Source code for bruges.noise.noise

# -*- coding: utf-8 -*-

:copyright: 2015 Agile Geoscience
:license: Apache 2.0
import numpy as np

from bruges.util import rms

[docs]def noise_db(a, snr): """ Takes an array of seismic amplitudes and SNR in dB. Args: a (ndarray): seismic amplitude array. snr (int): signal to noise ratio. Returns: Noise array, the same shape as the input. Note: it does *not* return the input array with the noise added. """ # Get the amplitude of the signal sigmean = rms(a) # Calculate the amp of the noise, # given the desired SNR noisemean = sigmean / 10.0**(snr/20.0) # Normal noise, centered on 0, # SD=sqrt(var), same shape as input noise = noisemean * np.random.normal(0.0, 1.0, a.shape) return noise