<u id="voqak"></u> 為了在CDMA系統(tǒng)中更好地應(yīng)用QDPSK數(shù)字調(diào)制方式，在分析四相相對(duì)移相（QDPSK)信號(hào)調(diào)制解調(diào)原理的基礎(chǔ)上，設(shè)計(jì)了一種QDPSK調(diào)制解調(diào)電路，它包括串并轉(zhuǎn)換、差分編碼、四相載波產(chǎn)生和選相、相干解調(diào)、差分譯碼和并串轉(zhuǎn)換電路。在MAX+PLUSⅡ軟件平臺(tái)上，進(jìn)行了編譯和波形仿真。綜合后下載到復(fù)雜可編程邏輯器件EPM7128SLC84-15中，測(cè)試結(jié)果表明，調(diào)制電路能正確選相，解調(diào)電路輸出數(shù)據(jù)與QDPSK調(diào)制輸入數(shù)據(jù)完全一致，達(dá)到了預(yù)期的設(shè)計(jì)要求。 Abstract: In order to realize the better application of digital modulation mode QDPSK in the CDMA system， a sort of QDPSK modulation-demodulation circuit was designed based on the analysis of QDPSK signal modulation-demodulation principles. It included serial/parallel conversion circuit, differential encoding circuit, four-phase carrier wave produced and phase chosen circuit, coherent demodulation circuit, difference decoding circuit and parallel/serial conversion circuit. And it was compiled and simulated on the MAX+PLUSⅡ software platform,and downloaded into the CPLD of EPM7128SLC84-15.The test result shows that the modulation circuit can exactly choose the phase，and the output data of the demodulator circuit is the same as the input data of the QDPSK modulate. The circuit achieves the prospective requirement of the design.
標(biāo)簽： QDPSK CPLD 調(diào)制解調(diào) 電路設(shè)計(jì)
上傳時(shí)間： 2014-01-13
上傳用戶(hù)：qoovoop
波長(zhǎng)信號(hào)的解調(diào)是實(shí)現(xiàn)光纖光柵傳感網(wǎng)絡(luò)的關(guān)鍵，基于現(xiàn)有的光纖光柵傳感器解調(diào)方法，提出一種基于FPGA的雙匹配光纖光柵解調(diào)方法，此系統(tǒng)是一種高速率、高精度、低成本的解調(diào)系統(tǒng)，并且通過(guò)引入雙匹配光柵有效地克服了雙值問(wèn)題同時(shí)擴(kuò)大了檢測(cè)范圍。分析了光纖光柵的測(cè)溫原理并給出了該方案軟硬件設(shè)計(jì)，綜合考慮系統(tǒng)的解調(diào)精度和FPGA的處理速度給出了基于拉格朗日的曲線擬合算法。 Abstract: Sensor is one of the most important application of the fiber grating. Wavelength signal demodulating is the key techniques to carry out fiber grating sensing network， based on several existing methods of fiber grating sensor demodulation inadequate， a two-match fiber grating demodulation method was presented. This system is a high-speed， high precision， low-cost demodulation system. And by introducing a two-match grating effectively overcomes the problem of double value while expands the scope of testing. This paper analyzes the principle of fiber Bragg grating temperature and gives the software and hardware design of the program. Considering the system of demodulation accuracy and processing speed of FPGA，this paper gives the curve fitting algorithm based on Lagrange.
標(biāo)簽： FPGA 光纖光柵 解調(diào)系統(tǒng)
上傳時(shí)間： 2014-07-24
上傳用戶(hù)：caiguoqing
a8259 可編程中斷控制 altera提供 The a8259 is designed to simplify the implementation of the interrupt interface in 8088 and 8086 based microcomputer systems. The device is known as a programmable interrupt controller. The a8259 receives and prioritizes up to 8 interrupts, and in the cascade mode, this can be expanded up to 64 interrupts. An asynchronous reset and a clock input have been added to improve operation and reliability.
