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One of the very first books published on the social impact of the mobile phone
was Timo Kopomaa’s The City in Your Pocket: Birth of the Mobile Information Society.
The book, published in 2000, was based on research that Kopomaa had under-
taken for Nokia and Sonera as part of his doctoral studies in the Centre for Urban
and Regional Studies at the Helsinki University of Technology. The first line he
writes in the book is peculiar: ‘Mobile communication is not a serious matter’. By
this, we assume he is referring to a view of the world that would regard the mobile
phone as little more than an unremarkable fact of everyday life – a simple play-
thing for the young, or a productivity tool for the business executive and busy
parent.
標簽：
Communications
Wireless
Mobile
and
上傳時間：
2020-05-30
上傳用戶：shancjb
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With the rapid growth of the wireless mobile applications, wireless voice has
begun to challenge wireline voice, whereas the desire to access e-mail, surf the
Web or download music (e.g., MP3) wirelessly is increasing for wireless data.
While second generation (2G) cellular wireless systems, such as cdmaOne1,
GSM2 and TDMA3, introduced digital technology to wireless cellular systems
to deal with the increasing demand for wireless applications, there is still the
need for more spectrally efficient technologies for two reasons. First, wireless
voice capacity is expected to continue to grow. Second, the introduction of
high-speed wireless data will require more bandwidth.
標簽：
Wireless
Systems
Mobile
Beyond
and
3G
上傳時間：
2020-05-30
上傳用戶：shancjb
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This is believed to be the first book that takes a view of nanotechnology from a
telecommunications and networking perspective. Nanotechnology refers to the manip-
ulation of materials at the atomic or molecular level. Nanotechnology is getting a lot
of attention of late not only in academic settings and in laboratories around the
world, but also in government and venture capitalists’ initiatives. There now is a
major drive to commercialize the technology by all sorts of firms, ranging from start-
ups to Fortune 100 companies.
標簽：
Nanotechnology
Applications
上傳時間：
2020-05-31
上傳用戶：shancjb
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This book is intended for the graduate or advanced undergraduate
engineer. The primary motivation for developing the text was to present a
complete tutorial of phase-locked loops with a consistent notation. I believe
this is critical for the practicing engineer who uses the text as a self-study
guide.
標簽：
Communications
Phase-Locked
Wireless
Loops
for
上傳時間：
2020-05-31
上傳用戶：shancjb
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Soon after Samuel Morse’s telegraphing device led to a deployed electri-
cal telecommunications system in 1843, waiting lines began to form by those
wanting to use the system. At this writing queueing is still a significant factor in
designing and operating communications services, whether they are provided
over the Internet or by other means, such as circuit switched networks.
標簽：
Telecommunication
Queueing
Packet
Theory
with
上傳時間：
2020-05-31
上傳用戶：shancjb
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Telecommunications is today widely understood to mean the electrical means of
communicating over a distance. The first form of telecommunications was that of
the Telegraph, which was invented quite independently in 1837 by two scientists,
Wheatstone and Morse. Telegraphy was on a point-to-point unidirectional basis and
relied on trained operators to interpret between the spoken or written word and the
special signals sent over the telegraph wire. However, the use of telegraphy did
greatly enhance the operations of railways and, of course, the dissemination of news
and personal messages between towns.
標簽：
Telecommunications
Understanding
Networks
上傳時間：
2020-06-01
上傳用戶：shancjb
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ABSTRACTThe flyback power stage is a popular choice for single and multiple output dc-to-dc converters at powerlevels of 150 Watts or less. Without the output inductor required in buck derived topologies, such as theforward or push-pull converter, the component count and cost are reduced. This application note will reviewthe design procedure for the power stage and control electronics of a flyback converter. In these isolatedconverters, the error signal from the secondary still needs to cross the isolation boundary to achieveregulation. By using the UC3965 Precision Reference with Low Offset Error Amplifier on the secondaryside to drive an optocoupler and the UCC3809 Economy Primary Side Controller on the primary side, asimple and low cost 50 Watt isolated power supply is realized.
