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SummaryIf you have follow the informations of sensor,you will know that sensors are always in a state of rapid progress.Now I will state a few things to prove it in the following.Sensor,also called Transducer, is a kind of detection device,it can receive the measured information and then output them according to a certain rule or other needed form to meet the transport, handling,storage,recording,displaying and controlling of imformation,etc. Know more about it,you can read the article : Most Comprehensive Sicence Popularizing of Sensor (detection device) Researchers created quantum control technique for quantum sensorsAs we all known,there is a common problem that designers are harder to deal with quantum sensing devices. How,University of Sydney researchers have sloved this trouble associated with this super-sensitive tech. They have created quantum control techniques in collaboration with Johns Hopkins Applied Physics Laboratory and Dartmouth College. This development will allow next-gen ultra-sensitive sensors to identify small signals and reject unwanted background noise.By applying the right quantum controls to a qubit-based sensor,the team adjust its response in a way  that guarantees the best possible exclusion of the background clutter—that is, the other voices in the room. In order to obtain and analyze signals, measurement protocols are set in place. Over the years, these protocols have lagged behind the advancement of electronic devices. The disparity has led to a phenomenon known as “spectral leakage,” which occurs when quantum sensors return unclear results.What's more, the new control protocols have reduced spectral leakage by several orders of magnitude by using improved sensor hardware. All the approach is relevant to nearly any quantum sensing application and can also be applied to quantum computing as it provides a way help identify sources of hardware error.‘quantum control techniques' is a major advance in how to operate quantum sensors.  New sensors uses for effective control of enviroment pollutionEnviromental pollution issue are always paid great attention by human being as the development of all the world. A team from the Faculty of Physics of Lomonosov Moscow State University has suggested using porous silicon nanowire arrays in highly sensitive gas sensors which may be used both for effective control of environment pollution levels and for the monitoring of air composition in closed spaces,from classrooms to space stations.According to researchers, these devices will be able to detect the presence of toxic and non-toxic gas molecules in the air at room temperature.Each sensor consists of an array of 10 micron long organized silicon nanowires with diameters ranging from 100 to 200 nm. Each nanowire has porous crystalline structure. The size of silicon crystals and pores between them in individual nanowire, varies from three to five nanometers.ey can be obtained by means of a cheap method of metal-assisted chemical etching. It is based on selective chemical etching, i.e. partial removal of surface layer from a bulk crystalline silicon with the use of metal nanoparticles as a catalyst. Moreover, the procedure is quick—at least 100 elements can be produced in a lab within just one hour.Such porous nanowires have huge specific surface area due to which their physical and chemical properties are extremely sensitive to molecular environment. It was also found out that the obtained samples exhibited an effective photoluminescence in the red spectrum region at room temperature. What's important,this gas sensors based on porous nanowires both work at home temperatures and also are reusable, because the all observed effects were completely reversible. Military sensor systems collect accurate informationCollecting accurate user and environmental information such as enemy's location,survive shock, vibration, moisture plays an important role in military system. Deployment complaints about the platform aside, Lockheed Martin’s Electro-Optical Targeting System (EOTS) for the F-35 Lightning II is a high-performance, lightweight, multi-function sensing solution for precision air-to-air and air-to-surface targeting (Figure 4). Integrated into the aircraft fuselage with a rugged sapphire viewport, the device talks to the aircraft via a fiber-optic interface.Presented as the first sensor to combine forward-looking and infrared search along with track functionality, EOTS enables situational awareness and precision delivery of laser and GPS-guided weapons. Advanced EOTS, the next iteration, will incorporate enhancements and upgrades like short-wave infrared, high-definition television, and an infrared marker.Today’s military sensors must operate well on their own, and function as part of a combined-arms approach with an interlaced network of sensing, to detect threats of any nature from any direction. One such way to address this is with a battlefield awareness solution like 3D Advanced Warning System (3DAWS) from BAE Systems, which can provide universal threat detection to an aircrew with a layered countermeasure defense.The modular and expandable system can integrate with fixed- and rotary-wing aircraft and countermeasure systems, with the flexibility to work with existing radar or laser warning systems. The core of the 3DAWS suite is the passively-cued, semi-active radio frequency 3D Tracker element, which serves as an adjunct to current and future passive threat detection systems. 

