Differential Phase Modulation Research Articles

Achievement splitting for topological states with pseudospin in phase modulation by using gyromagnetic photonic crystals

As we know, valley-Hall kink states or pseudospin helical edge states are excited by polarized-momentum-locking [left-handed circular polarization (LCP) and right-handed circular polarization (RCP)] because the valley-Hall kink modes or pseudospin polarized modes have intrinsic and local chirality, which is difficult for these states to achieve phase modulation. Here we theoretically design and study a compatible topological photonic system with coexistence of photonic quantum Hall phase and pseudospin Hall phase, which is composed of gyromagnetic photonic crystals with a deformed honeycomb lattice containing six cylinders. A typical kind of hybrid topological waveguide states with pseudospin-characteristic, magnetic field-dependent, and strong robustness against backscattering and perfect electric conductor (PEC) is realized in the present system. Furthermore, we re-design a structure with intersection-liked, achieve splitting for one-way pseudospin quantum Hall edge states by using phase modulation. Robustness of the one-way pseudospin-quantum Hall edge states in splitting has been demonstrated as well. Additionally, PEC inserted in transport channel brings optical path difference in waveguide transmission, which would influence splitting for hybrid topological waveguide states in phase difference modulation. This work not only provides a new way for manipulation (i.e., phase modulation) of hybrid topological waveguide states in compatible topological photonic system from distinct topological classes but also has potential in various applications, such as sensing, signal processing, and on-chip communications.

RIS-Assisted Joint Differential Polarization and Phase Modulation for Non-Coherent Receivers

RIS-Assisted Joint Differential Polarization and Phase Modulation for Non-Coherent Receivers

High-order orbital angular momentum mode-based phase shift-keying communication using phase difference modulation.

Orbital angular momentum (OAM) mode offers a promising modulation dimension for high-order shift-keying (SK) communication due to its mode orthogonality. However, the expansion of modulation order through superposing OAM modes is constrained by the mode-field mismatch resulting from the rapidly increased divergence with mode orders. Herein, we address this problem by propose a phase-difference modulation strategy that breaks the limitation of modulation orders via introducing a phase-difference degree of freedom (DoF) beyond OAM modes. Phase-difference modulation exploits the sensitivity of mode interference to phase differences, thereby providing distinct tunable parameters. This enables the generation of a series of codable spatial modes with continuous variation within the same superposed OAM modes by manipulating the interference state. Due to the inherent independence between OAM mode and phase-difference DoF, the number of codable modes increases exponentially, which facilitates establishing ultra-high-order phase shift-keying by discretizing the continuous phase difference and establishing a one-to-one mapping between coding symbols and constructed modes. We show that a phase shift-keying communication link with a modulation order of up to 4 × 104 is achieved by employing only 3 OAM modes (+1, + 2 and +3), and the decode accuracy reaches 99.9%. Since the modulation order is exponentially correlated with the OAM modes and phase differences, the order can be greatly improved by further increasing the superimposed OAM modes, which may provide new insight for high-order OAM-based SK communication.

Inverse Energy Flux in Tight Focusing of Vector Vortex Beam

In this paper, we focus on the study of the negative energy flow in the tight focusing of a radially polarized vortex beam. We know that, because of the coupling of the polarization state and the vortex charge, the on-axis energy flow in the focal region can be well modulated by changing the polarization order and the vortex charge of the incident vector beam. This shows that when the polarization order and the vortex charge satisfy the specific relation, the on-axis negative energy flow can be obtained in the focal region. Moreover, the initial phases of two polarization unit vectors also affect the evolution of the on-axis negative energy flow in the tight focusing of the radially polarized beam. The phase difference modulation of the two polarization unit vectors indicates two different modulations of the polarization state. Our work provides a more flexible modulation method for focal shaping and optical modulation.

Dual-use baseband signal design for RadCom with position index and phase modulation

This paper deals with the synthesis of dual-use signal to simultaneously achieve detection and communication for a dual-function radar communication (DFRC) system. A new position index and phase (PIP) modulation is proposed for information embedding, where position index modulation is realized by selecting the information embedding subpulses (InSp) positions. Moreover, differential phase modulation is utilized to distinguish InSp from other available subpulses. As for radar detectability, peak sidelobes level (PSL) of signal auto-correlation function is minimized. Meanwhile, constant-envelope and phases constraints are forced to ensure compatibility with the current hardware technique and modulation demand, respectively. To tackle the resulting nonconvex and NP-hard optimization problem, a spectral majorization-minimization (SM) dual-use baseband signal design method is proposed. In each iteration, the original problem is approximated by a tractable problem with a closed-form solution. Finally, simulation and semi-physical experimental results demonstrate the designed dual-use signal is capable of realizing high data rate communication and ensuring acceptable radar performance.

