59 lines
1.4 KiB
Python
59 lines
1.4 KiB
Python
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#!/usr/bin/env python3
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# -*- coding: utf-8 -*-
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"""
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Sound level meter implementation
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@author: J.A. de Jong - ASCEE
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"""
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from .wrappers import FilterBank, SPLowpass
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import numpy as np
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from .lasp_config import zeros
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from .lasp_common import TimeWeighting, P_REF
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__all__ = ['SLM']
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class Dummy:
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def filter_(self, data):
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return data
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class SLM:
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"""
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Sound Level Meter, implements the single pole lowpass filter
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"""
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def __init__(self, fs, weighcal,
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tw=TimeWeighting.default,
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nchannels = 1,
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freq=None, cal=None):
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self._weighcal = weighcal
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if tw is not TimeWeighting.none:
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self._lps = [SPLowpass(fs, tw[0]) for i in range(nchannels)]
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else:
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self._lpw = [Dummy() for i in range(nchannels)]
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self._Lmax = zeros(nchannels)
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@property
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def Lmax(self):
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return self._Lmax
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def addData(self, data):
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assert data.ndim == 2
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data_weighted = self._weighcal.filter_(data)
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# Squared
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sq = data_weighted**2
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if sq.shape[0] == 0:
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return np.array([])
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tw = []
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# Time-weight the signal
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for chan,lp in enumerate(self._lps):
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tw.append(lp.filter_(sq[:,chan])[:,0])
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tw = np.asarray(tw).transpose()
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Level = 10*np.log10(tw/P_REF**2)
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curmax = np.max(Level)
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if curmax > self._Lmax:
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self._Lmax = curmax
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return Level
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