Weak current College】 【power technology glossary (1)】.

Specific term abbreviations or
The symbol definition A AC-DC suitable electronic equipment can operate on AC or DC currents.
Also: ac dc, ac/dc, ac-dcAC-DC converter AC-DC CONVERTER a AC go to DC devices, commonly referred to as offline converters, AC voltage is rectifier for DC, or include power factor correction, or other features.
Also: ac dc converters, ac/dc converter, ac-dc converter AC power good signal AC-OK SIGNAL that signal is used to indicate the 115/230Vac power input AC voltage of conduction and interrupts. Height measuring ALTITUDE TESTING aircraft or other aircraft of electronic equipment for certain functions and features. According to military standards MIL-STD-810, usually require a high level test. Environment temperature AMBIENT TEMPERATURE ambient temperature usually refers to the most relevant to the power supply still air temperature. Apparent power APPARENT POWER AC circuit power values. This power is equal to the valid values in the circuit (rms) current and valid value (rms) the product of voltage, calculate the power, regardless of the power factor. B ball grid array BALL GRID ARRAYBGA a universal standard for IC SMT attach method that is used for plate installed VI chip. Bandwidth BANDWIDTH determine a phenomenon of frequency range must be considered. Substrate BASEPLATE power module has a installation of the aluminum plate. With that the substrate temperature is the temperature of the module. The substrate should be added to the heat sink thermal surface. BELLCORE specifications of BELLCORE SPECIFICATION Bellcore communications industry standards. Bipolar Transistor TRANSISTOR using BI-POLAR minority carrier through PN principle of transistors, and voltage control devices (MOSFET), the transistor to current controller. Leakage resistance BLEEDER RESISTOR for capacitor discharge, in the circuit can access a leak resistance, in order to produce very small leakage current. Coil skeleton BOBBIN wire transformer or inductor coil brackets. The framework also allows the coil and core insulation. Multiplier converter module BOOSTER CONVERTER in drive/multiplier module composite structure, received the drive module is "charged" module. In composite structures, many multiplier module can only received a drive module. Breakdown voltage BREAKDOWN VOLTAGE in the role of the voltage, the electric insulation was destroyed, and with it creates larger leakage current, even arc light sparks. In the power system, votalge refers to the input to the output or input and output to the top of the chassis, AC or DC voltages. BRIDGE bridge converter CONVERTER bridge converter DC-DC converter's circuit structure. In power transformers at both ends of the bridge structure, with two or four only source switching devices. Bridge rectifier BRIDGE RECTIFIER diode with four bridge full-wave rectification circuit. Electricity demand is higher than BROWNOUT issued charge or distribution of electricity, in order to reduce the power consumption, power companies typically will reduce the voltage of the AC power rationing. Aging BURN-IN power products factory, in order to exclude components early failure and other potential impacts, and should normally be run under the rated load for a period of time, this process is called aging the product. Bus converter module BUS CONVERTER MODULEBCMVTM of one, with the transit bus architecture IBA applications. BCM from a pre-soundness of pressure DC sources transit bus bar voltage isolation, to the non-isolated load dian converter. BCM than traditional brick-IBCs superior. C Canada Standards Association CANADIAN STANDARDS ASSOCIATIONCSA expressly the power component of the standards and safety requirements. Capacitively coupled CAPACITIVE COUPLING between the two circuits through discrete capacitors or parasitic signal coupling capacitors. Center-tapped CENTER TAP in transformers or inductor point lead electrical connector, both ends are usually coil Center tap turns should be equivalent. C-level C-GRADE an industry standard, the c-class devices operating temperature not lower than-20 parallel C. Chassis mounting structure CHASSIS MOUNT CONFIGURATION of various modules or Exchange front-end circuit directly mounted on the chassis, called the chassis installation structure. COMMON-mode noise-MODE NOISE on the two conductors have a datum point equivalent of noise, typically refers to the AC power line and the noise of the Middle Earth. COMPAC Huai of DC input power, the power supply meets industrial and communication products for EMC filter and transient protection requirements. Constant current power SUPPLY CONSTANT-CURRENT POWER when the supply voltage, load, ambient temperature changes or output voltage change over time, the output current stable and constant power. Voltage power SUPPLY VOLTAGE CONSTANT-POWER when the supply voltage, load, ambient temperature changes or output current drift over time, the output voltage remains stable and constant power. Control circuit CONTROL CIRCUIT closed-loop system in a circuit. The circuit there is usually an error amplifier, a control system to adjust the State of the system. Converter CONVERTER using inductor and capacitor filter with high-frequency switching function, which converts the DC input voltage for different DC output voltage of the circuit.

Weak current College】 【electronic industry in English (7)】.

G tubes of grid and generator, Earth symbol
Gain-gain
Gaincontrol gain adjustment
Gainfactor gain coefficients, magnified coefficient
Game shows, games
Gang coaxial, linked in, coaxial
Galvanometerrecorder optical amplitude cassette player
Gap gap, the gap
Gapalignment gap correction
Gapdepth gap depth
Gaplength gap width
Gaploss clearance loss
Gapwidth gap width
Gate gate, gate, threshold
Gauss Gaussian
Gemshorn synthesizer of a tone
General overall, General, General
Generator generator, oscillators, generator
Give to, given
Slide the sound device glidetone
Glidingfrequency slip frequency
Glissando playing audio, slip and slide
Glockenspiel Zhong Qin
GND ground, ground
Groundgong Gong
Grade level
Gradientmicrophone pressure differential microphone
Gram grams
Gramophone record player
Graph diagrams, graphs
Graphicdisplay graphics display
Graphicequalizer graphic equalizer, graphic equalizer
Grid grid, network
Grille Grill
Grillecloth speaker cloth
Groove recording line road
Ground grounding, and (potential)
Groundbus ground straps
Groundnoise background noise, background noise
Groundpotential ground potential
Group group, group
Guard protection
Guardband (tape) protection spacing
Guide belt column, guidance for
Guitar guitar, banjo
Gunmicrophone gun microphone, strong directional microphone