Warm hints: The word in this article is about 3000 words and reading time is about 15 minutes   This article is mainly talking about how to design better electromagnetic compatibility if LCD. Electromagnetic compatibility (EMC) is an inevitable issue in the design of LCDs. If the EMC design is not good, it will cause water ripples and strobe flash problems during the broadcast of the TV. EMC design is actually optimized for the electromagnetic interference generated in the product to meet the EMC standards of countries or regions. It is defined as the ability of a device or system to function properly in its electromagnetic environment and does not constitute unacceptable electromagnetic interference (EMI) to anything in the environment.       Catalog I. Brief Introduction II. Power Module EMC Design III. Main Drive Board EMC Design IV. Tuner Board EMC Design V. Whole Machine EMC Design FAQ   I. Brief Introduction Electromagnetic interference is generally divided into conducted interference and radiation interference. Conducted interference refers to the coupling interference of signals on one electrical network to another electrical network through conductive media. Radiated interference means that the interference source couples (disturbs) its signal to another electrical network through space.   The LCD structure mainly includes a liquid crystal display module, a power supply module, a drive module (mainly including the main drive board and a tuner board), and a key button module. General liquid crystal display modules have been tested by EMC before production. Here mainly introduces the design of the power module, drive module, button module, and the whole machine should pay attention to the electromagnetic interference problem.   EMI (ElectroMagnetic Interference) & EMC (Electromegetic Compatibility)   II. Power Module EMC Design The two main functions of the power supply section are to realize the backlight for driving the LCD screen and to provide DC power for other modules (including the drive module and the button module).   The design of the power module directly affects the entire system. If the design is not good, it will cause large water ripples in the TV. In severe cases, the TV will not be used. At the same time, it will seriously affect the normal use of other nearby equipment.   The power supply of LCDs is based on switching power supplies. The causes of electromagnetic interference problems caused by switching power supplies are complex. When designing the switching power supply, it is necessary to prevent the switching power supply from causing interference to the power grid and nearby electronic equipment. It is also necessary to strengthen the adaptability of the switching power supply itself to the electromagnetic interference environment.   To solve the EMC problem of switching power supplies, the following main measures should be taken into consideration during design:   Soft-switching technology: Inrush current and peak voltage are generated when the switching device is turned on/off. This is the main reason for electromagnetic interference and switching loss in the switch. Soft switching technology is an important method to reduce the loss of switching devices and improve the EMC characteristics of switching devices. This technology is mainly to switch the switching tube in the switching power supply at zero voltage and zero current to effectively suppress electromagnetic interference.   Modulation frequency control: Electromagnetic interference is changed according to the switching frequency, and the interference energy is concentrated on the discrete switching frequency point, resulting in large interference intensity. By distributing the energy modulation of the switching signal over a wide frequency band, a series of discrete sidebands are generated. This spreads out the interference spectrum, and the interference energy is distributed on the discrete frequency band, thereby reducing the electromagnetic interference intensity at the switching frequency point.   Component layout and routing: The components associated with the power input signal and output signal are placed near the corresponding ports to avoid interference due to the coupling path. Put components that are related to each other together to avoid interference caused by long traces.   Also, try to avoid parallel routing of signal lines. If unavoidable, try to increase the line spacing. Or add a ground wire in the middle to reduce the interference between each other.   III. Main Drive Board EMC Design The main driver board of the LCD mainly includes an analog signal portion, a high-speed digital circuit portion, and a noise source DC-DC power supply portion.   Component layout and routing: In the layout, the three parts of the analog signal part, the high-speed digital circuit part, and the noise source DC-DC power supply part should be reasonably separated so that the signal coupling between them is the minimum. In terms of device placement, the principle of associating the devices with each other is as close as possible, so that a good anti-noise effect can be obtained.   DC-DC Power Supply Part and Ground: On printed circuit boards, the power line and ground are the most important. Let analog and digital circuits have their own power and ground paths, respectively. The main means of overcoming electromagnetic interference is grounding.   On the driving board of the LCD, the ground of the power supply section (DC-DC) is mainly separated from other grounds such as the decoding and main chip processing, so as to reduce interference of the power supply on the image display and the television sound.   If there are analog ground and the digital ground when designing the circuit, they should be separated when the printed board is laid. To reduce mutual interference. In the layout of double-layer boards and multilayer PCBs, one layer of copper foil is generally used as a dedicated ground plane. The purpose of this is that this ground serves as a shield.   Integrated chip: In the same integrated chip, the ground is also separated from the analog ground and the digital ground. For example, the AD9883 analog-to-digital conversion chip of the AD company, which is often used as the main driver board of the LCD, can be floor-separated between the ground and digital sections of the analog section of the chip during the PCB design. Finally, connect the two points by a relatively short wire. Or connect the two places with a 1nF bypass capacitor.   Crystal oscillator: The clock circuit in the digital circuit is one of the main electromagnetic interference sources in current electronic products and is the main content of EMC design. Crystal is a strong source of radiation. The internal circuit of the crystal generates a large RF current, so that the ground lead of the crystal cannot sufficiently draw a relatively large Ldi/dt current to the ground plane with little loss, and as a result, the metal housing becomes a monopole antenna. The periphery of the crystal is a radiation field.   Therefore, the crystal oscillator circuit is far away from the interface circuit, such as serial port, address line, and data line. In order to avoid the interface circuit bringing the harmonic signal of the crystal out of the printed circuit board to cause electromagnetic interference. Two legs of the crystal oscillator must be added with an RC filter circuit. At the same time, be sure to connect the metal shell of the crystal to the ground on the printed board. In addition, the crystal is placed as close as possible to the chip pins. The ground is used to isolate the clock area, placing a local ground plane and connecting it to the ground through multiple vias.   