共查询到20条相似文献,搜索用时 15 毫秒
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DANIEL SLOMOVITZ MARIO DITTRICH GUILLERMO LANGWAGEN 《International Journal of Electronics》2013,100(6):1163-1165
A new instrument for measuring the frequency of power networks (50 Hz or 60 Hz) is proposed. It achieves 0· 01Hz of resolution in 20 ms of measuring time. This meter has a simple and low cost electronic circuit. 相似文献
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介绍了ETSI EN 300132-2 V2.4.6(2011-12)中针对电信和数据通讯设备直流电源端口的窄带和宽带低频传导发射,以及低频传导抗扰度的测试方法。另外介绍了标准中给出的一种宽带传导发射简化近似算法。 相似文献
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杨昆 《电信工程技术与标准化》2018,(9)
本文在不改变UPS高频机主电路拓扑结构和配电系统结构的前提下,提出一种利用UPS高频机的PWM整流器进行无功就地补偿控制方案,应用同步旋转坐标变换和瞬时功率理论设计控制算法,在不影响UPS有功功率的前提下,利用PWM整流器进行负载侧无功补偿,提高UPS容量利用率,改善负载侧电能质量,减小高低压配电室无功补偿容量,节省成本和占地。 相似文献
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In this paper, a series resonant converter with pulse-width modulation (PWM) control is presented as an ac voltage regulator module (VRM) for high frequency ac power distribution systems. The proposed topology has close-to-unity rated power factor, low total harmonic distortion in input current, zero voltage switching under all load conditions, low voltage stress of the active switch and high overall efficiency. Simulation and experimental results are presented to prove the performance of the proposed ac VRM converter. 相似文献
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《Vehicular Technology, IEEE Transactions on》1983,32(3):225-229
Low loss surface acoustic wave (SAW) filters have been developed for use in the radio frequency circuits of the mobile telephone transceiver. Both the UHF (800 MHz) and VHF (90 MHz) band-pass filters have exhibited high performance, and the employment of the SAW filters has shown advantages in UHF/VHF circuit integration for mass production. 相似文献
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In this paper, an asymmetrical pulse-width-modulated (APWM) resonant inverter topology is presented for high frequency AC power distribution systems. The inverter system is comprised of simple power and control circuitry. The detailed analysis shows that the proposed inverter has very low total harmonic distortion, near-zero switching losses, and fast transient response. A design procedure is illustrated as well. Simulation and experimental results are presented to prove the performance of the proposed inverter. 相似文献
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介绍柴油发电机组、开关电源、UPS、蓄电池等几种主要通信电源设备的使用方法及使用中须要注意的事项,提出了相应的维护建议. 相似文献
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基于0.22THz高功率回旋管振荡器设计了频率步进成像雷达,采用收发分开的双卡塞格伦天线,发射信号形式为频率步进脉冲信号,回旋管频率调节通过调整回旋管电子束电压或者超导磁场强度来实现。给出了成像雷达设计方案,对雷达最大作用距离和步进频率雷达系统高分辨一维距离像进行了分析,开展了ISAR成像仿真。理论计算和仿真结果表明,该雷达对于散射面积为0.01m2的目标探测距离可达到1.982 km,可分辨500m处间距2cm的点目标。该雷达可对低高度小目标进行高精度探测,比如对可携带武器和危险物质的无人机进行高精度探测与目标识别。 相似文献
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Orthogonal frequency division multiple access (OFDMA) is a promising technique for high data rate communications in future cellular systems. Since frequency resources are universally reused in every cell in a system, a typical OFDMA system tries to maximize the spectral efficiency. Users located near the cell‐edge tend to have the weakest signal strength. So they might experience severe inter‐cell interferences (ICIs). In this paper, we propose a sequential frequency reuse (SqFR) that reduces ICIs by a sequential sub‐channel allocation. By giving more power to sub‐carriers allocated to cell‐edge users, our SqFR significantly enhances the performance of cell‐edge users. The performance of the proposed SqFR is investigated via the analysis and simulations. Simulation results show that proposed SqFR improves the performance of cell‐edge users in an OFDMA system under both homogeneous and heterogeneous traffic conditions. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
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Balestro F. Chianale A. Privat G. Tawfik M.S. Vandeweerd I. Wittmann A.D. 《Solid-State Circuits, IEEE Journal of》1991,26(7):1047-1055
