Adaptive Line Enhancer Research Articles

IIR adaptive line enhancer filters for detection of gravitational waves from coalescing binaries

In this paper, we discuss the performances of infinite impulse response adaptive line enhancer (IIR ALE) filters compared with those of standard matched filters for detection of gravitational waves (GW) generated by coalescing binaries (CB). This comparison was performed with the help of numerical simulation, necessary to also provide a statistical characterization of the adaptive filters. The results of this preliminary analysis are also quite promising in connection with the relatively small computational power needed coupled with the robustness of these algorithms. In fact, a first possible and effective application of these filters is their use as real-time triggers for selecting candidates for further intensive analysis based on standard optimal methods.

Advanced current control implementation with robust deadbeat algorithm for shunt single-phase voltage-source type active power filter

A deadbeat current control implementation of shunt-type single-phase active power filter (APF) is considered. The deadbeat control technique is often proposed as an advanced current control method of APF, because the superiority of the digital control scheme to the analogue control one can be effectively utilised by adopting the deadbeat-control strategy. Although the one-dimensional deadbeat control method can attain a time-optimal response for APF compensating current, one sampling period is actually required for its settling time. This delay is a serious drawback for this control technique. To cancel such a delay and one more delay caused by DSP execution time, the desired APF compensating current has to be predicted two sampling periods ahead. For the prediction value, the reference value of one source voltage period before is employed as a based value. At the same time, an adaptive line enhancer (ALE) is newly introduced to predict the control error of two sampling periods ahead. By adding the ALE output as an adjustment term to the based value, the settling time is made short in the transient state. On the other hand, in the steady state, the THD (total harmonic distortion) of the utility grid side AC source current can be reduced as much as possible compared to the case when an ideal identification of the controlled system can be made. The experimental results obtained from a DSP-based APF are also illustrated and evaluated. The compensating ability of this APF treated here is extremely high in accuracy and responsiveness.

308 適応信号処理アルゴリズムによる転がり軸受の音響診断 : 適応線スペクトル強調器にIMS, GALおよびLSLアルゴリズムを用いた特性(計測・音質・診断,OS-19 音響・振動)

308 適応信号処理アルゴリズムによる転がり軸受の音響診断 : 適応線スペクトル強調器にIMS, GALおよびLSLアルゴリズムを用いた特性(計測・音質・診断,OS-19 音響・振動)

Frequency properties of an adaptive line enhancer

This paper presents the steady frequency response function (FRF) of an adaptive line enhancer (ALE) by using a z-transform method. The principle of ALE parameter selection is investigated and the physical meaning of its signal-to-noise ratio (SNR) enhancement is given clearly and directly. Simulation results show that the FRF of the ALE to simple harmonic input signals is as a tracking narrowband filter, and its phase shift at the input frequency is exactly zero. An experimental verification of the ALE frequency properties based on a digital processor board was also carried out. The results not only verify the theoretical analysis and frequency domain simulations, but also disclose that, with respect to multiple harmonic input signals, the ALE system functions as a tracking comb-like narrowband filter with zero-phase response at the input harmonic frequencies. This characteristic has potential application in phase-detection and variable-value tracking in preprocessing of unknown harmonic signals with background noise.

A novel algorithm for underwater moving-target dynamic line enhancement

When we use a traditional adaptive line enhancer (ALE) algorithm to detect an underwater moving target, there are two disadvantages: the ability to suppress colored Gaussian noise is low and the lower the SNR is, the worse the performance of the ALE algorithm. In order to greatly overcome these disadvantages, we take full advantage of the capability of higher order cumulants to alleviate the effect of colored Gaussian noise and develop a fourth order cumulant non-diagonal slice-based adaptive dynamic line enhancer (FOCNDSBADLE) algorithm and fourth order cumulant diagonal slice-based adaptive dynamic line enhancer (FOCDSBADLE) algorithm. The adaptive filtering coefficients of these algorithms are indirectly updated by the instantaneous fourth order cumulant slices. It is shown that these slices are comprised of noiseless sinusoids if the input signals are comprised of sinusoids corrupted by Gaussian noise. Therefore these algorithms are fit to handle highly colored Gaussian noise. Simulation tests are carried out using the measured data radiated by the underwater moving target. Simulation results have shown that the FOCNDSBADLE algorithm and FOCDSBADLE algorithm outperform the ALE algorithm and that the FOCNDSBADLE algorithm outperforms the FOCDSBADLE algorithm in the case of Gaussian noise.

