基于Multisim2001的DSB信号的调制与解调

随着计算机技术的发展,计算机辅助分析与设计在当今的电子线路设计中得到越来越广泛的应用。文章介绍了电路设计仿真软件Multisim2001功能和特点,并以Multisim2001软件在高频电子线路中对DSB信号的调制与解调的仿真分析方法为例。说明了用Multisim2001在电子电路的仿真分析方法。实例表明,使用Multisim1001不但提高了分析和设计效率,而且有助于提高学生的兴趣,培养创新能力。     

一种数字式全隔离信号采集电路的设计

设计了一款数字式高速全隔离的信号采集电路。以V/F、F/V变换实现了模拟信号的传输,以红外通信来实现采集板和处理板之间的通信,以高速A/D实现了对模拟信号的采集。经测试,达到了预期的设计效果,具有较高的实用价值。     

频率键控调制解调电路的设计

主要在频率键控FSK（Frequency-shift keying）技术的基础上,对频率键控调制解调电路的设计进行阐述,力争设计出体积小、功耗低、集成度高、抗干扰能力强的调制解调电路,符合未来通信技术设计的发展方向。     

2DPSK的调制解调及其SystemView仿真

对两种解调方式建立模型以及调制方法,从理论上解释2DPSK的解调原理,采用SystemView 软件进行仿真,并对两种模型的仿真过程及结果进行分析和比较.     

基于数字式锁相环的双向差动相位解调法设计

设计了应用于高精度干涉测量系统的双向差动相位解调法,利用锁相环的分频特性对测量信号进行降频处理,增加计数脉冲的数量,再结合双向差动相位解调法对信号进行鉴相,从而提高测量分辨力.在He-Ne双频激光外差偏振干涉信号处理实验装置中进行了实验,证明了该方法能够提高测量精度.     

基于DFB激光器的光纤光栅多路温度解调系统

介绍了一种基于DFB激光器和光纤光栅传感器多路测温系统的详细设计方案.分析了多路光纤光栅传感器测温的结构及其工作原理,并以STM32F107VCT6和AD7606为主控板核心,给出了该系统软件控制过程和硬件电路设计.实践表明,该系统测温精度高、测温范围广、使用方便、抗电磁干扰能力强、成本低、体积小,可以广泛用于各种电力系统设备多点测温.     

一种高精度I/F变换器的研究

捷联惯导系统中的加速度计是重要的惯性测量器件,其输出通常为模拟信号电流,目前电流的测量精度提高受到限制。本文通过电流频率变换器将其变换为与周期成正比的脉冲信号从而更精确的测量并且更便捷的采集数据。本文介绍了一种采用电流电压变换模块,AD模数转换器和AVR单片机构成的高速、高精度的电流频率变换系统,从而将传统的I/F变换精度从10-3提高到10-5。     

多极旋转变压器信号的软件解调实现

针对多极旋转变压器信号采用软件进行解调实现时遇到的四个问题:相位漂移、噪声干扰、相位调整和实时性,给出了详细的分析和有效的解决办法,具有良好的工程应用价值。     

基于AD6220调制样式识别信号预处理的实现

运用软件无线电的思想,使用AD6640和AD6620两种芯片,实现了信号调制方式识别的预处理。     

基于AD537V/F转换器的高精度智能测温仪设计

介绍了利用铂电阻PT1000作为温度传感器,以高精度、高线性度的电压/频率转换器AD537构建的高精度智能温度测量系统.利用AD537直接将电阻值转换成频率信号,供后续微处理器进一步处理.减少了一般测量系统中用电阻-电压转换电路以及信号调理电路带来的误差.经实际应用表明,此系统实现了高精度的温度测量,使误差不超过±0.2℃.     

Optical near-field harmonic demodulation in apertureless microscopy

Spatial derivatives of the optical fields scattered by a surface can be investigated by apertureless near-field optical microscopy by modulating sinusoidally the probe to sample distance and detecting the optical signal at the first and higher harmonics. Demodulation up to the fifth harmonic order has been accomplished on a sample of close-packed latex spheres by means of the silicon tip of a scanning interference apertureless microscope. The working principles of such microscope are reviewed. The experimental configuration used comprises a tuning-fork-based tapping-mode atomic force microscope for the distance stabilization, and a double-modulation technique for complete separation of the topography tracking from the optical detection. Simple modelling provides first indications for the interpretation of experimental data. The technique described here provides either artefact-free near-field optical imaging, or detailed information on the structure of the near fields scattered by a surface.     