【 Weak current College 】 electromagnetic spectrum (a) 】

Keywords: electromagnetic wave spectrum
Time: location: user: label type: operating frequency: standard: implementation of the company: solution providers: hardware providers:
【 Summary 】 electromagnetic spectrum (1)
Different bands of the electromagnetic wave propagation modes and features vary, their purpose is different. In the radio frequency allocation is important to note that interference problems. Because of the electromagnetic wave is characterized in accordance with their band, in addition to the spread of any law to constrain it. Therefore, if two radio stations with the same frequency (F) or extremely similar frequency and works in the same area (S), same time period (T), it will cause interference. Because modern radio frequency available range is limited and cannot be freely without order, and you want to carefully plan. So many people in foreign countries, the spectrum as the nature of a resource, make use of the frequency spectrum. A, spectrum utilization

The so-called spectrum utilization has two aspects. Namely: (1) the allocation of the frequency spectrum. Upcoming frequency depending on the business to be assigned, in order to avoid confusion in the use of frequencies; (2) spectrum savings.

From spectrum utilization point of view, since the total spectrum range is limited, each of the radio frequency spectrum shall endeavour to reduce, in order to accommodate more radio and reduce interference. This requires to compress each radio bandwidth, decrease the interval between the channel and reduce spurious emission.

Because of electromagnetic wave propagation in the world, so you will need to have an international agreement to address. Cannot be separately identified in a particular country. Therefore, to have a dedicated international meeting to discuss these and make recommendations or requirements. At the same time, due to the continuous development of science, the Division is continuously changing. Historically,on spectrum allocation of Conference have repeatedly, such as: 1906 1912, Berlin, London, Washington, 1927, 1932, Madrid, Cairo, 1938, 1947, Atlantic City and 1959 Geneva Conference.
　　　　　　　　　
Figure 1 ITU World frequency division
Figure 1 1959 Geneva meeting of the world is divided into three frequency partition map. 1 area for Europe and Africa; 2 areas for North and South America; 3 area to Asia and Australia.

ITU headquarters in Geneva, Switzerland on its Internet website at: http://www.itu.int. 2. frequency distribution of international institutions

Now for frequency assignment work by the world Organization of the International Telecommunication Union (ITU). It has: the international radio Consultative Committee (CCIR), to research-related technical issues and make recommendations; international frequency register (IFRB), responsible for the international use of the frequency of the registration management.

Consider the frequency of distribution and use is mainly based on the following points: (1) each band propagation characteristics of electromagnetic waves. (2) the characteristics of a variety of business and common requirements. Other conditions but also the history, technology development, and so on. Third, the radio business types

Following on the use of radio frequencies for business to do simple description:
(1) fixed communications business: fixed-point to communicate business.
(2) air fixed-point communications business: Air's secure flight have need of targeted traffic.
(3) broadcast service: includes sound radio and television broadcasting. Electro-voice broadcasting frequency bandwidth of 10 kHz, TV frequency bandwidth of 8 MHz (some countries for 6 MHz).
(4) mobile communications business: the mobile radio (on-board, ship-borne, airborne, etc) and land-based radio or mobile radio communication between the radio.
(5) aeronautical mobile communications business: air stations with aircraft radio communications, or communications between the aircraft.
(6) the maritime mobile communications business: in the shore-ship, or between the radio communications between ships.
(7) land-based mobile communications business: in the land mobile and base stations, or between a land mobile radiocommunication between.
(8) radio navigation business: radio navigation (including maritime and air navigation), direction, and other services. It requires a steady and uninterrupted work, and don't allow the blind spot (quiet zone).
(9) radio positioning business: generally refers to radar.
(10) space communications business: at the ground stations and space (satellite or space) or between the communication between the space station.
(11) radio astronomy business: is for radio astronomy with a business. Radio astronomy mainly observe stellar radiation of electromagnetic waves by, for example, the observation of single atoms of hydrogen of radiation (1420.405MHz) and so on.
(12) weather service: weather for radio communications, such as advertised meteorological reports, etc.
(13) the amateur radio service: abroad, there are amateur radio radio communication or research. These international is recognized, and specify the appropriate frequency.
(14) standard frequency business: send highly accurate for science and technology used standard frequency.
(15) timing signal business: the height of the advertised accurate signal timing.
(16), branch, medical frequency: in industry, science or medical often need to use high frequency current. Because their power is often very large, in order to prevent interference to communications, now also set aside certain frequency to use.
The above paragraph (11), (12), (14), (15) business is recognized should not be interfered with. Therefore, assigned to the business use of the frequency, other business should not be used, or only without disturbing conditions before use.
Radio frequency is usuallyAccording to the frequency level (i.e. the length of the wavelength) to divide the band. Band of standard does not fully consolidated, there are several slightly different partition method. Band Division usually as shown in table 1.
In addition, in the microwave band is also popular with an approach based on wavelength division band method, as shown in table 2. This Division was based on a military radar operating frequency (wavelength) confidentiality requirements, they only addressed a radar frequency bands of the work, not specifically its specific frequency. Subsequently the microwave components working frequency range and this Division has some form of hooks. Table 3 gives the microwave band new old name cross reference table. The primary information source for references:
[1] jianglin. Summary of radio wave propagation and spectrum utilization. Beijing: defense industry press, 1974
[2] Liu Yang Wang Yu-Min. automatic train identification system principles and applications-Beijing: China railway Publishing House, 2003
Edited: yangfan

College weak basic common sense】 【】 inkjet printer..

