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Instrumentation and Measurement, IEEE Transactions on

Issue 6 • Date Dec 1994

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Displaying Results 1 - 25 of 30
  • Calculation of the partial capacitance in a system of conductors within the calculable resistor

    Page(s): 929 - 932
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (292 KB)  

    A method for calculating the partial capacitance (PC) in a multiconductor system (a system of conductors) consisting of n conductors parallel to the shield axis inside earthed cylindrical shields is discussed. Formulas for the PC in SI units are given. The PC is defined as the conductor-to-conductor capacitance and conductor-to-shield capacitance. These methods and formulas are suitable for calculating the PC of Gibbings' resistors with a calculable ac/dc resistance ratio View full abstract»

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  • Improvement in the linearity of fast digital oscilloscopes used in averaging mode

    Page(s): 922 - 928
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (552 KB)  

    Accurate measurement of signals with very fast variations between values separated by several orders of magnitude is difficult. When signals are periodical, a fast digital oscilloscope may be used in averaging mode, but the measurement accuracy is mainly limited by analog-to-digital conversion (ADC) nonlinearity. In this paper, several methods for improving the conversion linearity are proposed. These methods are theoretically justified and experimentally validated. Several of these methods may be used simultaneously by an 8-bit digital oscilloscope to provide, in averaging mode, the linearity of an 11- or 12-bit ADC View full abstract»

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  • An automated electro-optic probing system for ultra-high-speed IC's

    Page(s): 843 - 847
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (488 KB)  

    This paper describes an automated optical probing system based on external electro-optic sampling for the internal diagnoses of ultra-high-speed IC's. A workstation-controlled environment, automatic probe positioner, and module-based system architecture make the system easy to use, and improve measurement accuracy and reproducibility. Voltage sensitivity is routinely obtained on an order of 1 mV/√(Hz) at frequencies up to 70 GHz. The system has been successfully applied to the internal-node measurement of on-wafer digital IC's operating at 20 Gb/s View full abstract»

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  • A single-mode optical fiber attenuator for intercomparison of attenuation

    Page(s): 837 - 842
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (396 KB)  

    This paper presents the results of the investigation for developing an attenuator to be used in an intercomparison of attenuation values in single-mode optical fiber systems. The attenuation measurements in single-mode systems have a polarization-dependence problem corresponding to the mode-dependence problem in the multimode fiber systems. Therefore, an attenuator in which a small polarizer is placed was developed in order to obtain polarization-independent characteristics. If this attenuator is used as a transfer standard for the measurement comparison, any reference condition on polarization will not be required View full abstract»

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  • Position detection of multiple light beams using phase detection

    Page(s): 830 - 836
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (548 KB)  

    Earlier work on lateral-effect position-sensitive detectors (PSD) has used an amplitude detection signal-processing scheme to determine the position of the centroid of the incident light beam on the PSD surface. In this work we introduce a phase detection method of position measurement which is based on detecting the phase difference between the sinusoidal currents flowing through the metal electrodes. A distributed transmission line model for the PSD and a one-pole model for the transimpedance preamplifier are used in the analysis of the sensor. Experimental results are presented and are found to be in close agreement with simulation results. It is seen that the spatial resolution is proportional to the modulation frequency. With a light modulation frequency of 50 kHz and the introduction of frequency multiplication (×8) after the transimpedance preamplifier, a spatial resolution of 2 μm is demonstrated. For application in multi-degree-of-freedom position sensors, we demonstrate the simultaneous detection of centroids of multiple light beams using frequency division multiplexing. Application of the phase method of position detection to a two dimensional PSD shows a maximum deviation from linearity of 1% over the working range of the PSD View full abstract»

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  • Classification of polynomial-shaped measurement signals using a backpropagation neural network

    Page(s): 933 - 936
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (372 KB)  

    Smoothly varying signals are frequently encountered in the field of instrumentation and measurement, and they can be accurately modeled by low-order polynomials. The order identification is difficult when the measured noisy signal has frequent order variations in the underlying polynomial. In this paper, we introduce a flexible real-time order estimator, which is based on a backpropagation neural network View full abstract»

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  • Calibration of spatially nonuniform sensitivity for a spectral line emission measuring system

    Page(s): 818 - 823
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (428 KB)  