標簽：
隔離
上傳時間：
2021-11-24
上傳用戶：kingwide
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配電網(wǎng)中,各種配電終端的電流、電壓、有功功率及無功功率等模擬量的采集是配電網(wǎng)自動化的重要環(huán)節(jié)。這些模擬量的采集也是各種儀器和家用電器的必要功能。因此,設(shè)計了基于嵌入式STM32F103單片機的交流電壓、交流電流及有功功率的采集系統(tǒng),通過電壓互感器TV1005M和電流互感器TA1005M分別檢測交流電壓和交流電流值;屏幕或者手機APP和WiFi模塊互聯(lián)后,可以實時顯示交流電壓、交流電流、功率及電量值;通過設(shè)定閾值功率,可以實現(xiàn)對電流的監(jiān)控和對電路的保護。In the distribution network,the collection of analog,such as current,voltage,active power,and reactive power at various distribution terminals is a very important part of distribution network automation. These analog acquisitions are also for various instruments and household appliances. Very important technology. Therefore,an AC voltage,AC current and active power acquisition system based on embedded STM32 F103 machine is designed,and AC voltage and AC current values are detected by voltage transformer TV1005 M and current Transformer TA1005 M respectively;After the screen or mobile phone APP and WiFi modules are interconnected,AC voltage,AC current,power,and power values can be displayed in real time;By setting the threshold power,the current can be monitored and the circuit can be protected.
標簽：
stm32f103
單片機
電流電壓采集
上傳時間：
2022-03-27
上傳用戶：shjgzh
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如果在調(diào)諧器或電視機附近使用本機或任何其他使用微處理器的電子設(shè)備，則可能會產(chǎn)生圖像的噪聲或干擾。如果發(fā)生這種情況，請采取以下步驟將本機安裝在盡可能遠離調(diào)諧器或T的地方。遠離調(diào)諧器或T，遠離本機的電源線和輸入/輸出連接電纜。尤其在使用室內(nèi)天線或300歐姆饋線。我們建議使用室外天線和75 Q / ohm同軸電纜Noise or disturbance of the picture may be generated if this unit or any other electronic equipment using microprocessors is used near a tuner or TV If this happens, take the following stepsInstall this unit as far away as possible from the tuner or T Run the antenna wires from the tuner or T away from this unit ' s power supply cord and input/output connection cables. Noise or disturbance tends to occur particularly when using indoor antennas or300 ohm feeder wires. We recommend using outdoor antennas and 75 Q/ohm coaxial cables
標簽：
功放
上傳時間：
2022-04-22
上傳用戶：
-
為了實時檢測血氧量,能使缺氧特別敏感的腦組織或心臟類疾病患者得到及時治療,采用近紅外雙波長透射式光電脈搏血氧測定法,以H橋電路對發(fā)射光源進行控制及通用運算放大器搭建濾波電路。運用參數(shù)理論計算和計算機仿真結(jié)果相對比的方法,通過Mu ltisim軟件對所設(shè)計電路進行仿真,仿真結(jié)果與理論參數(shù)計算相吻合,證明了電路參數(shù)設(shè)計的可行性,為血氧儀的實物制作提供參考。For real-time detection of oxygen saturation for timely treatment of the brain or heart,which are very sensitive to oxygen inadequacy,the near-infrared wavelengths double photoelectric pulse oximeter transmission method is adopted.The illuminant is controlled with the H bridge circuit and the filter circuit is built with general op-amps.Parameters by theoretical calculation is compared with the computer simulation results in Multisim and satisfactory results are obtained.It is shown that the design of the circuit parameters is feasible and can be a help in making the physical blood-oxygen monitor.
標簽：
multisim
光電二極管
濾波器
上傳時間：
2022-05-12
上傳用戶：