Improving the response of a wheel speed sensor using an adaptive line enhancer

In this paper, an Adaptive Line Enhancer (ALE) based on a Frequency-Domain Least-Mean-Square (FDLMS) adaptive algorithm is used to predict the response of a wheel speed sensor embedded in a car undergoing performance tests. In this case, an ALE is used to predict a signal buried in a broad-band noise background where we have little or no prior knowledge of the signal or noise characteristics. The results of the experiment show that this device behaves as an adaptive notch filter whose null points are determined by the frequency of the noise and/or interference corrupting the electrical signal, and these also show a significant improvement in the signal-to-noise ratio at the system output.

A Novel Robust Current Control Approach Using Adaptive Line Enhancer for Three-Phase Current Source Active Power Filter

An effective system control method is presented for applying a three-phase current-source PWM converter with a deadbeat controller to active power filters (APFs). In the shunt-type configuration, the APF is controlled such that the current drawn by the APF from the utility is equal to the current harmonics and reactive current required for the load. To attain the time-optimal response of the APF supply current, a two-dimensional deadbeat control scheme is applied to APF current control. Further more, in order to cancel both the delay in the two-dimensional deadbeat control scheme and the delay in DSP control strategy, an adaptive Line Enhancer (ALE) is introduced in order to predict the desired value of three sampling periods ahead. ALE has another function of bringing the robustness to the deadbeat control system. Due to the ALE, settling time is made short in a transient state. On the other hand, total harmonic distortion (THD) of source currents can be reduced as much as possible compared to the case that ideal identification of controlled system could be made. The experimental results obtained from the DSP-based APF are also reported. The compensating ability of this APF is very high in accuracy and responsiveness although the modulation frequency is rather low.

SnO<SUB>2</SUB>薄膜センサのホルムアルデヒド検出における適応線スペクトル強調器の応用

The volatile organic compound (VOC) is contained in indoor materials in buildings, such as paints and adhesives. The formaldehyde is a representative example of the chemical substances which affect people’s health. For detection of formaldehyde, we made SnO2 thin-film type sensors by the DC magnetron sputtering method. The sensor has Pt electrodes on one side of a glass substrate as the heater. The thickness of the heater is 500 nm. The SnO2 thin film is sputtered on the opposite side of the heater. The thickness of SnO2 thin film is 200 nm. Ag(1.6 wt.%) is added as a catalyst metal. As formaldehyde is low concentration of less than 1 ppm, the output signal from sensor is buried in noise, which is generated from the heater. The noise is considered as white noise. In this paper, noise cancellation method by using Adaptive Line Enhancer(ALE) is proposed to extract the sensor outputs. The least-square method (LMS) is adopted for the adaptive algorithm in the ALE. As a result of noise cancellation by using the ALE, the formaldehyde of 0.1 ppm concentration can be detected.

Current control implementation with deadbeat algorithm for three-phase current-source active power filter

An effective system control method is presented for applying a three-phase current-source PWM convertor with a deadbeat controller to active power filters (APFs). In the shunt-type configuration, the APF is controlled such that the current drown by the APF from the utility is equal to the current harmonics and reactive current required for the load. To attain the time-optimal response of the APF supply current, a two-dimensional deadbeat control scheme is applied to APF current control. To cancel both the delay in the two-dimensional deadbeat control scheme and the delay in DSP control strategy, an adaptive line enhancer (ALE) is introduced in order to predict the desired value of three sampling periods ahead. The ALE also brings robustness to the deadbeat control system. Owing to the ALE being in a transient state, the settling time is short. By comparison in a steady state, the total harmonic distortion ratio of source currents can be reduced as much as compared to the case that ideal identification of controlled system could be made. The experimental results obtained from a DSP-based APF are also reported. The compensating ability of this APF is very high in accuracy and responsiveness, although the modulation frequency is rather low.