    An apparatus for space- and time-resolved measurements of the spectral line emission from glow discharge plasmas is described. It utilizes two stages of microchannel plate image intensifiers and a computer-assisted data acquisition system. The image intensifiers have a significant level of dark noise, and their sensitivity is spatially nonuniform. The effect of the dark noise is reduced significantly by signal averaging. A calibration procedure using a movable stable source is followed so that quantitative measurements can be obtained despite the spatial nonuniformity View full abstract»

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  • A clock synthesis for switched-capacitor filters using microcontrollers

    Page(s): 943 - 945
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (284 KB)  

    The clock generation by software and by controller timer/counters is considered. The most complex case (when the controller has other tasks besides clock production) is resolved by the adaptable time delay compensation method. This method prevents the jitter which originates due to a different moment of interrupt request acceptance, and thus gives the same level of output clock jitter as for the microcontroller crystal oscillator (150 ps-standard deviation) View full abstract»

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  • Thermally regulated low-noise, wideband, I/V converter, using Peltier heat pumps

    Page(s): 900 - 905
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (548 KB)  

    An ultra-low-noise current-to-voltage converter capable of detecting currents of 1 pA or less in a bandwidth from dc to 20 kHz is described. This instrument exhibits the dc performances typical of a picoammeter together with the low noise level and the wide bandwidth of a modern current-to-voltage converter. Thanks to an excellent dc stability over time, continuous monitoring of phenomena involving currents in the picoampere range can be carried out, for hours or even days. Moreover, ultra-low-noise ac measurements of these currents in the kilohertz range can be performed. A new nonheating thermal controller, using the concept of letting the instrument operate 30°C below room temperature, has been designed and built. Two small Peltier heat pumps have been employed to cool the critical parts of the system, thus achieving a long-term stability of a few hundredths of degrees centigrade. With minor modifications in the input stage of this instrument, a high-transimpedance, ultra-low noise prototype has been built, which shows an input equivalent current noise as low as 4 fa/√(Hz) at 100 mHz View full abstract»

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  • Design rules for an experimental setup using an open-ended coaxial probe based on theoretical modelling

    Page(s): 810 - 817
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (748 KB)  

    In order to obtain a number of design rules for a setup involving an open-ended coaxial sensor to measure the dielectric constant of a material, several parameters are investigated. Using the recently developed spectral-domain model a clear view is given of the influence of the thickness of the test sample. Furthermore, a near-field study of the probe shows that reflections can occur at the transverse boundaries if the test sample is very small. The FDTD is used to investigate the minimum sample size required to simulate a medium that is infinite in the transverse direction. Finally, the influence of the flange of the probe is studied in order to determine the dimensions of the flange needed to correctly use the spectral-domain model View full abstract»

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  • An algorithm for locating short circuits among N signal paths using K-port parallel short detector

    Page(s): 918 - 921
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (340 KB)  

    To locate short circuits on a printed circuit board, a K-port parallel short detector can test K signal paths simultaneously. If the total number of signal paths N on a printed circuit board is larger than K, then we need to divide the testing process into multiple stages such that at most R signal paths are tested in each stage. In this paper, we design a parallel algorithm to locate all the short circuits among the N signal paths on a printed circuit board using a K-port parallel short detector where K<N. This algorithm consists of three main steps: (1) it partitions the set of signal paths {1,2,...,N} into disjoint sets S i's such that Si contains at most K signal paths, and then it bisects Si into two disjoint sets T2i-1 and T2i, (2) it locates all the short circuits in Si for all i, and (3) it locates all the short circuits between Si and Sj for all i≠j by testing T2i-1 against T2j-1, T2i-1 against T2j, T2i against T2j-1, and T 2i against T2j View full abstract»

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  • Analysis, design, and implementation of an AC bridge for impedance measurements

    Page(s): 894 - 899
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (496 KB)  

    The paper reviews the digital AC bridge. A more accurate and thorough analysis of the bridge is presented. Based on the analysis a simple adaptive algorithm is proposed in order to ensure fast conversion. In addition, a new design of the bridge, based on the TMS 320C25, is given. The system is implemented with the Dalanco Spry model 25 DSP board, on a software system designed whereby an IBM PC host computer provides control of the bridge. Experimental results are presented View full abstract»

