<code id="a6qsq"></code> This book was born from the perception that there is much more to spectrum use and sharing than one sees reflected in publications, whether academic, commercial or political. the former – in good research style – tend towards reductionism and concentrate on specific, detailed aspects. commercial publications tend to empha- size the positive aspects and they tend to put promise above practice. Given the ever increasing pace of technology development and recent successes of new wireless technologies, some pundits predict large-scale spectrum scarcity, potentially lead- ing to economic catastrophe. Although economic theory has a hard time explaining recent events that shook the world economy, the notion of spectrum scarcity is intui- tively acceptable, even if not correct or immediately relevant.
上傳時(shí)間： 2020-06-01
上傳用戶：shancjb
The radio spectrum is one of the most precious resources which must be managed to ensure efficient access for the wireless communication services which use it. The allocation and management of spectrum are administered by the regulatory authorities. Traditionally, spectrum allocation is carried out exclusively of its use in large geographic areas and assigning frequency bands to specific users or service providers is proved to be inefficient. Recently, substantial knowledge about dynamic spectrum access scheme has been accumulated to enable efficient spectrum sharing.
標(biāo)簽： Management Spectrum Access and
上傳時(shí)間： 2020-06-01
上傳用戶：shancjb
Radio frequency spectrum is a scarce and critical natural resource that is utilized for many services including surveillance, navigation, communication, and broadcast- ing. Recent years have seen tremendous growth in the use of spectrum especially by commercial cellular operators. Ubiquitous use of smartphones and tablets is one of the reasons behind an all-time high utilization of spectrum. As a result, cellular operators are experiencing a shortage of radio spectrum to meet bandwidth demands of users. On the other hand, spectrum measurements have shown that much spectrum not held by cellular operators is underutilized even in dense urban areas. This has motivated shared access to spectrum by secondary systems with no or minimal impact on incumbent systems. Spectrum sharing is a promising approach to solve the problem of spectrum congestion as it allows cellular operators access to more spectrum in order to satisfy the ever-growing bandwidth demands of commercial users.
標(biāo)簽： Spectrum Sharing Between Radars
上傳時(shí)間： 2020-06-01
上傳用戶：shancjb
A light-emitting diode (LED) is a semiconductor device that emits narrow-spectrum incoherent light when forward-biased.The color of the emitted light depends on the chemical composition of the semiconductor material used, and can benear-ultraviolet, visible or infrared. LEDs are more prevalent today than ever before, replacing traditional incandescent andfluorescent bulbs in many lighting applications. Incandescents use a heated filament, are subject to breakage and burnoutand operate at a luminous efficiency of 2% to 4%. Fluorescents are more efficient, at 7% to 12%, but require highdrive voltage and contain mercury, a toxic substance that may be eventually banned in certain countries. LEDs, however,produce light directly through electroluminescence, operate at low voltage and can deliver over 20% luminous efficiency.
上傳時(shí)間： 2013-11-07
上傳用戶：xiaoyuer
為了使音頻信號(hào)分析儀小巧可靠，成本低廉，設(shè)計(jì)了以2片MSP430F1611單片機(jī)為核心的系統(tǒng)。該系統(tǒng)將音頻信號(hào)送入八階巴特沃茲低通濾波器，對(duì)信號(hào)進(jìn)行限幅放大、衰減、電平位移、緩沖，并利用一單片機(jī)負(fù)責(zé)對(duì)前級(jí)處理后的模擬信號(hào)進(jìn)行采樣，將采集得到的音頻信號(hào)進(jìn)行4 096點(diǎn)基2的FFT計(jì)算，并對(duì)信號(hào)加窗函數(shù)提高分辨率，另一單片機(jī)負(fù)責(zé)對(duì)信號(hào)的分析及控制顯示設(shè)備。此設(shè)計(jì)精確的測(cè)量了音頻信號(hào)的功率譜、周期性、失真度指標(biāo)，達(dá)到較高的頻率分辨率，并能將測(cè)量結(jié)果通過(guò)紅外遙控器顯示在液晶屏上。 Abstract: o make the audio signal analyzer cheaper， smaller and more reliable， this system sends the audio signal to the eight-order butterworth filter， and then amplifies， attenuates， buffers it in a limiting range， transfers the voltage level of the signal before utilizing two MSP430F1611 MCU to realize the audio analysis. One is charged for sampling and dealing with the processed audio signal collected by the 4096 point radix-2 FFT calculation and imposes the window function to improve the frequency resolution. The other one controls the display and realizes the spectrum， periodicity， power distortion analysis in high resolution which is displayed in the LCD screen through the infrared remote control.
