共查询到19条相似文献，搜索用时 165 毫秒
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主要讨论64QAM全数字调制解调系统中,滤波器在基带成形(接收端为匹配滤波)和符号同步这两部分的实现方法。给出这两部分的实现思想:基带成形部分是由加窗的根升余弦滤波器来实现,结合FPGA,采取并行流水线和查找表的结构来实现。符号同步部分考虑插值滤波器的实现方法,采用能适用于Fallow结构的直线型插值、分段抛物线型插值和立方插值。最后,在此基础之上,仿真出FIR滤波器的滚降系数和码间串扰之间的关系,同时针对误差检测器的自噪声过大问题,提出一种在误差检测器中增加一个简单的高通滤波器这种改进方案来减小检测器的环路误差。 相似文献
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介绍了一种基于CPLD的IRIG-B(AC)码解调电路设计。该IRIG-B(AC)码解调电路具有实时秒脉冲和时、分、秒时间信息并行输出等功能。具有硬件电路和软件编程简单,AC码解调精度高,灵活度和稳定性高,可以方便的进行电路移植,是一种成功的IRIG-B(AC)时间码解调方案。 相似文献
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针对传统多带宽合成孔径雷达系统需要多个滤波器和多种采样时钟等问题,提出一种新的数字处理方法,并详细介绍了算法方案、仿真结果和基于现场可编程门阵列(FPGA)的算法实现.该方法仅需一个最高频率的采样时钟获取离散化数据,通过对数据的插值得到其他较低时钟频率的数据,而对不同带宽信号的滤波由数字滤波器来实现.这种方法简化了系统设计,提高了系统可靠性. 相似文献
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本文将扩频技术与MSK调制解调技术相结合,对于衡量MSK扩频调制解调系统设计方案的可行性、系统配置和参数设置等方面的难点进行分析,并利用SystemView对该系统进行仿真实现。通过对仿真结果的分析,为硬件系统设计提供了原理上的可行性,为硬件调试提供了经验和参考。 相似文献
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基于中频采样的星载合成孔径雷达的数据处理 总被引：1，自引：1，他引：0
研究了基于中频采样的星载合成孔径雷达(synthetic aperture RADAR, SAR)数据处理技术及其FPGA实现. 常规星载SAR系统对模拟解调后的视频数据进行采样,然后对数据进行压缩和格式化处理并下传. 采用中频采样技术实现星载SAR数据的正交解调和处理,对数字正交解调算法和合成孔径雷达BAQ压缩算法进行分析,完成FPGA的硬件设计和仿真. 结果表明,基于FPGA实现星载SAR中频采样的数据处理方法可行. 与传统模拟方法相比,中频采样系统性能和可靠性都有提高,是未来星载SAR数据处理的发展趋势. 相似文献
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研究了应用于电铁的单相有源电力滤波器,并分析了影响其性能的两个关键环节:谐波电流检测和补偿电流控制.用基于自适应原理的检测法检测出待补偿电流的指令值,并采用三角波调制电流控制方法,使逆变器产生出待补偿电流,来抵消因电铁牵引负荷的使用给电力系统带来的谐波影响.同时在MATLAB/SIMULINK的仿真软件下,建立了电铁牵引系统利用此滤波器进行谐波抑制的仿真模型,验证了方案的正确性和可行性. 相似文献
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传统的多模干涉结构已经被应用在模式分裂器或合成器应用方面上。在这里,多模干涉结构被最优化设计为一种边缘滤波器,应用在了一种集成比率式波长检测仪方面上。一种整体最优化的模拟退火设计法在这篇文章里面得到了介绍和应用,设计方法包括：多模光波导的长度和宽度,输入和输出光波导的位置等等。最优化设计后的器件的光谱响应非常适于波长测量。 相似文献
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最少OTA元件的电控有源多功能滤波器 总被引：1，自引：0，他引：1
由有源RC状态变量滤波器导出了一个新的OTA有源滤波器.该电路可在单一结构的不同端点上同时获得低通、带通和高通滤波功能,且具有很好的电调谐能力.该电路具有低g_m参数变化灵敏度,此外,电路只需要四个OTA元件,这是实现KHN电路所需要的最少元件数. 相似文献
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Optical chromatography involves the elegant combination of opposing optical and fluid drag forces on colloidal samples within microfluidic environments to both measure analytical differences and fractionate injected samples. Particles that encounter the focused laser beam are trapped axially along the beam and are pushed upstream from the laser focal point to rest at a point where the optical and fluid forces on the particle balance. In our recent devices particles are pushed into a region of lower microfluidic flow, where they can be retained and fractionated. Because optical and fluid forces on a particle are sensitive to differences in the physical and chemical properties of a sample, separations are possible. An optical chromatography beam focused to completely fill a fluid channel is operated as an optically tunable filter for the separation of inorganic, polymeric, and biological particle samples. We demonstrate this technique coupled with an advanced microfluidic platform and show how it can be used as an effective method to fractionate particles from an injected multicomponent sample. Our advanced three-stage microfluidic design accommodates three lasers simultaneously to effectively create a sequential cascade optical chromatographic separation system. 相似文献
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Supported lipid bilayer (SLB) platforms have been developed to transport and separate membrane-embedded species in the species'' native bilayer environment. In this study, we used the phase segregation phenomenon of lipid mixtures containing a polymerizable diacetylene phospholipid, 1,2-bis(10,12-tricosadiynoyl)-sn-glycero-3-phosphocholine (DiynePC), and a nonpolymerizable phospholipid, 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC), to create filter barrier structures in SLBs. Upon exposing the phase segregated samples to UV light, the DiynePC-rich domains could become crosslinked and remain fixed on the surface of the support, while the DOPC-rich regions, where no crosslinking could happen, could be removed later by detergent washing, and thus became the void regions in the filter. During the filter fabrication process, we used the laminar flow configuration in a microfluidic channel to control the spatial locations of the feed region and filter region in the SLB. The flow in a microfluidic channel was also used to apply a strong hydrodynamic shear stress to the SLB to transport the membrane-embedded species from the feed region to the filter region. We varied the DiynePC/DOPC molar ratio from 60/40 to 80/20 to adjust the cutoff size of the filter barriers and used two model membrane-embedded species of different sizes to examine the filtering capability. One of the model species, Texas Red 1,2-dihexa-decanoyl-sn-glycero-3-phosphoethanolamine triethylammonium salt (Texas Red DHPE), had a single-lipid size, and the other species, cholera toxin subunit B-GM1 complex, had a multilipid size. When the DiynePC/DOPC molar ratio was 60/40, both species had high penetration ratios in the filter region. However, when the ratio was increased to 70/30, only the Texas Red DHPE, which was the smaller of the two model species, could penetrate the filter to a considerable extent. When the ratio was increased to 80/20, neither of the model species could penetrate the filter region. The results showed the possibility of using phase segregation of a mixture containing a polymerizable lipid and a nonpolymerizable lipid to fabricate filter barrier structures with tunable cutoff sizes in SLBs. 相似文献