Performance analysis of the adaptive line enhancer with multiple sinusoids in noisy environment

In this paper, the performance analysis of the adaptive line enhancer when the input signal consists of multiple sinusoids embedded in noise is investigated. The performance is evaluated in terms of the signal-to-noise ratio gain at the filter's output. It is shown that, for multiple sinusoids, this gain is not only a function of the filter length, but also of three additional factors — the number of sinusoids, the noise power, and the amplitude of each sinusoid. Simulation results for a dual noisy sinusoidal input are presented to illustrate the validity of this analysis.

Two-Stage Adaptive Line Enhancer and Sliced Wigner Trispectrum for the Characterization of Faults from Gear Box Vibration Data

Impulsive sound and vibration signals in gears are often associated with faults which result from impacting and as such these impulsive signals can be used as indicators of faults. However it is often difficult to make objective measurements of impulsive signals because of background noise signals. In order to ease the measurement of impulsive sounds embedded in background noise, it is proposed that the impulsive signals are enhanced, via a two stage ALE (Adaptive Line Enhancer), and that these enhanced signals are then analyzed in the time and frequency domains using a Wigner higher order time-frequency representation. The effectiveness of this technique is demonstrated by application to gear fault data.

Vibration analysis for Bearing outer race condition diagnostics

This paper investigates defect detection methodologies for rolling element bearings through vibration analysis. Specifically, the utility of a new signal processing scheme combining the High Frequency Resonance Technique (HFRT) and Adaptive Line Enhancer (ALE) is investigated. The accelerometer is used to acquire data for this analysis, and experimental results have been obtained for outer race defects. Results show the potential effectiveness of the signal processing technique to determine both the severity and location of a defect. The HFRT utilizes the fact that much of the energy resulting from a defect impact manifests itself in the higher resonant frequencies of a system. Demodulation of these frequency bands through use of the envelope technique is then employed to gain further insight into the nature of the defect while further increasing the signal to noise ratio. If periodic, the defect frequency is then present in the spectra of the enveloped signal. The ALE is used to enhance the envelope spectrum by reducing the broadband noise. It provides an enhanced envelope spectrum with clear peaks at the harmonics of a characteristic defect frequency. It is implemented by using a delayed version of the signal and the signal itself to decorrelate the wideband noise. This noise is then rejected by the adaptive filter that is based upon the periodic information in the signal. Results have been obtained for outer race defects. They show the effectiveness of the methodology to determine both the severity and location of a defect. In two instances, a linear relationship between signal characteristics and defect size is indicated.

Evaluation of adaptive line enhancement forbeat-to-beat detection of ventricular late potentials

Ventricular late potentials are usually recovered by signal averaging techniques. Some recent studies have commented on the use of adaptive filtering techniques for the detection of these potentials on a beat-to-beat basis. The author reports an evaluation of the technique of adaptive line enhancement in this role. The ensemble of results suggests that the technique is unsuitable for the application.

Adaptive Signal Enhancement of Laser-Induced Breakdown Spectroscopy

A noise reduction technique to analyze laser-induced breakdown spectroscopy spectra is presented in this paper. This technique is an adaptive-type technique for noise minimization. It is based on an improved adaptive line enhancement to effectively increase the signal-to-noise ratio level in spectral data. It requires no a priori knowledge of the signal or of the noise, and it has the capability of on-line implementation. Medium and weak spectra are considered, and a comparison with traditional techniques is made to illustrate the applicability of the foregoing technique.

Development of an active muffler system for reducing exhaust noise and flow restriction in a heavy vehicle

This paper presents an application of an active muffler system for reducing exhaust noise in heavy vehicles. The signal-to-noise ratio associated with the process of estimating the transfer function of a secondary path was improved using conventional inverse modeling combined with an adaptive line enhancer as a control strategy. The simplified passive muffler using 2-duct perforated elements was combined with the active muffler system instead of a conventional passive exhaust system to reduce exhaust noise and flow restriction simultaneously. In experiments to estimate the transfer function of a secondary path, estimates using the inverse modeling method alone show many errors at the dominant frequencies of primary noise. Results obtained using the proposed algorithm correspond well to the actual transfer function as estimated without the primary noise. Control experiments with the proposed active muffler system have been implemented for stationary and driving states, respectively. Compared to the conventional passive muffler, the experimental results showed that the proposed active muffler could reduce the backpressure up to 60% as well as the overall sound pressure level below about 2200 rpm.

