Multiple Phase Shift Research Articles

Differential Effects of Light and Dark Phase Modifications on Jet Lag Adaptability in Mice

ABSTRACTIn chronobiology, shifting light/dark cycles is a common method to disrupt circadian rhythms. While the direction and magnitude of a phase shift (e.g., +6 denoting a 6‐h advanced shift) dictate the temporal change before and after the shift, little attention has been paid to the duration and relative proportion of daytime and nighttime during the shift, leading to a critical, unexamined variable in circadian research. In this study, we introduce the concepts of “L‐shift” (longer light phase on the shift day) and “D‐shift” (longer dark phase), and investigate how these variations impact the adaptability of mice to jet lag. By examining multiple phase shifts (12L vs. 12D, +6L vs. +6D, −6L vs. −6D), we demonstrate that L‐shifts not only facilitate faster adaptation but also significantly reduce the severity of sepsis in a jet lag‐sensitive lipopolysaccharide‐induced sepsis model. Further investigations with additional phase shifts at 1‐h intervals (+8 to +11) reinforced the enhanced fitness of mice under L‐shifts. Mechanistically, L‐shifts were found to increase sleep duration, thereby improving circadian entrainment, with sleep deprivation nullifying the adaptability differences between lighting protocols. These findings underscore a previously unrecognized factor in circadian biology and suggest that optimizing lighting protocols could profoundly improve adaptability to circadian disruptions. This research opens new avenues for enhancing therapeutic strategies and refining experimental designs in the field of chronobiology.

Studying the influence of correction codes on coherent reception of M-PSK signals in the presence of noise and harmonic interference

Objectives. Signals with multiple phase shift keying (M-PSK) exhibiting good spectral and energy characteristics are successfully used in many information transmission systems. These include satellite communication systems, GPS, GLONASS, DVB/DVB-S2, and a set of IEEE 802.11 wireless communication standards. In radio communication channels, the useful signal is affected by various interferences in addition to noise. One of these is harmonic interference. As a result, high intensity harmonic interference practically destroys the reception of M-PSK signals. One of the important requirements for the quality of data transmission is the system error tolerance. There are different ways of improving the quality of information transmission. One of these is the use of corrective encoding technology. The aim of the paper is to assess the noise immunity of a coherent demodulator of M-PSK signals using Hamming codes (7,4) and (15,11), and convolutional encoding with Viterbi decoding algorithm (7,5) when receiving M-PSK signals under noise and harmonic interference in the communication channel.Methods. The methods of statistical radio engineering, optimal signal reception theory and computer simulation modeling were used.Results. Experimental dependencies of the bit error rate on the signal-to-noise ratio and on the intensity of harmonic interference of coherent reception of M-PSK signals in a channel with noise and harmonic interference were obtained using computer simulation modeling. This was done without using correction codes and with Hamming code (7.4) and (15.11) and convolutional encoding with Viterbi decoding algorithm (7,5).Conclusions. It is shown that the application of the correction codes effectively corrects errors in the presence of noise and harmonic interference with lower intensity. The correction is ineffective in the presence of high intensity interference. These results can provide important guidance in designing the reliable and energy efficient system.

Multi-wavelength pinhole point diffraction interferometry for optics metrology with interferometric intensity based phase retrieval method

In this paper, we propose a multi-wavelength pinhole point diffraction interferometry (MPPDI) and a two-step phase extraction method based on the interferometric intensity information. MPPDI is mainly used to extend the dynamic measurement range of traditional pinhole point diffraction interferometry (PPDI) to realize the measurement of large-aperture and high-order aspheric surface. Spherical/aspherical optics will be test under three different wavelengths, and the corresponding interferograms are recoded by 3CMOS detector at the same moment. By combining different wavelengths, MPPDI can obtain a synthetic wavelength with a larger measuring range and greater flexibility. In interferometry, the choice of the wavelength of the light source has a great influence on the measurement range and accuracy. In MPPDI, we can choose different wavelength combinations to select the most suitable synthetic wavelength according to the asphericity of the tested mirror. To enhance efficiency and reduce the impact of air disturbances during phase shifts, we propose a new phase extraction method based on interferometric intensity to interpret the phase map of surface information. The background intensity of diffraction wavefront is firstly pre-recorded by 3CMOS, then phase-shift interferograms of test mirror is acquired with two-step piezoelectric ceramic driver (PZT) movement. From the analysis, it can be found that fringe modulation has tiny influence on the interferograms intensity. Therefore, based on global intensity distribution of fringe pattern and grayscale information, phase map can be retrieval using proposed two-step processing method (only single phase-shift). The two-step phase extraction method can reduce the number of phase shifts from 9 to 3, which improves the efficiency and reduces errors due to multiple phase shifts. MPPDI and two-step phase extraction we proposed have a larger measurement while reducing the number of phase shifts and avoiding error accumulation due to too many phase shifts. Suitable for large-aperture and high-order aspheric surface measurement.