罗兰-C数据解调与解码技术研究

罗兰-C数据通信已经成为罗兰-C系统扩展应用的重要方向,BPL长波授时系统和"长河二号"系统相继采用"Eurofix"技术实现了通信导航一体化。在对罗兰-C数据调制编码方式——三态脉冲位移字平衡调制、RS(Read-Solomon)和CRC(cycli-cal redundancy check)编码技术研究的基础之上,提出了一种基于交叉相关检测的罗兰-C数据解调、解码方法,并从数据获取、解调判决准则、RS纠错解码和CRC循环校验等方面详细论述了罗兰-C数据解调与解码的具体方法和算法流程,解决了罗兰-C接收机数据信息接收的关键技术。     

相差式测量仪表零点误差的分析

本文在典型的相差式测量仪表基本结构的讨论基础上,分析了电路系统中两信号通道模拟单元相位特性的差异以及数字单元中转换环节等在时间动态特性上的非一致性,从而揭示这类仪表零点误差的来源,形成及特点。本文的工作为研究在线自动校正技术提供了重要的依据。     

共振解调技术在设备故障诊断中的应用

共振解调技术是利用冲击脉冲含有无限丰富频谱成分的特点来提取设备在运转过程中存在的冲击故障的一种有效方法.介绍了共振解调技术在国内外机械设备故障诊断中的应用情况,通过齿轮的仿真数据验证了共振解调提取微冲击信号的有效性,并且利用该技术成功提取了某钢厂精轧机振动信号中的故障信息.     

Quantification of the modulated structures in TiPdCr alloys

Ti₅₀Pd_(50-x)Cr_xβ₂ alloys (B2, CsCl-type crystal structure) have been investigated as part of an overall study of the systematics of phase transformation behaviour and also for the commercial applicability of the shape memory effect at elevated temperatures. The phase transformations are unique in the sense that electron diffraction and high-resolution transmission electron microscopy of Ti₅₀Pd_(50-x)Cr_x alloys with x between 6 and 10 at.% reveal {110}_B2 modulated structures with periodicities between 3 and 4·5 planes that vary linearly with composition. Satellites along certain <110>* lying at incommensurate positions are observed in electron diffraction patterns and are consistent with transverse lattice displacements. High-resolution transmission electron microscopy (HRTEM) imaging usually reveals sinusoidal displacements; however, a few images appear ‘banded’ at three- and four-plane intervals suggesting the possibility that three- and four-plane commensurate packets combine to give the overall incommensurate satellite spacing. With the use of a newly developed technique for quantifying atomic displacements from HRTEM images, modulated phases in Ti₅₀Pd₄₃Cr₇ and Ti₅₀Pd₄₂Cr₈ alloys, where atoms are shifted from the cubic lattice sites by a transverse lattice displacement wave, have been studied. The real space displacements of the modulated structures were determined and compared to truly incommensurate and varying three- and four-plane wave packet combinations by examination of the goodness of fit as assessed by the correlation coefficient for a least-squares fit. In the cases of the Ti₅₀Pd₄₃Cr₇ and Ti₅₀Pd₄₂Cr₈ alloys, the incommensurate sine wave exhibited much better matching than the commensurate packets, indicating that these modulations are probably incommensurate.     

超声波测流技术和超声波流量计的应用

本文总结了超声波流量计测量技术的重点和难点,从仪表性能和测量的经济性、实用性等方面总结了超声波流量计应用的原则,对使用中如何选位、安装、维护提出了具体的建议。     

真空紫外反射率的测定

研制了一台测定真空紫外反射率的仪器.在真空紫外区可测量各种反射元件在不同入射角下的反射率.用壁稳氩弧光源在100—200um区对Al十MgF₂薄膜和CVD法制备的SiC镜的反射率进行了测定.并与Al膜的理论反射率曲线做了比较.     

The application of quadrature demodulation techniques for the investigation of flows

Quadrature demodulation is presented as a promising LDA-signal processing technique for the evaluation of pedestal free quadrature burst signal pairs in the base band. In difference to conventional techniques, the signal evaluation is performed in the time domain, where the primary information is given by the phase angle time function which directly corresponds to the path time function of a tracer particle in the measuring volume. Thus it is possible to measure the location, as well as the magnitude and sign of the velocity and the acceleration of single tracer particles in the measuring volume with high temporal resolution.     

基于EMD和Hilbert解调的齿轮箱故障诊断

针对复杂的齿轮箱振动信号难以提取出故障特征频率的问题,提出了一种将希尔伯特包络解调技术与经验模式分解(EMD)相结合的分析方法。首先对齿轮箱的故障信号进行了EMD分解,得到了本征模态函数(IMF分量),再对IMF分量进行了包络解调,得到了其调制信号,结合调制信号的频率成分可初步判断出齿轮箱中出现故障的齿轮;然后根据IMF分量与初始信号之间相关系数的大小,选择相关系数较大的分量重构信号,相当于对初始信号进行滤波;最后对重构的信号以啮合频率及其倍频为中心频率进行了带通滤波,对得到的信号进行了包络解调分析,再次进行了故障诊断,以验证故障诊断的准确性。整个过程通过对齿轮箱实测故障信号的分析加以验证。研究结果表明,该方法能够准确地提取出齿轮箱的故障特征频率,从而可以对齿轮箱故障进行有效地诊断。