Reference Carrier Research Articles

Performance Characteristics of a Newly Developed Asymmetric Seven-Level Inverter Utilizing Various Hybrid Pulse Width Modulation Strategies

This study unveils a notable breakthrough in inverter technology, holding promise for substantial improvements in voltage quality and the attenuation of harmonic distortions within power systems. This study concentrates on the design and implementation of a novel Seven-Level Asymmetric Inverter (NSLAI) by incorporating various hybrid Pulse Width Modulation (PWM) techniques. The primary goal is to improve the output voltage magnitude while decreasing the Total harmonics compared to conventional PWM methods. The investigation introduces a novel Seven-Level Asymmetric Inverter (NSLAI) with innovative Hybrid Pulse Width Modulation (PWM) strategy. The purpose of this study is to investigate the distinct features of a recently developed asymmetric seven-level inverter, with a focus on exploring its characteristics through the implementation of diverse hybrid pulse width modulation strategies. Hybrid PWM methodology intricately centers on enhancing voltage quality and achieving better harmonious spectral characteristics. The gate signal producing approach for this suggested PWM technology incorporates a hybrid PWM methodology that combines trapezoidal and sinusoidal waveforms, as well as a standard triangular carrier signal enabling NSLAI. The hybrid version of PWM practices is deliberately used to generate switching signals for the NSLAI. An intensive evaluation of numerous indicators of effectiveness across multiple modulation indexes leads in the demonstrating of quantitative findings that compare the unique Hybrid PWM practice with established PWM tactics. Notably, the hybrid reference Carrier Overlapping strategy has emerged as a leading approach surpassing conventional pulse width modulation techniques. It achieves a significantly higher fundamental Root Mean Square voltage output and remarkably lower percentage of Total Harmonic Distortion values compared to all within the hybrid reference Variable Frequency strategy. The principal analytical tool used in the modeling investigation is MATLAB-SIMULINK. This study marks a watershed moment in the development of inverters, claiming significant improvements in battery power quality and distortion caused by harmonics avoidance across power systems, as evidenced by extensive simulation and prototype-based discoveries.

An Area Equalization Modulation Strategy for Multilevel Converter Used in Large-Scale Battery Energy Storage Application

In this paper, a fundamental switched area equalization modulation strategy (AEMS) is presented for a multilevel converter (MLC) used in large-scale battery-energy storage (BES) system. In this AEMS, the switching angles are computed online by equalizing the area under the reference voltage signal and carrier signal. In this BES system, the AEMS provides simple and reasonably good voltage harmonics performance for MLC. MATLAB/Simulink model of a 13-level cascaded H-bridge (13-level CHB) with storage is developed and implemented in real-time using OPAL-RT to validate the concept. Various performance results under steady-state and dynamic conditions are obtained and presented in detail.

RETRACTED: Harmonics control of three phase voltage source inverter with random carriers and modified reference

The Harmonics control of any inverters can be decided by the PWM incorporated for the switches. In recent years the carrier and reference modification based research is going on the inverter field. This paper suggests that the alteration of carriers and references of the three phase voltage source inverter enhance the ability to decrease the harmonic content.This enhanced realization deals with the carrier and reference modification arrangement for three phase voltage source inverter through amalgamating the boosted reference and random triangular carrier. The boosted reference is the addition of sine reference with injection of 1/3rd of reference amplitude (3fs) in the middle portion of the reference wave. i.e., [Formula: see text] to [Formula: see text] and [Formula: see text] to [Formula: see text] . The proposed PWM scheme use two carriers, one is Triangle wave and another one is inverted Triangle wave. The process of selecting the winning carrier among the two triangle carriers is purely based on the LFSR technique. The spectral quality of the induction motor drives has improved by the random carriers. The simulation and experimental values are proving the validity of the PWM method. The PWMs are generated by using parallel processing enabled FPGA processor.

Comparison of Multi-Carrier Based Modified SPWM Techniques for Three Level FCMLI

In this paper, a three phase three level flying capacitor multi level inverter is simulated for various multi-carrier based sinusoidal pulse width modulation (PWM) techniques and the result obtained were evaluated. Two type waves named triangular and trapezoidal triangular (TT) waves are used as Carrier waves. Other than normal sinusoidal PWM, Modified sine PWM technique is also used for effective comparison. In Modified SPWM a Sinusoidal wave is used as reference wave and carrier waves conducting for first and last 60° intervals are used as carrier. The Total Harmonic distortion (THD) obtained in various techniques are compared between all the methods. The harmonics, THD, fundamental value of output voltage is observed for various techniques.

