Phase Difference Detection Research Articles

Design and Development of a Low-Cost Arduino-Based Electrical BioImpedance Spectrometer.

Background:Bioimpedance spectroscopy (BIS) is a device used to measure electrical impedance at frequencies from 0 Hz to 1 MHz. Many clinical diagnosis and fundamental researches, especially in the field of physiology and pathology, rely on this device. The device can be used to estimate human body composition, through the information of total body water, extracellular fluid and intracellular fluid, fat-free mass, and fat mass from its impedance. BIS analysis can provide physiological statuses such as ischemia, pulmonary edema, skin cancer, and intramuscular tumors. BIS is expected to be used even more widely, both for hospital or home-based use, particularly because BIS handy, compact, inexpensive, and less power-consuming with adequately accurate real-time. In previous research, the BIS design was based on the magnitude-ratio and phase-difference detection using the AD8302 gain-phase detector method which resulted in an operating range between 20 kHz and 1 MHz. However, the impedance was obtained from the logarithmic ratio magnitude which caused the device to have limited accuracy at frequencies <20 kHz.Methods:In this research, we conduct design and development of a low-cost arduino-based electrical bioimpedance spectrometer.Results:The low-cost bioimpedance spectrometry was successfully developed using AD9850 as the programmable function generator, OPA2134 as the OpAm of voltage-controlled current source, AD620A as the instrument amplifier and AD536A as the alternating current to direct current converter which could work accurately from 0 Hz to 100 kHz.Conclusion:The multi-frequency bioimpedance device developed in this research has the capability to safely measure the impedance of the human body due to its relatively stable electric current, which is equal to (0.370 ± 0.003) mA with frequencies ranging from 5 to 200 kHz and has an accuracy of over 90% in the frequency range of 10 Hz to 100 kHz.

Design of Electromagnetic Wave Resistivity Logging Toolfor Underground Coal Mine

Electromagnetic wave resistivity logging is an important method in oil logging, but it has not been applied in underground coal mine due to special working conditions and explosion-proof requirements. In this paper, through theoretical analysis and simulation, an electromagnetic wave resistivity logging tool is designed, which is suitable for underground coal mine. The detection of amplitude ratio and phase difference of weak signal is realized, and its performance index meets the actual working conditions.

Design of Electromagnetic Wave Resistivity Measurement System for Underground Coal Mine

In this paper, the measurement system of electromagnetic wave resistivity logging tool for underground coal mine is designed, which is based on DSP and FPGA. The detection of amplitude ratio and phase difference of weak signal is realized, and its performance index meets the design requirements and actual needs.

Technique of Phase Difference Detection TOF Sensor and Application for the Vehicle and Axle Detection

Technique of Phase Difference Detection TOF Sensor and Application for the Vehicle and Axle Detection

A Novel High Speed, Low Power, and Symmetrical Phase Frequency Detector with Zero Blind Zone and π Phase Difference Detection Ability

This paper presents a novel symmetrical phase frequency detector (PFD) sensitive to the falling edge of input clocks. Notably, the new PFD has an open-loop structure and no reset path, since UP and DN (outputs of the PFD) are never allowed to reach logic high simultaneously. Hence, the blind zone is completely eliminated in this case. Dead zone has been reduced to a great extent about 68 fs. Meanwhile, the proposed PFD is reliably capable of detecting from 0° to 360°, even 180° phase difference between clocks correctly by itself. The PFD has been simulated using the H-SPICE level 49 of a standard 0.18 μm CMOS process. It has been simulated in different conditions. Its maximum operating frequency at the worst-case conditions varied from 1.4 to 4.7 GHz at different supply voltages varied from 1.2 to 2.4 V. It can operate from very low frequencies up to 4.3 GHz at the power supply of 1.8 V, reliably. It can be used in high-speed and low-power applications. The new PFD consumes power within a range from 11.79 to 478.8 μW when operating at 50 MHz and 4.3 GHz, respectively. It has also been simulated in different process corners. Using the minimum size devices leads to a compact layout and die size of about 124.3 μm2.

Fast pulse train control using filled-aperture coherent beam combining for high-average-power laser systems.

This study demonstrates fast pulse train switching using a coherent polarization beam combiner with a phase difference detection (PDD) algorithm. Based on the highly stable feedback control obtained with the PDD algorithm, stable burst-mode extraction with an arbitrary duty cycle was achieved with a contrast ratio of 800:1 for a third-harmonic light (347nm) of a 5MHz pulsed Yb-doped fiber laser. The proposed method can be effectively used for high-speed switching in high-average-power pulsed laser systems.

