Acoustic signal processing based on the short‐time spectrum

The possibility of the application of an unmanned aerial vehicle (UAV) in search and rescue activities in a deep underground mine has been investigated. In the presented case study, a UAV is searching for a lost or injured human who is able to call for help but is not able to move or use any communication device. A UAV capturing acoustic data while flying through underground corridors is used. The acoustic signal is very noisy since during the flight the UAV contributes high-energetic emission. The main goal of the paper is to present an automatic signal processing procedure for detection of a specific sound (supposed to contain voice activity) in presence of heavy, time-varying noise from UAV. The proposed acoustic signal processing technique is based on time-frequency representation and Euclidean distance measurement between reference spectrum (UAV noise only) and captured data. As both the UAV and “injured” person were equipped with synchronized microphones during the experiment, validation has been performed. Two experiments carried out in lab conditions, as well as one in an underground mine, provided very satisfactory results.

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Industrial acoustic signal processing with graph based features

2017 IEEE 15th International Symposium on Intelligent Systems and Informatics (SISY) ◽

10.1109/sisy.2017.8080586 ◽

2017 ◽

Author(s):

Tibor Dobjan ◽

Peter Kardos ◽

Gabor Nemeth

Keyword(s):

Signal Processing ◽

Acoustic Signal

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A Generalized Method for Flat Plates Impact Detection and Location

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.543.171 ◽

2013 ◽

Vol 543 ◽

pp. 171-175

Author(s):

Jose Andrés Somolinos ◽

Rafael Morales ◽

Carlos Morón ◽

Alfonso Garcia

Keyword(s):

Signal Processing ◽

Flat Plate ◽

Acoustic Signal ◽

Experimental Results ◽

Piezoelectric Sensors ◽

Experimental Setup ◽

Flat Plates ◽

Impact Detection ◽

Timing Difference

In the last years, many analyses from acoustic signal processing have been used for different applications. In most cases, these sensor systems are based on the determination of times of flight for signals from every transducer. This paper presents a flat plate generalization method for impact detection and location over linear links or bars-based structures. The use of three piezoelectric sensors allow to achieve the position and impact time while the use of additional sensors lets cover a larger area of detection and avoid wrong timing difference measurements. An experimental setup and some experimental results are briefly presented.

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A Harmonic Tracking Technique for Recovery of Gear Motion From Non-Stationary Vibration Signals

Volume 3A: 15th Biennial Conference on Mechanical Vibration and Noise — Vibration of Nonlinear, Random, and Time-Varying Systems ◽

10.1115/detc1995-0383 ◽

1995 ◽

Author(s):

Christopher A. Lerch ◽

Richard H. Lyon

Keyword(s):

Diagnostic System ◽

Time Spectrum ◽

Time Dependent ◽

Invasive Technique ◽

Signal Distortion ◽

Vibration Signals ◽

Tracking Method ◽

Non Invasive ◽

Stationary Vibration ◽

Short Time

Abstract A method termed harmonic tracking is developed to recover time dependent gear motion from machine casing vibration. The harmonic tracking method uses short-time spectral generation and a subsequent set of algorithms to locate and track gear meshing frequencies as functions of time. The meshing frequencies are then integrated with respect to time to obtain the rotation of individual gears. More specifically, spectral generation is performed using the discrete Fourier transform, and the locating and tracking algorithms involve locating tones in each short-time spectrum and tracking them through successive spectra to recover gear meshing harmonics. The harmonic tracking method is found to be more robust than demodulation-based methods in the presence of measurement noise and signal distortion from the structural transfer function between gears and the casing. The harmonic tracking method is tested, both through simulation and experiments involving motor-operated valves (MOV’s) as part of the development of a diagnostic system for MOV’s. In all cases, the harmonic tracking method is found to recover gear motion with sufficient accuracy to perform diagnostics. The harmonic tracking method should be generally applicable to situations in which a non-invasive technique is required for determining the time-dependent angular speeds and displacements of gearbox input, intermediary, and output shafts.

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