A complete low voltage analog lock-in amplifier to recover sensor signals buried in noise for embedded applications

Gabal, M.; Medrano, N.; Calvo, B.; Martínez, P.A.; Celma, S.; Valero, M. R.

doi:10.1016/j.proeng.2010.09.051

Cited by 20 publications

(8 citation statements)

References 2 publications

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“…Actually it is also a kind of correlation detection. Figure.1 Lock-in amplifier experimental block diagram Gabal et al [8] studied the small AC sensor signals which were buried in noise. They thought that using low voltage simulated phase-locked amplifier to detect sensor signals with low SNR is very effective.…”

Section: (4) Lock-in Amplifiermentioning

confidence: 99%

Current progress on weak signal detection

Wang

Yang

Long

et al. 2013

2013 International Conference on Quality, Reliability, Risk, Maintenance, and Safety Engineering (QR2MSE)

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In machinery condition monitoring, weak signal is a type of signal that has very low signal-to-noise ratio (SNR). Therefore, it is necessary to develop effective methods so as to enhance or extract useful information from the noisy signal. These methods aim to solve the problem of de-noising and separation of mixed-signal. This paper investigated the current progress on weak signal detection methods, including traditional and emerging, linear and non-linear methods. The combination of various methods is presented according to their advantages and disadvantages of these methods. In the end, the future development of weak signal detection technology is summarized.

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Section: (4) Lock-in Amplifiermentioning

confidence: 99%

Current progress on weak signal detection

Wang

Yang

Long

et al. 2013

2013 International Conference on Quality, Reliability, Risk, Maintenance, and Safety Engineering (QR2MSE)

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“…Before, most large-scale ERT surveys used either high-frequency single-channel seismic dataloggers (e.g. Reftek Texan-125) or three-channel magnetotelluric dataloggers (Roßberg, 2007;Golden et al, 2004). However, the latter provided only a maximum sampling frequency of 8 Hz leading to anthropogenic noise energy folding into the signal frequency band (typically slightly below 1 Hz) due to aliasing effects.…”

Section: Introductionmentioning

confidence: 99%

“…In particular, performances at low frequencies are significantly better. The field of applications which require the detection of very low signals in noisy surroundings where the use of lock-in detectors from optics is widespread (Andersson et al, 2007;Masciotti et al, 2008;Holzman et al, 2005), impedance spectroscopy (Albertini and Kleemann, 1997), wireless networks (Gabal et al, 2010), biologic applications (Ferri et al, 2001;Johnson et al, 2002), electron spin resonance (ESR) (Vistnes et al, 1984;Murányi et al, 2004) to nuclear magnetic resonance (NMR) (Saam and Conradi, 1998;Caracappa and Thorn, 2003).…”

Section: Introductionmentioning

confidence: 99%

A remote-control datalogger for large-scale resistivity surveys and robust processing of its signals using a software lock-in approach

Oppermann¹,

Günther²

2018

Geosci. Instrum. Method. Data Syst.

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Abstract. We present a new versatile datalogger that can be used for a wide range of possible applications in geosciences. It is adjustable in signal strength and sampling frequency, battery saving and can remotely be controlled over a Global System for Mobile Communication (GSM) connection so that it saves running costs, particularly in monitoring experiments. The internet connection allows for checking functionality, controlling schedules and optimizing pre-amplification. We mainly use it for large-scale electrical resistivity tomography (ERT), where it independently registers voltage time series on three channels, while a square-wave current is injected. For the analysis of this time series we present a new approach that is based on the lock-in (LI) method, mainly known from electronic circuits. The method searches the working point (phase) using three different functions based on a mask signal, and determines the amplitude using a direct current (DC) correlation function. We use synthetic data with different types of noise to compare the new method with existing approaches, i.e. selective stacking and a modified fast Fourier transformation (FFT)-based approach that assumes a 1/f noise characteristics. All methods give comparable results, but the LI is better than the well-established stacking method. The FFT approach can be even better but only if the noise strictly follows the assumed characteristics. If overshoots are present in the data, which is typical in the field, FFT performs worse even with good data, which is why we conclude that the new LI approach is the most robust solution. This is also proved by a field data set from a long 2-D ERT profile.

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“…In the synchronous detection architecture much care needs to be taken for perfect matching of the frequency and phase values of the data with the reference signal, otherwise, the signal cannot be completely recovered. Gabal et al has shown the use of two parallel PSD to eliminate system phase dependence (Gabal et al 2010). Recently, Marcellis et al presented a LIA chip that performs automatic alignment of the relative phase between the input and the reference signal and performs self-tuning (De Marcellis et al 2013).…”

Section: Introductionmentioning

confidence: 99%

A portable battery powered microfluidic impedance cytometer with smartphone readout: towards personal health monitoring

Talukder

Furniturewalla

et al. 2017

Biomed Microdevices

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We present a portable system for personalized blood cell counting consisting of a microfluidic impedance cytometer and portable analog readout electronics, feeding into an analog-to-digital converter (ADC), and being transmitted via Bluetooth to a user-accessible mobile application. We fabricated a microfluidic impedance cytometer with a novel portable analog readout. The novel design of the analog readout, which consists of a lock-in-amplifier followed by a high-pass filter stage for subtraction of drift and DC offset, and a post-subtraction high gain stage, enables detection of particles and cells as small as 1 μm in diameter, despite using a low-end 8-bit ADC. The lock-in-amplifier and the ADC were set up to receive and transmit data from a Bluetooth module. In order to initiate the system, as well as to transmit all of the data, a user friendly mobile application was developed, and a proof-of-concept trial was run on a blood sample. Applications such as personalized health monitoring require robust device operation and resilience to clogging. It is desirable to avoid using channels comparable in size to the particles being detected thus requiring high levels of sensitivity. Despite using low-end off-the-shelf hardware, our sensing platform was capable of detecting changes in impedance as small as 0.032%, allowing detection of 3 μm diameter particles in a 300 μm wide channel. The sensitivity of our system is comparable to that of a high-end bench-top impedance spectrometer when tested using the same sensors. The novel analog design allowed for an instrument with a footprint of less than 80 cm. The aim of this work is to demonstrate the potential of using microfluidic impedance spectroscopy for low cost health monitoring. We demonstrated the utility of the platform technology towards cell counting, however, our platform is broadly applicable to assaying wide panels of biomarkers including proteins, nucleic acids, and various cell types.

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A complete low voltage analog lock-in amplifier to recover sensor signals buried in noise for embedded applications

Cited by 20 publications

References 2 publications

Current progress on weak signal detection

Current progress on weak signal detection

A remote-control datalogger for large-scale resistivity surveys and robust processing of its signals using a software lock-in approach

A portable battery powered microfluidic impedance cytometer with smartphone readout: towards personal health monitoring

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