【正文】 、紅外遙控信號(hào)接收器和解碼器（解碼芯片或單片機(jī)）、外圍電路等三部分構(gòu)成。因此，人們利用紅外編碼/解碼芯片及單片機(jī)設(shè)計(jì)出多種通用的紅外遙控收發(fā)系統(tǒng)，在各種設(shè)備之間進(jìn)行便捷快速的紅外信號(hào)的收發(fā)。接收器一般由接收電路、放大電路、解調(diào)電路、指令譯碼電路、驅(qū)動(dòng)電路、執(zhí)行電路等組成。1．3 紅外遙控收發(fā)器產(chǎn)品概況現(xiàn)在，紅外收發(fā)器按照工作模式和傳輸速率的不同可分為四大類：串行模式，；中速模式：；高速模式：最高速率為16Mbps。自1993年IRDA設(shè)定至今，紅外數(shù)據(jù)協(xié)會(huì)的會(huì)員已發(fā)展到了150多個(gè)，IRDA標(biāo)準(zhǔn)已經(jīng)獲得了業(yè)界的廣泛支持。由以下幾部分組成：Sharp等公司主要提供紅外發(fā)光二極管和光敏二極管；Agilent等公司主要設(shè)計(jì)制作紅外收發(fā)芯片；Infineon等公司主要從事紅外收發(fā)器封裝；IBM、Microsoft等公司則推出紅外數(shù)據(jù)收發(fā)器驅(qū)動(dòng)程序和紅外通信軟件。隨著技術(shù)的發(fā)展和成熟，傳輸方式正朝著點(diǎn)對(duì)多點(diǎn)的方向發(fā)展。從形式上看，它們之間似乎沒(méi)有關(guān)系，但如果按照他們的波長(zhǎng)依次排列，而和可見(jiàn)光相鄰的紅外線（包括遠(yuǎn)紅外線、中紅外線和近紅外線外）。紅外線是介于可見(jiàn)光和微波之間的一種電磁波，因此它具有相臨波的某些特性。只不過(guò)是溫度較高的物體輻射的紅外線較強(qiáng)，溫度低的物體輻射的紅外線較弱。由于可見(jiàn)光的最長(zhǎng)波長(zhǎng)是最短波長(zhǎng)的1倍（780nm380nm），所以也叫作一個(gè)倍頻程。由于紅外線為不可見(jiàn)光 ,因此對(duì)環(huán)境影響很小。由于紅外線遙控不具有像無(wú)線電遙控那樣穿過(guò)障礙物去控制被控制對(duì)象的能力 ,所以 ,在設(shè)計(jì)家用電器的紅外線遙控器時(shí) ,不必要像無(wú)線電遙控那樣 ,每一套(發(fā)射器和接收器)要有不同的遙控頻率或編碼(否則 ,就會(huì)隔墻控制或干擾鄰居的家用電器),所有同類產(chǎn)品的紅外線遙控器 ,可以有相同的遙控頻率或編碼 ,而不會(huì)出現(xiàn)遙控信號(hào)“串門(mén)”的情況。紅外線是不可見(jiàn)光，人眼是覺(jué)察不到的。常用的紅外發(fā)光二極管，其外形和發(fā)光二極管LED相似，它的基本工作電路如圖22所示。發(fā)射電路發(fā)射紅外線去控制相應(yīng)的受控裝置時(shí)，其控制的距離與D的發(fā)射功率成正比。減小脈沖占空比還可使小功率紅外發(fā)光二極管的發(fā)射距離大大增加。圖22紅外線發(fā)射與接收的方式有兩種，其一是直射式，其二是反射式。發(fā)射裝置把信源發(fā)出的二進(jìn)制信號(hào)經(jīng)過(guò)高頻調(diào)制后由紅外發(fā)光二極管發(fā)送出去，接收裝置把接收的紅外高頻信號(hào)由接收管接收后經(jīng)光電轉(zhuǎn)換再解調(diào)為原來(lái)信息的一種通信傳輸方式。其工作方式按發(fā)射 器 接 收器的布局不同可分為L(zhǎng)OS方式(LightofSight，直視方式)，漫射(diffuse)方式。紅外無(wú)線數(shù)字通信系統(tǒng)的工作范圍與其光發(fā)射器的光功率空間分布、通信質(zhì)量有關(guān)。在紅外無(wú)線通信系統(tǒng)中，由于光信號(hào)的反射、散射及背景光噪聲與干擾的影響等，紅外無(wú)線數(shù)字信道中存在多徑干擾及噪聲，這是提高信道質(zhì)量及進(jìn)行高速率應(yīng)用時(shí)應(yīng)解決的問(wèn)題。紅外無(wú)線數(shù)字通信系統(tǒng)接收部分包括光接收機(jī)部分及后續(xù)的采樣、濾波、判決、量化、均衡和解碼等部分。無(wú)線通信的方式有很多種，利用紅外光進(jìn)行通信具有以下特點(diǎn)： 具有良好的指向性，當(dāng)傳送設(shè)備和紅外接收端口排成直線，左右偏差不超過(guò)15度的時(shí)候，紅外裝置運(yùn)行效果最好；二進(jìn)制脈沖碼的形式有多種，其中最為常用的是PWM碼(脈沖寬度調(diào)制碼)和PPM碼(脈沖位置調(diào)制碼）。引導(dǎo)碼也叫起始碼，（不同的遙控系統(tǒng)在高低電平的寬度上有一定區(qū)別），用來(lái)標(biāo)志遙控編碼脈沖信號(hào)的開(kāi)始。為了提高抗干擾性能和降低電源消耗，將上述的遙控編碼脈沖對(duì)頻率為38KHz()的載波信號(hào)進(jìn)行脈幅調(diào)制(PAM），再經(jīng)緩沖放大后送到紅外發(fā)光管，將遙控信號(hào)發(fā)射出去。PT2262每次發(fā)射時(shí)至少發(fā)射4組字碼，PT2272只有在連續(xù)兩次檢測(cè)到相同的地址碼加數(shù)據(jù)碼才會(huì)把數(shù)據(jù)碼中的“1”驅(qū)動(dòng)相應(yīng)的數(shù)據(jù)輸出端為高電平和驅(qū)動(dòng)VT端同步為高電平。