An interface circuit for high-accuracy signal processing ofdifferential-capacitance transducers

The architecture is based on the idea that the ratio of one of the transducer capacitances to its total capacitance represents the offset binary equivalent of the physical quantity under measurement. An opamp-based capacitance-to-voltage converter is commonly used for capacitance detection, and an analog-to-digital (A/D) converter is used for the ratiometric operation. Analyses show that the interface can detect a capacitance change as small as 0.01% of the total capacitance. Experimental results are also given to confirm the analyses     

A digital filter chip for ECG signal processing

A VLSI implementation of a linear-phase digital filter for ECG signal processing has been designed. With a sampling rate of 100 Hz, the passband is from 0.5 Hz to 49.5 Hz with 0.5-dB ripple. The filter architecture is based on the use of recursive running-sum blocks, resulting in a very low computational complexity. Module generators have been used in the layout design for high integration density. The circuit has been designed for a 2.0-μm double-metal CMOS technology, having about 34000 transistors and a 15.43-mm² chip area     

机械信号处理的BSS算法及其比较研究

在由多个独立振动构成的复杂机械振动的状态监测和故障诊断中,复杂机械信号的分离和识别的效果往往是其故障诊断成功的关键.为了得到最佳的机械信号分离算法,对5类经典的盲源分离(BSS)算法的特点和性能进行了比较研究,提出了一套评价准则,使用典型的仿真机械信号,对其在机械故障诊断中的典型机械信号的分离效果进行了充分的实验和详细评估.之后,运用两组来自真实工业设备部件的振动数据去检验其结果.研究结果表明不同的BSS算法具有各自的特点,对处理不同类型的机械信号有不同的效果,其结果有指导意义.     

A novel signal processing technique for eddy-current testing ofsteam generator tubes

In eddy-current testing of steam generator tubes of nuclear power plants, the signals of defects may be corrupted by noise and other nondefect signals arising from the probe lift-off and the structures attached to the tubes, resulting in unreliable detection and inaccurate characterization of defects. In this paper, a novel signal processing technique is presented to reduce the noise and nondefect signals by the use of a wavelet transform. The noise and nondefect signals are reduced by first decomposing testing signals into wavelet components and then modifying the wavelet coefficients. The defect signals embedded in noise and nondefect signals are reconstructed through the inverse wavelet transform of the modified wavelet coefficients. The results of processing the one-dimensional and two-dimensional signals from eddy-current testing of tube test pieces show that this signal processing technique is effective for extracting defect signals embedded in noise and nondefect signals     

A new signal processing technique for d=1 channel codes

This paper presents a strategy for reducing nonlinearities at high-recording densities; new additional encoding scheme for DC-free d=1 channel codes, and, a partial response (1+D) system with 2-bit decoding. This encoding scheme, which to DC-free codes, reduces by one bit transition interval of d=1 codes, and ensures a wide margin of timing offset. In order to use erasures for the error correction code, the 2-bit decoding scheme is employed in-parallel to detect errors in the decoding procedure. An improvement in the error rate by using parallel decoding is shown     

超声换能器接触界面的非线性谐波

超声波在换能器中的非线性不仅引起劈刀振动的混乱而且导致芯片键合的失效,本文建立了超声波在接触界面传播的模型,并进行了数学仿真,最后在试验平台上采用多普勒测振仪测量了不同接触界面压力条件下的劈刀的振动波形,用剪切强度测试仪测试了键合强度。波形的畸变和高次谐波的产生是由于接触界面层的非线性引起的,为了保证键合强度应该将变幅杆和劈刀之间的拧紧力矩设定在一个合适的范围内,使接触界面层材料的二阶非线性系数最小。可以通过检测劈刀的高次谐波来反映超声键合的强度。     

Intelligent signal processing for detection system optimization

A wavelet-neural network signal processing method has demonstrated approximately 10-fold improvement over traditional signal processing methods for the detection limit of various nitrogen and phosphorus compounds from the output of a thermionic detector attached to a gas chromatograph. A blind test was conducted to validate the lower detection limit. All 14 of the compound spikes were detected when above the estimated threshold, including all 3 within a factor of 2 above the threshold. In addition, two of six spikes were detected at levels of half the concentration of the nominal threshold. Another two of the six would have been detected correctly if we had allowed human intervention to examine the processed data. One apparent false positive in five nulls was traced to a solvent impurity, whose presence was subsequently identified by analyzing a solvent aliquot evaporated to 1% residual volume, while the other four nulls were properly classified. We view this signal processing method as broadly applicable in analytical chemistry, and we advocate that advanced signal processing methods should be applied as directly as possible to the raw detector output so that less discriminating preprocessing and postprocessing does not throw away valuable signal.     

