2.5Gb/s Ga As MESFET定时判决电路

设计了 2 .5 Gb/ s光纤通信用耗尽型 Ga As MESFET定时判决电路 .通过 SPICE模拟表明恢复的时钟频率达2 .5 GHz,判决电路传输速率达 2 .5 Gb/ s.实验证明经时钟信号抽样后判决电路可产生正确的数字信号 ,传输速率达 2 .5 Gb/ s     

一款低不圆度WLAN 双频天线的设计与实现

提出了一种改进型的应用于无线局域网的双频印刷单极子天线。该天线可以覆盖IEEE 802. 11a/ b/ g (2. 4 ~2. 484GHz,5. 15 ~5. 825GHz)频段标准,其回波损耗小于10dB 的阻抗带宽在2. 4GHz 频段可达290MHz(2. 28 ~2. 57GHz),在5GHz 频段可达5. 53GHz(4. 34 ~9. 87GHz)。另外,在工作频带内,还获得了良好的全向辐射方向图 和天线增益。该天线的总体尺寸为22mm×44mm,结构紧凑, 且具有不圆度低、成本低和易于集成等优点, 因此具有 十分良好的应用潜质。     

一种RFID 双频微带天线的设计

提出了一种小型双频微带天线设计,用于手持式RFID 阅读器。采用矩形贴片和E 形贴片结构,利用空腔模型理论中短路加载和耦合谐振技术,实现了微带天线的小型化和双频性能。尺寸大小为30 mm×30 mm。工作频带则覆盖RFID 技术常用微波段2. 45 GHz(2. 4～2. 484 GHz)和5. 8 GHz(5. 725～5. 825 GHz)频段。使用HFSS软件进行了仿真优化,并对天线实物进行测试,与仿真结果吻合。最后得到的低频带宽在2. 40～2. 47 GHz,高频带宽在5. 67～6. 25 GHz,最大增益分别为2. 6 dBi 和4. 4 dBi。     

美国军用无线电频段的新命名

据JANE,5 Mil.comm,2982年报导,美国军用无线电频段采用新的命名。 频段频率范围 A 20一SOMHz B 250一500MHz C 500MHz一IGHz 1.浇 J K L M老式命名是: 频段 I 1一2 GHz 2一3 GHz 3一4 GHz 4甲一6 GHz 6一8 GHz 8一10 GHz 10一20 GHz 20一40 GHz4了‘60 GHz60一100 GHz XS。2一19 GHz K 19一36GHz Q 36一46GHz V 46一56GHz附加e 3.9一6.2GHz Ku 12.5一18GHz频谱的划分仍按旧式命名: ELFO一3 kHz极低频 VLF3一30 kHz甚低频 LF 30一300kHz低频 MF 3O0kHz一3MHz中频 HF3一30MHz高频 VHF 30一300MHz甚高频 …     

瑞萨科技高性能硅锗单片微波集成电路

瑞萨科技公司（Renesas Technology）推出一种用于无线局域网终端发射功率放大器的高性能2．4GHz／5GHz双模硅锗（SiGe）单片微波集成电路（MMIC）HA31010。HA31010的主要特性如下：2AGHz／5GHz双模操作，在单个芯片中集成了支持IEEE802．1lb／g无线局域网标准的2．4GHz频段放大器电路，和支持IEEE802．11a标准的5GHz频段放大器电路；     

脉幅有序变化OTDM信号的支路及群路全光时钟提取

将含暗帧脉冲的 4× 2 .5GHz的光时分复用 (OTDM)信号注入一含半导体光放大器 (SOA)的锁模光纤激光器 ,利用SOA的交叉增益调制效应 ,提取出 2 .5GHz的支路时钟信号和 5GHz,10GHz的群路时钟信号 ;群路时钟的提取机制是有理数谐波锁模机制。光时分复用信号采用暗帧脉冲不但可以用来识别支路信号 ,而且显著提高了支路时钟信号的质量     

一种新型陷波超宽带天线的设计

文章设计了一种具有陷波特性的超宽带印刷天线,使用高频结构仿真软件HFSS11.0对天线尺寸进行仿真和优化,对天线的阻抗特性、方向图进行了研究.仿真和测试结果表明,该天线在2.3GHz-5GHz和5.9GHz～12.6GHz的工作频段内电压驻波比小于2,且具有稳定的方向图;在5GHz～5.9GHz的阻带范围内具有良好的陷...     

