became the world’s leading communication equipment vendors and mobile phone manufacturers; in the 3G era, more countries and organizations participated in the formulation of mobile communication technical standards; in the 4G era, the technical standards tended to be unified.

In the past, the inconsistency of mobile communication technology standards has brought great inconvenience to major software and hardware manufacturers and operators. In 2018, the 3GPP 5G NR standard SA solution was released at the 80th meeting of 3GPP TSG RAN, marking the official release of the first truly complete international 5G standard.

According to the “2021 China Mobile Economic Development Report” issued by the Global Association for Mobile Communications Systems, the number of 5G connections in China will account for 87% of the number of global 5G connections in 2020. According to statistics from the Ministry of Industry and Information Technology, as of the first half of 2021, my country has a total of 961,000 5G base stations, ranking first in the world in terms of the number of base stations.

Recently, Xinke Mobile, a mobile communications company under the Xinke Group, launched the listing process on the Science and Technology Innovation Board, which has been accepted by the Shanghai Stock Exchange and Shenwan Hongyuan is the sponsor.

For this listing, Xinke Mobile plans to raise 4 billion yuan, of which 2.28 billion yuan will be used for 5G wireless system product upgrades and technology evolution research and development projects; 420 million yuan will be used for 5G industry private network and intelligent application research and development projects; 300 million yuan will be used In 5G fusion antenna and new room equipment research and development project; 1 billion yuan to supplement working capital.

Xinke Mobile chose the fourth set of listing criteria, that is, the estimated market value is not less than RMB 3 billion, and the operating income in the most recent year is not less than RMB 300 million. However, before the listing, Xinke Mobile still had many problems, such as the decline in main business income, long-term losses and excess debt ratio. How should Shinco Mobile, which has doubts about its business sustainability, “compete” with Huawei and ZTE?

Merged into Datang Mobile for free before listing, with high non-recurring losses

The predecessor department of Xinke Mobile was jointly established by the Academy of Posts and the Wuhan Optical Communication Technology Company, and it used to be named Hongxin Communication. After the reorganization of the Institute of Electrical Engineering and the Academy of Posts and Telecommunications to form China Xinke, through the overall arrangement of the business reorganization of Zhongke Xinke, Hongxin Communications was changed to a 100%-owned subsidiary of China Xinke (SS).

As of the issuance, China Xinke (SS) holds 51.27% of Xinke Mobile and is the controlling shareholder of Xinke Mobile. The actual controller is the State-owned Assets Supervision and Administration Commission of the State Council. As a mobile communications company under China Xinke, the prospectus disclosed that Xinke Mobile provides 4/5G mobile communication network solutions and comprehensive services for users in more than 30 provinces and nearly 100 cities across the country.

In October 2020, China Xinke integrated its mobile communications business. Xinke Mobile Co., Ltd. acquired 100% of Datang Mobile’s equity through the free transfer of state-owned equity. Actually controlled by SASAC. At the same time, the Electric Power Research Institute and Datang Holdings transferred 8118 communications-related patents (including unlicensed) and non-patent technologies they held to Datang Mobile for free.

Before the reorganization, Xinke Mobile was mainly engaged in the research and development, production, and sales of mobile communication antenna feeder equipment and room sub-equipment, as well as the provision of mobile communication technology services; Datang Mobile was mainly engaged in the research and development, production, and production of mobile communication system equipment and industry private network related products. Sales and some technical services.

After the aforementioned reorganization and free transfer, Xinke Mobile and its subsidiaries have become the sole bearer of China Xinke’s mobile communications business, focusing on the R&D, production and sales of mobile communications technology and products.

Specifically, the year before the reorganization (2019), Datang Mobile’s revenue was 1.161 billion yuan, accounting for 35.58% of Xinke’s revenue of 3.263 billion yuan. Datang Mobile’s total profit for the year was 1.646 billion yuan. Mobile’s net profit for the year was -39,582,600 yuan.

According to the relevant accounting standards, the net profit and loss of the subsidiaries arising from the business combination under the same control from the beginning of the year to the date of the merger is combined. Due to the large losses of Datang Mobile, from 2018 to 2020, the company’s non-recurring profit and loss resulted from the merger of subsidiaries under the same control. The net profit and loss amount of the current period from the beginning to the merger date reached 626 million yuan,- 1.646 billion yuan, 1.320 billion yuan, at a relatively high level.