High resolution polymer/air double-cavity Fabry–Perot fiber temperature sensor based on exposed core microstructured fiber

This study proposes a high-resolution optical fiber Fabry–Perot (FP) temperature sensor and it is based on an exposed-core microstructured optical fiber (ECF) coated by a ultraviolet curing polymer adhesive. Then, a small piece of multimode fiber (MMF) with large core diameter is spliced in front of ECF to expand the input light beam, and the parallel polymer/air double-cavity FP in such single-mode fiber (SMF)-MMF-ECF-SMF structure is constructed. Additionally, by employing a mobilized demodulation module, the interference signal is analyzed by phase demodulation method. The experimental results show that the temperature sensitivity of the sensor is 30.8 ℃−1 and the resolution is up to 1.6 × 10−4 ℃ in a range of 20 ℃–50 ℃, which can achieve high resolution temperature measurement. Furthermore, to alleviate the wavelength uncertainty of the demodulation device, a double-cavity self-reference differential phase modulation method is explored in the proposed parallel double-cavity FP. It shows that the stability could be improved to five times when system temperature is unstable, which offers an alternative method to further improve the temperature sensing resolution.

Асимптотически робастный инвариантный алгоритм демодуляции DPSK-сигналов при воздействии внешних помех с априорно неопределенными параметрами

The study aims at synthesizing an asymptotically robust invariant demodulation algorithm for DPSK signals with arbitrary modulation multiplicity used in aircraft communication systems and observed against the background of noise with an unknown probability distribution and a noise complex with a priori uncertain parameters. The analysis of the efficiency of the proposed algorithm is carried out by a computer simulation modeling. The algorithm implies automatic detection and rejection of narrowband pulse noise. This type of interference is typical for radio-navigation systems. It has been shown that the narrowband pulse noise should be eliminated if the signal-to-interference ratio becomes less than -10 dB. The use of the asymptotic robustness principle ensures the stability of the algorithm characteristics to changes in the character of the noise probability distribution density. It was found that the joint application of narrowband pulse interference elimination and the asymptotically robust approach provides reliable demodulation performance both when receiving against the background Gaussian noise and under the action of pulse interference and noise with "heavy tails". In addition, it has been shown that the use of signals with differential phase modulation, direct sequence spread spectrum, and the sidelobe levels of less than 10% effectively suppresses interference caused by multipath signal propagation.

Research of methods and means of signal modulation with high interference resistance in modern mobile networks

Systems of multiposition signals are investigated, on the basis of which it is possible to reach the transmission speeds close to the bandwidth of communication channels. In communications systems, where the most stringent requirements for noise immunity are the most effective, it is most efficient to use multi-position signals with phase-difference modulation, for which the equivalent energy is maximal. The optimal incoherent reception has the status of optimal for signal variants with an unknown and uniformly distributed initial phase. Optimal incoherent reception is understood as a non-coherent processing method that ensures the minimum probability of error when receiving signal elements in a channel with Gaussian white noise with a random and uniformly distributed initial phase of the received element (about which nothing else is known). All other non-informative parameters of the signal, except for the initial phase, primarily - the frequency and processing interval, with optimal non-coherent reception, must be known precisely. As for the signal amplitude, when using signals with equal energy, it may be unknown. With regard to FM signals, the optimal incoherent method of reception can be used only to determine the phase of the transmitted difference (and not the absolute phase), which is fundamentally unknown with this processing method. The main method of synthesis of algorithms for optimal incoherent reception of signals from FRM-1 is considered, which considers all possible situations when processing signals on two parcels. An algorithm for optimal incoherent reception of signals from FDM-1 is developed, suitable for implementation with any set of information phase differences. The algorithm of optimal incoherent reception of signals from FDM-2 is developed. It is concluded that the optimal incoherent reception of signals from the FDM allows, by increasing the processing interval, to approach the potential impedance of the given signal system without evaluating the initial phase.