Multilevel objective measures of interaural phase difference detection

Sensitivity to interaural phase difference (IPD) cues is critical for localizing sound and hearing in background noise. Recent work from multiple laboratories has explored electrophysiologic methods for assaying IPD sensitivity with the aim of developing an objective measure of binaural hearing. Such a measure would be useful in a variety of clinical and research applications such as understanding the effects of aging on binaural hearing; fine-tuning hearing aids/cochlear implants to maximize binaural benefit; and assessing neural damage after a traumatic brain injury. Here, we present data from an ongoing study evaluating a novel “multi-level” (brainstem, midbrain, and cortex) simultaneous measure of IPD acuity. Amplitude modulated (20, 40, and 80 AM) carrier tones (125, 250, and 500 Hz) with IPDs embedded in them (7 deg–180 deg) were used to generate auditory evoked potentials in young, normal hearing listeners. Neural responses corresponding to the carrier tones (frequency following responses), amplitude modulation envelopes (envelope following responses), and cortical change detection (acoustic change complex) were measured simultaneously to provide a multi-level snapshot of neural IPD processing. Parametric data presented here demonstrate feasibility and limitations of this approach for measuring IPD encoding at multiple levels of the auditory system.

An Electromagnetic Tracking Method Based on Phase Difference Detection

Electromagnetic tracking has widely been used in many fields, such as virtual reality, motion tracking, and biomedicine. Especially in surgical navigation systems, electromagnetic tracking offers a cost-effective alternative to traditional X-ray fluoroscopy. In this paper, we present a new magnetic tracking method based on phase difference detection. Two 3-axis magnetic sources and one 3-axis sensor are needed in the tracking system. The position and orientation of the sensor can be obtained simply by measuring the phase difference between the square of the synthetic magnetic induction intensity at the position of the sensor and the square of the excitation current of the magnetic source. The experimental results indicate that this method has a good tracking accuracy and speed. The mean position error is less than 0.1 cm, and the theoretical tracking time can be less than 3.5 ms when the frequency of the excitation current is no less than 1 kHz. Furthermore, antinoise simulations show that the tracking performance of this method is more robust against environmental noise than that of existing methods. Therefore, the electromagnetic tracking method proposed in this paper has good application prospects in many respects. It enables real-time tracking with high accuracy and a strong antinoise ability.

High-definition and high-sensitivity CMOS image sensor with all-pixel image plane phase-difference detection autofocus

In this paper, we describe an overview of autofocus (AF) technology for digital still cameras, video camcorders, and smartphones. Subsequently, we propose a CMOS image sensor (CIS) with all-pixel image plane phase-difference detection AF (PDAF) and describe a device structure and an optical design for fast and high-quality AF and low-noise imaging. To perform both PDAF and imaging function in all pixels, an individual pixel is composed of two horizontally displaced sub-photodiodes (PDs) and one microlens (ML). In particular, we describe PD and pixel isolation technology for high-definition, high-sensitivity, and low-noise PDAF-CIS with about front-side-illuminated (FSI) 6.4-µm-size pixel and back-side-illuminated (BSI) 1.X µm-size pixels.

Study on the Detection Method of Ultrasonic Hydrogen Concentration

In this paper, the ultrasonic phase difference detection method is proposed aiming at the problem existing in hydrogen detection technology. The method is based on the significant difference between the sound speed of hydrogen and other gases. Using the double channel design, the ultrasonic speed difference is transformed into the phase difference. The measured phase difference is used to reflect the change of gas concentration, and the measurement accuracy is improved. Digital temperature sensor is used to compensate the environment temperature, and the working temperature range of the sensor is enlarged. The experimental results show that the relative error of this measurement method is less than 2%, which meets the requirements of relevant national standards, and realizes the fast, high accuracy, low power consumption, low cost detection, and has high theoretical significance and application value.

