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Instrumentation and Measurement, IEEE Transactions on

Issue 5 • Date Oct 1994

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Displaying Results 1 - 17 of 17
  • A Doppler radar for multiple targets

    Page(s): 706 - 710
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (328 KB)  

    A programmable instrument for the simultaneous measurement of velocities and acceleration or deceleration of different objects becomes possible through the use of spectral analysis of the Doppler signal. Programmable gain and frequency synthesis is under software control. Spectra for different segments of the Doppler time series are displayed versus time. When scaled, velocity versus time is displayed. By integration, velocity versus distance could also be displayed. Curve fitting is applied to chosen segments so that velocity and acceleration or retardation can be calculated. The raw digitized Doppler signals as well as calculated results are stored on disk for further off-line review and editing View full abstract»

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  • Bias of mean value and mean square value measurements based on quantized data

    Page(s): 733 - 739
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    This paper investigates the imperfect fulfilment of the validity conditions of the noise model quantization. The general expressions of the deviations of the moments from Sheppard's corrections are derived. Approximate upper and lower bounds of the bias are given for the measurement of first- and second-order moments of sinusoidal, uniformly distributed, and Gaussian signals. It is shown that because of the uncontrollable mean value at the input of the ADC (offset, drift), the worst-case values have to be investigated; it is illustrated how a simple-form envelope function of the errors can be used as an upper bound. Since the worst-case relative positions of the signal and the quantization characteristics are taken into account, the results are valid for both midtread and midrise quantizers, while in the literature results are given for a selected quantizer type only View full abstract»

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  • Compensation of timing jitter-induced distortion of sampled waveforms

    Page(s): 726 - 732
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (604 KB)  

    The presence of timing jitter between the trigger signal and the sampling strobe in an equivalent-time sampling oscilloscope causes distortion of the recorded waveform. Two methods exist to estimate the waveform from the jittered measurements. One method, called the median method, is based on the calculation of the point-by-point median of a large set of waveform measurements. It is shown here that this method is asymptotically biased if noise is present and if the waveform is nonmonotonic. Another method, called the pdf deconvolution method, is based on an estimation of the jitter probability density function and on a technique to deconvolve this density function from the average of all recorded waveforms. To estimate the jitter probability density function, it is assumed that the waveform has a part which can very well be approximated by a ramp during a time span which is smaller than the standard deviation. It is shown that a significant asymptotic bias is introduced by the method when this assumption is violated. A novel approach is proposed, based on a parametric model of the jitter probability density function, which results in an asymptotic unbiased estimate of the jitter probability density function. The method is experimentally verified, and it is explained why this method is especially useful when one is interested in the Fourier spectrum of the recorded waveform View full abstract»

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  • A single-phase three-wire watt-to-pulse frequency converter using simple PWM and its accuracy analysis

    Page(s): 770 - 774
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    Many types of electronic watthour meters have been developed; however, they are complicated and expensive for household meters. Therefore, cutting cost of the meters has been required especially for the most popular single-phase three-wire (one-phase three-wire) system in Japan. For this purpose, the authors developed a very simple one-phase three-wire watt-to-pulse frequency converter (W-F converter) for the watthour meter. In this new converter, a general-purpose one-chip quad operational-amplifier (op-amp) IC is used as a main component of the converter, for lower initial cost without a custom IC. As the one-chip quad op-amp IC has four op-amps, two op-amps are used for two watt sensors, and the other two op-amps for a de current-to-pulse frequency converter (I-F converter). The watt sensor uses a multiplier using an approximate pulse-width modulation (APWM) with only a comparator with hysteresis and a CR circuit, replacing the conventional Miller integrator which needs an op-amp. Therefore, the total number of op-amps of the developed one-phase three-wire W-F converter is reduced to four, obtained by one one-chip IC. Although the APWM has nonlinearity, it is negligible without instability. As the converter developed does not need any special custom IC or component and is very simple, the total cost can be very low View full abstract»

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  • Nonlinear readout signal processing using the DataWave video signal processor

    Page(s): 748 - 752
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (444 KB)  

    Implementation of digital signal processing operations as part of the data acquisition process in high-energy physics detectors requires very high-speed devices. Signal processors are not typically used in these applications due to inadequate processing performance. New components developed for high-definition television (HDTV) are considered to be applicable for these purposes. By using programmable signal processors a superior reconfigurability can be obtained, as opposed to VLSI-based custom implementations. Where the algorithms are fixed when-the design has been completed. This paper presents one such processor, the DataWave video signal processor, and describes how some nonlinear algorithms for readout signal processing can be implemented with it. The operations selected include an order statistic filter structure and an FIR-order statistic hybrid (FIR-OS) filter with trainable coefficients and rank operator. Comments on the suitability of the DataWave processor for different kinds of algorithms are also given View full abstract»

