Pressure calibration of a digital microelectromechanical system microphone by comparison

Abstract

In the field of noise control and monitoring, a new generation of small and low-cost microelectro-mechanical system (MEMS) microphones is nowadays widely adopted. MEMS microphones, after recognition as traceable measurement instruments, could open up promising measurements based on wireless sensor networks. Current standards do not apply specifically to digital microphones. In this work, a pressure calibration procedure by comparison is carried out for a digital MEMS microphone and a sensitivity parameter suitable for metrological purposes is proposed. Measurement procedure and results between 20 Hz and 20 kHz are presented along with uncertainty contributions.

Towards large-scale calibrations: a statistical analysis on 100 digital 3-axis MEMS accelerometers

“…The signal is acquired by means of a Serial Peripheral Interface (SPI), which is a synchronous serial communication interface used for connecting digital devices. The 1-bit signal from the ΣΔ-ADC is then converted through a decimation process and a low pass filter into a standard 16bit-signed PCM (Pulse Code Modulation) signal [6] with a nominal sampling frequency rate of 1666 Hz. However, sampling frequencies up to -6% of the target, i.e.…”

Characterization of Mems Microphone Sensitivity and Phase Distributions with Applications in Array Processing

“…However, since these methods are designed for condenser microphones, modifications are required for application on MEMS microphones due to their different form factor. Such modifications are reported by Prato et al [20], who adapted the IEC 61094-5 free-field comparison method (±0.37 dB at 1 kHz, 95% confidence interval), and by Wagner and Fick [21], who adapted the IEC 61094-2 pressure reciprocity technique (±0.12 dB at 1 kHz, 95% confidence interval). Also, Zuckerwar et al [22] report a substitution method for frequencies up to 80 kHz with uncertainty of ±0.41 dB (68% confidence interval).…”

Traceability of digital 3-axis MEMS accelerometer: simultaneous determination of main and transverse sensitivities in the frequency domain

“…In digital measuring systems, the output physical quantities are directly digitized by the analog-to-digital converters, and the related 'indication' is given in bit-strings; as a consequence, calibration of digital measuring systems is carried out by defining the relation between a 0/1 sequence and a physical quantity. The resulting 'quotient' is a digitized sensitivity since the numerator unit of measurement is related to a n-bit 0/1 sequence converted into a decimal number (Decimal n-bit ) and the denominator is the unit of the reference measured physical quantity [21,22]. Therefore, the sensitivity of a digital MEMS accelerometer is expressed, in linear units, as Decimal n-bit /(m s −2 ), similarly to typical sensitivity of analog accelerometers, expressed in linear units, in terms of V/(m s −2 ).…”

“…)-(21).Values are expressed in (m s −2 )/Decimal 16-bit-signed . × 10 −3 −1.54 × 10 −6 3.67 × 10 −6 −5.89 × 10 −6 1.30 × 10 −3 4.94 × 10 −6 14.2 × 10 −6 14.7 × 10 −6 1.29 × 10 −3 × 10 −5 1.40 × 10 −5 1.44 × 10 −5 0.97 × 10 −5 2.77 × 10 −5 1.44 × 10 −5 1.44 × 10 −5 1.44 × 10 −5 1.75 × 10 −In the same way, the sensitivity matrix S along with the associated expanded uncertainty matrix U(S) at 10 Hz are shown in equations (22)-(23).…”