A Software Digital Lock-In Amplifier Method with Automatic Frequency Estimation for Low SNR Multi-Frequency Signal

Wang, Yifan; Cheng, Yuhua; Chen, Kai; Wang, Li; Wang, Hongrong

doi:10.3390/app12136431

Cited by 8 publications

(6 citation statements)

References 31 publications

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“…Despite the DFT's higher computational complexity, O(N 2 ) for N samples and N frequency values, it can be calculated with faster algorithms, such as the fast Fourier transform (FFT), with complexity O(N log N). Even so, FFT presents a higher computational complexity than the direct calculation of amplitude and phase using DLIA, which could explain the difficulty to find reports of embedded sensor applications using FFT as a synchronous detection method [28,29].…”

Section: Introductionmentioning

confidence: 99%

Phase sensitive detection for embedded sensors

Machado,

Ribeiro

2024

Meas. Sci. Technol.

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The measurement of some physical properties requires detection of both amplitude and phase of an applied test signal. In portable sensors, this needs to be performed locally with integrated analog circuits or digital processing. Wireless sensor network (WSN) allows the measurements over wide areas but raises a challenge of using efficient algorithm for phase sensitive detection (PSD) in nodes with constrained processing capacity. It is not straightforward to compare different PSD methods because their performance is closely related to the fine tuning of their parameters such as filter order and cut-off frequency.We propose a methodology to compare several PSD methods subjected to the same response time to assess its ability to provide accurate estimation in the presence of noise. We also determine the computational complexity of the investigated methods in terms of the number of operations required. We investigate both continuous and windowed operation. The methods were tested through simulations and verified using a dedicated embedded system.Our findings demonstrate that Goertzel algorithm rendered the best results, with smaller estimation error and less computation complexity.

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Section: Introductionmentioning

confidence: 99%

Phase sensitive detection for embedded sensors

Machado,

Ribeiro

2024

Meas. Sci. Technol.

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“…To solve this problem few methods based on FFT have been proposed recently to track the frequency of lock-in amplifiers. However, the amplitude extraction results of these methods are not much accurate due to the limitation of FFT [29,30].…”

Section: Introductionmentioning

confidence: 99%

A Novel Power Measurement Method Using Lock-In Amplifiers with a Frequency-Locked Loop

Cho

Choi

2023

Electronics

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The extensive use of renewable energy systems with grid-connected inverters (GCIs) causes harmonic injection. Similarly, the imbalance in energy demand and supply causes frequency fluctuations. As a result of the increased harmonics and frequency fluctuations, the accuracy of power measurement using conventional methods continues to decline. Precision in power measurement is an essential factor for the billing and management of power supply and demand. Moreover, it is challenging to build a supply plan for the power demand and to manage the billing for the power consumption. To solve these problems, this paper proposes a novel method based on Lock-in Amplifier (LIA) and Lock-in Amplifier Frequency-Locked Loop (LIA-FLL) to measure the power with high precision and accuracy. The proposed method first tracks the variations in the input signal frequency using LIA-FLL and generates the updated reference signals for LIA. After that, the LIA is used to extract the accurate amplitude of each frequency component. The proposed method results in accurate and precise measurement, even with harmonics and frequency fluctuations. The validity of the proposed method is verified by comparing the power measurement results with the classical method, FFT, and ZERA COM3003 (a commercially available power measurement reference instrument).

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“…Simultaneously, phase alignment technology is extensively employed in precision measurements [17,18] and can be categorized into two structures. One approach [19][20][21] employs a dual-channel method for phase alignment, where a pair of orthogonal reference signals is multiplied by the input signal to calculate the current phase difference and ultimately achieve phase alignment. While this method allows for a precise measurement of resistance and capacitance, it does lead to an increase in the circuit's power consumption.…”

Section: Introductionmentioning

confidence: 99%

Research and Implementation of a Demodulation Switch Signal Phase Alignment System in Dynamic Environments

Xue,

Yu,

Sui

et al. 2023

Sensors

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In the space gravitational wave detection mission, inertial sensors play the role of providing an inertial reference for the laser interferometric measurement system. Among them, the capacitance sensor serves as the core key technology of the inertial sensor, used to measure the relative position of the test mass (TM) in the electrode cage. The capacitance sensor utilizes synchronous demodulation technology to extract signals from the AC induction signal. When the phase of the demodulation switch signal is aligned, the synchronous demodulator can most effectively filter out noise, thus directly influencing the performance of the capacitance sensor. However, since the TM is in a suspended state, the information read by the capacitance sensor is dynamic, which increases the difficulty of demodulation phase alignment. In light of this, a method is proposed for achieving the phase alignment of the demodulation switch signal in a dynamic environment. This is accomplished by adjusting the phase of the demodulation switch signal, and subsequently computing the phase difference between the AC induction signal and the demodulation switch signal. At the same time, a measurement and evaluation method for phase deviation is also proposed. Ultimately, an automatic phase alignment system for the demodulation switch signal in dynamic environments is successfully implemented on an FPGA platform, and tests are conducted on a hexapod PI console platform to simulate dynamic environments. The experimental results demonstrate that the system accurately achieves phase alignment in the static environment, with a phase deviation of 0.1394 rad. In the simulated dynamic environment, the phase deviation is 0.1395 rad.

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A Software Digital Lock-In Amplifier Method with Automatic Frequency Estimation for Low SNR Multi-Frequency Signal

Cited by 8 publications

References 31 publications

Phase sensitive detection for embedded sensors

Phase sensitive detection for embedded sensors

A Novel Power Measurement Method Using Lock-In Amplifiers with a Frequency-Locked Loop

Research and Implementation of a Demodulation Switch Signal Phase Alignment System in Dynamic Environments

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