<br> <BR> one, ink cartridges, ink cartridges, print heads, ink jet print head top term is the difference between the print head, ink jet printer is the main component; ink cartridge is used to store ink, and the print head and .together are referred to as cartridge ink cartridge (Note: one is the print head and ink cartridge boxes together, and the ink runs out, replace the entire cartridge. split the print head cartridge and ink cartridge is separate from the ink just exhausted .you can replace the ink cartridge, print costs low. Second, the integration of ink cartridges and split the difference between integration refers to the part of the cartridge color inkjet printer, the head (print head) and ink cartridges made of a whole, once the ink .exhausted, we must replace the entire cartridge. <BR> such series printer CANON BC-20 (BJC - 4000), BC-22E (BJC - 4000), BC-60 (BJC - 7000), etc., HP .products are more integrated structure is used; and split cartridge is separated from the nozzle and the ink cartridges, ink is running out to use as long as the replacement ink cartridge. For example S020089 (EPSON COLOR 800), S020108 (EPSON COLOR 800) and so on. .compared with each other, the benefits of integrated structure can be easily upgraded inkjet head, sub-structure has the advantage of relatively low cost of ink cartridges. Third, the characteristics of six-color printing technology that we know the output of high quality inkjet printer than the reason .the better mid-range, one important reason is that the relationship between the color ink. The printer output image is a colorful ink of different colors mixed together, the first by the CMY (three colors), with subsequent use CMYK ( .Green, blue, red, yellow, black) four-color composition. and then later in order to further enhance the ability to control the color, on the basis of the original four-color color added to the formation of the transition of two six-color printing. HP to increase the blue and TANSEI .light magenta, LEXMARK increase the orange and green. increased after six colors, one is able to mix the 32 different colors, so as to solve the shortage of four-color printer brought the level of color are not clear and the color is not enough natural color transition .shortcomings. In addition, since the technology is the added light, so it can transfer to more types of intermediate color printing even more outstanding. four, four re-tone technique is who first used the "Four color technology" is the first to use the company CANON ., which by controlling the drop of four concentrations (the concentration of cyan and magenta are diluted by a third, half diluted black, yellow, no dilution) change, and control the print head at some point the number of ink-jet ( .divided into 0 - 3 times, that does not spray, spray once, the second spray, spray three times), to produce four types of concentration methods to show any kind of subtle color changes color, any color can be expressed in the .between a minor scratch in the progressive nature of the limitations. This is the resolution enhancement of color inkjet printer in another typical application. We know that the concentration of fine color images need to reflect the change, but the traditional .the standard way of malpractices cyan, magenta, yellow and black ink to spray 100% paper, not well reflect the concentration., and a color inkjet printer on the print media, the reasons for the requirements of more demanding .Although the color inkjet printer with a good performance / price ratio, making it win the trust of many home users. but it should be recognized that it has many shortcomings, concentrated in three areas: First, the ink-jet printer .using a water-based ink, and therefore determines its specificity, in addition to the performance of the ink to the output quality, the print media used (paper) is also a great relationship. If the print media choice is not good, the ink jet to the media .will be saturated after, thus affecting the brightness of the color and clarity, so that the output of reach good results. Experimental results show that the vast majority of inkjet printers, the use of plain paper, even if the chosen mode of 720dpi * 720dpi inkjet .to print, or special paper 360dpi * 360dpi, and the effect is good. Even with an ordinary paper, different brands and even different batches of the same brand of paper, prints may have a larger difference. This is why high-end color inkjet printer .The main reason for special paper is more expensive, remember, 720dpi resolution and above, only changes in the special paper to achieve the "photo" class effect. This technological breakthrough of the past, simply use the resolution of the printer means to increase the print product .to get the best results. <BR>.

【 Weak current College 】 Protel software in high frequency circuit wiring skills 】