Study of interference resistance of autocorrelative receiving methods in broadband communication systems

Modern broadband communication systems are not able to completely eliminate the effects of interference characteristic of various communication channels, namely interference caused by the multipath nature of signal propagation and concentrated interference which reduce the reliability of information transmission. Although the picture is qualitatively clear, the variety of interference and the specificity of the impact of some of them on broadband communication systems do not allow one to quantitatively take into account the impact of all interference at the same time. Therefore, there is a need to study the issue of increasing immunity to various reception methods. This article is devoted to the study of methods of increasing immunity to interference in broadband communication systems with fluctuating interference using autocorrelation methods of reception. The probability of errors in a multi-position system with orthogonal signals at incoherent reception with incoherent accumulation is investigated. Probabilities of errors during autocorrelation reception of signals with single phase-difference modulation are analyzed. The article defines that the immunity of intercorrelation methods of reception does not depend on the base of the signal, and the immunity of autocorrelation methods depends on the base and at the same energy is lower in the signal with a larger base (larger number of elements). The results of the work characterize the interference immunity of multi-position systems with different reception methods and the dependence of the immunity of a group of autocorrelation reception methods on the number of elements N or the FT base of the composite signal. According to the results of the work, the composite signals from the FRM in all reception methods provide a gain in energy twice as compared to the systems with orthogonal signals.

Методы приема и синхронизации сигналов автоматической локомотивной сигнализации

The article discusses the problems of existing methods of receiving automatic cab signalling on railway transport, an original method of receiving and processing data is proposed. The need to solve the problems is due to the requirement of a qualitative improvement in the reliability of receiving codes, and as a consequence, the capacity of existing lines. First of all, this refers to a significant increase in the quality of reception and processing of information flows from rail lines. Today it is difficult to imagine the organization of the movement of rolling stock without relying on automatic block systems with secondary sealing of tonal track circuits by frequency modulation signals or automatic cab signaling without the use of multivalued automatic cab signaling with phase-difference modulation. Taking into account the objective fact of noise emission from the operation of energy-intensive railway equipment and modern locomotives, the issues of reliability and noise immunity of receiving discrete information (including signals of traditional automatic cab signaling) are becoming more and more urgent. Analysis of the reasons for the decrease in the reliability and noise immunity of railway automation and telemechanics systems, and, consequently, traffic safety also comes to the fore.

A DFE-Enhanced Phase-Difference Modulation Signaling for Multi-Drop Memory Interfaces

This brief presents a phase-difference modulation signaling enhanced by decision feedback equalization for multi-drop memory interfaces. The phase-difference modulation signaling enables efficient data communication via a multi-drop channel, but only if the stub lengths are specially engineered. In this brief, the phase-difference modulation signaling is combined with decision feedback equalization to extend the applicable channel range. A test chip with a phase-difference-modulation transmitter and a decision feedback equalization receiver was fabricated in 65-nm CMOS technology. With a 2-tap decision feedback equalization, the test chip achieved the data rate of 7.8 Gb/s/pin via the both multi-drop channels with a long 10-cm stub and a short 2-cm stub, whereas the previous work without decision feedback equalization does not work with the 2-cm stub channel at 7.8Gb/s/pin.

A 7.8 Gb/s/pin, 1.96 pJ/b Transceiver With Phase-Difference-Modulation Signaling for Highly Reflective Interconnects

This paper presents a phase-difference-modulation transceiver with simple clock recovery for highly-reflective interconnects. By greatly suppressing reflective intersymbol interferences with two new enabling mechanisms, phase–difference modulation enables high-speed data communication through highly-reflective multi-drop channels without utilizing decision feedback equalization. A systematic analytical approach is presented, and provides guidelines on how to determine channel and signaling parameters to exploit the two enabling mechanisms based on a newly derived formula of a single bit response of a channel. In addition, we propose a phase-difference amplifier that relieves the timing constraint of the bit decision at the receiver. By deserializing the received signals using the clock embedded in the received signals, the phase-difference amplifier can greatly reduce the design complexity of the clock recovery circuit. The proposed transceiver was fabricated in 65-nm CMOS technology. In single-ended mode, the transceiver achieved a maximum speed of 7.8 Gb/s/pin at energy cost of only 1.96 pJ/b while overcoming 10 in-band notches without decision feedback equalization. Also, the phase-difference amplifier enables clock recovery at power and area costs of only 0.12 pJ/b and 550 $\mu \text{m}^{2}$ , respectively, in single-ended 6-Gb/s/pin operation.

Linearized segmentation method for measuring the phase transfer function of a silicon Mach-Zehnder modulator by using the beat-frequency technique.