上傳時(shí)間： 2013-12-11
上傳用戶：jasonheung
This application report discusses the design of non-invasive optical plethysmographyalso called as pulsoximeter using the MSP430FG437 Microcontroller (MCU). Thepulsoximeter consists of a peripheral probe combined with the MCU displaying theoxygen saturation and pulse rate on a LCD glass. The same sensor is used for bothheart-rate detection and pulsoximetering in this application. The probe is placed on aperipheral point of the body such as a finger tip, ear lobe or the nose. The probeincludes two light emitting diodes (LEDs), one in the visible red spectrum (660nm) andthe other in the infrared spectrum (940nm). The percentage of oxygen in the body isworked by measuring the intensity from each frequency of light after it transmitsthrough the body and then calculating the ratio between these two intensities.
標(biāo)簽： Pulsoximeter Single-Chip Des
上傳時(shí)間： 2013-10-27
上傳用戶：黑漆漆
為提升虛擬儀器傳輸速率與實(shí)時(shí)性能，擴(kuò)展監(jiān)測(cè)范圍，在VC的軟件平臺(tái)上設(shè)計(jì)了一種全功能虛擬示波器。與傳統(tǒng)虛擬示波器相比，該系統(tǒng)采用嵌入式系統(tǒng)完成信號(hào)采集，采用工業(yè)以太網(wǎng)為傳輸介質(zhì)，通過(guò)線性插值算法和多線程編程思想，實(shí)現(xiàn)波形顯示、參數(shù)計(jì)算、頻譜分析以及波形存儲(chǔ)及回放功能。實(shí)驗(yàn)結(jié)果表明，該虛擬示波器可以實(shí)現(xiàn)20 kHz采樣頻率下的波形精確顯示，達(dá)到預(yù)期的各項(xiàng)指標(biāo)。 Abstract: o enhance the transfer rate and real-time of virtual instrument performance， expand scope of monitoring， this paper uses the VCs software platform to design a fully functional virtual oscilloscope. Compared with traditional virtual oscilloscope， this system adopts the embedded system to complete the data acquisition， industrial Ethernet as the transmission medium used by the linear interpolation algorithm and multi-threaded programming ideas， namely to achieve waveform display， parameter calculation， spectrum analysis and waveform storage and playback. Experimental results show that the virtual oscilloscope can accurately display the waveform with 20kHz sampling frequency， and achieve the desired targets.
標(biāo)簽： 以太網(wǎng) 虛擬 波器設(shè)計(jì)
上傳時(shí)間： 2013-11-25
上傳用戶：wbwyl
THIS M-FILE USES THE TRANFER MATRIX METHOD TO EVALUATE THE COUPLED-MODE ％EQUATIONS. THE REFLECTION SPECTRUM OF THE GRATING AND THE TRANSMISSION ％SPECTRUM, DELAY AND DISPERSION OF THE FABRY-PEROT FILTER ARE SIMULATED
標(biāo)簽： THE COUPLED-MODE REFLECTION EQUATIONS
上傳時(shí)間： 2015-08-11
上傳用戶：CHINA526
The Engineering Vibration Toolbox is a set of educational programs written in Octave by Joseph C. Slater. Also included are a number of help files, demonstration examples, and data files containing raw experimental data. The codes include single degree of freedom response, response spectrum, finite elements, numerical integration, and phase plane analysis.
標(biāo)簽： C. Engineering educational Vibration
上傳時(shí)間： 2013-11-29
上傳用戶：jkhjkh1982
％WAVETEST Example Matlab script for WAVELET, using NINO3 SST dataset ％ ％ See "http://paos.colorado.edu/research/wavelets/" ％ Written January 1998 by C. Torrence ％ ％ Modified Oct 1999, changed Global Wavelet Spectrum (GWS) to be sideways, ％ changed all "log" to "log2", changed logarithmic axis on GWS to ％ a normal axis.
標(biāo)簽： WAVETEST colorado Example WAVELET
上傳時(shí)間： 2014-01-06
上傳用戶：hullow
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