From 2018 to the first half of 2021, the net profit attributable to the parent company of Xinke Mobile was -605 million, 1.637 billion, 1.752 billion and -620 million, respectively. After deducting non-recurring gains and losses, the net profit attributable to the parent was- 13.0585 million yuan, -42.6911 million yuan, -4.497 billion yuan and -671 million yuan.

Main business income declined, 90% of accounts receivable

During the reporting period (2018 to the first half of 2021), Xinke Mobile’s revenue came from the two major businesses of mobile communication network equipment and mobile communication technology services. In 2019, Xinke’s mobile network equipment and technical service revenues fell by 20.53% and 6.33%, respectively. In 2020, the network equipment business rebounded by 10.12%, but the technical service business continued to be sluggish, and revenue fell again by 5.88%.

Specifically, Xinke Mobile’s network equipment mainly includes the network equipment business of the mobile communication access network, and the core is the deployment of the core key technologies of mobile communication and the research, development, production and service provision of base station related equipment.

Covers mobile communication system equipment such as the baseband processing unit BBU, remote radio unit RRU, and antenna-based antenna feed equipment (antennas, feeders, and other passive components) used for low-cost coverage in indoor scenarios. In addition, it also includes customized industry private network equipment for enterprise users in all walks of life.

In the 5G era, large-scale antenna technology solutions are introduced in order to meet the requirements for large-scale broadband network performance. Due to the large-scale increase in the number of antennas, the industry has realized the integration of RRU and antenna feeders to form AAU products and constitute characteristic hardware equipment in the 5G era One, it forms a 5G base station system with BBU.

But on the whole, according to the prospectus, the 5G network still uses the traditional construction method of “BBU+RRU+antenna” similar to 4G in the initial stage of construction. Compared with the BBU and RRU products in the 4G period, Shinco Mobile’s 5G series products still maintain A similar form of 4G.

From the perspective of Xinke’s mobile equipment business alone, in 2018, Xinke Mobile has not deployed 5G system equipment, and the source of system equipment revenue is a single 4G system equipment. The revenue for the year was 774 million yuan. In 2019, Xinke Mobile’s 4G system equipment revenue was substantial. It fell 67.96% to 248 million yuan, while 5G system equipment was in its infancy, with revenue of 13.229700 million yuan.

Entering 2020, with the layout of 5G system equipment, Xinke Mobile will shift its focus and bet its revenue on 5G system equipment that year, with revenue of 437 million yuan and 4G system equipment revenue of 191 million yuan. In general, Shinco’s mobile device business revenue fell by 20.53% in 2019. Thanks to the increase in revenue from 5G system equipment, Shinco’s mobile network equipment revenue rebounded in 2020. However, the company’s revenue has entered a downward channel except for 5G system equipment.

Compared with 4G and previous communication technologies, the biggest feature of 5G mobile communication is that the downstream application scenarios focus on the integration with the Internet of Things technology and the real economy. According to the International Telecommunication Union (ITU), the three major usage scenarios of 5G include smart homes/buildings, smart cities, 3D video, ultra-high-definition screens, autonomous vehicles, and industrial automation. However, the current market is still imperfect, and the space for 5G to play is limited.

In addition, Xinke’s mobile technology service revenue has also continued to be sluggish. The company’s technical services are mainly based on integrated mobile communications services, which accounted for more than 80% of technical service revenue in the past three years, supplemented by operation and maintenance service revenue.

The integrated services of Xinke Mobile mainly include wireless network planning, construction and optimization. Revenue from 2018 will be reduced from 2.610 billion yuan to 2.087 billion yuan in 2020. Even though the revenue of network operation and maintenance services has increased, but the proportion is affected, Xinke Mobile Technology The overall service revenue dropped from 2.779 billion yuan to 2.45 billion yuan in 2020. In the first half of this year, Xinke’s mobile technology service revenue was 766 million yuan.