Digital devices is moving in a high-speed, low power, small size, high anti-interference, this trend on the printed circuit board design made a lot of new requirements. Protel software application in China has been quite common, however, many designers only concern to Protel software's "Chief pass rate", Protel software to adapt to device characteristics changes do improved did not used to design, which not only makes the software more serious waste of resources, but also makes a lot of new devices with superior performance is difficult to play. This article is intended to be used in high-frequency circuit wiring general introduction on request, to Protel for Windows V1.5 software as an example to introduce the high-frequency circuit wiring Protel software can provide some special measures.
(1) high frequency circuit is often integrated high wiring density, multilayer PCB is both a necessary wiring is also an effective means to reduce interference. Protel for Windows V1.5 provides 16 copper layers and four power layer, selecting layers can significantly reduce the size of plates, can take full advantage of the middle tier to set a mask that can better achieve the nearest grounding, can effectively reduce parasitic inductance, can effectively reduce signal transmission length can significantly reduce the signal crosstalk and so on, all of which are on the high-frequency circuit of reliable work. Have the same kind of material, the four-storey plate than the dual panel of low noise 20dB.　　However, the higher the lamellar several more complex manufacturing process, the higher the cost. (2) high-speed circuit device PIN bending of the leader among the less the better. High-frequency circuit wiring of leader best full line, you need to turn the available 45 degree line or arc turn, such requirements in the low-frequency circuit is only used to improve the steel foil fixing strength, high frequency circuit, meet this requirement but can reduce the emission of high-frequency signal external and mutual coupling.　　With Protel wiring is available in the following two pre-set, one is in the "Options" menu's "Track Mode" submenu of the booking to 45/90 90 Line or Arc/Line way wiring, the second is in the "Auto" in the menu "Setup" the Autorouter ... open Routing Passes "dialog box, select the" Add Arcs ", so that the automatic routing ends so that the angle of an arc. (3) high frequency circuit device PIN of the leader as short as possible. Protel meet minimum cabling is the most effective means is in auto City line before the individual focus on high speed networks for the "wiring" by appointment only. First, open the "Netlst" menu's "Net" submenu of the Edit, a "Net" dialog box, Change the dialog "OptimizeMethod (routing optimization mode)" selected as the "Shortest (minimum) to Rp."　 Secondly, from the overall consideration, component layout in "Auto" and the "Placement Tools-Shove" Auto "in the" Density (density check) "to contrast adjust elements arranged in a compact and" Netlist "menu 's" Length "and" Info "menu selection" function, Lengthof on selected required minimum focus network wiring length measurement. (4) high frequency circuit device PIN leader among alternative less between layers, the better. The so-called "leader of alternating between the less the better" refers to the component during the connection process with through-hole (Via), the fewer the better, according to a survey, a hole can bring about 0.5 pF capacitance, reducing the hole number can significantly increase the speed. Protel software designed specifically to provide this functionality, it Auto menu Setup the Autorouter ... "to open the Routing dialog Passes", a "Advanced" section, the "Smoothing" is set to on. (5) high frequency circuit wiring to note that the signal cable close parallel alignment introduced "crosstalk", where it is not possible to avoid parallel distribution, parallel signal line reverse layout to "large" to substantially reduce interference. The same level of parallel alignment is almost impossible to avoid, but in the adjacent two-layer, the alignment of the direction must be taken as mutually perpendicular, this is not difficult to Protel but easily overlooked. In "Auto" in the menu "Setup Autorouter ... The open dialog box that allows Routing Lagers on each layer alignment direction intended for preselection of orientation: Horizontal, Vertical and "No", many users Prefer-ence accustomed choose "No Preference (no specific orientation)", is of the opinion that such a high rate of Chief Administrator, however, in the high-frequency circuit wiring in best in adjacent layers respectively take alternating horizontal and vertical layout. The same level of parallel alignment cannot be avoided, but you can reverse the plates to reduce the large area laying ground wire interference (this is a commonly used double panel, multi-layer boards can use intermediate power layer to achieve that functionality), Protel software only provides a simple "Fill" feature to meet this demand, now Windows of Protel addition also in the "Edit" menu of "Place" option offers higher placement Plane "Polygon", namely: polygon rasterization (MAL) copper foil surface, if you place it on the polygon with the entire surface of a plate, and the grid (bars) and GND circuit of network connectivity, then the feature will be able to achieve a monolithic circuit board side of the "shop copper", after "shop copper circuit board in addition to" improve mentioned high anti-interference ability, but also on the thermal, plate strength can benefit you, also, in the circuit board fixed metal chassis Department if the Tin bar, not only can enhance the strength, security contact fixed, can use the metal chassis constitute appropriate publicCollinear. In the software menu open the feature is visible to a "Place Polygon Plane dialog box, it will ask you whether you want to take the place of polygon rasterization (bars) and network connected (connect net), connected item, exit the dialog box will prompt you for the network name to connect to the given power GND network will be able to play the role of shielding layer. At the same time also will ask you "shop copper" pattern is a horizontal bar (horizonta), a vertical bar (vertica) or grid (both).　 Choose the grid will have better shield effect, at the same time, the size of the grid network (referred to as the "eye habits") determines the basis to focus on shielding disturbance frequency. (6) on particularly important signal line or local unit implement ground surrounded by measures. The measures in Protel software can automatically, it is the "Edit" menu of "Place" under the "Outline Select-ed Items" that is: draw the selected object in the outer contour line.　 With this feature, you can automatically on the selected important signal cable to the so-called "package" deal, of course, this feature is used to clock and other units to handle partial to pack on the high-speed system will also be very useful. (7) various signal alignment could not form loops, ground cannot form the current loop. Protel autorouting alignment principles in addition to the previously mentioned minimum principles, based on the X direction, based on the y direction and Daisy-shaped (daisy) alignment, use the Daisy-shaped alignment can effectively avoid the formation of loops while routing.　 Specific to open ' Netlist "menu 's" Net "submenu of the Edit, a" Net "dialog box, Change the dialog" Optimize Method (routing optimization mode) "selected as a" Daisy Chain ". (8) each IC blocks high-frequency should be set up near a decoupling capacitor.　 As Protel software to automatically place the component does not consider the decoupling capacitor and the decoupling of the relationship between the location of integrated circuits, software, so that they are too far decoupling effect compromised, then you must manually move the symbol ("Edit" and "Move" and "component") means the prior intervention both location, close to. (9) analog ground, digital ground, etc., to the common ground for HF choke points. In the actual Assembly HF choke link is often used when the center hole to wear with wires in high frequency ferrite beads, circuit diagram no expression to it in General, thus forming a network table (netlist) do not contain such elements, wiring will be ignored. In response to this reality, but in principle diagram as inductance, the PCB component library separately for it to define a component package, wiring before it manually moved to the join point near the public ground of suitable location.

【 Weak current College 】 electromagnetic compatibility EMC shielding technology analysis 】