THE ENHANCEMENT OF IMPULSIVE NOISE AND VIBRATION SIGNALS FOR FAULT DETECTION IN ROTATING AND RECIPROCATING MACHINERY

Impulsive sound and vibration signals in machinery are often caused by the impacting of components and are commonly associated with faults. It has long been recognized that these signals can be gainfully used for fault detection. However, it tends to be difficult to make objective measurements of impulsive signals because of the high levels of background noise. This paper presents an enhancement scheme to aid the measurement and characterization of such impulsive sounds, called a two-stage Adaptive Line Enhancer (ALE), which exploits two adaptive filter structures in series. The resulting enhancer signals are analyzed in the time–frequency domain to obtain simultaneous spectral and temporal information. In order to apply the two-stage ALE successfully, the filter parameters and adaptive algorithms should be chosen carefully. Conditions for the choice of these parameters are presented and suggestions are made for suitable adaptive algorithms. Finally, the techniques developed are applied to the diagnosis of faults within an internal combustion engine and to data from an industrial gearbox.

Analytic behavior of the LMS adaptive line enhancer for sinusoids corrupted by multiplicative and additive noise

The least mean squares adaptive line enhancer (LMS ALE) has been widely used for the enhancement of coherent sinusoids in additive wideband noise. This paper studies the behavior of the LMS ALE when applied to the enhancement of sinusoids that have been corrupted by both colored multiplicative and white additive noise. The multiplicative noise decorrelates the sinusoid, spreads its power spectrum, and acts as an additional corrupting noise. Closed-form expressions are derived for the optimum (Wiener filter) ALE output SNR as a function of the residual coherent sine wave power, the noncoherent sine wave power spectrum, and the background additive white noise. When the coherent to noncoherent sine wave power ratio is sufficiently small, it is shown that a nonlinear (e.g., square law) transformation of the ALE input results in a larger optimum ALE output SNR.

BEARING CONDITION DIAGNOSTICS VIA VIBRATION AND ACOUSTIC EMISSION MEASUREMENTS

This paper investigates defect detection methods for rolling element bearings through sensor signature analysis, specifically the use of a new signal processing combination of the high-frequency resonance technique and adaptive line enhancer. Two transducers, the accelerometer and the acoustic emission sensor, are used to acquire data for this analysis. Experimental results are obtained for inner race and outer race defects. Results show the potential effectiveness of the signal processing technique to determine both the severity and location of a defect.

Detection of gravitational waves from coalescing binaries in the time domain

We propose a multistep procedure for the on-line detection and analysis of gravitational wave signals emitted during the coalescence of compact binaries. This procedure, based on a hierarchical strategy, consists of a rough analysis of the gravitational wave signal using adaptive line enhancers (ALE) filters and the controlled random search (CRS) optimization algorithm followed by a refined analysis using the classic matched-filtering technique. The results of simulations for the rough analysis are quite promising both for the relatively small computational power needed and for the robustness of the algorithms used, so that it could be very helpful for gravitational wave detection with very large baseline interferometric detectors like LIGO and VIRGO.

Comparative study of four adaptive frequency trackers

We study and compare four algorithms for adaptive retrieval of slowly time-varying multiple cisoids in noise: the adaptive notch filter, the multiple frequency tracker, the adaptive estimation scheme, and the hyperstable adaptive line enhancer. The local behavior of the algorithms in a neighborhood of their equilibrium state [assuming high signal-to-noise ratio (SNR) and large data sample] for a two-cisoid signal is treated in a similar way to the linear filter approximation technique used for a single-cisoid case. The validity of the results is confirmed by computer simulations.