On the Use of Near-Field Constellation Focusing for Physical Layer Security with Extremely Large Antenna Arrays

In the fast-changing world of wireless communications, the combination of extremely large antenna arrays (ELAAs) and energy-efficient transmission methods is envisioned for the 6G. The application of directivity in the transmitted constellation can increase physical layer security (PLS) and promote the energy efficiency of transmission. In such scenarios, large constellations can be divided into multiple binary phase shift keying (BPSK) components, with each component being individually amplified and transmitted by an antenna. In this work, we consider an ELAA acting as a transmitter and constellation decomposition at the sub-array level. We investigate the impact of considering a near-field channel model in terms of secrecy rate and mutual information. In addition to the energy efficiency of the constellation decomposition, it is demonstrated that the particularities of near-field beamforming increase the PLS, namely in terms of robustness to eavesdropping.

Extension of Zero-Voltage Switching Region of Wide Volage Ratio Range Dual-Active-Bridge Converter by LC Antiresonant Network

Zero-voltage switching (ZVS) for dual active bridge (DAB) with wide voltage conversion ratio has a contradiction with low conduction loss, especially under light power transmission. Root mean square (RMS) increase of inductor current is unavoidable just by optimizing modulation schemes. Inspired by the various frequency (VF) and various inductor (VI), this article proposes a DAB converter with the capability of regulating the impedance of the resonant tank to extend the ZVS region. With an <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LC</i> antiresonant circuit in series with original inductor, the equivalent inductance of the resonant network of the proposed converter increases along with the switching frequency within the designed frequency range. Thereby, when the voltage mismatches and the transferred power decreases, a large impedance is obtained by slightly increasing frequency to help to achieve ZVS. Moreover, the proposed DAB is found that single phase shift (SPS) has nearly identical characteristics of ZVS and conduction loss compared with multiple phase shift modulation. The benefit of this is that the complexity of close-loop control is significantly reduced just considering the switching frequency and external shift phase. In addition, ZVS characteristics and optimal control method are analyzed in detail. Finally, a 2 kW 360-400V/40-60V prototype is built, and the main experimental results are provided to verify the feasibility of the proposed converter and soft switching range of all switches.

Wavefront Reconstruction Using Two-Frame Random Interferometry Based on Swin-Unet

Due to its high precision, phase-shifting interferometry (PSI) is a commonly used optical component detection method in interferometers. However, traditional PSI, which is susceptible to environmental factors, is costly, with piezoelectric ceramic transducer (PZT) being a major contributor to the high cost of interferometers. In contrast, two-frame random interferometry does not require precise multiple phase shifts, which only needs one random phase shift, reducing control costs and time requirements, as well as mitigating the impact of environmental factors (mechanical vibrations and air turbulence) when acquiring multiple interferograms. A novel method for wavefront reconstruction using two-frame random interferometry based on Swin-Unet is proposed. Besides, improvements have been made on the basis of the established algorithm to develop a new wavefront reconstruction method named Phase U-Net plus (PUN+). According to training the Swin-Unet and PUN+ with a large amount of simulated data generated by physical models, both of the methods accurately compute the wrapped phase from two frames of interferograms with an unknown phase step (except for multiples of π). The superior performance of both methods is effectively showcased by reconstructing phases from both simulated and real interferograms, in comprehensive comparisons with several classical algorithms. The proposed Swin-Unet outperforms PUN+ in reconstructing the wrapped phase and unwrapped phase.