Electric, magnetic, electromagnetic shielding is different!
Magnetic field of the shield, is a meaningful and theoretical implications of the problem according to conditions, electromagnetic shielding can be divided into static and static magnetic shielding and shield three scenarios, each of these three situations both qualitative distinction, and intrinsically linked, you cannot mix. electrostatic shield in static equilibrium State, whether they are hollow conductor or solid conductor; no matter how many live conductor itself, or conductor is in the external field, will provide equipotential body, its internal field is zero, this is the theoretical basis of electrostatic shield, because closed conductor electric field inside the shell has a typical meaning and relevance, we closed conductor electric field inside the shell, for example on electrostatic shield for some discussion. (A) closed conductor shell internal electric field is not supported by shell, electric charge or affect no as shell and shell charged body outside the charge q, then the static induction make shell wall when charged. static balance without electric field inside the shell-this is not to say that the charge is not in the outside Shell Shell within the farm, root power field. due to the shell wall induction out charge, their different signs and q in the shell internal space at any point to fire-field strength to zero. Thus the internal conductor shell will not be affected by shell charge q or other electric field in the outer shell-induced charge up the automatic adjustment function. If the grounding conductor shell, the shell will be along on the induction of positive charge into the underground Earth wire. electrostatic conductor after balance with the Earth, and other potential intensity still inside the cavity to zero if there is a charge cavity, the cavity and the ground conductor still equipotential, conductor without electric field due to the cavity wall now-have induced chargedifferent signs, the cavity with the electric field by the electric field. shell, shell within charge arising out of the electric charge on the shell is not affected by the above discussion shows, closed conductor shell or not, regardless of the ground is not affected by the electric field inside the shell, the effect of electric charge. (二)接地封闭导体壳外部电场不受壳内电荷的影响.如果壳内空腔有电荷q,因为静电感应,壳内壁带有等量异号电荷,壳外壁带有等量同号电荷,壳外空间有电场存在,此电场可以说是由壳内电荷q间接产生.也可以说是由壳外感应电荷直接产生的.但如果将外壳接地,则壳外电荷将消失,壳内电荷q与内壁感应电荷在壳外产生电场为零.可见如果要使壳内电荷对壳外电场无影响,必须将外壳接地.这与第一种情况不同.这里还须注意:①我们说接地将消除壳外电荷,但并不是说在任何情况壳外壁都一定不带电.假如壳外有带电体,则壳外壁仍可能带电,而不论壳内是否有电荷.②实际应用中金属外壳不必严格完全封闭,用金属网罩代替金属壳体也可达到类似的静电屏蔽效果,虽然这种屏蔽并不是完全、彻底的.③在静电平衡时,接地线中是无电荷流动的,但是如果被屏蔽的壳内的电荷随时间变化,或者是壳外附近带电体的电荷随时间而变化,就会使接地线中有电流.屏蔽罩也可能出现剩余电荷,这时屏蔽作用又将是不完全和不彻底的.总之,封闭导体壳不论接地与否,内部电场不受壳外电荷与电场影响;接地封闭导体壳外电场不受壳内电荷的影响.这种现象,叫静电屏蔽.静电屏蔽有两方面的意义:其一是实际意义:屏蔽使金属导体壳内的仪器或工作环境不受外部电场影响,也不对外部电场产生影响.有些电子器件或测量设备为了免除干扰,都要实行静电屏蔽,如室内高压设备罩上接地的金属罩或较密的金属网罩,电子管用金属管壳.又如作全波整流或桥式整流的电源变压器,在初级绕组和次级绕组之间包上金属薄片或绕上一层漆包线并使之接地,达到屏蔽作用.在高压带电作业中,工人穿上用金属丝或导电纤维织成的均压服,可以对人体起屏蔽保护作用.在静电实验中,因地球附近存在着大约100V/m的竖直电场.要排除这个电场对电子的作用,研究电子只在重力作用下的运动,则必须有eE<meg,可算出E<10-10V/m,这是一个几乎没有静电场的“静电真空”,这只有对抽成真空的空腔进行静电屏蔽才能实现.事实上,由一个封闭导体空腔实现的静电屏蔽是非常有效的.其二是理论意义:间接验证库仑定律.高斯定理可以从库仑定律推导出来的,如果库仑定律中的平方反比指数不等于2就得不出高斯定理.反之,如果证明了高斯定理,就证明库仑定律的正确性.根据高斯定理,绝缘金属球壳内部的场强应为零,这也是静电屏蔽的结论.若用仪器对屏蔽壳内带电与否进行检测,根据测量结果进行分析就可判定高斯定理的正确性,也就验证了库仑定律的正确性.最近的实验结果是威廉斯等人于1971年完成的,指出在式F=q1q2/r2±δ中,δ<(2.7±3.1)×10-16,可见在现阶段所能达到的实验精度内,库仑定律的平方反比关系是严格成立的.从实际应用的观点看,我们可以认为它是正确的.静磁屏蔽静磁场是稳恒电流或永久磁体产生的磁场.静磁屏蔽是利用高磁导率μ的铁磁材料做成屏蔽罩以屏蔽外磁场.它与静电屏蔽作用类似而又有不同.静磁屏蔽的原理可以用磁路的概念来说明.如将铁磁材料做成截面如图7的回路,则在外磁场中,绝大部份磁场集中在铁磁回路中.这可以把铁磁材料与空腔中的空气作为并联磁路来分析.因为铁磁材料的磁导率比空气的磁导率要大几千倍,所以空腔的磁阻比铁磁材料的磁阻大得多,外磁场的磁感应线的绝大部份将沿着铁磁材料壁内通过,而进入空腔的磁通量极少.这样,被铁磁材料屏蔽的空腔就基本上没有外磁场,从而达到静磁屏蔽的目的.材料的磁导率愈高,筒壁愈厚,屏蔽效果就愈显著.因常用磁导率高的铁磁材料如软铁、硅钢、坡莫合金做屏蔽层,故静磁屏蔽又叫铁磁屏蔽.静磁屏蔽在电子器件中有着广泛的应用.例如变压器或其他线圈产生的漏磁通会对电子的运动产生作用,影响示波管或显像管中电子束的聚焦.为了提高仪器或产品的质量,必须将产生漏磁通的部件实行静磁屏蔽.在手表中,在机芯外罩以软铁薄壳就可以起防磁作用.前面指出,静电屏蔽的效果是非常好的.这是因为金属导体的电导率要比空气的电导率大十几个数量级,而铁磁物质与空气的磁导率的差别只有几个数量级,通常约大几千倍.所以静磁屏蔽总有些漏磁.为了达到更好的屏蔽效果,可采用多层屏蔽,把漏进空腔里的残余磁通量一次次地屏蔽掉.所以效果良好的磁屏蔽一般都比较笨重.但是,如果要制造绝对的“静磁真空”,则可以利用超导体的迈斯纳效应.即将一块超导体放在外磁场中,其体内的磁感应强度B永远为零.超导体是完全抗磁体,具有最理想的静磁屏蔽效果,但目前还不能普遍应用.电磁屏蔽电磁场在导电介质中传播时,其场量(E和H)的振幅随距离的增加而按指数规律衰减.从能量的观点看,电磁波在导电介质中传播时有能量损耗,因此,表现为场量振幅的减小.导体表面的场量最大,愈深入导体内部,场量愈小.这种现象也称为趋肤效应.利用趋肤效应可以阻止高频电磁波透入良导体而作成电磁屏蔽装置.它比静电、静磁屏蔽更具有普遍意义.电磁屏蔽是抑制干扰,增强设备的可靠性及提高产品质量的有效手段.合理地使用电磁屏蔽,可以抑制外来高频电磁波的干扰,也可以避免作为干扰源去影响其他设备.如在收音机中,用空芯铝壳罩在线圈外面,使它不受外界时变场的干扰从而避免杂音.音频馈线用屏蔽线也是这个道理.示波管用铁皮包着,也是为了使杂散电磁场不影响电子射线的扫描.在金属屏蔽壳内部的元件或设备所产生的高频电磁波也透不出金属壳而不致影响外部设备.用什么材料作电磁屏蔽呢?因电磁波在良导体中衰减很快,把由导体表面衰减到表面值的1/e(约36.8%)处的厚度称为趋肤厚度(又称透入深度),用d表示,有电磁屏蔽 ,电磁场在导电介质中传播时,其场量(E和H)的振幅随距离的增加而按指数规律衰减.从能量的观点看,电磁波在导电介质中传播时有能量损耗,因此,表现为场量振幅的减小.导体表面的场量最大,愈深入导体内部,场量愈小.这种现象也称为趋肤效应.利用趋肤效应可以阻止高频电磁波透入良导体而作成电磁屏蔽装置.它比静电、静磁屏蔽更具有普遍意义.电磁屏蔽是抑制干扰,增强设备的可靠性及提高产品质量的有效手段.合理地使用电磁屏蔽,可以抑制外来高频电磁波的干扰,也可以避免作为干扰源去影响其他设备.如在收音机中,用空芯铝壳罩在线圈外面,使它不受外界时变场的干扰从而避免杂音.音频馈线用屏蔽线也是这个道理.示波管用铁皮包着,也是为了使杂散电磁场不影响电子射线的扫描.在金属屏蔽壳内部的元件或设备所产生的高频电磁波也透不出金属壳而不致影响外部设备.用什么材料作电磁屏蔽呢?因电磁波在良导体中衰减很快,把由导体表面衰减到表面值的1/e(约36.8%)处的厚度称为趋肤厚度(又称透入深度),用d表示,有其中μ和σ分别为屏蔽材料的磁导率和电导率.若电视频率f=100 MHz,对铜导体(σ=5.8×107/ ?m,μ≈μo＝4π×10-7H/m)可求出d=0．00667mm.可见良导体的电磁屏蔽效果显著.如果是铁(σ＝107/ ?m)则d=0.016mm.如果是铝(σ＝3.54×107/ ?m)则d＝0.0085mm.为了得到有效的屏蔽作用,屏蔽层的厚度必须接近于屏蔽物质内部的电磁波波长(λ=2πd).如在收音机中,若f＝500kHz,则在铜中d＝0.094mm(λ=0.59mm).在铝中d＝0.12mm(λ=0.75mm ).所以在收音机中用较薄的铜或铝材料已能得到良好的屏蔽效果.因为电视频率更高,透入深度更小些,所需屏蔽层厚度可更薄些,如果考虑机械强度,要有必要的厚度.在高频时,由于铁磁材料的磁滞损耗和涡流损失较大,从而造成谐振电路品质因素Q值的下降,故一般不采用高磁导率的磁屏蔽,而采用高电导率的材料做电磁屏蔽.在电磁材料中,因趋肤电流是涡电流,故电磁屏蔽又叫涡流屏蔽.在工频(50Hz)时,铜中的d＝9.45mm,铝中的d＝11.67mm.显然,采用铜、铝已很不适宜了,如用铁,则d＝0.172mm,这时应采用铁磁材料.因为在铁磁材料中电磁场衰减比铜、铝中大得多.又因是低频,无需考虑Q值问题.可见,在低频情况下,电磁屏蔽就转化为静磁屏蔽.电磁屏蔽和静电屏蔽有相同点也有不同点.相同点是都应用高电导率的金属材料来制作;不同点是静电屏蔽只能消除电容耦合,防止静电感应,屏蔽必须接地.而电磁屏蔽是使电磁场只能透入屏蔽体一薄层,借涡流消除电磁场的干扰,这种屏蔽体可不接地.但因用作电磁屏蔽的导体增加了静电耦合,因This even if only for electromagnetic shielding and grounding as well or better, this electromagnetic shielding also play the role. In conclusion, electrostatic shield electrostatic shielding and static magnetic shielding, electromagnetic shielding physical content, physical condition, shielding effect is different, the material has to start from the specific circumstances, but they are all screened electromagnetic fields, there is a nature links.