A linearity segmentation method for measuring the phase shift curve of silicon Mach-Zehnder modulators (SMZMs) as a function of applied electric field is presented. Applying a small sinusoidal signal to the traveling-wave electrode of the SMZM, the upper and lower arms of the SMZM produce differential phase modulation effect. Meanwhile, a local oscillator source with a wavelength-adjustable function is employed to heterodyne the intensity modulated optical signal of the SMZM; thus, the modulated intensity signal in the optical field domain is transformed into the low-frequency electric field domain. Meanwhile, a balanced detector with a low-speed transimpedance amplifier is exploited to realize photoelectric conversion, which can suppress the direct-current component and improve the anti-noise ability. Extracting the beat-frequency and first-order harmonic sideband signals in the case of phase bias is 0 and π, respectively, the phase shift slopes of the upper and lower arms can be calculated under different reverse PN voltages, and we can achieve the phase shift as a function of the modulation frequency and reverse PN voltage. The proposed method is supported by the simulation and measurement results and the key parameters of the SMZM, such as the radio frequency half-wave voltage, chirp characteristic, 3 dB bandwidth, etc., can be acquired from the phase shift curves of the upper and lower arms.

An Efficient DWT DAPM Technique for PAPR Reduction in OFDM System

In this paper, Discrete Wavelet Transform (DWT) Orthogonal Frequency Division Multiplexing (OFDM) system is compared with Discrete Cosine Transform (DCT) and Discrete Fourier Transform (DFT) OFDM systems. The channel noise is modelled with A white Gaussian Model (AWGN), the fading is the impairment in the channel and modelled by Rayleigh fading which is frequency selective fading channel and flat fading channel. The comparisons of Peak to Average Power Ratio (PAPR) and Bit Error Rate (BER) are made using modulation techniques such as Differential Amplitude and Phase Modulation (DAPM), Quadrature Amplitude Modulation (QAM) and Pulse Amplitude Modulation (PAM). Simulation results shows that PAPR is 4.497 dB for DWT-DAPM combination, 4.684 dB for DWT-QAM combination and 6.211 dB for DWT- PAM combination at 10-3 Complementary Cumulative Distributive Function (CCDF).The performance Analysis with the combination of DFT, DCT with DAPM, QAM and PAM are also compared. The BER is 0.01816, 0.01806 at 20 dB SNR in frequency selective channel, flat fading channel for DWT-DAPM and for DWT- QAM, AWGN channel BER is 0.01765 at 20dB SNR.

SYNTHESIS OF INVENTORIES TO THE INTERFERENCE OF INFORMATION AND TELECOMMUNICATION SYSTEMS

The article deals with the development of analytical algorithms of information and telecommunication systems formation that are invariant to the obstacle (additiveornon-aditiveone). The basic approaches to determine the class of obstacles for which an invariant system can be constructed are discussed and analyzed in detail. It is established that the invariance property of a feedback system guarantees the given probability of receiving information, but it does not guarantee a preset speed of information transmission. Studies have shown that invariance is achieved by reducing the noise immunity of additive noise. In a second-order phase-difference modulation system, the error probability is invariant to the signal frequency, but it is greater than the error rate in the system with phase-difference modulation at a constant signal frequency. As a result of the conducted researches it is established that the maximum of the undetected error does not depend on the characteristics of the interference, but is determined solely by the parameters of the correction code. The ways of improving the qualitative characteristics of information and telecommunication systems to ensure their invariance to the obstacle have been determined by analytical means, which is confirmed by simulation results and experimental data

Design and Impedance Control of a Traveling Wave Ultrasonic Motor with a Spherical Rotor

A traveling wave ultrasonic motor (TWUM) with a spherical rotor was designed and fabricated for a haptic interface. The mechanical characteristics testbed was set up to test the performance of the motor under the modulation of frequency and phase difference, as well as for conducting haptic interaction, and the phase difference modulation based on certain frequency was adopted as the driving mode for the proposed motor. Due to the complexity and uncertainty of the contact mechanics of the stator and rotor, the direct torque control effect of the TWUM is not ideal for the force feedback. In this paper, the impedance control method was adopted to realize the force interaction based on positional proportional–integral–derivative (PID) control. The virtual linear spring and virtual wall experiments are conducted to verify the effect of the proposed method. Results show that the position-based impedance control method has a better effect than direct torque control for the haptic interaction based on an ultrasonic motor (USM).