Capacitance decoupling: Capacitance decoupling is used to reduce electromagnetic interference. Capacitor decoupling can be divided into three types: overall, partial, and inter-board.   The overall decoupling capacitor operates at low frequencies, providing a stable voltage and current for the entire board. It should be placed close to the printed circuit board power cord and ground. The typical decoupling capacitor value is 0.1μF. The typical value of the distributed inductance of this capacitor is 5μH. The 0.1μF decoupling capacitor has 5μH distributed inductance. Its parallel resonant frequency is about 7MHz. That is to say, it has a better decoupling effect for noise below 10MHz, and it has almost no effect on noise above tens of MHz. So for noise above 20MHz, use a 0.01μF capacitor decoupling.   The local decoupling capacitor makes the supply voltage obtained by the integrated circuit more stable; in addition, the high-frequency noise of the device is bypassed.   The decoupling capacitance between boards refers to the capacitance between the power plane and the ground plane and mainly solves the high-frequency transient current generated in the power supply. A 10~100uF electrolytic capacitor is connected across the input of the power supply. If the position of the printed circuit board is allowed, the anti-interference effect of the electrolytic capacitor with 100uF or more will be better. The lead of the decoupling capacitor can not be too long, generally close to the integrated circuit power supply, the connection should be rougher.   Bead filtering: Bead filtering is applied to all signal inputs (such as YPBPR and VGA) on the motherboard. Magnetic beads are designed to suppress high-frequency noise and spike interference on signal lines and power lines, and also have the ability to absorb electrostatic pulses. It acts as a high-frequency resistor, which attenuates high frequencies. The device allows the DC signal to pass and filter out the AC signal.   When selecting beads, you must pay attention to the following factors:   1. What is the unwanted signal frequency range? 2. Who is the noise source; 3, how much noise attenuation; 4. What is the environmental condition (temperature, DC voltage, structural strength); 5. What is the circuit and load impedance? 6. Is there room to place beads on the PCB board?   The first three can be judged by observing the impedance frequency curve provided by the manufacturer. The three curves in the impedance curve are very important, namely the resistance R, inductive reactance X, and total reactance Z. As shown in Figure 1:     Figure 1: Impedance curve and equivalent circuit topology that reflect the bead resistance, inductive reactance, and total inductance   The total impedance is described by the following formula (1):   Z=(R + 2πFL)   From this curve, beads are selected that have the maximum impedance in the frequency range where attenuation of the noise is desired, and where the attenuation of the signal is as small as possible at low and DC.   Chip beads can affect the impedance characteristics under excessive DC voltage. In addition, if the operating temperature rises too high or the external magnetic field is too large, the impedance of the beads will be adversely affected.   Whether using chip beads or chip inductors is also mainly in applications. Chip inductors are needed in the resonant circuit. When it is necessary to eliminate unwanted electromagnetic interference noise, the use of chip beads is the best choice.   IV. Tuner Board EMC Design The tuner board mainly includes a tuner section and an audio processing section.   When conducting the circuit design of the tuner board part and the layout of the PCB board, it is necessary to pay special attention to the electromagnetic interference problem. The following points must be considered:   （1）First, separate the land of the TUNER section (ie the simulated ground) from the land of the other sections. （2） Be sure to connect the metal shell of TUNER to the ground. The connection points can better eliminate electromagnetic interference. The tuner TUNER inherently has a high-frequency circuit, so it must be shielded. （3）When selecting the interface terminals (such as AV terminal, S-VIDEO terminal, etc.), try to use terminals with good conductivity and strong anti-electromagnetic interference, and also connect the ground of the interface terminal with the earth completely. At the same time also added magnetic beads filter. （4）The signal line should be as short and straight as possible. If it cannot be avoided, fly line transitions can be used. Signal lines should not form a ring. Because the ring is equivalent to the number of turns of the coil, the radiation effect of the ring wiring is the strongest. （5）Try to reduce dead copper in large areas. The solution is to connect them to the ground. If a large area of dead copper forms the antenna, electromagnetic interference will be introduced. （6）Do not run under quartz crystals and under noise-sensitive devices.   The audio processing section should pay special attention to the layout of the printed circuit board, first of all, avoid high-speed signal lines and audio and video lines together. For example, if you connect the clock line SCL and the data line SDA in the I2C bus to the traces of the audio line. Since the clock line SCL and the data line SDA in the I2C bus are constantly changing, they interfere with the sound. Obviously, for example, when you use a TV remote control to switch to a TV channel, you can hear a regular "click, click" sound from the speaker. This may be because of the above issues that were overlooked in the PCB layout.     V. Whole Machine EMC Design   The assembly drawing in the whole machine (taking one of the models as an example) is shown in Figure 2: Figure 2: In-machine assembly drawing of a model that reflects various EMI concerns   The connection line numbered 5 in the figure above is the screen line of the digital panel connection screen. Because the screen line is mainly on the screen data. It will cause a great disturbance to the system. The best way to reduce interference is to use twisted pairs and shielded wires. If it is a TTL screen, the screen line needs to be shielded or a magnetic ring outside the connection line. If on the LVDS screen, you need to use twisted pair, plus a magnetic ring. In order to reduce the screen line to the entire system of electromagnetic interference. With shielded twisted pair, the signal current can flow on the two inner conductors, and the noise current flows in the shield layer, thus eliminating the coupling of the common impedance, and any interference will induce the two conductors at the same time so that the noise cancels.   A magnetic ring is also required on the connection between the power supply and the main control board (referenced 4). The main reason is that the power cord will generate relatively large electromagnetic interference to the motherboard.   A magnetic ring should also be added to the connection between the keypad and the motherboard (referenced 9). The main reason is that there is a constant data change (remote control receiver head) on the keypad which causes electromagnetic interference to the system. Plus magnetic rings can effectively shield electromagnetic interference.   A magnetic ring is added to the audio cable (labeled 10) connected to the speaker to reduce the electromagnetic interference from the audio output to the system. If there is a cable (label 6, 7, 8) between the motherboard and the tuner board, you need to add a magnetic ring on the cable. To reduce the electromagnetic interference between cables.   