【 Weak current College 】 Stadium Sports race timing and scoring system overview 】

1 Overview

Timing points system is the one responsible for various sports competitions technology support system front (venue) of the data collection and distribution of proprietary systems, it is responsible for all types of sports competition results and achievements in information acquisition and processing, transport, distribution, competition results data through dedicated technical interface (interface, Protocol) are transmitted to the referee, coach, computer information systems, TV and comment system, live large-screen display system, etc.

Due to the non-repetitive sports contests, determines the timing of score system is a real-time performance very strong, very high reliability requirements for computer technology as the core of the e-service system. Therefore, the timing points system itself is composed of separate collection, allocation, evaluation, displaying, publishing system, so that all information in real-time, accurate, fast and authoritative.
Timing device is the score sports competition in electronic equipment, timing points system design is reasonable, relationship to the entire sports system runs stable and reliable, and directly affect the entire sports games smoothly.

Timing points system is the sport competitions of important projects, is the key to success or failure of the contest, each individual sports competitions have corresponding specialized timing and scoring systems. These systems vary, but are individual results processing system-level data collection systems, in addition to providing computer performance processing system race data, you need to connect in some of the projects and other work on TV, the timing system is extremely high score required stability and reliability of work.

Our timing points system implementation, ultimately must be reported to the Director of the related project management Center for final confirmation, coordination on specific project timing equipment and field results score for dealing with the relationship between the interface and the timing of implementation of score system engineering technical supervision.

