The first practical examples of mobile communications were used in many countries like the USA, the UK and Germany in military services, and played a significant role in the First World War to transfer important information from the front to headquarters to take further actions. Good and secure wireless communications were an important need for all military services – army, navy and air force. In this respect, the Second World War was a big experimental battlefield for the development and evolution of mobile radio. It was in the interests of governments that after the Second World War the military investment should be paid Back by civilian use, and all western European countries started their so-called first generation of mobile communication networks.
標(biāo)簽： Multimedia Business Mobile The
上傳時間： 2020-06-01
上傳用戶：shancjb
Although the origins of radio frequency based wireless networking can be traced Back to the University of Hawaii’s ALOHANET research project in the 1970s, the key events that led to wireless networking becoming one of the fastest growing technologies of the early 21st century have been the ratification of the IEEE 802.11 standard in 1997, and the subsequent development of interoperability certification by the Wi-Fi Alliance (formerly WECA).
標(biāo)簽： Networking Technology Wireless
上傳時間： 2020-06-01
上傳用戶：shancjb
It has been said that the move from narrowband to broadband access is the second revolution for the Internet — ‘broadband is more bandwidth than you can use’. Once users have experienced broadband access there is no turning Back. A whole new world of applications and services becomes possible. No longer is it the ‘world- wide wait’. The speed of response and visual quality enabled by broadband finally allows the Internet to reach its true potential.
上傳時間： 2020-06-06
上傳用戶：shancjb
December 2007, San Jose, California: It seems a long time ago. I walked into a big networking company to head their small Power over Ethernet (PoE) applications team. Surprisingly, I hardly knew anything about PoE prior to that day, having been a switching-power conversion engineer almost all my life. But it seemed a great opportunity to widen my horizons. As you can see, one notable outcome of that seemingly illogical career choice five years ago is the book you hold in your hands today. I hope this small body of work goes on to prove worthy of your expectations and also of all the effort that went into it. Because, behind the scenes, there is a rather interesting story to relate—about its Backdrop, intertwined with a small slice of modern PoE history, punctuated by a rather res- tive search for our roots and our true heroes, one that takes us Back almost two centuries
上傳時間： 2020-06-07
上傳用戶：shancjb
RFID (radio-frequency identification) is the use of a wireless non-contact system that uses radio-frequencyelectromagnetic fields to transfer datafrom a tag attached to an object, for the purposes of automatic identification and tracking [38]. The basic technologies for RFID have been around for a long time. Its root can be traced Back to an espionage device designed in 1945 by Leon Theremin of the Soviet Union,whichretransmittedincidentradiowaves modulatedwith audioinformation. After decades of development, RFID systems have gain more and more attention from both the research community and the industry.
標(biāo)簽： Infrastructure RFID as an
上傳時間： 2020-06-08
上傳用戶：shancjb
We are in the era of ubiquitous computing in which the use and development of Radio Frequency Iden- tification (RFID) is becoming more widespread. RFID systems have three main components: readers, tags, and database. An RFID tag is composed of a small microchip, limited logical functionality, and an antenna. Most common tags are passive and harvest energy from a nearby RFID reader. This energy is used both to energize the chip and send the answer Back to the reader request. The tag provides a unique identifier (or an anonymized version of that), which allows the unequivocal identification of the tag holder (i.e. person, animal, or items).
標(biāo)簽： Identification Wireless
上傳時間： 2020-06-08
上傳用戶：shancjb
I can remember buying my first electronic calculator. I was teaching a graduate level statistics course and I had to have a calculator with a square root function. Back in the late 1960s, that was a pretty high-end requirement for a calculator. I managed to purchase one at the “educational discount price” of $149.95! Now, I look down at my desk at an ATmega2560 that is half the size for less than a quarter of the cost and think of all the possibilities built into that piece of hardware. I am amazed by what has happened to everything from toasters to car engines. Who-da-thunk-it 40 years ago?
標(biāo)簽： Beginning Arduino for
上傳時間： 2020-06-09
上傳用戶：shancjb
Inventors have long dreamed of creating machines that think. This desire dates Back to at least the time of ancient Greece. The mythical figures Pygmalion, Daedalus, and Hephaestus may all be interpreted as legendary inventors, and Galatea, Talos, and Pandora may all be regarded as artificial life ( , Ovid and Martin 2004 Sparkes 1996 Tandy 1997 ; , ; , ).
上傳時間： 2020-06-10
上傳用戶：shancjb
本設(shè)計(jì)介紹了一種基于STM32單片機(jī)控制的智能水杯,可利用插口式電源或無線充電底座為加熱器提供能量,并在達(dá)到某種飲品所需溫度時進(jìn)行保溫。水杯內(nèi)置充電電池,可選用USB接口或無線充電。在水杯內(nèi)部設(shè)置無線模塊,用戶利用手機(jī)App與水杯進(jìn)行匹配進(jìn)行加熱操作,加熱完后水杯會通過手機(jī)App和液晶顯示屏實(shí)時反饋液體溫度,通過指示燈顯示電量情況等,給用戶進(jìn)行提醒。該智能水杯設(shè)計(jì)創(chuàng)新,實(shí)用價值較高。This paper introduces an intelligent water cup based by STM32 microcontroller,it can provide energy for the heater by socket type power supply or wireless charging base,and hold temperature needed for some kind of drink.Builtedin rechargeable battery,water cup can use USB or wireless charging.The wireless module is set up inside it,and customers can use mobile App to match and heat.After heating,water cup feeds Back liquid temperature through the mobile App,and then displays on LCD,reminds users through the indicator light.The intelligent water cup is designed innovatively and has high practical value.
上傳時間： 2022-03-28
上傳用戶：
主要內(nèi)容介紹 Allegro 如何載入 Netlist，進(jìn)而認(rèn)識新式轉(zhuǎn)法和舊式轉(zhuǎn)法有何不同及優(yōu)缺點(diǎn)的分析，透過本章學(xué)習(xí)可以對 Allegro 和 Capture 之間的互動關(guān)係，同時也能體驗(yàn)出 Allegro 和 Capture 同步變更屬性等強(qiáng)大功能。Netlist 是連接線路圖和 Allegro Layout 圖檔的橋樑。在這裏所介紹的 Netlist 資料的轉(zhuǎn)入動作只是針對由 Capture（線路圖部分）產(chǎn)生的 Netlist 轉(zhuǎn)入 Allegro（Layout部分）1． 在 OrCAD Capture 中設(shè)計(jì)好線路圖。2． 然後由 OrCAD Capture 產(chǎn)生 Netlist（annotate 是在進(jìn)行線路圖根據(jù)第五步產(chǎn)生的資料進(jìn)行編改）。 3． 把產(chǎn)生的 Netlist 轉(zhuǎn)入 Allegro（layout 工作系統(tǒng)）。 4． 在 Allegro 中進(jìn)行 PCB 的 layout。 5． 把在 Allegro 中產(chǎn)生的 Back annotate（Logic）轉(zhuǎn)出（在實(shí)際 layout 時可能對原有的 Netlist 有改動過），並轉(zhuǎn)入 OrCAD Capture 裏進(jìn)行回編。
上傳時間： 2022-04-28
上傳用戶：kingwide
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