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  • Differential inductive ratio transducer with short-circuiting ring for displacement measurement

    Page(s): 777 - 780
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (248 KB)  

    This paper describes a differential inductive ratio transducer (DIRT) with a short-circuiting ring (SCR) which is smaller in size, lighter in weight, has 500 turns in each coil, has a laminated core of mumetal, is rugged in construction, and is lower in cost. It has linear and hysteresis-free response with immunity to undesirable variations in excitation conditions and influencing parameters. Due to the differential ratio mode of operation, there is a cancellation of common factors in the numerator and denominator. These factors have the terms containing the influence of constant errors due to leakage flux and finite resistance of the SCR, and variable errors due to changes in the excitation conditions and temperature. This process makes the transducer smart in its behavior. It has a full range of displacement up to ±37.5 mm, sensitivity of 0.0933 V·mm-1, resolution of 0.1 μm, temperature drift of 4.6 ppm/°C for a change in temperature from 30 to 70°C, stability within ±0.09% for an excitation variation from 1 to 5 V, and within ±0.015% for a frequency variation from 1 to 10 kHz. It is suitable for use in all types of environments, including hostile conditions View full abstract»

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  • A novel microwave method for detection of long surface cracks in metals

    Page(s): 719 - 725
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (516 KB)  

    A novel microwave technique for detecting long surface cracks in metals is described. This technique utilizes an open-ended waveguide to probe the surface of a metal. In the absence of a crack the metal surface is seen as a relatively good short-circuit load. However, in the presence of a crack higher order modes are generated which in turn change the reflection properties at the waveguide aperture. This change brings about a perturbation in the standing wave characteristics which is then probed by a diode detector. The experimental and theoretical foundations of this technique are given, along with several examples. It is shown that cracks a fraction of a millimeter in width are easily detected at around 20 GHz or lower. Smaller cracks can be detected at higher microwave frequencies View full abstract»

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  • The seemingly paradoxical noise behavior of some active circuits

    Page(s): 764 - 767
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (336 KB)  

    The equivalent input noise for some active circuits does not increase when the signal bandwidth increases or when some of their resistors have a larger value. This seemingly paradoxical behavior is caused by the different transfer functions for the signal and the respective noise sources associated with these resistors View full abstract»

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  • Fitting the exogenous model to measured data

    Page(s): 758 - 763
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (512 KB)  

    The paper deals with the problem of fitting a statistical model to observations. The proposed approach relies on modeling data as drawn from an exogenous process, namely a doubly stochastic random sequence, where a real, nonnegative process modulates a Gaussian, possibly complex, one. Approximating the modulating component by a random constant ensures that measured data can be completely specified based on a first- and second-order statistical characterization. In the following we demonstrate that ascertaining to what extent that approximation holds is paramount to solving a binary hypothesis testing problem. In particular, proper data processing leads to a distribution-free test, namely to a test statistic which is one and the same independent of the data distribution and correlation. The performance of the test has been assessed via Monte Carlo simulation: its operating characteristics show that it represents a powerful tool for achieving an accurate statistical description of real data View full abstract»

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  • Analysis of an open-ended coaxial probe with lift-off for nondestructive testing

    Page(s): 711 - 718
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (544 KB)  

    The open-ended coaxial probe with lift-off is studied using a full-wave analysis, and an uncertainty analysis is presented. The field equations for the following terminations are worked out: (1) the sample extends to ∞ in the positive axial direction, (2) the sample is backed by a well-characterized material, and (3) the sample is backed by a short-circuit termination. The equations are valid for both dielectric and magnetic materials. The model allows the study of the open-ended coaxial probe as a nondestructive testing tool. The analysis allows a study of the effects of air gaps on probe measurements. The reflection coefficient and phase are studied as a function of lift-off, coaxial line size, permittivity, permeability, and frequency. Numerical results indicate that the probe is very sensitive to lift-off. For medium to high permittivity values and electrically small probes, gaps on the order of fractions of a millimeter strongly influence the reflection coefficient. In order for the field to penetrate through the air gap, larger size coaxial line or higher frequencies need to be used. A comparison of the theory to experiment is presented. The results are in close agreement. A differential uncertainty analysis is also included View full abstract»

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  • A causal regularizing deconvolution filter for optimal waveform reconstruction

    Page(s): 740 - 747
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (588 KB)  

    A causal regularizing filter is described for selecting an optimal reconstruction of a signal from a deconvolution of its measured data and the measurement instrument's impulse response. Measurement noise and uncertainties in the instrument's response can cause the deconvolution (or inverse problem) to be ill-posed, thereby precluding accurate signal restoration. Nevertheless, close approximations to the signal may be obtained by using reconstruction techniques that alter the problem so that it becomes numerically solvable. A regularizing reconstruction technique is implemented that automatically selects the optimal reconstruction via an adjustable parameter and a specific stopping criterion, which is also described. Waveforms reconstructed using this filter do not exhibit large oscillations near transients as observed in other regularized reconstructions. Furthermore, convergence to the optimal solution is rapid View full abstract»