Phase-shifted fiber Bragg grating filters based on counter-propagating cladding modes coupling.

In this paper, we comprehensively analyze counter-propagating cladding mode assisted phase-shifted fiber Bragg gratings (FBGs) and propose an ultra-narrow bandwidth laser line filter based on such gratings. Full vector modal analysis has been used to obtain the mode guiding and its coupling characteristics. We show that the transmission spectrum of the counter-propagating cladding mode assisted FBGs can be tailored by incorporating single or multiple phase shifts along the grating length. Phase shifts open up narrowband transmission windows inside the stop band of the Bragg grating, and the transmitted wavelength can be altered by controlling the amount of phase shift. Unlike conventional FBGs, the grating discussed here has access to the evanescent field of the excited counter-propagating cladding mode, which opens up the possibility of refractive index based tuning of resonance wavelength. Further, the bandwidth of the proposed grating is two orders of magnitude smaller than that of the conventional LPGs. As an alternative application, we also show that with the right length ratio, the multiple phase shifts can also be used to create a very flattened single transmission peak inside the stop band. The effects of grating regulating factors such as the grating length, grating strength, location of the phase shift, and index apodization on the linewidth of the narrow central peak of π PS-FBG are also investigated. We present a clear physical explanation of various factors involved in the counter-propagating cladding mode coupling in such phase-shifted Bragg grating. Due to its extremely narrow transmission window, our study can find application in developing sensors for measuring parameters with greater accuracy. Such phase-shifted Bragg gratings can also be used to create an all-fiber demultiplexer for multichannel systems and fiber optic sensors as a particular application.

Optimal reception of multiple phase shift keying and quadrature amplitude modulation signals with non-coherent processing of harmonic interference

Objectives . Analysis of the reception noise immunity of multiple phase shift keying (M-PSK) and quadrature amplitude modulation (M-QAM) signals has demonstrated a significant reduction in the quality of reception of discrete information due to the presence of various types of non-fluctuating interference in a radio communication channel including targeted harmonic interference. Therefore, the development of algorithms for compensating the influence of such forms of interference is an urgent task. While various methods for combatting this kind of interference, these vary in terms of their effectiveness. The aim of the present work is to synthesize and analyze the optimal algorithm for the reception of M-PSK and M-QAM signals with incoherent processing of harmonic interference. Methods . Various statistical radio engineering and computer simulation methods were used in accordance with optimal signal reception theory. Results . Synthesis and analysis of the optimal algorithm for receiving M-PSK and M-QAM signals with incoherent processing of harmonic interference were carried out. In addition to calculating the correlation integrals in the receiver, it is necessary to form weight coefficients, whose value depends on the correlation of the interference oscillation (extracted from the received mixture) with a sample of the interference stored in the receiver. The dependences of the bit error probability on the signal-to-noise ratio, interference detuning, and inaccuracy in setting the frequency and level of the interference sample in the receiver were obtained. It is shown that the higher the gain in the noise immunity of reception, the greater the intensity of the harmonic interference. Conclusions . The synthesized receiver circuit effectively compensates for harmonic interference. However, the efficiency of its operation depends on the detuning of the harmonic interference relative to the center frequency of the spectrum of the useful signal. The scheme for incoherent processing of harmonic interference remains operational even with small (within ±10%) inaccuracies in setting the frequency and the level of the interference copy in the receiver.

Unifying the Transformer Current in Multiple Phase Modulation Without Current Spike During Load Transients

To accelerate the dynamic response in a dual active bridge converter, feed-forward control can be applied in parallel to the conventional PI controller for closed-loop control. The transformer current thus changes significantly due to the phase shift change. A current spike can appear during load transients, particularly when using multiple phase shift modulation. Effort has been made in the previous literature to implement active compensation between two different steady-state operations to eliminate the transformer current spike; however, this results in a complicated control structure. This letter thus proposes a novel modulation method unifying the transformer current for dual phase shift and triple phase shift modulation to mitigate the transformer current spike when switching among various phase shift controls during load transients. By applying the proposed pulsewidth modulation strategy, the instantaneous value of the transformer current stays the same at the beginning of the switching period even with different steady-state modulation techniques. Also, full-operation-range zero-voltage switching can be realized for the primary side or the secondary side switches by combining with the proposed modulation strategy. An experimental prototype demonstration validates the proposed modulation strategy.