An Indirect Current Phase Detection Method Applied to Automatic Phase Compensation Driver for 1Φ BLDC Fan Motor

The inductance of the stator winding of BLDC motors will cause the current to lag behind the back-EMF, and the lag will result in the drop of the operating efficiency and increase the acoustic noise and vibration of the fan motor. This article proposes a low cost, simple structure, and more efficient method to perform the phase compensation. The indirect method to detect the zero-crossing point (ZCP) of the winding current will avoid the extra power loss of the current sensor. The automatic phase compensation utilizes the phase difference detection of the back-EMF and winding current and then switches the power transistors with the phase advance automatically to eliminate the current lag. The related experimental results corroborate the feasibility and effectiveness of the proposed driving method.

Accuracy enhancement in low frequency gain and phase detector (AD8302) based bioimpedance spectroscopy system

Bioimpedance spectroscopy (BIS) is the measurement of the impedance of biological tissues. In the development of a low cost, portable BIS system the gain and phase difference detection (GPD) method is usually used. However this method suffers from low accuracy at low frequencies due to the presence of spikes or peaks. Detection and removal of these peaks will improve the performance of the GPD based BIS system at low frequencies. Peak detection in physiological signals is a well developed area. A lot of algorithms have been developed in the past for the determination of peaks in signals and their time of occurrence. For real-time processing, microcontroller based peak detection algorithms have also been developed in the past. In this paper, the problem of the GPD method at low frequency is examined closely and then three algorithms were used to mitigate it. The first is based on a moving average filter, the second is a simple peak detection and elimination (SPD) and the last is a peak detection based on the frequency of the input signal to the GPD (SFPD). These algorithms were evaluated with both simulated and measured data. Four parameters were used to indicate the performance of the algorithms; run-time, RMSE, sensitivity and positive predictability. The RMSEs were less than 0.17 for moving average, 0.07 for SPD and 0.08 for SFPD. The run-times was less than 10 ms for SFPD while that for the SPD and moving average were around 30 ms and 80 ms respectively. In all it was found that the algorithms based on peak detection have better results. The computational simplicity of the algorithms makes them suitable for microcontroller based implementation.

Phase-modulated dual-homodyne interferometer without periodic nonlinearity

A novel dual-homodyne interferometer, in which one interferometer acts as the reference interferometer and the other as the measurement one, is proposed to eliminate periodic nonlinearity for nanometer displacement measurement. By using one electro-optic phase modulator to modulate the common reference arm of the two interferometers, the DC interference signals of homodyne interferometers are modulated to AC signals. The measured displacement is carried on the phase difference change of the two AC interference signals. To address the influence of unequal fluctuations of the DC offsets of interference signals on the zero-crossing phase detection, a new phase difference detection method is proposed by counting the sample numbers in positive and negative half periods of interference signals. The merits of this interferometer are not only eliminating the nonlinear errors inherent to heterodyne and homodyne interferometers but also having the abilities of strong anti-interference, insensitivity to laser power drift and the unequal gain of detectors, as well as not demanding quadrature signals. An experiment of nanometer displacement measurement was performed to verify the feasibility of the interferometer, and the results show that sub-nanometer accuracy can be realized without periodic nonlinearity. The large displacement experiment shows that the results obtained with the proposed interferometer are in good accordance with those obtained from a comparison interferometer. These results show that the proposed interferometer can realize large displacement measurement with nanometer accuracy.

A Low Noise and High Sensitivity Image Sensor with Imaging and Phase-Difference Detection AF in All Pixels

A Low Noise and High Sensitivity Image Sensor with Imaging and Phase-Difference Detection AF in All Pixels

Cortical Measures of Binaural Processing Predict Spatial Release from Masking Performance.

Binaural sensitivity is an important contributor to the ability to understand speech in adverse acoustical environments such as restaurants and other social gatherings. The ability to accurately report on binaural percepts is not commonly measured, however, as extensive training is required before reliable measures can be obtained. Here, we investigated the use of auditory evoked potentials (AEPs) as a rapid physiological indicator of detection of interaural phase differences (IPDs) by assessing cortical responses to 180° IPDs embedded in amplitude-modulated carrier tones. We predicted that decrements in encoding of IPDs would be evident in middle age, with further declines found with advancing age and hearing loss. Thus, participants in experiment #1 were young to middle-aged adults with relatively good hearing thresholds while participants in experiment #2 were older individuals with typical age-related hearing loss. Results revealed that while many of the participants in experiment #1 could encode IPDs in stimuli up to 1,000 Hz, few of the participants in experiment #2 had discernable responses to stimuli above 750 Hz. These results are consistent with previous studies that have found that aging and hearing loss impose frequency limits on the ability to encode interaural phase information present in the fine structure of auditory stimuli. We further hypothesized that AEP measures of binaural sensitivity would be predictive of participants' ability to benefit from spatial separation between sound sources, a phenomenon known as spatial release from masking (SRM) which depends upon binaural cues. Results indicate that not only were objective IPD measures well correlated with and predictive of behavioral SRM measures in both experiments, but that they provided much stronger predictive value than age or hearing loss. Overall, the present work shows that objective measures of the encoding of interaural phase information can be readily obtained using commonly available AEP equipment, allowing accurate determination of the degree to which binaural sensitivity has been reduced in individual listeners due to aging and/or hearing loss. In fact, objective AEP measures of interaural phase encoding are actually better predictors of SRM in speech-in-speech conditions than are age, hearing loss, or the combination of age and hearing loss.