電力系統(tǒng)（或電力能源系統(tǒng)），提供電力到現(xiàn)代社會(huì)，已成為產(chǎn)業(yè)界不可缺少的組成部分。一個(gè)個(gè)類似的系統(tǒng)在世界各地大多數(shù)大城市運(yùn)行了數(shù)年。他們從發(fā)電機(jī)提供功率只有很短的距離。這是一個(gè)單相線路傳輸為4,000伏，超過(guò)21公里距離的系統(tǒng)。19世紀(jì)90年代，有很大的爭(zhēng)議在于直流或交流電力行業(yè)是否應(yīng)該統(tǒng)一。首次三相交流電線1893年投產(chǎn)于北美南加州1根 2300V，12公里長(zhǎng)的線路。最后北美的60赫茲標(biāo)準(zhǔn)獲得通過(guò)，雖然50赫茲在許多其他國(guó)家仍在使用。在中國(guó)，各級(jí)使用電壓為10，35，110級(jí)高壓，220，330（僅在西北）和500千伏超高壓類?；疽蟮诫娫聪到y(tǒng)是提供一個(gè)客戶可接受的電壓和頻率不間斷的能源供應(yīng)。電力系統(tǒng)穩(wěn)定，可廣泛定義為干擾財(cái)產(chǎn)的權(quán)力系統(tǒng)，可繼續(xù)經(jīng)營(yíng)的狀態(tài)下正常運(yùn)行的平衡條件和后向遭受恢復(fù)一個(gè)可以接受的平衡狀態(tài)。這一方面是受穩(wěn)定的發(fā)電機(jī)轉(zhuǎn)子的動(dòng)態(tài)角度和功角的關(guān)系，然后提到“轉(zhuǎn)子角穩(wěn)定”。傳統(tǒng)上，穩(wěn)定性問(wèn)題一直是一個(gè)保持同步運(yùn)行最主要的問(wèn)題。系統(tǒng)在任何階段的故障或誤操作可能導(dǎo)致給客戶的電力供應(yīng)中斷。隨著交流/直流轉(zhuǎn)換設(shè)備的發(fā)展，高壓直流（HVDC）傳輸系統(tǒng)已經(jīng)成為更具吸引力和經(jīng)濟(jì)性的特殊情況。為了避免電壓增殖數(shù)值無(wú)限，業(yè)界標(biāo)準(zhǔn)了電壓水平。有許多不同頻率在使用：25，50，60，125，和133赫茲。（2）交流發(fā)電機(jī)比直流發(fā)電機(jī)簡(jiǎn)單得多。在1888年，尼古拉特斯拉取得多項(xiàng)交流專利，包括電動(dòng)機(jī)，發(fā)電機(jī)，變壓器和輸電系統(tǒng)。如此高的電壓發(fā)電和電力消耗是可以接受的，因此，電壓轉(zhuǎn)換有一個(gè)方便的手段成為了必要。最初的直流系統(tǒng)被廣泛使用，盡管如此，他們幾乎完全被交流系統(tǒng)所取代。這是一個(gè)直流系統(tǒng)組成蒸汽發(fā)動(dòng)機(jī)驅(qū)動(dòng)的直流發(fā)電機(jī)，送給59個(gè)客戶。therefore, a convenient means for voltage transformation became a development of the transformer and AC transmission by and JD Gibbs of Paris, France, led to AC electric power 1889, the first AC transmission line in North America was put into operation in Oregon between Willamette Falls and was a singlephase line transmitting power at 4,000 V over a distance of 21 the development of polyphase systems by Nikola Tesla, the AC system became even more 1888, Tesla held several patents on AC motors, generators, transformers, and transmission bought the patents to these early inventions, and they formed the basis of the presentday AC the 1890s, there was considerable controversy over whether the electric utility industry should be standardized on DC or the turn of the century, the AC system had won out over the DC system for the following reasons:（1）Voltage levels can be easily transformed in AC systems, thusproviding the flexibility for use of different voltages for generation, transmission, and consumption.（2）AC generators are much simpler than DC generators.