Therefore, the revenue growth rate of Xinke Mobile in the past three years has been weak and even declined, from 5.142 billion yuan in 2018 to 4.48 billion yuan in 2019. Although revenue in 2020 has rebounded slightly to 4.518 billion yuan, it is still difficult to reach 2018. . As of the first half of this year, Xinke Mobile’s operating income was 1.453 billion yuan.

But the bigger risk is that 90% of Xinke Mobile’s revenue has not been recovered. The prospectus shows that from 2018 to the first half of 2021, the accounts receivable of Xinke Mobile reached 4.222 billion yuan, 3.69 billion yuan, 3.723 billion yuan and 3.345 billion yuan, respectively, accounting for 93.86 billion yuan in current operating income. %, 96.73%, 96.41% and 135.48%.

In addition, the amount of bad debt provisions (including contract assets) accrued in each period reached 612 million yuan, 650 million yuan, 642 million yuan and 602 million yuan respectively. Xinke Mobile gave four explanations for this. First, the fourth quarter revenue accounted for a relatively high proportion, and the payment cycle was relatively long; second, the company’s mobile communications integrated services accounted for a relatively high proportion, and the integrated service settlement cycle was longer; The main downstream customers of Xinke Mobile are telecommunications operators and large government and enterprise customers. The payment process requires multi-level approval, resulting in a long payment collection cycle.

During the reporting period, Xinke Mobile’s bad debt reserves exceeded 600 million yuan in each year. In addition, Xinke Mobile’s accounts receivable within one year accounted for only 61.25% on average, and the average age of 90% of the company’s accounts receivable and contract assets was within 3 years.

Not only that, but also with the same industry ZTE (000063.SZ), Jingxin Communication (2342.HK), Tongyu Communication (002792.SZ) Mobi Development (0947.HK), Shenglu Communication (002446.SZ), China Comparing Beitong (603220.SH) and Runjian (002929.SZ), etc., the accounts receivable of Xinke Mobile 1.10 times/year, 0.98 times/year, 1.04 times/year and 0.7 times/year during the reporting period The turnover rate is still lower than the industry average of 1.90 times/year, 1.86 times/year, 1.86 times/year and 1.91 times/year.

In particular, compared with ZTE and Tongyu’s account receivable turnover rate of more than 2 times/year, Xinke Mobile is even more vulnerable. Although the proportion of bad debts in Xinke Mobile was relatively small in the past few years, the company’s working capital has been significantly affected.

Competitiveness is apparently insufficient, what is the solution to the cash flow dilemma?

The mobile communication industry is a typical technology-intensive and capital-intensive industry. The industry’s high R&D investment, long cycle, and high risk make each generation of mobile communication technology require a large amount of capital investment. Communication standards and underlying core technologies have been achieved. And the process of product research and development and subsequent commercialization.

In order to maintain market competitiveness, Xinke Mobile vigorously engages in research and development. From 2018 to the first half of 2021, Shinco Mobile’s R&D expenditures were all at the level of over 1 billion yuan, which were 1.086 billion yuan, 1.486 billion yuan, 1.420 billion yuan and 595 million yuan, respectively. The R&D expense ratios corresponded to as high as 21.10%, 33.10%, 31.36% and 40.82%, far exceeding the industry average of 8.54%.

However, Shinco Mobile’s insufficient investment in industrialization, supply chain construction, market development, and service capabilities, coupled with the historically low maturity of the TDD technology ecosystem, has not formed a large-scale market application, resulting in a serious shortage of early-stage investment recovery. At present, Xinke Mobile has accumulated a total loss of 4.614 billion yuan from 2018 to the first half of 2021. As of June 2021, Xinke Mobile’s audited undistributed profit is as high as -7.18 billion yuan.

Under the continuous loss, the net cash flow generated by the company’s operating activities also continued to lose money, which were -519 million yuan, -878 million yuan, -80 million yuan, and 1.685 billion yuan, respectively. At the same time, it is also facing high debt pressure. According to the prospectus, during the reporting period, Xinke Mobile generated an average of more than 2 billion short-term borrowings each year, and the combined asset-liability ratio reached 91.60%, 105.60%, 89.11% and 70.14%.