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  • A neural network approach for identification and fault diagnosis on dynamic systems

    Page(s): 867 - 873
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (732 KB)  

    The possibilities offered by neural networks for system identification and fault diagnosis problems in dynamic systems are investigated. In particular, an original “neural” procedure is illustrated: its sensitivity and response time enable it to be used in on-line fault diagnosis applications. Some examples are also reported. Even though they pertain to a simple linear dynamic system, these examples highlight the general applicability and advantages of a neural approach View full abstract»

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  • Source width insensitive optical position sensor

    Page(s): 848 - 856
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (628 KB)  

    Several position sensors that achieve high-resolution position sensing based on moment calculation of the detected photocurrents from a sensing array have recently been described in the literature. These sensors generally have transfer functions that are independent of source intensity, but are dependent on source shape and size relative to the sensing arrays. This is detrimental in astronomical sensing applications where the sensing array may not be able to completely capture the diffuse source under observation, or where the source may be fluctuating with time. This paper describes a modified sensor system which decreases the errors due to source size variations by subtracting a normalizing current from each photocurrent before processing. The concept is verified using a commercial 1.2 μm CMOS process View full abstract»

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  • An active vertical-direction gravity compensation system

    Page(s): 786 - 792
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (556 KB)  

    To perform simulations of partial or microgravity environments on Earth requires some method of compensation for the Earth's gravitational field. This paper discusses an active compensation system that modulates the tension in a counterweight support cable in order to minimize state deviation between the compensated body and the ideal weightless body. The system effectively compensates for inertial effects of the counterweight mass, viscous damping of all pulleys, and static friction in all parts of the gravity compensation (GC) system using a hybrid PI (proportional plus integral)/fuzzy control algorithm. The dynamic compensation of inertia and viscous damping is performed by PI control, while static friction compensation is performed by the fuzzy system. The system provides a very precise gravity compensation force, and is capable of nonconstant gravity force compensation in the case that the payload mass is not constant View full abstract»

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  • Simple weight-integrating A/D converters with high noise rejection

    Page(s): 912 - 917
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (460 KB)  

    It is shown that the use of simple weight-integrating functions (stepwise or triangle) in integrating A/D converters ensures a high level of noise rejection (NMRR-up to 80 dB if the actual period of power line-related noise differs from its nominal value by less than ±1%). This result can be improved (with NMRR up to 90 dB and more) if the time of weight integration is synchronized with the actual or predicted noise period. Theoretical and experimental data are considered and discussed View full abstract»

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  • Integrated instrumentation amplifier for the phase readout of piezoresistive strain gauges

    Page(s): 906 - 911
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    An integrated instrumentation amplifier combined with a bandpass filter has been fabricated in a bipolar process for the phase readout of piezoresistive sensors. Changes in the resistance can be measured directly using an ac-operated bridge configuration. A special technique has been employed to convert these changes into a phase angle relative to the excitation signal. The instrumentation amplifier should have a very high Common-Mode Rejection Ratio (CMRR) at a relatively high bridge operating frequency (100 kHz) in order to actually exploit the advantages of this readout method. The filter should have a well-determined phase behavior to prevent a change in the frequency from affecting the output phase angle. Special emphasis has been placed on the compatibility between micromachining technologies in silicon and bipolar processing, so that a fully integrated smart silicon micromechanical sensor can be made View full abstract»

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  • Measurement of the thickness of dielectric thin films on silicon photodetectors using the angular response to incident linearly polarized light

    Page(s): 799 - 802
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (324 KB)  

    A simple and accurate technique for measuring the thickness of dielectric thin films on solid state photodetectors is described. It is based on the angle-of-incidence-dependent response of the detector to incident p(TM)- or s(TE)-polarized monochromatic light. The method is applied to determine the thickness of SiO2 films on planar-diffused Si photodiodes to within ±1 nm View full abstract»

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  • A wideband analog continuum correlator for radio astronomy

    Page(s): 782 - 785
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (312 KB)  

    Design details for a 1-GHz bandwidth analog continuum cross-correlator for the Owens Valley Millimeter Array are presented. The correlator uses a pair of microwave mixers fed in phase quadrature to realize a complex multiplier for each baseline in the array. Very fast 180° phase switching is included to reject spurious signals View full abstract»

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  • A novel frequency calibration device using color television subcarrier