Accurate determination of MFM tip’s magnetic parameters on nanoparticles by decoupling the influence of electrostatic force

Magnetic force microscopy (MFM) has become one of the most important instruments for characterizing magnetic materials with nanoscale spatial resolution. When analyzing magnetic particles by MFM, calibration of the magnetic tips using reference magnetic nanoparticles is a prerequisite due to similar orientation and dimension of the yielded magnetic fields. However, in such a calibration process, errors caused by extra electrostatic interactions will significantly affect the output results. In this work, we evaluate the magnetic moment and dipole radius of the MFM tip on Fe3O4 nanoparticles by considering the associated electrostatic force. The coupling of electrostatic contribution on the measured MFM phase is eliminated by combining MFM and Kelvin probe force microscopy together with theoretical modeling. Numerical simulations and experiments on nickel nanoparticles demonstrate the effectiveness of decoupling. Results show that the calibrated MFM tip can enable a more accurate analysis of micro-and-nano magnetism. In addition, a fast and easy calibration method by using bimodal MFM is discussed, in which the acquisition of multiple phase shifts at different lift heights is not required.

Observation of multiple fractional quanta in a superconducting bilayer disk with a pinhole

The magnetic-flux quantum (Φ0) cannot be generally divided into smaller ones in a usual superconductor. If a subdividing path is present, the science and technology of the superconductor drastically change. In previous studies, we experimentally presented a new, easy way to subdivide Φ0 into smaller quanta (Φf) using an ultrathin Nb bilayer with a through-pinhole (H. Ishizu, H. Yamamori, S. Arisawa, K. Tokiwa, Y. Tanaka, Physica C 595 (2022) 1354029.). However, because of an experimental technical problem, we could not use a higher field to generate more than one Φf. It was not clear if multiples of Φf could be trapped in a pinhole (in a usual superconductor, multiples of Φ0 are trapped in a pinhole). In this study, we observed multiple fractional phase shifts with a direct-current superconducting interference device (SQUID) placed on an ultrathin Nb bilayer disk containing a through-pinhole using an improved modification of an experimental procedure. The phase shift for the SQUID with the bilayer disk is an integer multiple of a basic fractional phase shift divided by 2π. However, we did not observe the fractional phase shift for a SQUID with a single-layer disk. These observations indicate that multiple fractional flux quanta are trapped in the bilayer disk. According to the vortex-molecule model, if the vortex molecule is larger than the bilayer disk, such quanta can be trapped. This is one example of altering a fundamental (universal) physical constant. The SQUID can more sensitively detect Φf than Φ0, rendering the design of novel superconducting electronics possible.

A CNN-MPSK Demodulation Architecture with Ultra-Light Weight and Low-Complexity for Communications

Modulation is an indispensable component in modern communication systems and multiple phase shift keying (MPSK) is widely studied to improve the spectral efficiency. It is of great significance to study the MPSK modulations of symmetric phases in practice. Based on convolutional neural networks (CNNs), we propose a generic architecture for MPSK demodulation, referred to as CNN-MPSK. The architecture utilizes a single-layer CNN and a pooling trick to crop network parameters. In comparison with conventional coherent demodulation, the CNN-MPSK eliminates three modules, i.e., carrier multiplication, bandpass filter and sampling decision. Thus, we can avoid π-inverted phenomenon from the multiplication of two carrier waves with different phases, as the carrier multiplication is not employed. In addition, we can reduce errors introduced by sampling decision. Furthermore, we conduct bit-error-rate tests for binary-PSK, 4PSK, 8PSK, and 16PSK demodulation. Experimental results reveal that the performance of CNN-MPSK is almost the same to that of conventional coherent demodulation. However, the CNN-MPSK demodulation reduces computational complexity from O(n2) to O(n) as compared to the latter one. Additionally, the proposed scheme can be readily applied for demodulation of non-symmetric MPSK constellations that maybe distorted by linear and nonlinear impairments in communication systems.