The high debt ratio and working capital pressure make Xinke Mobile not only face the risk of capital allocation, but also means that the investment in future industrialization capabilities and supply chain construction will be insufficient.

From the perspective of operating gross profit alone, Xinke Mobile’s performance is also no advantage. From 2018 to 2020, Xinke Mobile’s comprehensive gross profit margin dropped from 21.71% to 8.50%. Among them, in 2019 and 2020, the gross profit margin of Xinke Mobile’s 5G system equipment is negative -53.08% and -57.31%, respectively.

According to the company, it is due to the high initial investment cost of 5G system equipment, and Shinco Mobile has adopted a strategic quotation in order to actively explore the market. Compared with the average gross profit margin of comparable companies in the same industry, Xinke Mobile is significantly lower.

In the industry, the industry companies of mobile communication network equipment companies include Huawei, ZTE (000063.SZ), Ericsson (Ericsson, ERIC.O), Nokia (Nokia, NOK.N), Jingxin Communications (2342.HK), and Unicom (002792.SZ), Mobi Development (0947.HK) and Shenglu Communication (002446.SZ), etc.

Under the background of my country’s full commercial use of 5G in 2020, in the centralized procurement of mobile 5G phase II wireless network main equipment in March of that year and the joint centralized procurement of wireless main equipment in the 5GSA new project of China Telecom and Unicom in April, the winning bidders include Huawei, ZTE, Ericsson and Letter Branch moved four companies.

Among them, the centralized procurement of Huawei’s total number of winning base stations was 271,900, and the winning share was 56.05%; ZTE’s total number of winning base stations was 150,100, and the winning share of 30.95% ranked second; Ericsson ranked second with a total of 51,900 winning base stations. Fourth, the bid-winning share was 10.70%, and Xinke Mobile only won the bid for a total of 11,200 base stations that year, which was at the bottom with 2.3% of the bid-winning share.

In the first half of this year, in July of this year, in the centralized procurement of 5G700M wireless network main equipment of China Mobile Broadcasting Corporation and the joint centralized procurement of wireless main equipment (2.1G) of China Unicom’s 5GSA construction project, Huawei and ZTE have stable leading advantages, and the number of winning base stations is respectively 428,000 and 232,900. Shinco Mobile and Ericsson won 25,000 and 17,300 bids respectively. Although the share of Shinco Mobile’s winning bids has increased compared with last year, it is nearly ten times different from the number of bids won by ZTE, the second place.

However, it is worth noting that Xinke Mobile’s income dependence on China Mobile is very high. From 2018 to the first half of 2021, the revenue from China Mobile accounted for 62.62%, 51.81%, 47.19% and 45.87% of the total revenue, on average. Half of the revenue comes from China Mobile.

The Links:   G101EVN030 NL10276BC20-11

Facilitating forensic investigation-FLIR thermal imaging camera makes “blood fingerprints” clearer

When we watch some criminal investigation TV dramas, when the examiner needs to find evidence of blood stains, they usually spray luminol to the relevant area and turn off the lights. This adds a certain comedy effect to film and television dramas, but it is not the best solution for reality detectors who need to find specific evidence of blood stains in less than ideal situations. In reality, researchers have been looking for alternative methods to detect very low concentrations of blood on fabrics, and recently they have found the answer in thermal imaging technology.

When we watch some criminal investigation TV dramas, when the examiner needs to find evidence of blood stains, they usually spray luminol to the relevant area and turn off the lights. This adds a certain comedy effect to film and television dramas, but it is not the best solution for reality detectors who need to find specific evidence of blood stains in less than ideal situations. In reality, researchers have been looking for alternative methods to detect very low concentrations of blood on fabrics, and recently they have found the answer in thermal imaging technology.

Facilitating forensic investigation-FLIR thermal imaging camera makes &#8220;blood fingerprints&#8221; clearer

Blood is invisible in its own infrared spectrum, but spraying water vapor on blood stained samples can create a thermal signal. This thermal imaging method can replace luminol in forensic testing and become a new detection solution. Today, let’s talk about chemistry researchers Dr. Michael Myrick and Dr. Stephen Morgan and their team at the University of South Carolina researching the use of thermal imaging cameras as an alternative to detecting and recording evidence of biological fluids (such as bloodstains at crime scenes) in the field of forensic applications. .