The magnetic ring added above can be added according to the specific situation and can be determined by repeated experiments.   Use of shields: In general, shields are required for liquid crystal display modules, main control boards (including digital boards and tuner boards), and power supplies.   The main frequency of the main chip is the main cause of electromagnetic interference. Frequency harmonics of the main frequency are most likely to produce electromagnetic interference. In the experiment conducted by EMC, the frequency harmonics of the main frequency had large electromagnetic interference. The main chip must be shielded during design. The main shielding measures include a metal shield on the digital board. Adding a shield is the most effective way to resist electromagnetic interference. However, because of the heat dissipation problem of the driver board and the entire system, it is required that the holes on the shield cover be used to dissipate heat. However, its maximum size must be less than 1/100 of the shortest wavelength of noise.   The shield on the tuner board is mainly shielded from the TUNER section.   The shielding of the power supply section is particularly important. If the shielding of the power supply section is not good, it will cause large interference. This will not lead to conduction. And because the heat of the power supply is very severe, the shield must pay attention to the problem of heat dissipation.   Usually, shields have openings and seams that can cause electromagnetic leaks. As a result, the shielding effect is not good. Solve electromagnetic leaks at joints by using electromagnetic seal gaskets at the joints. The electromagnetic leakage of the opening in the shield is related to the size of the opening, the characteristics of the radiation source, and the distance from the radiation source to the opening. The requirement for shielding is met by designing the size of the opening and the distance of the radiation source to the opening. FAQ   1. What can cause electromagnetic interference? Electromagnetic interference (EMI) is a disturbance caused by an electromagnetic field which impedes the proper performance of an electrical device. EMI can come from man-made or natural sources such as the sun or the Earth's magnetic fields.   2. How do you stop electromagnetic interference? The simplest way to reduce magnetically induced interference is to use twisted pair wires. This applies both for shielded and unshielded cables and for interference caused by shield currents or from other sources. Twisting the wires forces them close together, reducing the loop area and therefore the induced voltage.   3. How do you make electromagnetic interference? Plug both devices into a wall outlet in the same house or building. Since the wall outlets in most houses are tied to the same ground, the ground is a common source of conducted interference, especially from the low frequency hum of an electric motor. Turn on both devices at the same time.   4. Is electromagnetic interference bad for you? There is no doubt that short-term exposure to very high levels of electromagnetic fields can be harmful to health. ... Despite extensive research, to date there is no evidence to conclude that exposure to low level electromagnetic fields is harmful to human health.   5. What are three types of interference? Electromagnetic interference (EMI) Co-channel interference (CCI), also known as crosstalk. Adjacent-channel interference (ACI) Intersymbol interference (ISI)   6. What material can block electromagnetic fields? Typical materials used for electromagnetic shielding include sheet metal, metal screen, and metal foam. Common sheet metals for shielding include copper, brass, nickel, silver, steel, and tin.   7. What blocks electromagnetic interference? Carbons. Carbon materials (e.g., coke, graphite, graphene, carbon fiber, carbon nanofiber and carbon nanotube) are not only conductive electrically, they are good absorbers of electromagnetic radiation over a wide frequency range.   8. Can humans cause electromagnetic interference? The human body functions as an antenna in the low-frequency band used by HBC. Owing to this antenna function, electromagnetic waves radiating from electronic devices or wireless services cause electromagnetic interference (EMI) in HBC devices.   9. What are two sources of electromagnetic interference that can affect data transmission? Electromagnetic interference can be categorized as follows: Narrowband EMI or RFI interference typically emanates from intended transmissions, such as radio and TV stations or mobile phones. Broadband EMI or RFI interference is unintentional radiation from sources such as electric power transmission lines.   10. What is the EMC? Electromagnetic Compatibility, also known as EMC, is the interaction of electrical and electronic equipment with its electromagnetic environment, and with other equipment. All electronic devices have the potential to emit electromagnetic fields. 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The world's smallest diode, the size of a single molecule, has been developed collaboratively by U.S. and Israeli researchers from the University of Georgia and Ben-Gurion University of the Negev (BGU).     "Creating and characterizing the world's smallest diode is a significant milestone in the development of molecular electronic devices," explains Dr. Yoni Dubi, a researcher in the BGU Department of Chemistry and Ilse Katz Institute for Nanoscale Science and Technology. "It gives us new insights into the electronic transport mechanism." Continuous demand for more computing power is pushing the limitations of present day methods. This need is driving researchers to look for molecules with interesting properties and find ways to establish reliable contacts between molecular components and bulk materials in an electrode, in order to mimic conventional electronic elements at the molecular scale. An example for such an element is the nanoscale diode (or molecular rectifier), which operates like a valve to facilitate electronic current flow in one direction. A collection of these nanoscale diodes, or molecules, has properties that resemble traditional electronic components such as a wire, transistor or rectifier. The emerging field of single molecule electronics may provide a way to overcome Moore's Law— the observation that over the history of computing hardware the number of transistors in a dense integrated circuit has doubled approximately every two years - beyond the limits of conventional silicon integrated circuits. Prof. Bingqian Xu's group at the College of Engineering at the University of Georgia took a single DNA molecule constructed from 11 base pairs and connected it to an electronic circuit only a few nanometers in size. When they measured the current through the molecule, it did not show any special behavior. However, when layers of a molecule called "coralyne," were inserted (or intercalated) between layers of DNA, the behavior of the circuit changed drastically. The current jumped to 15 times larger negative vs. positive voltages—a necessary feature for a nano diode. "In summary, we have constructed a molecular rectifier by intercalating specific, small molecules into designed DNA strands," explains Prof. Xu. Dr. Dubi and his student, Elinor Zerah-Harush, constructed a theoretical model of the DNA molecule inside the electric circuit to better understand the results of the experiment. "The model allowed us to identify the source of the diode-like feature, which originates from breaking spatial symmetry inside the DNA molecule after coralyne is inserted." Reference: CLCS145V0-G PACDN004SR  SLVU2.8.TCT    