安德鲁推出适于移动且降低干扰的新型WiMAX天线

近日，全球通讯系统与通讯产品的领导者安德鲁公司推出了一种新型的天线，以迎合在2．5GHz（2．3～2．7GHz）频谱范围内建立wiMAx无线网络的需要。     

一种基于仿生学的小型双陷波超宽带天线

基于仿生学原理,以对称牛头形设计了一款小型超宽带双陷波功能微带天线。该天线包括带有“牛角”的对称牛头形的主体辐射单元,采用共面波导结构进行馈电。通过仿真及实验验证可以看出该天线在3. 3 ～3. 8GHz 和5. 0～5. 5GHz 具有良好的陷波特性,天线的驻波比从2.1GHz 覆盖到了14.4GHz (VSWR<2),相对阻抗带宽超过了149%。     

一种基于键合线电感的LC-VCO设计方法

提出一种利用键合线电感设计VCO的方法,利用HFSS(High Frequency Structure Simulator)软件,建立电感仿真模型,在5 GHz以下与库模型相吻合.仿真结果表明,差分键合线电感受工艺偏差的影响小于15%,并提出一种减小互感的方式,使电感值在1～5 GHz范围内增加15%～175%.利用HFSS提取的等效电路,设计了一款输出频率为2～3.6 GHz的宽带压控振荡器(VCO),当工作在3.6 GHz时,1 MHz频偏处的相位噪声为-111 dBc/Hz,电流为1.5 mA.电路版图面积仅为0.1 mm2,较之采用片上电感的VCO(0.19 mm2),面积减小45%.     

Multirate Sampling Method for Acceleration Control System

This paper focuses on the realization of high-performance motion control based on acceleration control. A disturbance observer is used to construct an acceleration control system. A high sampling frequency is known to be effective for improving the performance. Characteristics of acceleration control are investigated to discuss the relationship between the performance and a sampling frequency of the system. The needs for a high sampling frequency for an output are then described. Based on these considerations, a novel multirate sampling method for the acceleration control system is proposed. An output sampling period is set shorter than an input sampling period, and control calculation is executed at each output sampling period in the method. The disturbance observer is redesigned for application to the multirate system. Stability analysis is performed to verify the validity of the proposal. Feasibility of the proposed method and its influence on the performance are also verified by experimental results     

Efficient Reconstruction Algorithms Using Shifted Lattices

In this paper, we consider sampling theory for irregular sampling sets of minimal density which are structured. An efficient method for the reconstruction of band-limited discrete signals from sampling sets which are unions of shifted lattices is developed. These sets are not necessarily periodic. A signal can be reconstructed from its samples provided the sampling set and the spectrum of the signal satisfy certain compatibility conditions. While explicit reconstruction formulas for unions of sampling lattices are possible, it is more convenient to use a recursive algorithm. A numerical example utilizing nonperiodic sampling sets implemented in MATLAB is given. The theory and the related algorithm has been applied to speech and image processing examples.     

Practical consideration for bandpass sampling

The uniform bandpass sampling theorem has been modified to cope with sampling frequency instability and carrier frequency variations. Minimum sampling rates for given sampling and carrier frequency variations are derived. A robust bandpass sampling method is proposed which requires the sampling frequency to be such that the carrier frequency is on the 1/4 or -1/4 sampling frequency grid     

A 2.4 GHz CMOS sub-sampling mixer with integrated filtering

A sub-sampling mixer that incorporates sampling switches and hold capacitors into the parallel resonant LC load of an LNA is proposed. The noise figure of the proposed sub-sampling mixer is lower than that of a standard sampling circuit because the proposed mixer has narrow-band gain and input noise filtering properties. A novel level-shifting clock buffer with fast rise and fall times to drive the mixer sampling switches is presented. The mixer was fabricated in a 0.18 /spl mu/m CMOS process and measured results are presented for an RF input frequency of 2.42 GHz and a sampling frequency of 100 MHz. With a measured noise figure of 21.8 dB, the proposed circuit shows improved performance compared to other published sub-sampling mixers.     