Problems with traditional luminol

Luminol itself is a kind of powder, mixed with hydrogen peroxide and used on the surface of the fabric for testing. If blood is present, the iron in hemoglobin catalyzes the reaction between luminol and hydrogen peroxide, releasing electrons as photons visible to blue light. However, luminol can also react with substances other than iron, which may lead to misjudgment.

Dr. Myrick explained that luminol reacts with various substances such as aromatic amines, copper salts, and bleach. In addition, it has a problem. It may also have a potential impact on DNA testing: Although it does not directly damage DNA, it may affect certain genetic markers.

Facilitating forensic investigation-FLIR thermal imaging camera makes &#8220;blood fingerprints&#8221; clearer
The water absorption/desorption characteristics of blood are similar to the water absorption/desorption characteristics of cotton, so even if whole blood is imprinted on cotton, it is blurred.

When spraying luminol on blood stains, it may blur or wash away the blood stains. “If there is a pattern, such as a fingerprint, and you soak it in a liquid, you may lose it completely,” Dr. Myrick said. This will lose all opportunities to identify fingerprints on the fabric. Excessive dilution of blood stains can also cause subsequent DNA testing of the sample to become a bubble.

Research process of infrared imaging application

Dr. Myrick and his team are always looking for a better way: to visualize blood stains and other biological fluids for medical testing. Myrick is particularly interested in detection methods that can be observed for more than a few seconds, are repeatable, and do not damage the sample. He and his team began to study the use of infrared reflection to visualize blood stains. Although infrared reflections do work, blood stains are always blurred in thermal images.

“Relying solely on thermal imaging is not the best way to visualize chemical controls,” Dr. Myrick admitted. He and his team are looking for ways to increase sensitivity to blood and use steam as a way to create strong absorption bands in the infrared spectrum window. However, in the process of trying to improve the method, the team stumbled upon a better method.

The task of graduate student Wayne O’Brien was to soak a piece of cotton cloth with deuterium oxide sprayed from a travel steam jet and measure the reflectance. O’Brien happened to record an infrared video of steam sprayed on cotton cloth and made an amazing discovery.

“At the moment the steam was turned on, in the infrared video he showed me, the blood stains diluted 100 times were like a light bulb. This amazing phenomenon was very difficult to see before, and it was in the middle of the image in an instant. Bright,” Myrick said.

In addition, unlike luminol, which fades immediately, they found that the effect of water vapor on the blood-stained fabric is continuous. Myrick said: “If you take a piece of cloth and put it in a humid environment where the temperature rises, you can see blood indefinitely. It will not appear and disappear from time to time. As long as you put it in a humid environment, You can see it forever.”

Thermal imager + water vapor, the blood mark is invisible

Myrick’s team used their findings to study blood fingerprints on three types of fabrics. The “fingerprints” came from a custom rubber stamp. These “fingerprints” were wetted and printed on three different types of dyed fabrics. Each piece of fabric is printed with two fingerprint blood prints, one of which is 10 times diluted and the other is undiluted. Then, let the blood mark air dry for 24 hours.

When it is necessary to image the bloodstain, the researchers exposed the sample to the deionized water vapor of the garment steamer. For a long period of time, they steamed the cloth every three seconds and paused the recording during each steaming interval.

Spraying water vapor on the sample directly generates heat, and Dr. Myrick likens this process to walking out of a dry air-conditioned room to the hot and humid outdoors. Every piece of clothing you wear will immediately absorb water vapor, and the temperature will rise slightly, which is obvious in the infrared image.

Just like adding moisture to produce heat, removing the steam source will cause cooling. However, hydrophobic fabrics like acrylic or polyester can only hold a very small amount of water and reach equilibrium quickly. Therefore, the blood stain area will cool down more slowly than other areas of the cloth, which creates a temperature difference, which is easy to identify in the infrared image.

Facilitating forensic investigation-FLIR thermal imaging camera makes &#8220;blood fingerprints&#8221; clearer
Complete blood print on acrylic fabric, left: thermal image during steam exposure to moisture,
Right: Evaporative cooling after exposure, the contrast is sufficient to distinguish fingerprint ridge patterns.