Soft-Switching Bidirectional Switched-Capacitor DC–DC Converter With Multiple Phase Shift Control Methods

In this article, a bidirectional bridge modular switched-capacitor (BBMSC) dc–dc converter is proposed with soft switching and multiple phase shift control methods, including in-bridge single phase shift (ISPS) control, out-of-bridge single phase shift (OSPS) control, and dual phase shift (DPS) control method. The topology, phase shift control scheme, and operating states are analyzed. Then the circuit characteristics, such as output power and current stress characteristics, are given to analyze and compare the advantages of different phase shift control methods. In addition, the efficiency characteristics of various phase shift control methods are compared and analyzed from the perspective of magnitude of reverse power. A 300-W experimental prototype is constructed to verify the working principle and efficiency characteristic. The comparison of different phase shift control methods is validated by experimental results.

Data-Driven Bandpass Filter Design for Estimating Symbol Rate of Sporadic Signal at Low SNR

Symbol rate is one of the most important parameters in signal demodulation process. In real-time signal processing, traditional symbol rate estimation algorithms for the Multiple Phase Shift Keying (M-PSK) and the Multiple Quadrature Amplitude Modulation (M-QAM) are based on the Fourier transform of signal’s complex envelope. At the low signal-to-noise ratio (SNR), the accuracy of symbol rate estimation can be improved by increasing the number of symbols as much as possible. However, this improvement is infeasible in many applications such as the energy-limited Internet of Things devices and sporadic noncooperative transmissions. In this paper, we propose a data-driven bandpass filter (BPF) design scheme for accurate estimation of symbol rate under low SNR with only a small number of symbols available. The proposed scheme considerably improves the estimation performance by optimizing the BPF design using the equivalent dynamic linearization model with time-varying pseudo-partial derivatives. Specifically, the proposed scheme iteratively optimizes the upper and lower cut-off frequencies of the BPF based on the measured complex envelope spectrum until achieving the optimal BPF. Therefore, the peaks of the complex envelope spectrum are extracted as the estimate of the symbol rate by applying the optimal BPF. Experimental results indicate the promise of the proposed scheme as an efficient symbol rate estimator for sporadic signal at low SNR and with a small number of symbols.

Simple and Robust Log-Likelihood Ratio Calculation of Coded MPSK Signals in Wireless Sensor Networks for Healthcare

The simple and robust log-likelihood ratio (LLR) computation of coded Multiple Phase Shift Keying (MPSK) signals in Wireless Sensor Networks (WSNs) is considered under both phase noncoherent and Rayleigh fading channels for healthcare applications. We first simplify the optimal LLR for phase noncoherent channel, the estimation of the instantaneous channel state information (CSI) for both the fading amplitude and the additive white Gaussian noise (AWGN) is successfully avoided, and the complexity-intensive process for zero-order Bessel function of the first kind is also perfectly eliminated. Furthermore, we also develop the simplified LLR under Rayleigh fading channel. Correspondingly, the variance estimation for both AWGN and the statistical characteristic of the fading amplitude is no longer required, and the complicated process for implementation of the exponential function is also successfully avoided. Compared to the calculation of optimal LLR with full complexity, the proposed method is implementation-friendly, which is practically desired for energy-limited WSNs. The simulations are developed in the context of low-density parity-check (LDPC) codes, and the corresponding results show that the detection performance is extremely close to that of the full-complexity LLR metrics. That is, the performance degradation is efficiently prevented, whereas complexity reduction is also successfully achieved.