    Page(s): 945 - 946
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (172 KB)  

    The conventional frequency calibration devices using the color television subcarrier, utilize a frequency synthesizer to generate the calibrated frequency signal into the signal which is the same in nominal frequency with the chroma subcarrier signal. Then it is calibrated by the phase comparison method with the 3.57 MHz chroma subcarrier signal. This paper describes a new method and does not use the frequency synthesizer but uses a simpler device to accomplish the calibration. The measuring accuracy is better than that of conventional devices View full abstract»

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  • Adaptive multifrequency modulation method for an advanced laser range finder

    Page(s): 857 - 860
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (364 KB)  

    The intensity of a laser beam is modulated with radio frequencies (RF), in a laser range finder. The modulated laser beam is directed to a target, and the reflected light is detected. The phase of the RP signal from the detector is measured. A semitransparent obstacle between the laser and the target degrades the accuracy of the range measurement. In this paper, an adaptive multifrequency modulation method is proposed and experimentally verified to overcome this problem View full abstract»

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  • A triangular connection Hopfield neural network approach to analog-to-digital conversion

    Page(s): 882 - 888
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (624 KB)  

    A Hopfield-type neural network approach which leads to an analog circuit for implementing the A/D conversion is presented. The solution of the original symmetric connection Hopfield A/D converter sometimes may reach a “spurious state” that does not correspond to the correct digital representation of the input signal. An A/D converter based on the model of nonsymmetrical neural networks is proposed to obtain the stable and correct encoding. Due to the infeasible conventional RC-active implementation, a cost-effective switched-capacitor implementation by means of Schmitt triggers is adopted. It is capable of achieving high performance as well as a high convergence rate. Finally, a simulation using a tool called SWITCAP is conducted to verify the validity and performance of the proposed implementation View full abstract»

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  • Computerized digitizing technique for DLTS measurements

    Page(s): 936 - 939
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (380 KB)  

    An enhanced version of an algorithm developed by Maguire and Marshall in their computerized DLTS system is presented. Improvements consist of introducing analysis of partial processing of digitized transients by deleting the initial part, which usually includes the loading transient caused by the measurement circuit RC constant. Also, a method to calculate trap concentration without using correlation functions is added. Some of the limitations involved with the use of this algorithm are also discussed View full abstract»

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  • Theory and practice in measuring wood grain angle using microwaves

    Page(s): 803 - 809
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (672 KB)  

    Knowledge of wood grain inclination is critical for achieving improved lumber strength grading. This paper describes an instrumentation system and theory for using microwaves to measure wood grain angle in real time. By using an electrically modulated scattering dipole with a homodyne microwave system, it is found both theoretically and experimentally that the amplitude reading of the modulated scattered signal provides an excellent means far measuring wood grain angle. In addition, the phase output of the system can be used to identify the sign of the grain angle. Two widely used wood species, Douglas Fir and Spruce, are measured at different moisture levels to verify the theoretical prediction experimentally. Preliminary data analysis shows that reliable measurement of grain angles up to about 30° can be made for wood within a wide range of specific gravity and moisture content. Through the experimental measurements, the potential of such a system for industrial use is demonstrated View full abstract»

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  • The use of capacitance in the measurement of angular and linear displacement

    Page(s): 939 - 942
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (440 KB)  

    This paper describes the use of capacitor bridges in instrumentation for the measurement of relatively large angular and linear displacements. The particular feature of interest lies in the use of printed circuit board technology which allows repeatability at low cost associated with a rugged overall structure. Two possible electronic configurations are described, one being direct and the other using feedback in which the output depends only on the ratio of the capacitances. Experimental results are given for examples of angular and linear devices. They show that this approach readily yields devices with an accuracy of ±1% and indicates that results considerably better than this are ultimately possible View full abstract»

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Aims & Scope

Papers are sought that address innovative solutions to the development and use of electrical and electronic instruments and equipment to measure, monitor and/or record physical phenomena for the purpose of advancing measurement science, methods, functionality and applications.

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Editor-in-Chief
Prof. Alessandro Ferrero
Dipartimento di Elettrotecnica
Piazza Leonardo da Vinci 32
Politecnico di Milano
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alessandro.ferrero@polimi.it
Phone: 39-02-2399-3751
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