Warm hints: The word in this article is about 3000 words and reading time is about 15 minutesSummaryThis article is mainly about space monitoring and location technology of AR&VR equipment. All AR&VR products must have accurate spatial monitoring and positioning capabilities in order to achieve a full range of head， hand interactions in order to provide users with a more realistic virtual experience. CoreResearch on space monitoring and location technology of AR&VR equipmentPurposeIntroduce space monitoring and location technology of AR&VR equipmentProductAR&VR EquipmentCategoryElectronic productsApplicationsAR&VR technologyTechnologyInside-out space monitoring and positioning and outside-in space monitoring and positioning     Catalogs CatalogsI、Current Status of AR&VR ProductsV、 PC VRII、Cardboard productsVI、Space positioning technology categoryIII、Head motion controlled all-in-one            machine1. Inside-out space monitoring and positioning technologyIV、 AIO machine with space monitoring and positioning2. Outside-in space monitoring and positioning technology  Introduction I、Current Status of AR&VR ProductsThere are many AR&VR products already on the market. The price varies from Cardboards to Hololens, and the user experience varies greatly. First of all, VR products can be divided into the following categories: cardboard products, one-touch control integrated machine, AIO machine with space monitoring and positioning, PC VR.  DetailII、Cardboard productsCardboard productsThis kind of product is the simplest VR product. It comes from Google's carton VR box. Simply, it uses two convex lenses to project the contents of the mobile phone into screens. It uses the IMU inside the phone to judge the user's head movement to adjust the movement direction of the VR display content. This kind of product began to ship a large number of domestic white cards in 2015, but the overall effect of VR depends on the configuration of the mobile phone and the quality of the optical lens. It is only an entry-level VR experience product.The first generation VR products of game companies and some domestic video content are basically in this form. The most representative is the Storm Box, with a BT control handle for menu selection. The emergence of this type of product has indeed played a big role in the promotion of the entire VR industry, but its drawbacks are also very obvious. The Cardboard-style VR device ushered in a particularly big opportunity in 2016, that is, Google proposed Daydream VR. Google wants to enhance the VR Cardboard users’ experience, and hopes to be able to dominate the entire VR ecosystem in 2016. The Daydream mobile phone Pixel, Pixel XL and Daydream Viewer wearing the Cardboard were released in the year, and also equipped with a built-in IMU remote control handle. According to Google's requirements for VR device user experience, it must reach a mobile phone with a certain hardware configuration, and with Daydream Viewer running related VR applications, so that users will not be dizzy. Since 2016, with the launch of products such as Huawei P9 and Lenovo MotoZ, there are more and more mobile phones supporting Daydream. It is expected that, in 2017, these products will completely break the stalemate of the poor Cardboard user experience.III、Head motion controlled all-in-one machineAll-in-one machineAIO machine, as its name, is a VR device that does not need to be inserted into a mobile phone or connected to a PC. Currently, there are representative DaPeng, Xiaoniao, KanKan, etc. Most of the products are listed in 2016. The features of these products are basically the same use of 1080p or 2K resolution display screens (some of which also use 2Kx2 dual screens) with specially designed FIN products designed for VR products aspherical optical lens. The overall picture quality and distortion have improved a lot. However, these products have a common feature, that is, only a simple head control, can only sit or stand in place by shaking his head to achieve VR control, can not do the first hand interaction. In order to remedy this defect, there are currently some external accessories with spatial position detection (the built-in IMU handle, somatosensory backpack, spatial positioning light ball, etc.) to enhance the overall VR user experience.IV、 AIO machine with space monitoring and positioningAIO machine with space monitoring and positioningSpace monitoring and positioning are generally two ways, Inside-out and Outside-in. Inside-out senses the spatial information outside the device through the built-in sensor and performs related positioning. The Outside-in is just the opposite. It uses an external sensor to sense the position of the VR device and provides positioning information to the VR application. For the all-in-one machine, the current view has selected the Inside-out solution without exception, thus avoiding the need to install an external sensor in advance. The user can pick up the VR device at any time and anywhere. It is expected that some of the major products coming on the market in 2017, such as the second generation of the DaPeng AIO Machine and the Storm AIO Machine, will have space positioning capabilities, which will greatly enhance the VR user experience, especially VR games.V、 PC VRPC VRThe most representative products are the HTC Vive, Sony PSVR and HTC Oculus. After the three swordsmen went public in 2016, the HTC Vive has become a standard configuration for the VR experience room. Many other industry customizations are based on Vive. Sony PSVR has sold about 1 million units in less than half a year, which has greatly improved the overall level of user experience in the entire VR industry. The feature of these three products is the use of external space positioning technology. For example, Vive uses an external infrared laser transmitter, head and handle senses transmitter location to determine its position and trajectory. PSVR and Oculus use external sensors to sense the visible light or infrared light emitted by the headlights and the handle to determine the positions of the heads and the handles, so that the heads and the handles can accurately know their respective relative positions and trajectories in space at any time. This can make the application of VR more realistic.Next, let’s talk about AR products. At present, there is a big gap between AR products. Some AR glasses products only project virtual information, images, etc., and are not actually related to the actual environment where the user is located. Such products can only achieve 6DOF motion tracking by the projected virtual information following the head movement. But it is impossible to fuse the virtual object with the actual environment where the user is. For example, the famous ODG, the latest product only supports 6DOF motion tracking, there is no spatial positioning function.AR product ODGShanghai Zhishi's smart glasses also have similar functions to those of ODG, but their positioning is a live broadcast from the first point of view. Therefore, only relevant information and videos for shooting can be displayed in the glasses without spatial positioning. However, it is understood that they are also developing a built-in TOF depth camera glasses, which can achieve 6DOF + spatial positioning function.Shanghai Zhishi's smart glassesThe currently available AR products have the best space monitoring and positioning capabilities. The best match for virtual objects is the Lenovo Phab2 Pro based on Google's Tango space positioning technology and the Microsoft Hololens. Although these two products are very different in shape, they are essentially the full integration of 6DOF+SLAM, achieving spatial positioning and motion tracking. Their AR effects can basically be virtual objects and the actual environment. Convergence, no matter how the user moves or views from what angle, the feeling is just like the real object is in front of me. However, Hololens' accuracy and stability of 6DOF+SLAM are still higher than those of Tango in terms of the effect of actual use. This is closely related to the choice of hardware design platform, type and number of sensors, and core algorithms.Hololens ARIn addition, there are actually many companies in the country that are developing related AR products. Among them, the distinctive feature of Micro Eye's SMAKKEST is not only similar to Hololens, but also similar to Hololens in terms of function. The effect of 6DOF+SLAM is said to be recognized by Hololens.  