All-optical phase-preserving amplitude-regeneration technology based on bidirectional orthogonal-pumped semiconductor optical amplifier configuration

The phase-preserving amplitude regeneration scheme based on the bidirectional orthogonal-pumped semiconductor optical amplifier (SOA) is proposed in this work. Experimental investigation into the multiple four-wave mixing (FWM) process from the pump, the signal and their corresponding reflective fields is carried out in detail. The regeneration performance obtained from the product between co-propagating fields is also discussed, including its dependence on the signal launch power and the signal quality, to quantify the amplitude regeneration and the phase preserving behaviors. The amplitude distortion is suppressed by 2.2 dB experimentally, confirming the regeneration capability of the proposed scheme. Moreover, the regeneration performance is further investigated for multiple phase shift keying (MPSK) signals through the simulation. According to the numerical results, the operational parameters of the regenerator are the same for advanced modulation formats, proving the robust operation of the proposed bidirectional orthogonal-pumped SOA configuration.

Transport Properties of Multiple Phase Shift Keying Modulated Perfect Optical Vortex in Turbulent Absorbing Seawater

Transport Properties of Multiple Phase Shift Keying Modulated Perfect Optical Vortex in Turbulent Absorbing Seawater

Development of point diffraction interferometer by a dimension-reduction-based phase-shifting algorithm.

To avoid exhaustive calibration of the shifter device in point diffraction interferometers, we present a dimension-reduction-based method to reconstruct the phase map from more phase-shifting fringe patterns with three or more frames. The proposed method assumes that the intensity space can be described adequately by the sine and cosine of multiple phase shifts introduced, which are the basis of the intensity space. Then, low-dimensional approximations of high-dimensional intensity spaces are determined by the newly developed reduced basis decomposition technique. Finally, the phase is reconstructed using the low-dimensional surrogates of the intensity spaces without the knowledge of accurate phase steps. Numerical and experimental studies demonstrated that the proposed method outperforms the existing popular phase reconstruction techniques in terms of accuracy and efficiency. Moreover, the performance of the proposed method is not limited by variations in the background and modulation, unlike the existing phase-shifting-algorithm-based approaches.

Multiple-Symbol Detection Scheme for IEEE 802.15.4c MPSK Receivers over Slow Rayleigh Fading Channels

Although the full multiple-symbol detection (MSD) for IEEE 802.15.4c multiple phase shift keying (MPSK) receivers gives much better performance than the symbol-by-symbol detection (SBSD), its implementation complexity is extremely heavy. We propose a simple MSD scheme based on two implementation-friendly but powerful strategies. First, we find the best and second-best decisions in each symbol position with the standard SBSD procedure, and the global best decision is frozen. Second, for the remaining symbol positions, only the best and second-best symbol decisions, not all the candidates, are jointly searched by the standard MSD procedure. The simulation results indicate that the packet error rate (PER) performance of the simplified MSD scheme is almost the same as that of the full scheme. In particular, at PER of 1 × 10 − 3 , no more than 0.2 dB performance gap is observed if we just increase the observation window length N to 2. However, the number of decision metrics needed to be calculated is reduced from 256 to 2. Thus, much balance gain between implementation complexity and detection performance is achieved.

Experimental Demonstration of Wavelength-tunable In-Series DFB Laser Array with 100-GHz Spacing

We have proposed and experimentally demonstrated a four-channel wavelength-tunable in-series DFB laser array with 100-GHz channel spacing. Compared to the in-parallel laser array, the optical combiner is not utilized and the extra power loss induced by the combiner is avoided. A linearly chirped Bragg grating with multiple phase shifts implemented in the laser cavity is utilized to reduce the grating interference among different lasers. Besides, the reflector sections are inserted at two ends to provide grating feedback for two side channels. With the feedback, all the channels work with low threshold currents. The linearly chirped Bragg grating requires precise control of grating phase variation, which is quite difficult for traditional e-beam-lithography-based method. Here we used the reconstruction-equivalent-chirp technique to fabricate the grating, and precise control of the grating phase is achieved. From the experimental results, the laser arrays work with high output power (>10 mW), relative intensity noise near the relaxation oscillation frequency of below -130 dB/Hz, stable single-mode operation, and high-uniform channel spacing. Fast channel switchings (<; 600 ns) are obtained by on/off laser switching. Such laser performance enables the proposed laser array to be applied in the dense wavelength division multiplexing technology, especially when fast channel switching is needed, such as the NG-PON2 system.