ОРТОГОНАЛЬНЫЕ ФАЗОКОДИРОВАННЫЕ СИГНАЛЫ С ДОПОЛНИТЕЛЬНОЙ ОТНОСИТЕЛЬНОЙ ФАЗОВОЙ МАНИПУЛЯЦИЕЙ

The paper examines the version of a equal-energy orthogonal phase-coded signals with additional differential phase modulation of codewords. Adding differential phase modulation of codewords to the phase-coded signal made it possible to reduce the probability of bit error while maintaining the possibility of incoherent detection. A single differential quadrature phase modulation of codewords provides the lowest probability of bit error among the signals under consideration, but in the absence of a frequency offset. At small frequency offsets, the single differential binary phase modulation of codewords has the smallest bit error probability. However, two-fold differential binary phase modulation with a slight loss relative to a single differential modulation in the AWGN channel has the lowest sensitivity to the frequency offset. Additional differential phase modulation it possible to reduces the number of orthogonal signals while preserving the probability of a bit error, or reduces the probability of a bit error while maintaining the occupied bandwidth.

Suppression of backreflection error in resonator integrated optic gyro by the phase difference traversal method.

The phase difference traversal (PDT) method is proposed to suppress the backreflection-induced error in resonator integrated optic gyro (RIOG). Theoretical analysis shows that the backreflection-induced zero-bias fluctuation is periodical and sine/cosine-like. By forcing the phase difference between the CW and CCW incident light to traverse the interval [0, 2π] repeatedly and rapidly enough, the fluctuation can be low-pass filtered and, hence, the backreflection-induced error can be effectively suppressed. A RIOG apparatus is built up, with multi-wave hybrid phase modulation to traverse the phase difference and in-phase modulation to set the operation point. A short-term bias stability of 0.0055 deg/s and a long-term bias stability of 0.013 deg/s are successfully demonstrated which, to the best of our knowledge, are the best results reported to date for the buried-type silica waveguide ring resonator-based RIOG.

Four-Dimensional Modulation and Stokes Direct Detection of Polarization Division Multiplexed Intensities, Inter Polarization Phase and Inter Polarization Differential Phase

We propose and experimentally demonstrate modulation and Stokes space direct-detection (DD) of four orthogonal dimensions or degrees of freedom (DOF) of a single laser being the intensity on two orthogonal polarizations, the inter-polarization phase and the inter-polarization differential phase. At the transmitter, a dual-polarization in-phase quadrature-phase (DP-IQ) modulator driven by a 4-channel digital-to-analog converter is employed to imprint the transmitted data onto the aforementioned four DOF. Transmitted symbols for each polarization are drawn from multi-ring/multi-phase constellations, e.g., 2-ring/4-ary phase shift keying (PSK) or 2-ring/8PSK, resulting in a polarization division multiplexed (PDM) format with intensity, inter-polarization phase, and inter-polarization differential phase modulation (PDM-IM-IPM-IDPM). At the receiver, a novel DD front-end 1 1 A direct-detection front-end refers to a family of receivers that employ a self-beating mechanism in which the received signal beats with itself or its polarization tributaries beat with themselves. Unlike a coherent front-end, a direct-detection front-end does not incorporate a local oscillator (LO) laser.

A Comparison of Two Objective Measures of Binaural Processing

There has been continued interest in clinical objective measures of binaural processing. One commonly proposed measure is the binaural interaction component (BIC), which is obtained typically by recording auditory brainstem responses (ABRs)—the BIC reflects the difference between the binaural ABR and the sum of the monaural ABRs (i.e., binaural − (left + right)). We have recently developed an alternative, direct measure of sensitivity to interaural time differences, namely, a following response to modulations in interaural phase difference (the interaural phase modulation following response; IPM-FR). To obtain this measure, an ongoing diotically amplitude-modulated signal is presented, and the interaural phase difference of the carrier is switched periodically at minima in the modulation cycle. Such periodic modulations to interaural phase difference can evoke a steady state following response. BIC and IPM-FR measurements were compared from 10 normal-hearing subjects using a 16-channel electroencephalographic system. Both ABRs and IPM-FRs were observed most clearly from similar electrode locations—differential recordings taken from electrodes near the ear (e.g., mastoid) in reference to a vertex electrode (Cz). Although all subjects displayed clear ABRs, the BIC was not reliably observed. In contrast, the IPM-FR typically elicited a robust and significant response. In addition, the IPM-FR measure required a considerably shorter recording session. As the IPM-FR magnitude varied with interaural phase difference modulation depth, it could potentially serve as a correlate of perceptual salience. Overall, the IPM-FR appears a more suitable clinical measure than the BIC.