AnalysisVI、Space positioning technology categorySpace monitoring and positioning technology, in fact, can be divided into two major categories initially, one is the Inside-out space monitoring and positioning, and the other is the Outside-in space monitoring and positioning.1. Inside-out space monitoring and positioning technologyInside-out space monitoring and positioning technology, technology is essentially similar to the process of human-to-environmentally-aware environment of the human eyewear. It senses the external space from the inside of the device and is therefore called the Inside-out positioning method. Inside-out space monitoring and positioning technology is also divided into two categories. One is the spatial monitoring and positioning based on SLAM technology. This is also a basic function required by the fiery robotics industry. SLAM is the English abbreviation for simultaneous localizatiion and mapping. It means that the device itself starts to move from an unknown location in an unknown environment, locates itself according to location estimates and maps during the movement, and builds incremental maps based on its own positioning to achieve autonomous detection and positioning navigation of the device itself. . At present, most AR products use Inside-out spatial location technology.The representative products of the space monitoring and positioning technology based on SLAM are Lenovo Phab2 Pro Tango mobile phone and Hololens. Both use depth monitoring + Fisheye and IMU fusion for sports monitoring. The difference is that the depth monitoring technology is different (Tango uses TOF, and Hololens uses structured light) and the number of Fisheye motion and feature point monitoring is different. Hololens' spatial positioning effect is more accurate and stable than Tango's, and Hololens' effect is in low light and glass light transmission. The current Tango victory, but Tango technology is not static, the next generation of Tango technology also supports multiple Fisheye camera.The Lenovo Phab2 Pro Tango phone uses a TOF depth camera, a 155-degree FOV Fisheye motion monitoring camera and an RGB camera, Fisheye motion monitoring camera with IMU data fusion, feature point matching, providing the device with a complete trajectory The monitoring, together with the cloud image information of the TOF depth camera, can plot the position of the device itself in space and the trajectory of the movement in real time. At the same time, through Tango's own zone learning function, when returning to the space that has already passed, once the Fisheye camera By detecting the stored feature points and matching them, it is possible to quickly perform spatial positioning. This is very important for AR equipment and it ensures that users can quickly use it anytime, anywhere. The working principle of Tango is not explained here. You can refer to Lin Shigong's another article for detailed understanding.The working principle of TangoThe Hololens design of Microsoft is very unique and very affluent. It has newly developed an HPU (Holographic Processing Unit) based on Intel's CPU and GPU technology. The device adopts the configuration of CPU+GPU+HPU. Like Tango, it does not need to External PCs look to achieve complete space monitoring and positioning. On the sensor side, depth monitoring uses two structured light cameras with four structured light-grating emitters for depth monitoring. In addition, there are two Fisheye cameras on the left and right of Hololens, so that more feature points in the space environment can be monitored. Hololens' space positioning accuracy and stability are therefore much higher than those of Tango.HPU（Holographic Processing Unit）The other type is based on the marker (pointer) space monitoring and positioning technology, simply put some like two-dimensional code, special color graphics patterns or light spots as markers in the actual space, equipment to monitor these markers The location of the point to determine their position and movement trends. The HTC Vive is a representative of this type. The following figure shows the working principle of spatial location of the HTC Vive.The working principle of spatial location of the HTC ViveVive emits laser light through two fixed laser emitters. Each base station has an infrared LED array. Two infrared laser emitters with rotating shafts perpendicular to each other are distributed. One is X-axis scanning, and the other is Y-axis scanning. The lasers have a fixed phase difference of 180 degrees. When one of the lasers emits an X-axis scan, the other laser emits a Y-axis scan.The HTC Vive has a shell that is densely covered with 32 light sensors, each oriented in different directions. These sensors are used to receive the infrared laser emitted by a fixed laser emitter. The computer connected to Vive controls all the devices to operate synchronously. The light sensor on the head reveals the time when the laser light reaches each sensor in the X-axis and Y-axis directions and the phase relationship between the two different laser emitters, and the phase difference of each light sensor can be calculated. Accurately locate the head position and trajectory.There are 24 light sensor on the Vive handle. The working principle and head of the handle are the same. It will not be repeated here.The HTC Vive ShellIn addition, it is necessary to mention that domestic Ximmerse, they also introduced a VR device for the Outside-in space positioning package design, through this space positioning package, can provide space-free VR devices with similar accuracy with the HTC Vive Space monitoring and positioning capabilities. The positioning package includes a dual camera module, two control handles with a light ball. When used, the dual camera module is externally mounted on the head display. The dual camera captures the light ball of the control handle to determine the position of the handle in the space, and the handle Through BT to transmit its 6DOF information to the module, the module fuses the 6DOF and the position information of the ball to achieve omni-directional positioning, thereby improving the interaction of the first hand. The advantage of this solution is that under any ambient lighting conditions, the positioning accuracy is not affected by the ambient light, and the positioning accuracy is high. However, this solution cannot monitor and locate the overall space environment in which the user is located. It can only monitor the spatial position information of the photo ball handle, but its advantage is that the original VR device without space positioning can have at least similar HTC Vive. Spatial