上傳時(shí)間： 2014-11-29
上傳用戶(hù)：zhyiroy
傳統(tǒng)的基于位置信息的服務(wù)（LBS）的隱私保護(hù)需要LBS提供者（簡(jiǎn)稱(chēng)LSP）與用戶(hù)之間通過(guò)第三方作為中介來(lái)進(jìn)行信息交換，但這種模式極易遭到攻擊者攻擊。為此提出一種基于K-匿名機(jī)制的隱形空間算法KABSCA（k-anonymity based spatial cloaking algorithm ），通過(guò)移動(dòng)設(shè)備獨(dú)立建立一個(gè)分布式網(wǎng)絡(luò)直接與LSP通訊進(jìn)而避免了第三方的安全威脅。仿真實(shí)驗(yàn)顯示:使用這種算法，用戶(hù)可以享受到高質(zhì)量的信息服務(wù)以及高度的隱私保護(hù)。
標(biāo)簽： hoc LBS 移動(dòng)Ad 環(huán)境
上傳時(shí)間： 2013-11-06
上傳用戶(hù)：540750247
Modbus詳解(全書(shū)+PDF)
標(biāo)簽： Modbus Controller Based
上傳時(shí)間： 2013-10-09
上傳用戶(hù)：lijinchuan
The Tri-Mode Ethernet MAC (TEMAC) UltraController-II module is a minimal footprint,embedded network processing engine based on the PowerPC™ 405 (PPC405) processor coreand the TEMAC core embedded within a Virtex™-4 FX Platform FPGA. The TEMACUltraController-II module connects to an external PHY through Gigabit Media IndependentInterface (GMII) and Management Data Input/Output (MDIO) interfaces and supports tri-mode(10/100/1000 Mb/s) Ethernet. Software running from the processor cache reads and writesthrough an On-Chip Memory (OCM) interface to two FIFOs that act as buffers between thedifferent clock domains of the PPC405 OCM and the TEMAC.
上傳時(shí)間： 2013-10-26
上傳用戶(hù)：yuzsu
針對(duì)飛行模擬器座艙數(shù)據(jù)采集的復(fù)雜性，設(shè)計(jì)了一種基于以太網(wǎng)分布式的數(shù)據(jù)采集控制系統(tǒng)，該系統(tǒng)是RCM5700微處理器模塊上的以太網(wǎng)應(yīng)用。在系統(tǒng)的基礎(chǔ)上具體討論了PoE技術(shù)的應(yīng)用，在傳輸數(shù)據(jù)的網(wǎng)線上同時(shí)提供電流，提出并實(shí)現(xiàn)了一種包括輔助電源在內(nèi)的完整可靠的PoE供電方案。設(shè)計(jì)采用美國(guó)國(guó)家半導(dǎo)體的LM5073和LM5576并根據(jù)不同的負(fù)載情況，進(jìn)行穩(wěn)定可靠的電壓轉(zhuǎn)換，以滿(mǎn)足數(shù)據(jù)采集電路的要求。實(shí)驗(yàn)結(jié)果表明：該設(shè)計(jì)穩(wěn)定可靠，滿(mǎn)足低于13 W的采集節(jié)點(diǎn)供電要求，提高了模擬器信號(hào)采集系統(tǒng)的通用性和標(biāo)準(zhǔn)化程度，避免了以往數(shù)據(jù)采集節(jié)點(diǎn)單獨(dú)繁瑣的電源設(shè)計(jì)。 Abstract: Aiming at the complexity of large avion simulation and controlling，the simulator cabin distribute data collecting and control system was designed. This system is the application of RCM5700 on Ethernet. Based on this system，PoE technique that makes Ethernet can also provide power were expounded with emphasis and included FAUX design the PoE resolution was realized. To achieve the requirement of this system，LM5073 and LM5576 were used to DC-DC switch. From the data of experiment，the design filled the requirement of power-need of node whose power was lower than 13W. The application of the technique can advance the degree of simulation data collections currency and standardization and avoid designing additional power system.
標(biāo)簽： 以太網(wǎng) 分布式 數(shù)據(jù)采集 控制系統(tǒng)
上傳時(shí)間： 2013-11-09
上傳用戶(hù)：xyipie
在現(xiàn)代通信系統(tǒng)中，電話語(yǔ)音的頻帶被限制在300 Hz～4 kHz的范圍內(nèi)，帶來(lái)了語(yǔ)音可懂度和自然度的降低。為了在不增加額外成本的前提下提高語(yǔ)音的可懂度和自然度，進(jìn)行了電話語(yǔ)音頻帶擴(kuò)展的研究。提出了一種改進(jìn)的基于碼本映射的語(yǔ)音帶寬擴(kuò)展算法：在碼本映射的過(guò)程中，使用加權(quán)系數(shù)來(lái)得到映射碼本。客觀測(cè)試結(jié)果表明，用此算法得到的寬帶語(yǔ)音的譜失真度比用一般的碼本映射降低至少2%。主觀測(cè)試結(jié)果表明，用此算法得到的寬帶語(yǔ)音具有更好的可懂度和自然度。 Abstract: In modern communication systems， the bandwidth of telephone speech is limited from 300Hz to 4 kHz， which reduces the intelligibility and naturalness of speech. Telephone speech bandwidth extension is researched to get wideband speech and to improve its intelligibility and naturalness， without increasing extra costs. This paper put forward an improved algorithm of speech bandwidth extension based on codebook mapping. In the process of codebook mapping， weighted coefficients were used to get mapping codebook. Objective tests show that spectral distortion of wideband speech obtained by this algorithm reduces at least 2%， comparing to conditional codebook mapping. Subjective tests show that the wideband speech obtained by this algorithm has better intelligibility and naturalness.