Interferometric all-optical switches for ultrafast signal processing

All-optical switches find applications in ultrahigh-speed network-user interfaces and in specialized high-speed processors, such as data regenerators and encryptors and microwave signal generators. We describe a semiconductor optical-amplifier-based single-arm interferometric switch called the ultrafast nonlinear interferometer. We discuss how the gain and the refractive-index nonlinearities in semiconductor optical amplifiers have an impact on the all-optical switch design, and we review experimental results obtained with the ultrafast nonlinear interferometer.     

Certification of signal processing algorithms for analytical instruments

Translated from Izmeritel'naya Tekhnika, No. 7, pp. 7–9, July, 1990.     

一种窄带水声信号数字处理系统

针对窄带水声接收机参数估计精度低、目标识别能力差的弱点,提出了数字鉴宽的概念及方法,利用复杂可编程逻辑器件(Complex Programmable Logic Device, CPLD)实现对窄带水声信号宽度的精确识别.该方法可广泛适用于数字滤波和机械滤波窄带水声接收电路,鉴宽结果性能稳定、可靠,可满足大多数窄带水声系统对信号及其宽度识别的精度要求.同时,根据实际水声系统对水声接收机增益调节的需要,提出了利用MSP430单片机及 D/A器件实现水声接收机手动及自动增益控制的方法,它可应用于各种水声接收电路中.所提出的窄带水声信号处理方法有算法简便、实用的优点,使用的理想效果在实际应用中得到了验证.     

一种对超声波连续检测系统中回波信号处理的新方法

“喷淋水耦合多探头高能超声动态检测系统”能对各种刚性管材各处的壁厚进行高速、连续的探测,系统检测效果取决于对回波信号的处理.文章探讨了利用放大及逻辑运算等电路处理方法来处理回波信号以获得稳定的壁厚脉冲的新方法,采用这种新方法还可以通过计算机检测系统多图形地显示壁厚曲线、超标报警.     

A model for signal processing and predictive control of semi-active structural control system

The theory for structural control has been well developed and applied to perform excellent energy dissipation using dampers. Both active and semi-active control systems may be used to decide on the optimal switch point of the damper based on the current and past structural responses to the excitation of external forces. However, numerous noises may occur when the control signals are accessed and transported thus causing a delay of the damper. Therefore, a predictive control technique that integrates an improved method of detecting the control signal based on the direction of the structural motion, and a calculator for detecting the velocity using the least-square polynomial regression is proposed in this research. Comparisons of the analytical data and experimental results show that this predictor is effective in switching the moving direction of the semi-active damper. This conclusion is further verified using the component and shaking table test with constant amplitude but various frequencies, and the El Centro earthquake test. All tests confirm that this predictive control technique is effective to alleviate the time delay problem of semi-active dampers. This predictive control technique promotes about 30% to 40% reduction of the structural displacement response and about 35% to 45% reduction of the structural acceleration response.     

故障滚动轴承振动信号的半盲处理方法研究

利用旋转机械的振动信号的循环平稳特性,采用基于二阶统计量（Second Order Statistic,SOS）的盲均衡技术从多个传感器信号中恢复出“真实的”振动源信号,实现了同类信号的数据级融合。以滚动轴承故障信号的阶次谱结构为先验知识,提出了用于滤波性能评价的两个指标,实现了盲均衡滤波器参数的优化,从而给出了一种可用于滚动轴承故障诊断的半盲信号处理方法。采用某型单级减速齿轮箱的实验数据验证了该方法的有效性。     

Digital signal processing for an open-loop fiber-optic gyroscope

Open-loop fiber-optic gyroscopes (FOG's) are generally less stable than closed-loop FOG's, yet they offer simpler implementation. We propose a modification of the harmonic division algorithm for an open-loop FOG, which is more stable and also simpler for implementation than the original one. It is shown that when the analog signal is properly sampled and quantized, the performance of our algorithm reaches that of closed-loop FOG's. Our algorithm may be implemented by the use of off-the-shelf component, and does not require an integrated optics circuit.     

核磁共振测井信号调理与回波提取技术研究

针对核磁共振激励发射信号CPMG序列的特点,采用一种微弱信号调理技术对核磁共振回波信号进行预处理以便于回波信号的提取,并提出了一种相敏检波算法以提取相应的微弱回波信号.信号接收调理电路设计采取了隔离板与前置放大板配合协调工作,以达到防止高压发射信号冲击和微弱信号调理的作用.目前已经利用该信号调理技术与DPSD算法成功提取出相应的核磁共振回波信号.