positioning capabilities.Ximmerse2. Outside-in space monitoring and positioning technologyOutside-in space monitoring and positioning technology is currently the VR device is a relatively mature space positioning technology, Sony PSVR and Oculus are based on a similar program, but Oculus is in an external infrared camera plus point initiative marks the way to get Higher accuracy and faster response time. The PS VR directly uses the PS 3's MOVE system. The principle is similar to that of the Kinect. An external binocular depth camera is used for motion recognition and tracking. There is a light indication on the head, and a different color light ball is at the top of the handle. The external dual camera checks the trajectory of the headlight and the ball on the handle at any time. At the same time, the PS StaTIon receives the IMU information of the head display and handle returned by the BT. , Through the calculation you can get a complete headshot and handle movement trajectory and positioning in space.PS StaTIonFrom the principle and the effect of actual use, the space monitoring and positioning precision of HTC Vive is not high, although Sony's gaming and PSVR wearing wearing their own moderate than Vive better, but the spatial positioning accuracy is not high, it affects the VR The overall experience of the game. So we see from Sony's official website a new spatial orientation of Sony patent, this patent is to be ready for the next generation of PVSR, from the description of the patent point of view should be similar to HTC's fixed laser emitters way, with this program The current practice of PSVR is the opposite. Instead of using an external camera to take pictures (outside-in positioning), the external VR signal is used to locate the direction of the VR helmet in space. This can provide similar HTC Vive usage accuracy (probably higher), and can capture the user's various poses and trajectories 360 degrees without dead ends.Outside-In positioningOculus space monitoring and positioning technology with Sony PSVR similar difference is PSVR camera uses a dual monitor visible external program, and is an active Oculus uses infrared light to the head and the handle are placed significant infrared emitting LED , Through an external infrared camera for shooting and capturing the headlights and infrared light spot information on the handle, so as to obtain head trajectory and handle movement trajectory and spatial position information.Whether it is Sony PSRV or Oculus's Outside-in program, there is a problem, that is, the external camera is fixed, and when the user is back to the camera, the camera can not detect the head and the handle on the light, may There is a possibility of missed supervision, thus affecting the user experience, which does not exist on the HTC Vive.Another Marker point-based Outside-in space monitoring and positioning technology is Ximmerse's photosphere with dual-camera solution. This is contrary to their previously mentioned Inside-out solution, where dual camera monitors have been placed. Indoor fixed position, and then put the ball in the VR head and handle, head and handle during the movement of a dual camera monitor recorded head and handle in the space of the three-dimensional position and their movement data, through BT or WiFi is passed to VR heads to perform related operations and processing, and feedback is implemented on the screen to allow them to freely move around in the virtual environment and interact with things in the virtual world.Lightball + Dual Camera SolutionAnalog of Lightball + Dual Camera SolutionHere is a video about Augmented Reality vs Virtual Reality:Augmented Reality vs Virtual Reality - AR vs VR | The Future ! | Tamil Tech  Book RecommendationVirtual, Augmented, and Mixed Realities in EducationThis book describes the current state of the art of various types of immersive learning: in research, in practice, and in the marketplace. It discusses advanced approaches in the design and development for various forms of immersive learning environments, and also the emerging innovations in assessment and research in the field.--by Dejian Liu, Chris Dede, Ronghuai Huang, John Richards Experience on Demand: What Virtual Reality Is, How It Works, and What It Can DoVirtual reality is able to effectively blur the line between reality and illusion, pushing the limits of our imagination and granting us access to any experience imaginable. With well-crafted simulations, these experiences, which are so immersive that the brain believes they’re real, are already widely available with a VR headset and will only become more accessible and commonplace. But how does this new medium affect its users, and does it have a future beyond fantasy and escapism?--by Jeremy Bailenson  Relevant information about "Research on Space Monitoring and Location Technology of AR&VR Equipment"About the article " Research on Space Monitoring and Location Technology of AR&VR Equipment", If you have better ideas, don't hesitate to  write your thoughts in the following comment area. You also can find more articles about electronic semiconductor through Google search engine, or refer to the following related articles. 

SummarryWhen I see this paper,The things occurred in my mind is that I need to let others to know it and prevent it.From morning until now,I always solve my computer's Trojans.This is terrible. Trojans may break our computer although it look like there doesn't matter.Trojans aren everywhere even the hardware in some instances, hardware Trojans could even open backdoors in custom silicon. BodyOutsourcing has reshaped the way electronics products are made – and helped to cut manufacturing costs massively. But, as production margins have fallen, so too has trust in the organisations that make up the supply chain. Companies which rely on outsourced manufacturing are having to come up with ways of ensuring that the products shipped to them have not had secure keys leaked or stuffed with viruses and compromised software. Even custom silicon is not safe.Almost a decade ago, researchers from Case Western Reserve University described to delegates at the IEEE High-Level Design Validation and Test Workshop the ways in which they could see hardware malware – or Trojans – being introduced to an IC-design project. The widespread use of foundry services, third-party intellectual property and standard-cell libraries – as well as designers bribed to make circuit-level changes – all provide ways in which Trojans could be sneaked into circuitry.Once it receives a trigger signal, the Trojan could open a backdoor to the group that wanted it introduced. In some use-cases, the Trojan may be introduced simply to compromise the product; no matter how it is used. However, the nature of IC design makes hardware Trojans difficult to deploy as they require skills and levels of access that are probably out of reach of most cybercriminals. But other, lower hanging, fruit remains available to them. State actors have the skills, access and motive that may make the surrepticious deployment of some kinds of silicon highly attractive to them. In practice, such organisations may not bother trying to introduce backdoors without the knowledge of the manufacturer or find other ways to make gain access to secrets. In 2015, the BBC identified declassified documents that confirmed the government convinced Crypto AG in the mid-1950s to compromise the security of its C-52 electromechanical encryption machines. Rather than making physical changes to the hardware itself, the company told the US National Security Agency (NSA) and the UK’s GCHQ which models target governments