標(biāo)簽： 映射 帶寬 擴(kuò)展 語(yǔ)音
上傳時(shí)間： 2014-12-29
上傳用戶(hù)：15501536189
雙絞線(TP:Twisted Pairwire)是綜合布線工程中最常用的一種傳輸介質(zhì)。雙絞線由兩根具有絕緣保護(hù)層的銅導(dǎo)線組成。把兩根絕緣的銅導(dǎo)線按一定密度互相絞在一起,可降低信號(hào)干擾的程度,每一根導(dǎo)線在傳輸中輻射的電波會(huì)被另一根線上發(fā)出的電波抵消。雙絞線一般由兩根22～26號(hào)絕緣銅導(dǎo)線相互纏繞而成。如果把一對(duì)或多對(duì)雙絞線放在一個(gè)絕緣套管中便成了雙絞線電纜。在雙絞線電纜(也稱(chēng)雙扭線電纜)內(nèi),不同線對(duì)具有不同的扭絞長(zhǎng)度,一般地說(shuō),扭絞長(zhǎng)度在38.1cm至14cm內(nèi),按逆時(shí)針?lè)较蚺そg,相臨線對(duì)的扭絞長(zhǎng)度在12.7cm以上。與其他傳輸介質(zhì)相比,雙絞線在傳輸距離、信道寬度和數(shù)據(jù)傳輸速度等方面均受到一定限制,但價(jià)格較為低廉。目前,雙絞線可分為非屏蔽雙絞線(UTP:Unshilded Twisted Pair)和屏蔽雙絞線(STP:Shielded Twisted Pair)。雖然雙絞線主要是用來(lái)傳輸模擬聲音信息的,但同樣適用于數(shù)字信號(hào)的傳輸,特別適用于較短距離的信息傳輸。在傳輸期間,信號(hào)的衰減比較大,并且產(chǎn)生波形畸變。采用雙絞線的局域網(wǎng)的帶寬取決于所用導(dǎo)線的質(zhì)量、長(zhǎng)度及傳輸技術(shù)。只要精心選擇和安裝雙絞線,就可以在有限距離內(nèi)達(dá)到每秒幾百萬(wàn)位的可靠傳輸率。當(dāng)距離很短,并且采用特殊的電子傳輸技術(shù)時(shí),傳輸率可達(dá)100Mbps～155Mbps。由于利用雙絞線傳輸信息時(shí)要向周?chē)?信息很容易被竊聽(tīng),因此要花費(fèi)額外的代價(jià)加以屏蔽。屏蔽雙絞線電纜的外層由鋁泊包裹,以減小幅射,但并不能完全消除輻射。屏蔽雙絞線價(jià)格相對(duì)較高,安裝時(shí)要比非屏蔽雙絞線電纜困難。類(lèi)似于同軸電纜,它必須配有支持屏蔽功能的特殊連結(jié)器和相應(yīng)的安裝技術(shù)。但它有較高的傳輸速率,100米內(nèi)可達(dá)到155Mbps。
上傳時(shí)間： 2013-11-05
上傳用戶(hù)：pwcsoft
稀疏表示分類(lèi)算法（Sparse Representation-based Classification，SRC）在人臉數(shù)據(jù)庫(kù)上有很高的識(shí)別性能。然而，對(duì)于姿態(tài)變化，SRC的識(shí)別效果并不理想。針對(duì)SRC算法不能解決測(cè)試樣本與訓(xùn)練樣本存在偏移誤差的問(wèn)題，本文提出了基于SRC的改進(jìn)算法。該算法將每一類(lèi)的訓(xùn)練樣本單獨(dú)作為訓(xùn)練字典，利用迭代校正和基于金字塔分層機(jī)構(gòu)的運(yùn)動(dòng)偏移估計(jì)方法得到最終的偏移量，最后對(duì)校正后的測(cè)試樣本使用SRC算法實(shí)現(xiàn)分類(lèi)。實(shí)驗(yàn)結(jié)果表明該方法對(duì)于有偏移誤差的人臉圖像具有較好的魯棒性及識(shí)別率。
標(biāo)簽： SRC 算法 人臉識(shí)別 中的應(yīng)用
上傳時(shí)間： 2013-11-15
上傳用戶(hù)：haiya2000
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