Complex DSP (digital signal processor) ASICs (application-specific integrated circuits) typically feature high-quality filters implemented as dedicated blocks. FIDYS (filter 1di synthesis system) is a new VLSI recursive filter compiler, specifically designed to meet those needs. It is fully integrated from behavioral frequency template specifications down to layout. It comprises a specific approximation and synthesis procedure, the generation of a systolic architecture with parameterized pipelining based on dedicated bit-serial operators, and final generation of a densely packed layout based on a minimal dedicated set of 1-μm CMOS basic cells. A lossless discrete integrator ladder filter structure is used. It features an outstanding low sensitivity and a high degree of modularity and regularity that directly result in streamlined hardware and an efficient placement with minimal routing overhead. Examples of representative applications for telecommunications circuits are presented 相似文献
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为了有效实现高谐波抑制并提高功率附加效率,提出了一种适用于4G-LTE无线通信系统的高效F类功率放大器。该功率放大器使用了低电压p-HEMT晶体管和小型微带抑制单元,能够在低射频输入功率下产生n次谐波抑制和较高的功率附加效率(power added efficiency,PAE)。采用谐波平衡法对提出的功率放大器进行了仿真分析,并对其进行了实际制造。通过实际测量对仿真结果进行了验证。测量结果显示,提出功率放大器的工作频率为1.8 GHz,带宽为100 MHz,平均PAE为76.9%,且具有2V的极低漏极电压。射频输入功率范围分别为0-12 dBm时,最大输出功率和增益分别为23.4和17.5 dBm。 相似文献
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The authors describe the application of the FREDA (field reporting data) system, which was developed to manage quality data from the field. FREDA provides a methodology for data analysis and a tool for feedback activities that lead to final quality improvement. The application of FREDA to the LINEA-UT digital switching system is presented 相似文献
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It is shown that a pulse-width modulation circuit may be made to approach ideal product-modulator behaviour at low frequencies. The output of such a modulator contains sum and difference-frequency components: it is shown that the sum-frequency components may be made to cancel each other out completely in a 3-phase system. 相似文献
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Partial-band interferences are known to have a deleterious effect on the receiver performance in frequency-hopping communication systems. We consider the rejection of such interferences using an array of sensors. A simple yet effective method is proposed based on a constant power algorithm. The principle behind this method is that partial-band interferences contribute to power variations in the received signal, hence, the idea to constrain the output power of the array to be constant in order to reject interferences. It is shown that the algorithm converges in a reasonably low number of hops. Additionally, it achieves a nearly optimal signal-to-interference-plus-noise ratio without requiring any information about the location of the desired user. Finally, its robustness to synchronization errors is illustrated via numerical simulations. 相似文献
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雷达通信一体化系统是缓解无线电频谱拥塞和频谱资源短缺的高效解决方案。在雷达的最小信号噪声比和最小通信传输速率的约束条件下,通过构建混合整数非线性优化模型,提出了子载波和功率联合分配方法,实现系统总发射功率的最小化。首先将优化模型转化为线性模型并添加罚因子,然后选择用于雷达或通信目的的子载波。考虑到雷达性能和通信性能评价标准的差异,对用于雷达或通信目的子载波设置不同的发射功率约束,最终通过循环优化实现子载波和功率的联合分配。数值仿真结果表明,所提方法显著节约了功率资源。 相似文献
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A fundamental analysis of active ripple filters for powder circuits operating in 1-10 MHz range is presented. The improved understanding derived from this analysis allows filter circuits with gains five to ten times higher than previously reported to be built. Besides providing further reduction in the size of 1 MHz ripple filters, these higher gains make the active filters valuable for power circuit switching near 10 MHz 相似文献
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Nematollah Ezzati Sohrab Abdollahzadeh 《Analog Integrated Circuits and Signal Processing》2010,65(1):97-103
In this paper, a novel adaptive tuning system used in Gm-C continuous time (CT) filters has been presented. The novelty of
this method is the generation of quasi-gradient functions for the adaptive algorithm. By this method we have implemented the
fully adaptive tuning algorithm on chip, and received more than 95% precision for the all characteristics of Gm-C filter.
All the circuit level simulations and prototype fabrication have been done using 0.6 μ CMOS technology of AMS. 相似文献