Our Publications

This is a list of the available publications from the project

Microphone Carousel – Exploiting the Hydrostatic Pressure Gradient for the Calibration of Measurement Microphones

Joint interactive poster by Marvin Rust and Christoph Kling to the  CTBTO SnT23 conference. Details can be found in the link.

Challenges of Low Frequency Seismometer Calibrations

Joint interactive poster by Leonard Klaus, Franck Larsonnier, Jacob H. Winther, and Thomas Bruns to the  CTBTO SnT23 conference. Details can be found in the link.

Determination of the frequency response of seismic & infrasonic IMS station sensors using an on-site calibration approach

Presentation by Michaela Schwardt, Christoph Pilger, Thomas Bruns, Leonard Klaus, Samuel Kristoffersen, Franck Larsonnier, Lars Ceranna, Patrick Hupe, and Peter Gaebler to the  CTBTO SnT23 conference. Details can be found in the link.

Transfer standard sensors for disseminating traceable calibrations to the field

Joint poster by Richard Barham, Dominique Rodrigues, Freya Malcher, Ben Ford, Franck Larsonnier, and Michaela Schwardt to the  EGU23 General Assembly. Details can be found in the link.

Traceable Calibration of Seismometers

Joint poster by Leonard Klaus, Franck Larsonnier, Jacob Holm Winther, Michaela Schwardt, Michael Kobusch, and Thomas Bruns to the  EGU23 General Assembly. Details can be found in the link.

A laser pistonphone designed for absolute calibration of infrasound sensors from 10 mHz up to 20 Hz

Joint poster by Dominique Rodrigues, Paul Vincent, Richard Barham, and Franck Larsonnier to the  EGU23 General Assembly. Details can be found in the link.

Low-frequency standards for hydroacoustics in the Infra-AUV project

Joint poster by Freya Malcher, Ben Ford, Richard Barham, Can Çorakçi, Alper Biber, Stephen Robinson, Sei-Him Cheong, Justin Ablitt, and Lian Wang to the  EGU23 General Assembly. Details can be found in the link.

Extension of reciprocity calibration of microphones to frequencies below 1 Hz

Joint poster by Erling Sandermann Olsen to the  EGU23 General Assembly. Details can be found in the link.

Determination of the frequency response of seismic and infrasonic IMS station sensors using a traceable on-site calibration approach

Joint poster by Michaela Schwardt, Christoph Pilger, Samuel Kristoffersen, Franck Larsonnier, Paul Vincent, Leonard Klaus, Thomas Bruns, and Lars Ceranna to the  EGU23 General Assembly. Details can be found in the link.

Calibration of sensors for airborne infrasound utilizing the hydrostatic pressure gradient

Joint poster by Christoph Kling, Marvin Rust, and Christian Koch to the  EGU23 General Assembly. Details can be found in the link.

Application of controlled vibration sources for traceable on-site calibration of seismometers

Joint poster by Christoph Pilger and Michaela Schwardt to the  EGU23 General Assembly. Details can be found in the link.

A Study of Defects on Infrasound Wind Noise Reduction Systems (WNRS) Using In Situ Calibration

Joint poster by Paul Vincent , Samuel Kristoffersen , Alexis Le Pichon , and Benoît Alcoverro to the  EGU23 General Assembly. Details can be found in the link.

Microphone measurements in the vicinity of wind power plants: Results for the wind park in Gagel, Saxony Anhalt, Germany

This document compiles the results of a sound measurement campaign in the vicinity of a wind park to provide objective data for a quantitative characterisation of noise emission in the infrasound frequency range. Microphone measurements were carried out at a wind park near Gagel, Saxony Anhalt, Germany and were compared with results obtained with microbarometers nearby. The experimental setup, the data acquisition and the analysis are described, and narrowband and octave band spectra are calculated and depicted. Reference data are given which allow a first assessment of the noise situation.

Efficient very low frequency primary calibration method for accelerometers

Contribution to the XXIII IMEKO World Congress in Yokohama, Japan

This article describes an extension to the usual primary calibration of accelerometers according to ISO 16063 which tackles the problem of extremely long measuring times for low frequency excitation. The method utilizes a superposition of sine-signals at discrete frequencies in order to determine the complex frequency response for several frequencies in a single run. The article describes the synthesis of the excitation signal taking care of the detection of potential harmonic distortion. It explains the process of data analysis extending the well-known sine-approximation to simultaneous multi-frequency fitting including a period-wise slicing of the data.

Finally, some examples of real measurements are provided.

Progress in the realisation of ultra- low frequency vibration calibrations

Contribution to the XXIII IMEKO World Congress in Yokohama, Japan

presenting some considerations found relevant when preparing laboratory premises for low frequency and ultra-low frequency calibration in general along with recent results from the DPLA system built on a high-performance analysis system realising the ISO 16063-11 Method 3.

Specifications and testing strategies for measurement devices for noise exposure determination in the infrasound frequency range

This document compiles specifications and requirements with which measurement devices shall comply, when applied for noise exposure determination in the frequency range of 1 Hz to 20 Hz. It reviews available European standards and documents with respect to regulations about the measurement of infrasound and the IEC 61672-series of standards concerning requirements of sound level meters. Beginning with these results, the necessary specifications for sound level meters that should be applied in the infrasound frequency range are discussed. Because of the specific properties of sound in this frequency range, typical malfunctioning scenarios known from measurement and testing practice are considered. Specification lists for measuring instruments and requirements of testing facilities summarise the most important conclusions for further discussion.

Metrology for low-frequency sound and vibration: A introduction to the Infra-AUV project.

Contribution to CTBT Science and Technology Conference 2021 (SnT2021)

Session: T4.1 - Performance Evaluation and Modelling of the Full Verification System and its Components: Oral session

Infra-AUV is a new EU project that will establish primary measurements standards for low frequency phenomena across the fields of airborne and underwater acoustics and vibration (seismology). Combining expertise from the national measurement institutes and geophysical monitoring station operators, it will develop both high-precision laboratory-based methods of calibration and methods suitable for field use. Infra-AUV will also address requirements for reference sensors that link laboratory calibration capabilities to field requirements for measurement traceability. ...

Panel Discussion at the SnT 2021

Invited participation of the JRP's coordinator to a panel discussion on
Innovation affecting CTBT: pertinent to IMS monitoring system (sensors)

A Study of the stability exhibited by hydrophones when exposed to variations in temperature and hydrostatic pressure

Contribution to the 6th Underwater Acoustics Conference & Exhibition (UACE 2021)

Inter-laboratory testing is often undertaken between different National Metrology Institutes (NMIs) by
comparison exercises with laboratories calibrating the same hydrophones. The expectation is that results
will be within a small tolerance with each other, ensuring consistency among the different laboratories.
Hydrophone performance can vary when devices are exposed to different temperatures and hydrostatic
pressures, and the degree of variance is different for each model. This can cause sensitivity discrepancies in
the data being measured from different NMIs if the environmental conditions are not controlled. ...

Infra-AUV project: Metrology for low-frequency sound and vibration

Contribution to Annual Conference of the European Geoscience Union in 2021 (EGU 2021):

Infra-AUV is a new EU project that will establish primary measurements standards for low frequency phenomena across the fields of airborne and underwater acoustics and vibration (seismology). Combining expertise from the national measurement institutes and geophysical monitoring station operators, it will develop both high-precision laboratory-based methods of calibration and methods suitable for field use. Infra-AUV will also address requirements for reference sensors that link laboratory calibration capabilities to field requirements for measurement traceability.
...

The Slides