2 characteristics of timing points system:

2.1 unified planning and centralized management

Timing points information system is a large, functional requirements strictly, an extensive response to the various departments of systems engineering. The system of information exchange frequent, data-processing complex subsystems and no uniform technical standards, therefore, the internal interface of the variety and occupy a considerable amount of system development. Must achieve the unified planning, centralized management, the technical force and decentralized funds, reduce unnecessary multiport coordination and technical overlap and ensure an efficient and reliable system.

As a sports contest is a non-recurring special industry activity, at the same time, the quality of the information project depends on the construction site by the project characteristics, comprehensive understanding of the depth of understanding. Therefore, in a contract project should first choose to sporting competition, large games have a deep understanding and made appropriate engineering units of the company and to implement in order to effectively guarantee the investment and the system has high adaptability and reliability in order to obtain a higher success rate.

2.2 pipe room reservation

Comprehensive sports information system is based on electronic technology, computer technology and communication technology as the core of highly automated and efficient sports race information service system, is a large-scale comprehensive sports organizations in the management of an important component of host city or area specific embodiment of comprehensive strength. At the same time also is complex, a huge project, the system has a broad, branch number, more frequent cross-modify, adapt, long construction period.

The venue construction period, should be reserved for scoring engine, radio and TV combined zones; be integrated information management system, display the control room, swimming pool, jumping, competition venues, arbitration recording system of pipe channel.

In the stadium field should be set to several signal well, connecting pipeline and corresponding power supply;

Diving in swimming pool play and end camera settings pipeline reserved;

Set timings in the spectacular venues reserved score pipeline;

In the gym area around set several information outlets and timed scoring pipeline is reserved.
3 timing points system main features

Timing points system is based on competition rules on competition in performance information collection, data processing, monitoring, quantitative processing, display published work process, timing and recording (on), measurement, display, transmission components, the system should meet the following features:

1), the composition of the system must meet the functional and rational, constitute a rigorous programme.

2), the system should have good user interface and system connection interface, and a backup security measures.

3), the system immediately and accurately complete event information collection, processing and delivery, to preserve the original performance data.

4), requires most of the events on the arranging using automated systems, reducing manual intervention.

5), the system should have completed a variety of events, onsite competition results or results information display.

6), the system should have the venue display, live scores, TV standard interface capabilities.

7), the system should have the contest scene environment conditions of adaptive capacity, and to other system provides timing points system-allocated transmission capacity of performance information

Each campaign item corresponds with a specific timing and scoring system, and each has a different content and technology, timing points system is composed of a variety of technical equipment and a specialized line press sports features organized, for the good timing points system operation, you must first ensure that every work of system the complete basic functionality. In order to guarantee the consistency and test scores, you typically use individual impartiality Association specify products, timing points system is the sport competitions, sporting achievements of ultimate sources, from the use of perspective, is the point to multipoint, different systems of information, the need to develop a different adapter interface, and complete and field results processing subsystem onAdd-in.

4 timing principles of construction of score system

Timing points is a sports contest is an indispensable part, is on the competition process time determination or cumulative, score is on the runner's motion behavior and environment for determination, warnings and score accumulated records, final complete control of the contest procedure, provide a comparison of quantitative evaluation of the results, will result in the configuration of the monitor is a real-time display. At the same time, provide to the relevant system needs of race information.

Timing points system in principle:

1), timing devices by individual score competition authority according to the requirements for the preparation of the competition, and must ensure that the individual timing points system integrity and comply with the requirements of the latest contest rules.

2), scoring device must use the project management center of sport and Sports Association finds products, timing device adopts international sports organizations recognized by the device.

3), in order to save investment, taking into account the established after the equipment and usage, display device to use dot-matrix display, consider configuring the corresponding multiple display software.

4), live timing and scoring device must have a computer communication data interface for data information automatically, high-speed processing and publication of the results of the competition.

5), system, device installation, commissioning and operation of the equipment supplier and professionally trained and participated in many major sports events in rich practical experience of personnel.

Each time the scoring system is appropriate for each campaign item and equipped, but also to meet domestic and international sports organizations to individual requirements, ensuring the success of a sports contest.
5 time points system composition and classification:

Individual match scoring system of timing are according to the rules of the technical requirements established for the project. At the same time in the scene during the race scoring systems are subject to the fair in the individual competition Committee of dispatch, not arbitrary action.

System composition and equipment classified as:

1) electronic timing devices

2) scoring equipment

3) electronic measuring equipment

4) e-referee equipment

5) e prompt equipment

6) technical interface equipment

Electronic timing system equipment in specialized on time data determination, cumulative or processing, precision high, accuracy should be up to 1/1000 second, electronic timing system can be divided into time slots to control timing and speed of determination of the timing of two categories:

Window control timing: for time-limited game project exercise time control, General requirements are set with the length of time, reset, interrupt, recovery time and alarm
Speed measurement timing: the racing game project to automate the movement of time measurement, comparison, ordering, and other functions.

Electronic scoring system is in accordance with the rules of the game on the runner's motion behavior and its environmental factors for determination, warnings and score a cumulative record and, ultimately, complete control of the competition process, to quantify results data, will result in the configuration of the monitor to display real time accurately. Transmitted to the relevant parts of the game information.

Electronic measurement systems and equipment requirements for height, distance, wind speed, wind direction and other competition environment factors for precise measurements, in order to provide a variety of data and finally verify results.

E ref device (device) is the use of modern advanced high-tech means making, as the race referee services integrated electronic information systems. Mainly used in fierce competition, winning moment, depending on how big the game project. With fast and accurate minimize the interference of the human factor.

E Tip equipment in the game as players provide sound, light, signal, in order to remind the game progresses.

Technical interface device is timed scoring system for all kinds of different devices and games technology supports various subsystems to signal data exchange interface matching device. For the race information on different devices and Interworking between the subsystem and accurate reading, it is essential to source information (data, signal, and so on) to transform processing, in order to achieve timing equipment and various subsystems of score between the technically meet the match, the match score data signal transfer smooth clear, accurate and real time.

