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<li id="msksq"></li> 正交頻分復(fù)用技術(shù)（Orthogonal Frequency Division Multiplexing， OFDM）非常適合高速通信系統(tǒng)，但存在高峰均功率比（PAPR）的問(wèn)題。對(duì)OFDM系統(tǒng)中如何降低PARR的問(wèn)題進(jìn)行了研究，討論了降低PAPR的主要方法，重點(diǎn)分析了選擇性映射法（SLM），并在此基礎(chǔ)上提出了一種基于預(yù)編碼矩陣的改進(jìn)算法，最后通過(guò)matlab進(jìn)行了算法仿真，仿真結(jié)果表明，改進(jìn)算法在使得OFDM系統(tǒng)在降低峰均功率比的性能上得到了進(jìn)一步的改善。
上傳時(shí)間： 2014-01-23
上傳用戶：zwei41
Abstract: Many industrial/scientific/medical (ISM) band radio frequency (RF) receivers use an external Sallen-Key datafilter and a data slicer to generate the baseband digital output. This tutorial describes the ISM-RF Baseband Calculator,which can be used to calculate the filter capacitor values and the data slicer RC components, while providing a visualexample of the baseband signals.
上傳時(shí)間： 2013-11-04
上傳用戶：jkhjkh1982
摘 要： 針對(duì)非同分布的Nakagami信道，基于矩生成函數(shù)MGF(Moment Generation Function)的分析方法，提出正交空時(shí)分組碼系統(tǒng)STBC(Space-Time Block Coding)的一種快速性能評(píng)估算法，不需要涉及超幾何函數(shù)積分運(yùn)算，可在中高信噪比時(shí)，快速準(zhǔn)確地估計(jì)STBC系統(tǒng)的符號(hào)錯(cuò)誤概率性能。在平坦瑞利衰落信道下的計(jì)算機(jī)仿真表明，該算法與已有的STBC系統(tǒng)的近似估計(jì)算法相比，具有較優(yōu)的性能。 關(guān)鍵詞： 正交空時(shí)分組碼； MIMO； MGF； 誤符號(hào)率
上傳時(shí)間： 2014-12-29
上傳用戶：如果你也聽(tīng)說(shuō)
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
機(jī)電類比法是一種把機(jī)械量通過(guò)一定的計(jì)算等效類比為電量的方法，其在對(duì)電子機(jī)械系統(tǒng)的分析中應(yīng)用非常廣泛。它能夠把一個(gè)較復(fù)雜的機(jī)械系統(tǒng)類比為我們熟知的電路系統(tǒng)來(lái)進(jìn)行分析，從而使問(wèn)題的分析得到簡(jiǎn)化。本文通過(guò)對(duì)振弦式傳感器的分析介紹了機(jī)電類比法，并對(duì)使用電路進(jìn)行了相關(guān)的分析。 Summary：The electromechanical analogy is assort of analysis which is to analogize the mechanical system by using circuit system , it applied widely in the filed of analysis the electronic-mechanical system. The analysis can take a complex mechanical system analogous to a circuitry that we well-known, which can simplify the problems. In the paper, the electro-mechanical analogy method is briefly introduced by analysis the vibrating wire sensor，and have a correlation analysis about the circuit we used.關(guān)鍵詞： 機(jī)電類比法 振弦式傳感器 頻率 振蕩 反饋Keyword：electro-mechanical analogy method，vibrating wire sensor，frequency, oscillation, feedback 0 引言振弦式傳感器是屬于頻率式傳感器的一種。所謂頻率式傳感器就是能直接將被測(cè)量轉(zhuǎn)換為振動(dòng)頻率信號(hào)的傳感器，這類傳感器一般是通過(guò)測(cè)量振弦、振筒、振梁、振膜等彈性振體或石英晶體諧振器的固有諧振頻率來(lái)達(dá)到測(cè)量引起諧振頻率變化的被測(cè)非電量的目的，其也稱為諧振式傳感器[1]。在分析該類傳感器中，由于其涉及到頻率，就容易讓人聯(lián)想到在電子技術(shù)中接觸到的RLC振蕩電路。因此可以嘗試著用類比的方法使之對(duì)應(yīng)起來(lái)分析,即機(jī)電類比法分析。
上傳時(shí)間： 2013-11-16
上傳用戶：paladin
The CC1101 is a low-cost sub- 1 GHztransceiver designed for very low-powerwireless applications. The circuit is mainlyintended for the ISM (Industrial, Scientific andMedical) and SRD (Short Range Device)frequency bands at 315, 433, 868, and 915MHz, but can easily be programmed foroperation at other frequencies in the 300-348MHz, 387-464 MHz and 779-928 MHz bands.CC1101 is an improved and code compatibleversion of the CC1100 RF transceiver. Themain improvements on the CC1101 include:
標(biāo)簽： 1110 CC 片上系統(tǒng) 方案
上傳時(shí)間： 2013-11-12
上傳用戶：363186
RFID（Radio Frequency Identification）技術(shù)是利用射頻通信實(shí)現(xiàn)的一種非接觸式自動(dòng)識(shí)別技術(shù)。擁有廣闊的發(fā)展前景和巨大的市場(chǎng)潛力。本文介紹了RFID技術(shù)的原理、特點(diǎn)，深入分析了信號(hào)傳輸時(shí)所采取的反方向散射的調(diào)制方式，影響傳輸距離的因素，最后介紹了在遠(yuǎn)程RFID自動(dòng)識(shí)別系統(tǒng)中的讀寫沖突和防沖突算法，更好的解決了遠(yuǎn)程RFID系統(tǒng)存在的沖突問(wèn)題。
標(biāo)簽： RFID 遠(yuǎn)程 技術(shù)探討
上傳時(shí)間： 2013-10-11
上傳用戶：fdfadfs
Abstract: The process of designing a radio system can be complex and often involves many project tradeoffs. Witha little insight, balancing these various characteristics can make the job of designing a radio system easier. Thistutorial explores these tradeoffs and provides details to consider for various radio applications. With a focus on theindustrial, scientific, medical (ISM) bands, the subjects of frequency selection, one-way versus two-way systems,modulation techniques, cost, antenna options, power-supply influences, effects on range, and protocol selectionare explored.
標(biāo)簽： 無(wú)線
上傳時(shí)間： 2013-12-13
上傳用戶：eastgan
Abstract: This application note discusses a design for a phantom antenna power-supply system compatible with theDigital Satellite Equipment Control (DiSEqC) communication standard, using the MAX16948 automotive dual, highvoltageLDO/switch. The presented application circuit provides a remote antenna power supply and also enables onewaycommunication from the radio head unit to the remote antenna. This system architecture offers flexibility inDiSEqC tone-burst frequency choice (100Hz to 30kHz), enabling users the ability to select the best frequency for theirapplication.
標(biāo)簽： 數(shù)字衛(wèi)星 控制 兼容 供電系統(tǒng)設(shè)計(jì)
上傳時(shí)間： 2013-11-17
上傳用戶：fnhhs
Abstract: This application note describes system-level characterization and modeling techniques for radio frequency (RF) and microwavesubsystem components. It illustrates their use in a mixed-signal, mixed-mode system-level simulation. The simulation uses an RF transmitterwith digital predistortion (DPD) as an example system. Details of this complex system and performance data are presented.
標(biāo)簽： 射頻 仿真 微波系統(tǒng) 建模
上傳時(shí)間： 2013-12-18
上傳用戶：onewq
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