Accurate submicron edge detection using the phase change of a nano-scale shifting laser spot

Accurate edge detection with lateral super-resolution has been a critical issue in optical measurement because of the barrier imposed by the optical diffraction limit. In this study, a diffraction model that applies scalar diffraction theory of Fresnel–Kirchhoff is developed to simulate phase variance and distribution along edge location. Edge position is detected based on the phase variation that occurs on the edge with a surface step-height jump. To detect accurate edge positioning beyond the optical diffraction limit, a nanopositioning stage is used to scan the super steep edge of a single-edge and multi-edges submicron grating with nano-scale, and its phase distribution is captured. Model simulation is performed to confirm the phase-shifting phenomenon of the edge. A phase-shifting detection algorithm is developed to spatially detect the edge when a finite step scanning with a pitch of several tenth nanometers is used. A 180nm deviation can occur during detection when the step height of the detecting edge varies, or the detecting laser spot covers more than one edge. Preliminary experimental results show that for the edge detection of the submicron line width of the grating, the standard deviation of the optical phase difference detection measurement is 38nm. This technique provides a feasible means to achieve optical super-resolution on micro-grating measurement.

OM-D E-M1の像面位相差AF

OM-D E-M1の像面位相差AF

Phase Frequency Detector Using Transmission Gates for High Speed Applications

In this paper a new phase-frequency detector is proposed using transmission gates which can detect phase difference less than 500ps. In other word, the proposed Phase-frequency Detector (PFD) can work in frequencies higher than 1.7 GHz, whereas a conventional PFD operates at frequencies less than 1.1 GHz. This new architecture is designed in TSMC 0.13um CMOS Technology. Also, the proposed PFD achieves a capture range approximately twice that of conventional PFDs. The simulation results support the theoretical predictions. To validate correct performance of this novel PFD, it is then used in a conventional delay locked loop structure.

Paper] A Low Noise and High Sensitivity Image Sensor with Imaging and Phase-Difference Detection AF in All Pixels

In this paper, we describe a device structure and optical design for a CMOS image sensor with phase-difference detection photodiodes (PD) for autofocus (AF) function. The individual pixel of this image sensor is composed of two horizontally displaced PDs separated by a PN junction. All the effective pixels function as both the imaging and the phase-difference detection AF (PDAF). We have realized a low dark random noise (1.8e- at 1PD, 2.5e- at 1pixel) and high sensitivity (78Ke-/lx.sec at 1green pixel) image sensor with the imaging and the PDAF functions in all the effective pixels.

A GaAs MMIC-based X-band Dual Channel Microwave Phase Detector based on MEMS Microwave Power Sensors

By sensing the output powers of two channels with MEMS microwave power sensors, a wideband 8-12GHz dual channel microwave phase detector is presented. In order to detect phase difference between reference signal and testing signal in entire 0-360° at X-band, artificial 45° phase lead and 45° phase lag are introduced in two channels, additionally. The proposed phase detector is composed of power dividers, power combiners, 45° (at 10GHz) coplanar waveguide (CPW) transmission delay lines, MEMS capacitive power sensors and thermoelectric power sensors. The two CPW transmission lines result in 45° phase lead and 45° phase lag at 10GHz, and the two different kinds of power sensors are used to detect the combined powers. The fabrication of the phase detector is compatible with GaAs Microwave Monolithic Integrated Circuit (MMIC) technology. The phase detection measurement is accomplished at 10GHz with 0-180° phase shift between testing signals generated by a tunable analog phase shifter. Phase detection results in two channels show that the normalization of the measured results fit the calculated results well, though the results of phase lead have a little of deviation.