According to the different events match the characteristics of their own, different items on the timing of the different requirements of score, to categorize the various events, in accordance with the different categories, timing points system can be divided into the following categories:

5.1 online project

Online project is to follow through the end of the chronological order as the main criterion to determine the player's game ranking, most such projects is one of the highlights of the games.

Online project: Athletics (track), swimming, cycling, rowing, kayaking, slalom, speed racing, equestrian (handicap), speed skating, short track speed skating, etc.
Online project timing points system is mainly responsible for collecting race time information, because the game is highly competitive, and some of the projects of timing precision score required to achieve 1/1000 second, not the naked eye or general timing equipment to complete the score, while at the same time, the timed scoring system will match results quickly sent to score processing, on-site show, TV broadcast system, system calling time is high, it can be done manually. Sports competitions of the accuracy, timeliness, and non-repeatability in such projects reflect the most prominent. Therefore, the requirements for online project timing scoring system with very high accuracy, stability, reliability, absolute and highly automated, key equipment should be in the form of the backup.
5.2, categories item

Categories of the contest is a project of referee on the player's game performanceEvaluation and scoring of the form, all the judges scoring statistics, as players rank in the major standards.

On the basis of the categories are: gymnastics, rhythmic gymnastics, trampoline, diving, synchronized swimming, martial arts (taolu) equestrian (dressage), figure skating, etc.

Comment on the classification of the timing of the project is to improve the referee score system efficiency an important guarantee for such a large amount of data, score calculation complex, in the course of the game, part of the emergency change games will have more games at the same time, the timed scoring system must be in a very short time accurately completed competition result records, statistics, computing, and at the same time, the timing system will score results promptly sent to the scene shows, television, and other peripheral systems, time is very high, not artificial. Sports competitions of the accuracy, timeliness, variability in these projects reflect the extremely prominent, therefore, requested categories project timing points system must have a high accuracy, high reliability, high adaptability, highly automated features.

5.3, ring and note the category project

Note the classification project is through acquisition or statistics ' distance, height, number of rings, conversion of grading information, scores for processing statistics, as players game ranking of the main criteria.

Note the classification project: shooting, archery, athletics (Tin), modern pentathlon, sailing, windsurfing, weight lifting, etc.

Note the classification project timing points system is mainly responsible for record players in the game during the game scores, game scores quickly sent to score processing, show, TV broadcast, and other systems. Some items, such as shooting, track and field (the field events), archery, etc., the use of electronic devices to replace the artificial competition result records, recording accuracy even reach dozens microns, the equipment requires extremely high, another part of the project, such as weight lifting, modern pentathlon, timing points system also requires an approval role, timely boot process, making the game competition. Sports competitions of the accuracy, timeliness, non-repetitive in such projects reflect the extremely prominent, therefore, wish to categorize the project's time scoring system must have a high accuracy, high reliability, high adaptability, highly automated features.

5.4, contest, class projects

The match against the type of project is generally by team or two players to complete, to the relationship between the two sides in the competitions, as players rank in the major standards. Confrontation is comprehensive games category in the categories up for a class project, its characteristics are directly involved in the fight against the two projects, most of the results of the competition you can judge for themselves the audience.

Against such projects include: wrestling, judo, taekwondo, boxing, martial arts, boxing, fencing, football, basketball, volleyball, beach volleyball, handball, water polo, baseball, softball, hockey, tennis, badminton, table tennis, etc.

According to the results obtained on how it is done, you can also form a broken down into scoring against class project forms of confrontation and score. Scoring form against the types of projects include: wrestling, judo, taekwondo, boxing, martial arts and boxing, such a project score diversity, the need for specific judging by the referees, the score form against the types of projects include: fencing, football, basketball, volleyball, beach volleyball, handball, water polo, baseball, softball, hockey, tennis, badminton, table tennis, etc., this type of project score simple and intuitive, the audience will be able to direct the results of the competition.
Confrontation of timing points system, is by displaying the way secondary to the competition, while at the same time as the site displays the system and TV broadcast system to provide services, such a device generally require long hours of continuous use, so you need to have a high reliability and stability.

The scoring system FBI 6 timing and practiced kg

Timing points system construction, particularly in software projects, because the needs are complex and professional, so the success rate for single use run is very low, to reach the normal use of athletic competition, must go through many levels of repeated debugging, full system test and hop gained even more important. Including:

6.1 network test

Internal network debugging. To venues network center room as the core for debugging network system connectivity, Omni-directional debugging backbone network, local network, the complexes network and the specific information of network connectivity, and test your network performance, especially network system reliability and security.

6.2 system test

System integration must be in network connectivity and a variety of computer equipment in place on the basis of the system is network and application testing and debugging the service system, the system of joint technical content widely and work coordination capacity, you need to make multiple debugging.

System test to contest information system as the core, individual site performance handling systems plan selection of representative projects, analog layout results and performance, simulation requirements cover contest. Comprehensive results processing system simulation statistics medals and total score, and provides internet network.

6.3 system-in-training

To race for the core, the relevant sector facilitate commissioning. -Practice must all connected network, computer equipment and devices in place, the timing and scoring information systems test conducted on the basis of success.

System-in-training in the race Department of unified arrangement, individual competition authority in competition centers organizations athletes, according to the tournament regulations for part of the project of simulation games, scoring system and live timing results processing system combined with race organization and management of work, become familiar with the race field work processes, in order to participate in official competitions and laid the basis for running.

7. closing remarks

Timing points system is held in the stadium events enable basic technical facilities. According to the organising different events and venues, the use of timed scoring equipment are also different, specific programmes should be according to theMesh contest rules and game action requires design. System is reliable and accurate results for athletes, and related information in a timely manner by the big-screen device displayed, so the presence of guests, the judges and the audience will be able to keep abreast of the latest game information.