Adaptive Threshold Scheme for Pulse Detection under Condition of Background Nonstationary Noise

Abstract

The paper describes a new adaptive threshold scheme for detecting pulses in high-frequency signals against a background of non-stationary noise. The result of the scheme operation is to determine the pulse boundaries by comparing the signal amplitude-time parameters with the threshold. The threshold value is calculated in non-overlapping windows of fixed length and depends only on the background noise level. The detected pulses undergo additional shape checking, taking into account their characteristics. The parameters of the algorithms for detecting pulses and checking their shape can be adjusted for any type of high-frequency pulse signals. This threshold scheme is tuned to detect pulses in high frequency geoacoustic emission signals. The results of the scheme operation on an artificial signal and on fragments of a geoacoustic signal are given, a comparison is made between the proposed scheme and the previously used (outdated) one. The new threshold scheme proposed by the authors is less sensitive to the choice of the initial threshold value and it is more stable in operation. When processing 15-minute fragments of a geoacoustic signal, the new scheme correctly detects, on average, 5 times more pulses.

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“…To detect pulses from the signals under investigation, we propose a threshold scheme [ 13 ]. The pulse beginning and end are determined by comparing signal amplitude with the threshold value S .…”

Adaptive Approach to Time-Frequency Analysis of AE Signals of Rocks

“…As the result, the audio files, containing meteorological and industrial noises, were removed. After that, pulses were distinguished in each audio file by an original adaptive threshold algorithm [21].…”