Facilitating forensic investigation-FLIR thermal imaging camera makes &#8220;blood fingerprints&#8221; clearer
Complete blood print on polyester fabric, left: thermal image during steam exposure to moisture, right: evaporative cooling after exposure.

In the first set of records, they installed a 50mm lens for the FLIR A6751sc SLS thermal imager to image the entire bloodstain. FLIR A6751sc provides fast frame rate and 480ns integration speed, enabling researchers to record fast thermal transients. The second set of records used a 13mm lens, allowing Myrick’s team to observe a single enlarged “fingerprint” ridge pattern. In both cases, the team used FLIR’s ResearchIR software to operate the thermal imager.

Facilitating forensic investigation-FLIR thermal imaging camera makes &#8220;blood fingerprints&#8221; clearer
The 10-fold diluted blood print on polyester shows fingerprint ridge patterns and halos caused by blood coagulum wicking.

Myrick’s team found it difficult to image blood marks on cotton cloth. This is because the ratio of water to the total weight is as high as 20%, and the water absorbed by the cotton cloth is equivalent to the water absorbed by the blood stain itself. In contrast, synthetic fibers such as acrylic and polyester have weak water absorption.

“Cotton is a complex fabric, full of loose fibers,” Myrick added. “And the thread absorbs water at different speeds, and the response of a single fiber is extremely fast.”

Facilitating forensic investigation-FLIR thermal imaging camera makes &#8220;blood fingerprints&#8221; clearer
The single thread in the blood stamp is in Sharp contrast with the rest of the cotton cloth

Therefore, the team was very successful in imaging the enlarged ridges on the cotton cloth. They noticed that there was a clear contrast between the whole blood on the cotton float and the whole blood in other areas. This comparison is only visible during the 30 ms period when the float silk can absorb steam.

“FLIR A6751sc allows us to perform high-speed measurements. In fact, the fiber will only light up in one frame of the thermal video,” Myrick explained. After that, most of the fabric has absorbed enough water vapor, thus eliminating the thermal difference between whole blood and cotton.

The blood mark is only faintly visible during steaming. Like the acrylic sample, there is a weave that prevents the fabric from coming into contact with the blood mark. However, compared with the weft yarn (horizontal direction), the warp yarn (vertical direction yarn) is convex, so the blood coagulum on the warp yarn is more obvious.

Facilitating forensic investigation-FLIR thermal imaging camera makes &#8220;blood fingerprints&#8221; clearer
The ridge break occurs at the position where the acrylic fabric prevents the blood mark from contacting the fabric completely

According to Myrick’s research results, thermal imaging is a viable alternative to luminol when determining whether there are blood stains on the fabric. It can even be said that thermal imaging is more preferable, because the water vapor that assists in imaging will not further dilute the blood stains, and there is no possibility of ruining the evidence. Although the use of water vapor will bring some challenges to blood stain imaging on cotton cloth, a high-speed, high-resolution thermal imaging camera can provide a workaround. Scientific research thermal imaging cameras such as FLIR A6751sc have the frame rate and integration speed required to record the rapid heating or cooling of loose cotton fibers, which can be enhanced by magnifying the lens. Myrick and his team will continue to study the application of high-speed imaging on cotton threads in order to improve this process.

FLIR A6750 series

The FLIR A6750 mid-wave infrared thermal imaging camera has a short exposure time and a high-speed window frame rate, making it ideal for recording fast thermal events and fast-moving targets. This refrigerated indium antimonide thermal imager can freeze the motion of moving objects and accurately measure their temperature, as well as perform a variety of non-destructive tests. With 327,680 (640×512) pixel infrared resolution and high sensitivity, it can generate clear images, which is very suitable for inspection of precision instruments.

Facilitating forensic investigation-FLIR thermal imaging camera makes &#8220;blood fingerprints&#8221; clearer
FLIR A6750 series thermal imaging cameras can be seamlessly connected with FLIR ResearchIR Max software,
Browse, record and process the thermal data obtained by the thermal imager. Another software development kit (SDK) is available.

The Links:   LM64C12P 2MBI200U4B-120