had bought – a practice that would allow the agencies to target decryption resources more effectively. In 2013, the NSA came under suspicion of encouraging the use of algorithms supplied by specialist RSA that had been subtly weakened to make decryption easier. While some ICs behave as if they have Trojans installed, in reality the backdoors were placed intentionally into the silicon by authorised designers. Usually, they are debug aids that were meant to stay secret, but often did not. Five years ago, Sergei Skorobogatov of the University of Cambridge and Christopher Woods of Quo Vadis Labs used side-channel emissions from the devices to uncover the key that would open the backdoor in the JTAG circuitry of an FPGA and to provide access to the encryption keys stored inside. Although side-channel emissions provide one way to determine whether an IC has been compromised with a backdoor, designers have other options available through the deployment of EDA techniques with Trojan detection in mind. As with anything in cybersecurity, a cat-and-mouse game has produced ever more subtle ways of introducing Trojans and more powerful ways of detecting them. The hardware Trojan is the subject of regular hacking competitions between research teams. For example, the Cyber Security Awareness Week (CSAW) organised by New York University has run several challenges around Trojans. In these challenges, red teams try to circumvent the detection mechanisms used by blue teams. 2013’s CSAW challenge focused on methods to beat FANCI, a largely effective detector developed at Columbia University and NYU. FANCI works on the basis that a Trojan would only have a loose connection to the design such that its logic would seem to be practically unreachable. Code-coverage analysis of the RTL can identify such unconnected lumps of circuitry and flag them up as possible Trojans. A couple of years later, the DeTrust technique created by Jie Zhang and colleagues at the Chinese University of Hong Kong showed one method for fooling FANCI: spreading the suspicious logic across many otherwise independent gates. Months later, Syed Haider and coworkers from the University of Connecticut developed the hardware Trojan catcher (HaTCH), designed to track down stealthier functions inserted at the logic level. Rather than isolate the Trojans before manufacture so they can be removed, HaTCH focuses on remediation. It adds tagging circuitry to legitimate cores that work to prevent any on chip Trojans from activating or succeeding in displaying malicious behaviour, such as opening a backdoor. A more wide-ranging technique that could serve as a defence against Trojans is to insist that all IP be supplied with formal proofs that describe the operations it would be allowed to perform. Any changes would be flagged by formal-verification tools during design and prototyping. Such approaches could still be vulnerable to attacks that tweak designs below the abstraction of RTL. As with the cases where the NSA is understood to have sought the help of manufacturers, weakened encryption is one of the most likely ways in which a practical hardware Trojan might work and evade detection by all but side-channel analysis. And it is possible using a tiny change at manufacture according. At the 2013 International Workshop on Cryptographic Hardware and Embedded Systems, Georg Becker and colleagues from the University of Massachusetts at Amherst showed a proof of concept that simply switched dopants used for one of the transistors in an inverter within a larger AOI standard cell (see figure 1). The result would be an inverter that generated a constant output.A transistor that no longer switched might be caught by a scan test looking for stuck-at faults. But embedded in a pseudorandom number generator, the inverter’s problem could be very hard to track down. Once there, the Amherst team estimated the fault could massively reduce the entropy of the random numbers it produced, resulting in very weak cryptographic keys. In 2014, Takeshi Sugawara of Mitsubishi Electric and a team from the company and Ritsumeikan University showed such a tiny change in manufacturing could be detected after the fact. A combination of focused ion beams and scanning electron microscopy can reveal the dopants diffused into the substrate. It is an expensive proposition, involving delayering of the design and extensive analysis against a layout that contains a map of the expected dopants. However, for the kinds of high-value cryptographic IC that might be the targets of well-financed attackers, it is arguably one more in a list of checks that are readily justified. As with other areas of embedded cybersecurity, the most feasible approach to dealing with the risk of hardware Trojans is one of focusing effort. Architectures such as Trustzone pull functions that need high levels of protection into a small portion of the overall SoC. In principle, this subset is much easier to verify than a design that calls for the either chip to analysed for vulnerabilities. If the secure core is guaranteed to not leak information or provide trapdoors, the value to an attacker of putting a Trojan in the more weakly protected part of the SoC diminishes greatly. For the user of SoCs and the buyer of IP to go into them, the question then becomes one of the level of expected risk and the degree of trust they can put in staff, suppliers and contractors.

Researchers at Chalmers University of Technology, Sweden, have demonstrated an integrated amplifier with the lowest noise performance so far. The amplifier offers new possibilities for detecting the faintest electromagnetic radiation, for example from distant galaxies.Last year, Chalmers reported a world record for a low-noise amplifier in the prestigious journal Electron Device Letters. The amplifier exhibited a minimum noise figure of 0.018 dB across a bandwidth of 4-8 GHz. However, since the low-noise amplifier was designed in a hybrid solution, scaling up to larger quantities turned out to be very difficult.Chalmers has now in collaboration with a company called Low-Noise Factory published an article on an integrated ultra-low-noise amplifier. The scientists have developed a unique indium phosphide-based process for what is known as high electron mobility transistors (HEMT). Transistors and other semiconductor components have been fabricated on a monolithic chip on an indium phosphide wafer. All parts of the design such as semiconductor layers, components, process and circuit design have been optimised for the lowest noise performance.As a result, an integrated 2.0 x 0.75 mm amplifier with an ultra-low-noise figure of 0.045 dB was demonstrated. The amplifier had a very large bandwidth of 0.5-13 GHz and a high gain exceeding 38 dB across the frequency band. In order to show such extreme performance, the amplifier was cooled to minus 260 degrees of Celsius."The combination of high gain, large bandwidth and ultra-low-noise figure makes this circuit very attractive for large multipixel arrays containing thousands of antennas," says Jan Grahn, research group leader at Chalmers."The integrated ultra-low-noise process enables the fabrication of thousands of amplifiers with identical performance. One potential future application is in the world's largest radio telescope SKA (Square Kilometer Array) that is being planned, an international project where the Onsala Space Observatory at Chalmers is one of the acting members. In huge applications such as the SKA, even a small noise-figure reduction in the first low-noise amplifier in the receiver chain may potentially bring about major savings in the final system design."