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This paper reports a tunable visual color filter based on a microfluidic transmission grating. The grating lines are formed by the microflows in an array of evenly spaced straight microchannels. In experimental study, the transmission of white light measures a shift of visual color from red to blue in the zeroth order diffraction in response to a change of the refractive index from 1.3290 to 1.3782 in the microflows. The merit of large tunability of transmission peak (Δλ=408 nm) makes this grating potential for various applications in biological and chemical measurements, such as space- and time-resolving micropattern spectrophotometers and separation of the fluorescence from the excitation. 相似文献
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《Journal of The Franklin Institute》2021,358(15):7916-7937
In this study, a novel M-estimation based sparse grid quadrature filter (MSGQF) is proposed to improve the robust performance of the nonlinear system. We present a systematic formulation of the sparse grid quadrature filter (SGQF), and extend it to the discrete-time nonlinear system with abnormal measurement values. The M-estimation method is introduced in the SGQF, which uses the Huber’s cost function to update the measurement covariance. Convergence on the modified robust SGQF is established and proved. The sufficient conditions are shown to ensure stochastic stability of the MSGQF. A target tracking problem has been conducted to demonstrate the accuracy of the MSGQF. When measurement abnormal values appear, it outperforms the unscented Kalman filter (UKF), the cubature Kalman filter (CKF) and the SGQF. Theoretical analysis and simulation results prove that the MSGQF provides significant performance improvement in the robustness of the nonlinear system. 相似文献
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《Journal of The Franklin Institute》2021,358(13):6526-6544
This paper investigates a class of nonlinear systems with actuator fault. In particular, fuzzy logic systems have been used to approximate the unknown nonlinear functions, backstepping procedure is adopted to design controller for the system with mismatched condition, command filter is utilized to eliminate the explosion of complexity of the backstepping and also to compensate the output of a filter subjected to the derivative of the virtual control. The stability of the closed-loop system and the convergence of the tracking error are proved via Lyapunov Theorem. In addition, two numerical simulation examples are illustrated the effectiveness of the proposed approach. 相似文献
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Aim is to study the antidiabetic effect of a compound GII purified earlier from the water extract of fenugreek (Trigonella foenum graecum) seeds by Murthy and his colleagues (patented in India and USA) in diabetic rabbits. Diabetes was induced in rabbits by injecting
80 mg/kg bw of alloxan intravenously into rabiits. Rabbits were subdivided into subdiabetic [fasting blood sugar (FBG) up
to 120 mg/dl with abnormal glucose tolerance in glucose tolerance test (GTT)], moderately diabetic (FBG below 250 mg/dl) and
severely diabetic (FBG above 250 mg/dl). Blood glucose and glycosylated hemoglobin (HbA1C) were estimated by procedures in
the kits of Stangen Immunodiagnostics, Mumbai using, respectively, glucose oxidase method and absorbance at 415 nm. Serum
insulin was estimated by the ELISA method as described in the kit of Boehringer Mannheim Immunodiagnostics, Mumbai, India.
GII was found to improve blood glucose utilization in GTT and reduced FBG and HbA1C. In the present communication detailed
studies were carried out with GII in the subdiabetic, moderately diabetic and severely diabetic rabbits. GII at a dose of
50 mg/kg bw per day brought down the elevated FBG levels in the untreated subdiabetic (FBG 96.6 ± 7 mg/dl), moderately diabetic
(150.1 ± 14 mg/dl) and severely diabetic rabbits (427 ± 46 mg/dl) to normal in 12, 15 and 28 days of treatment. It improved
serum HbA1C and insulin levels also in these rabbits. Intermittent therapy once a week for 6 weeks with GII at the same dose
brought down the FBG values to normal in the subdiabetic (FBG 96.0 ± 2 mg/dl) and in the moderately diabetic rabbits to 133.0 ± 12 mg/dl.
After stopping therapy of the subdiabetic and moderately diabetic rabbits whose FBG values came to normal after treatment
with GII 50 mg/kg bw, the values remained normal for 1 week and showed a tendency to increase only after 15 days. If these
animal studies are applicable to humans these results indicate that a diabetic person need not take GII daily when once the
FBG value comes to normal or near to normal. Patients might be able to take GII only when the FBG value shows tendency to
increase. So, intermittent therapy is possible with the potent product GII of the fenugreek seeds which is of a great advantage. 相似文献