Synthetic deconvolution of explosive acoustic signals in colored noise

Abstract

A method is described for synthesizing acoustic signals from explosive charges and compensating for small variations of detonation depth. A single explosive source signal is measured under conditionsof optimum signal‐to‐noise ratio and depth compensated by the simple time expansion/contraction transformation f′(t) =f(ct), where c is specified by the bubble pulse period. A method is presented for precise determination of the bubble pulse period from the received signals. When corrected for acoustic spreading and absorption losses this signal is used as the input signal for deconvolution. The problem of noise generation in deconvolution is discussed and a filter for minimizing the effects of noise is employed based on least‐squares linear estimation. Differences between synthetic and measured signal levels in one‐third‐octave bands from 31.5 to 3150 Hz averaged 0.2 dB with a standard deviation of 0.6 dB. In the deconvolved traces sharp spikes were obtained and bubble pulses removed. The methods described permit deconvolution of acoustic signals at low frequencies in colored noise and in situations where a satisfactory source signal cannot be measured.