Interdependent quality control of collocated seismometer and accelerometer

Estimating ‘noise-floor PSD’ by using two or three collocated seismometers: an alternative approach

“…If N 0 rr ≪ N qq , then Eq. 1 can be simplified (Tasič and Runovc 2012) This equation can also be applied to determine the accelerometer self-noise using a quieter seismometer (Tasič 2018).…”

“…It was divided into four equal parts, so a 6-h seismic segment was used in each calculation. To reduce the impact of orientation misalignments and impact of gain differences to the "self-noise" calculation, data from seismometers CMG-3ESPC-'B' and STS-2 are transformed to the space of seismometer CMG-3ESPC-'A' (Tasič andRunovc 2012, 2013). For the "self-noise" evaluation, Welch's method (Welch 1967) for the PSD estimation was applied using a Matlab (C) built-in function with a Hanning window of length 2 21 and with 50% overlapping time-series segments.…”

“…The orientation misalignment between seismometers can increase the estimated noisefloor but this is seemingly increased noise-floor and is due to the orientation misalignment. By transforming of the space of the three component measurements of the particular seismometer into the space of the selected seismometer, this effect is avoided (Tasič andRunovc 2012, 2013). In this way, we also avoid the influence that inaccurate generator constants have on the measurement (Tasic and Runovc 2014).…”