Implementation, Characterization, and Evaluation of an Inexpensive Low-Power Low-Noise Infrasound Sensor Based on a Micromachined Differential Pressure Transducer and a Mechanical Filter

Abstract

The implementation, characterization, and evaluation of a low-cost infrasound sensor developed at the Infrasound Laboratory at the New Mexico Institute of Mining and Technology (Infra-NMT) are described. This sensor is based on a commercial micromachined piezoresistive differential pressure transducer that uses a mechanical high-pass filter to reject low-frequency outband energy. The sensor features a low-noise, 2.02-mPa rms (0.5-2 Hz), 5.47-mPa rms (0.1-20 Hz), or 5.62-mPa rms (0.05-20 Hz), flat response between 0.01 and at least 40 Hz; inband sensitivity of 45.13 ± 0.23 /xV Pa"'; and a nominal linear range from -124.5 to +124.5 Pa. Intended for outdoor applications, the influence of thermal changes in the sensor's response has been minimized by using a thermal compensated pressure transducer powered by an ultralow drift (<5 ppm °C"') and noise {<AßW from peak to peak) voltage reference. The sensor consumes a minimum of 24 mW and operates with voltages above 8 V while drawing 3 mA of current. The Infra-NMT specifications described above were independently verified using the infrasound test chamber at the Sandia National Laboratories' (SNL's) Facility for Acceptance, Calibration, and Testing (FACT), and the following procedures are for comparison calibration against traceable reference stands in voltage and pressure. Because of the intended broad frequency response of this sensor, the testing chamber was configured in a doublereference sensor scheme. A well-characterized microbarometer (with a flat-amplitude response between 0.01 and 8 Hz) and a microphone (with a flat-amplitude response above 8 Hz) were used simultaneously in this double-reference test configuration.

Application of the Monopole Source to Quantify Explosive Flux during Vulcanian Explosions at Sakurajima Volcano (Japan)

“…Global Positioning System (GPS) time stamped pressures signals were continuously recorded with 24-bit DataCube loggers at 200 Hz. Sensors were identical micro electro-mechanical systems-based infrasonic microphone (infraBSU) characterized by a single-pole corner at 26 s. The operation and response of this type of sensor is discussed in Marcillo et al (2012). We use data from KURA station channels 1, 2, 4, and 6 because their recordings were cleanest in terms of wind noise.…”

Introduction to an Open Community Infrasound Dataset from the Actively Erupting Sakurajima Volcano, Japan

“…BSU sites consisted of infrasonic microphones packaged at BSU's infrasound lab, which incorporate AllSensors MEMs pressure transducers with ranges up to 1250 Pa and flat frequency response above ∼0:04 Hz. Operation and calibration of this type of microphone is discussed in Marcillo et al (2012). BSU pressure data was digitized at 200 Hz using 24-bit Omnirecs DATA-CUBE recorders.…”

Upper Atmosphere Heating From Ocean‐Generated Acoustic Wave Energy

“…Three InfraBSU infrasound microphones were used (Marcillo et al, 2012). The balloon maintained a nominal altitude of 33 km, with occasional downward excursions of several thousand meters.…”