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  • On a circuit theory approach to evaluate the stray capacitances of two coupled inductors

    Page(s): 774 - 776
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (260 KB)  

    This paper provides a method for evaluating three lumped equivalent capacitances which take into account the physical effects of stray capacitances in two coupled inductors. Capacitance evaluation is performed in two steps: (i) initially, the resistance and leakage inductance of each winding, together with the magnetic core equivalent impedance, are evaluated by means of discrete parameter estimation; (ii) successively, the three equivalent capacitances are evaluated by resolving a linear set of three algebraical equations after the natural oscillation frequencies of the two coupled inductors in experimental tests are determined. The paper provides both the definitions and the mathematical theory on which the method is based. The actual response of two coupled inductors was compared with the response of the identified model; tests showed a good correlation between them View full abstract»

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  • Sequenced, dual-pulse TEA N2-laser for optical diagnostics

    Page(s): 768 - 769
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    A simple spark gap is incorporated into a subnanosecond TEA N2 laser system for generating sequenced, dual-pulse output. The time interval between the two laser pulses can be varied from about 10 to over 100 ns. This makes the system very suitable for optical diagnostics of fast transient plasmas. It provides a cost-effective alternative to electrooptic-based systems View full abstract»

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  • Design of a microwave multisine source using allpass functions estimated in the Richards domain

    Page(s): 753 - 757
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (304 KB)  

    In this paper a low-crest-factor microwave multisine source is developed. This is a broadband, periodic signal with a low crest factor (peak factor to effective value ratio). The design method consists of generating a pulse with a broad spectrum, amplitude filtering to get the desired power spectrum, and phase filtering for lowering the crest factor. A new technique to realize microwave phase filters is described. First, the properties of a rational allpass function in the Richards variable are examined. This enables us to estimate the coefficients using a nonlinear optimization technique, The function is realized with coupled transmission line filters. Using this general technique, a microwave multisine consisting of 20 components in the band [100 MHz, 2 GHz] is realized with a crest factor of 2 View full abstract»

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  • Measurement of radio channels using an elastic convolver and spread spectrum modulation. I. Implementation

    Page(s): 689 - 694
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    Using spread spectrum signals a measurement system has been built in order to measure the radio channel in steel works. It transmits a 511-chip long maximum length sequence with a chip rate of 44 MHz: binary phase shift keying modulated onto a 1.75 GHz carrier. A surface acoustic wave convolver yields the channel's impulse response with a time resolution of about 20 ns. The periodic autocorrelation performed within a measurement window removes aperiodic correlation sidelobes which limit the dynamic range of a matched-filter implementation. Additionally, absolute time delay measurements of all echoes were obtained using a synchronization cable connecting receiver and transmitter. Compared to other spread spectrum correlation techniques, the convolver makes possible a much simpler real-time measurement setup View full abstract»

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  • Measurement of radio channels using an elastic convolver and spread spectrum modulation. II. Results

    Page(s): 695 - 699
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (404 KB)  

    A spread spectrum measurement system using a surface acoustic wave convolver has been used to measure radio wave propagation in steel works at 1.75 GHz with an echo delay resolution of ≈20 ns. Due to the high metal content of the factory halls, path loss is found to be small and its exponent to range between 1.1 and 2.3 only. We observed a delay spread between 82 and 548 ns depending on the size of the steel mill, its construction and machinery. Characterizing the radio channel by a stochastic delay line model the echo amplitude probability distribution is found to fit a Rician or log-normal distribution rather than a Rayleigh distribution. The fit of the amplitude distributions is determined by a χ2 hypothesis test. From the channel impulse response the coherence bandwidth is deduced to range between 2.4 and 27.4 MHz View full abstract»

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  • Timing experiment with geodetic GPS receiver

    Page(s): 700 - 705
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (416 KB)  

    In view of the availability of a new generation of geodetic GPS receivers coupled with the introduction of selective availability (SA) on the C/A-code, the use of these types of GPS receivers for timing applications has been extensively reviewed. The common-view mode shows an improvement in timing accuracy (15 to 25 ns) over the one-way mode (around 100 ns) even in the presence of SA. A model has also been introduced to reduce the detrimental effect of SA on the time accuracy even in the one-way mode. The utilization of this model on the experimental observations shows a remarkable reduction in jitter to about 20 ns 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
Milano 20133 Italy
alessandro.ferrero@polimi.it
Phone: 39-02-2399-3751
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