水质化学需氧量检测的自动进样器的研制

摘要： 重铬酸盐法测定水质化学需氧量过程中,针对传统的手工进样安全性差、精度不高等缺点,研制了一种用于实验室水质化学需氧量检测的新型自动进样装置。同时也可以用于强腐蚀性液体进样,装置可以满足16个试管进样,通过触摸屏的参数设置,可以调整进样顺序,进样次数,进样时间。设计中采用液位传感器和定量聚四氟乙烯管,提高了进样的精度,保证在1ml以内。实验结果证明该装置有效克服了实验室人工进样操作时间长、操作复杂、进样精度差的问题。     

导航信号的射频直接采样与数字下变频方法

研究导航信号的射频直接采样与数字下变频方法,并对1.2GHz和1.5GHz2个频点附近的导航信号进行了仿真验证。首先运用带通采样原理,选择合适的采样频率完成对导航信号的射频直接采样,然后结合积分梳状滤波器、半带滤波器,对采样后的信号进行抽取滤波,实现了降采样率的目的。最后,通过Matlab对5个频点的导航信号进行了仿真验证,完成了导航信号的射频直接采样并降低了采样率,恢复且分离了原始导航信号,从而验证了射频直接采样与数字下变频方法是可行的。     

A Cost Effective Reference Data Sampling Algorithm Using Fractal Analysis

A random sampling or systematic sampling method is commonly used to assess the accuracy of classification results. In remote sensing, with these sampling methods, much time and tedious work are required to acquire sufficient ground truth data. So, a more effective sampling method that can represent the characteristics of the population is required. In this study, fractal analysis is adopted as an index for reference sampling. The fractal dimensions of the whole study area and the sub‐regions are calculated to select sub‐regions that have the most similar dimensionality to that of the whole area. Then the whole area's classification accuracy is compared with those of sub‐regions, and it is verified that the accuracies of selected sub‐regions are similar to that of whole area. A new kind of reference sampling method using the above procedure is proposed. The results show that it is possible to reduce sampling area and sample size, while keeping the same level of accuracy as the existing methods.     

Predictive interpolation and decimation of narrow-band signals

A digital filter design and optimization method for sampling rate alteration of narrow-band signals is presented. The resulting predictive finite-duration impulse-response filters are used to remove the aliasing or imaging frequency components when the sampling rate is changed. The sampling rate can be changed either by an integer factor or a rational factor. A least-squares-based generalization is developed for optimal wide-band noise attenuation     

A new approach for estimating spectra from randomly sampled sequences

Random sampling is one of the methods that can overcome the Nyquist limit when evaluating a frequency spectrum of a signal. However, the computational complexity becomesN ² as the FFT cannot be used. A new approach, called hybrid additive random sampling, is proposed. This new scheme is devised by concatenating random sampling sequences in such a way that symmetry is created in the transform kernel for reducing the computational effort while the anti-alias property is maintained. A savings of the least 75% in computation is achieved. The sampling scheme is also found to be suitable for parallel implementation. In this paper, the algorithms for generating the sampling sequence and evaluating the spectrum are described in detail. The performances of the scheme in terms of noise, accuracy, etc., are compared with genuine random sampling and another approach proposed previously. The advantages and limitations are included.     

Mixed-mode sampling and error estimation in digital wattmeters

The problem of estimating the error due to the discrete-time approximation in sampling digital wattmeters is dealt with. The complementary characteristics of two different sampling strategies, based on equally spaced or randomly generated sampling instants, are discussed. A mixed-mode sampling strategy, which can also provide an estimate of the error, is proposed.