A Multivariable Detection Device Based on a Capacitive Microphone and Its Application to Security

Watanabe, Kajiro; Ishigaki, Tsukasa; Higuchi, Tomoyuki

doi:10.1109/tim.2009.2030716

Cited by 10 publications

(5 citation statements)

References 9 publications

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“…Instrumentation amplifiers [4] and active-feedback operational amplifiers [9] have been used as sensor preamplifiers. These amplifiers have high input impedance relative to the sensor output impedance but, in practice, these amplifiers are a type of differential input and so cannot be connected to a single output sensor such as a capacitive sensor, as shown in Fig.…”

Section: Discussionmentioning

confidence: 99%

“…Sensors which work in cooperation with active electronics preamplifiers are called active sensors, typical examples of which are phototransistors, CMOS image sensors, microelectromechanical systems (MEMS), and capacitive sensors using an electret film sensor. The electret film sensor has been widely used in audio microphones, and following reports of its very high sensitivity and accuracy as a low-cost pressure sensor [1], its application has expanded quickly to fields such as vibration sensing, earthquake sensing, security sensing, and human vital sign sensing [2]- [4].…”

Section: Introductionmentioning

confidence: 99%

“…For example, the J-FET drain current decreases by 2.5% with every 10 C rise in temperature. Instrumentation amplifiers [4] and active-feedback operational amplifiers [9] are used to improve the characteristics, but these preamplifiers require differential inputs and so cannot be used in single output sensors such as capacitive sensors using an electret film.…”

Section: Introductionmentioning

confidence: 99%

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Design of a Preamplifier for Capacitive Sensors With Wide Low-Frequency Range and Low Drift Noise

Nakamura¹,

Kurihara

Watanabe

et al. 2012

IEEE Sensors J.

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This paper describes a novel DC-coupled single input preamplifier which is robust to drift noise and variation due to the circuit operation conditions. The preamplifier is intended for capacitive sensors such as the capacitive electret film type sensor, which is one of the most sensitive and accurate sensors presently available. There are both DC-coupled and AC-coupled conventional preamplifiers available for such sensors. However, DC-coupled preamplifiers do not always suppress drift noise and variation, while AC-coupled preamplifiers require a large capacitor to expand the frequency range, thus making the large-scale integration (LSI) very large and inducing problems associated with the large capacitor. We describe a DC-coupled preamplifier with wider low-frequency range as well as less drift noise and variation. The design combines a time constant amplifier and rail-to-rail transconductance amplifier, and is implemented in an LSI with 6-GHz f T bipolar 11-V process with 5-V supply voltage.For an LSI with this preamplifier, the output voltage variation due to changes in load current is within 35 mV, whereas the variation for a conventional preamplifier is proportional to the load current up to 2.5 V. The output voltage drift due to changes in temperature and load current is restricted to within 35 mV for load resistance of 1-5 k, whereas the drift for a conventional preamplifier is 800 mV.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Design of a Preamplifier for Capacitive Sensors With Wide Low-Frequency Range and Low Drift Noise

Nakamura¹,

Kurihara

Watanabe

et al. 2012

IEEE Sensors J.

Self Cite

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“…Microphones are also getting used for security purpose. [1] The microphone converts the sound into a small electric current. Whenever a person speaks, sound waves enter the microphone; generate energy.…”

Section: Introductionmentioning

confidence: 99%

Trust Worthiness of Microphones

2022

IRJMETS

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Microphones are used everywhere. A microphone is built into many new devices so that they can be controlled by voice. Nowadays, microphones are the most important part of IOT devices. Microphones are used in voice assistant bars, smart watches, refrigerators, and many other devices. Microphones in some IOT devices work the entire time the device is running. Because it should cause a lot of data collection. This data is used for a better user experience. But is it safe to collect so much data from everyday life? As we get used to it widely and cover almost every aspect of our daily lives, are they considered trusted devices? Because we rely on them for many reasons, yet they are trusted by everyone? This research suggested opinions about the credibility of microphones and their use. Microphones are an important part of our daily life. So if it is believed to be credible how devices with built-in microphones should be secured and if it is not believed to be trusted how devices with built-in microphones should join these devices and spread awareness to support the privacy of people's microphones, this thing is also mentioned later in this research.

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“…But the utilization of smart sensors is an approach to increase performance and overcome costs in monitoring systems. They use standard off-the-shelf sensor and add signal processing, communication and integration capabilities in their functionality [4,5]. This paper is a smart sensor, integrated as a low-cost SOC.…”

Section: Introductionmentioning

confidence: 99%

Real Time SOC Based Low Cost Smart Sensor Using DWT on FPGA

Mohan¹

2012

IJAREEIE

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ABSTRACT:In this world of fast growing technology all the monitoring systems require the features like high performance instrumentation, low-cost primary sensors, online signal processing, portability, and versatility. Introduction of smart sensor comes up with all these features. Commercially available monitoring equipment cannot easily achieve versatility and portability. But smart sensor approach will increase the performance and overcome costs in monitoring systems. They use standard off-the-shelf sensors and add signal processing, communication and integration capabilities in their functionality. This paper proposes implementation of real time system-on-chip (SOC) based smart sensor for time-frequency analysis of the signals like voltage, electric current and vibrations by applying discrete wavelet transform (DWT) on field programmable gate array(FPGA). The proposed smart sensor uses a proprietary hardware processing unit. This unit includes a multiplier accumulate unit (MAC) for computing real time discrete wavelet transform for all the input signals. The proposed designs of MAC uses a modified booth multiplier and carry save adder for area optimization and propagation delay. This design can connect to different primary sensors without additional instrumentation and shows obtained results in 2-D view on a video graphics array screen or liquid crystal display. For presentation purposes, hardware computed results will be sending to a PC through an RS232 interface and plotting in MATLAB. The SOC-based smart sensor module will be designing and developing in Xilinx 12.2 ISE using VHDL and simulating in Modelsim 6.3f.

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A Multivariable Detection Device Based on a Capacitive Microphone and Its Application to Security

Cited by 10 publications

References 9 publications

Design of a Preamplifier for Capacitive Sensors With Wide Low-Frequency Range and Low Drift Noise

Design of a Preamplifier for Capacitive Sensors With Wide Low-Frequency Range and Low Drift Noise

Trust Worthiness of Microphones

Real Time SOC Based Low Cost Smart Sensor Using DWT on FPGA

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