Wave motion signal processing device, wave motion signal processing method, and recording medium

1 . A wave motion signal processing device comprising:

a memory storing instructions; and

a processor connected to the at least one memory and configured to execute the instructions to:

generate a first spectrum with high resolution and a second spectrum with low resolution based on an input signal derived from a wave motion detected by at least one sensor;

extract, from the second spectrum, a first peak satisfying an extraction condition in a target time frame;

track, in the first spectrum, a second peak satisfying the extraction condition with regard to a time frame following the target time frame from which the first peak is extracted; and

generate a peak waveform, which is time-series data of a frequency including a plurality of second peaks, using the first peak as a starting end.

2 . The wave motion signal processing device according to claim 1 , wherein

the processor is configured to execute the instructions to

convert, for each time frame, the input signal in a time domain into a frequency spectrum that is a signal in a frequency domain,

arrange the frequency spectrum in time series to generate the first spectrum,

calculate a representative value of an amplitude of a frequency for each bin obtained by cutting out the first spectrum at a unit frequency for each unit time using the first spectrum, and

generate the second spectrum based on the computed representative value, and

track a plurality of the second peaks following the first peak by sequentially extracting, in the first spectrum, the second peaks satisfying the extraction condition for a plurality of the time frames following the target time frame.

3 . The wave motion signal processing device according to claim 2 , wherein

the processor is configured to execute the instructions to

calculate, with regard to the first peak extracted from a bin of the target time frame, a peak frequency at which an amplitude inside the bin is maximum and a frequency change amount,

estimate, based on the peak frequency and the frequency change amount, a frequency prediction value of a peak following the first peak, detects, within a tracking range in accordance with the estimated frequency prediction value, the second peak satisfying the extraction condition from the time frame following the target time frame, and

track, with regard to a time frame following the time frame in which the second peak is detected, a second peak following the first peak by sequentially detecting the second peak following the second peak.

4 . The wave motion signal processing device according to claim 1 , wherein

the processor is configured to execute the instructions to

convert, for each time frame, the input signal in a time domain into a frequency spectrum that is a signal in a frequency domain,

thin out frequency components of the frequency spectrum,

arrange the frequency spectrum from which frequency components are thinned out in time series to generate the second spectrum, and

locally generate the first spectrum by increasing resolution around where the first peak and second peak are extracted, and

track a plurality of the second peaks following the first peak by sequentially extracting the second peaks satisfying the extraction condition in the locally generated first spectrum for a plurality of the time frames following the target time frame.

5 . The wave motion signal processing device according to claim 1 , wherein

the processor is configured to execute the instructions to

determine, when a predetermined time has elapsed since the second peak is last detected, that the second peak detected last is a third peak at an ending end, and

generate the peak waveform that has the first peak as a starting end, passes through a plurality of the second peaks, and has the third peak as an ending end.

6 . The wave motion signal processing device according to claim 1 , wherein

the processor is configured to execute the instructions to

calculate at least one of a representative value and a variance with regard to an amplitude of a frame included in a bin of the target time frame, and

the extraction condition includes at least one condition of

a first extraction condition that the representative value is equal to or more than a first threshold,

a second extraction condition that the representative value divided by a noise level is equal to or more than a second threshold,

a third extraction condition that a sharpness of the representative value is equal to or more than a third threshold,

a fourth extraction condition that the variance is equal to or less than a fourth threshold, and

a fifth extraction condition that the representative value has a maximum value.

7 . The wave motion signal processing device according to claim 1 , wherein

the processor is configured to execute the instructions to

leave one peak waveform and deletes the other peak waveforms with regard to the overlapping peak waveforms, and

delete the peak waveform with regard to the peak waveform that has a time length less than a predetermined length.

8 . The wave motion signal processing device according to claim 1 , further comprising wherein

the processor is configured to execute the instructions to

estimate a trajectory of a mobile object having a wave source of the wave motion based on at least one of the peak waveforms.

9 . A wave motion signal processing method executed by a computer, the method comprising:

generating a first spectrum with high resolution and a second spectrum with low resolution based on an input signal originating from a wave motion detected by at least one sensor;

extracting, from the second spectrum, a first peak satisfying an extraction condition in a target time frame;

tracking, in the first spectrum, a second peak satisfying the extraction condition with regard to a time frame following the target time frame from which the first peak was extracted; and

generating a peak waveform, which is time-series data of a frequency including a plurality of second peaks, having the first peak as a starting end.

10 . A non-transitionary recording medium having a program recorded therein that causes a computer to execute:

a process of generating a first spectrum with high resolution and a second spectrum with low resolution based on an input signal originating from a wave motion detected by at least one sensor;

a process of extracting, from the second spectrum, a first peak satisfying an extraction condition in a target time frame;

a process of tracking, in the first spectrum, a second peak satisfying the extraction condition with regard to a time frame following the target time frame from which the first peak was extracted; and

a process of generating a peak waveform, which is time-series data of a frequency including a plurality of second peaks, having the first peak as a starting end.