（3）AC motors are much simpler and cheaper than DC first threephase line in North America went into operation in 1893——a 2,300 V, 12 km line in southern the early period of AC power transmission, frequency was not poses a problem for 60 Hz was adopted as standard in North America, although 50 Hz was used in many other increasing need for transmitting large amounts of power over longer distance created an incentive to use progressively high voltage avoid the proliferation of an unlimited number of voltages, the industry has standardized voltage USA, the standards are 115, 138, 161, and 230 kV for the high voltage(HV)class, and 345, 500 and 765 kV for the extrahigh voltage(EHV) China, the voltage levels in use are 10, 35, 110 for HV class, and 220, 330(only in Northwest China)and500 line will be built in the near future in Northwest the development of the AC/DC converting equipment, high voltage DC(HVDC)transmission systems have bee more attractive and economical in special HVDC transmission can be used for transmission of large blocks of power over long distance, and providing an asynchronous link between systems where AC interconnection would be impractical because of system stability consideration or because nominal frequencies of the systems are basic requirement to a power system is to provide an uninterrupted energy supply to customers with acceptable voltages and electricity can not be massively stored under a simple and economic way, the production and consumption of electricity must be done fault or misoperation in any stages of a power system may possibly result in interruption of electricity supply to the , a normal continuous operation of the power system to provide a reliable power supply to the customers is of paramount system stability may be broadly defined as the property of a power system that enables it to remain in a state of operating equilibrium under normal operating conditions and to regain an acceptable state of equilibrium after being subjected to a disturbance..Instability in a power system may be manifested in many different ways depending on the system configuration and operating , the stability problem has been one of maintaining synchronous power systems rely on synchronous machines for generation of electrical power, a necessary condition for satisfactory system operation is that all synchronous machines remain in synchronism or, colloquially “in step”.This aspect of stability is influenced by the dynamics of generator rotor angles and powerangle relationships, and then referr