Proportional-Resonant and Unipolar Switching Control of Single-Stage Solar Photovoltaic Grid Interfaced System

ABSTRACT In the proposed work, a new control is used with inner loop as a current control and the outer loop as a voltage control of a solar photovoltaic (PV) array-fed single-phase grid interfaced system, using a voltage-source converter (VSC). It deals with the power quality mitigation, which includes power factor correction, harmonic mitigation in abnormal conditions such as grid voltage sag and swell and irradiation changes. The PI (Proportional–Integral) controller is used as an inner current loop control for reference and sensed DC link voltage balancing and to generate the command for the harmonics accurately, which generates the reference current. The PI controller is used for generating reference current and PR (Proportional-Resonant) is used for generating voltage reference, which, in turn, produces modulating signal within the limit of carrier wave. A comparison between reference voltage and carrier gives unipolar switching, attaining three levels for the VSC. Here, the maximum power point tracking (MPPT) is achieved by an incremental conductance (INC) method. Experimental performance is studied at dynamic abnormal conditions such as voltage sag and voltage swell in order to investigate the total harmonic distortion (THD) of the grid current and point of common coupling (PCC) voltage, which are observed within the IEEE-519 standard.

Nonlinear Error Compensation of PGC Demodulation With the Calculation of Carrier Phase Delay and Phase Modulation Depth

We propose a novel phase generated carrier (PGC) demodulation method by simultaneously calculating the carrier phase delay ( θ ) and the phase modulation depth ( m ) to compensate the nonlinear error introduced by θ and m . Firstly, θ is calculated by adopting the fundamental in-phase and quadrature harmonic components and their differential components. Secondly, this calculated θ is used to set the phases of the harmonic components of reference carrier signal to obtain three new harmonic components independent of θ . Later, m is calculated and compensated by adopting the three new harmonic components and their differential components to obtain the demodulated result. Theoretical analysis and realization of the method are described in detail. Simulation and displacement measurement experiments with different θ and m are carried out to validate the proposed method. The experimental results demonstrate that the proposed method can accurately calculate and compensate θ and m , and effectively eliminate the nonlinear error of the demodulated signal.

Simple Design on Nanoscale Receivers Using CNT Cantilevers

To develop nanoscale sensors with future potential, a nanoscale receiver utilizing the nanomechanical vibration of a cantilever composed of a carbon nanotube, had been proposed for detecting the digital information carried by wireless signals. The introduced receiver includes two essential parts: a phase detector and demodulator, which employ a reference signal and carrier signal, respectively. Additional components such as electrical circuits and oscillators are required to excite these signals, increasing the sensor size. This study presents a design method for simplifying the receiver structure to contribute to sensor miniaturization. This study theoretically derives a tractable form that can describe the performance of the introduced receiver. This form enables the determination of a simple receiver structure with performance enhancement from a mathematical perspective. Using the proposed method, either the reference wave or carrier signal can be excluded from the receiver, simplifying its structure. The results are demonstrated through a numerical simulation.

National standards of the harmonic coefficient unit of the Russian Federation and the Republic of Belarus: results of comparisons

The results of additional comparisons of the national standards of the unit of the harmonic coefficient of Russia (VNIIFTRI) and the Republic of Belarus (BelGIM) are presented. A mass-produced harmonic coefficient meter was used as a reference carrier. The differences between the harmonic coefficient unit reproduced by national standards the reference values do not exceed the extended uncertainty for all measured values of the harmonic coefficient and at all frequencies. Thus, the measurement and calibration capabilities of the laboratories participating in the comparisons are confirmed.

Development of blind frame synchronization for transfer system with differential space-time block coding

The object of this research is the methods and algorithms for frame synchronization used in multi-antenna radio systems (Multiple Input Multiple Output – MIMO). The implementation of radio communication systems and, in particular, MIMO, implies that the demodulator synchronizes the phase of the reference carrier and the time of signal processing processes. Time synchronization is divided into symbolic and frame synchronization. As for the synchronization of the reference carrier and symbol synchronization, these types of synchronization are provided by traditional methods and are not considered in this paper. The frame synchronization in the vast majority of cases is provided by the use of pilot signals (sync words). At their core, they are markers and are periodically embedded in the data stream to indicate the beginning of another new data block. The resources of the transmission system, spent on the transmission of pilot signals, are not used to transmit user information, as a result of which the efficiency of using the time-frequency resource of the system is degraded. To a lesser extent, there are so-called «blind» signal processing methods based on the redundancy properties of the transmitted signal. These methods have no drawbacks from the use of pilot signals and are divided into methods for assessing the state of the communication channel, signal identification, and synchronization. Based on this, such methods are of practical interest.In this work, let’s propose a frame synchronization method for demodulating differential space-time block coding signals using MIMO technology. The synchronization algorithm does not require the use of preambles and sync words, which ensure efficient use of the time-frequency resource. An analysis of the structure of the algorithm and the simulation results show its performance at low signal-to-noise ratios in the transmission system. The algorithm does not require knowledge of the state of the communication channel, has low computational complexity compared to existing analogues, and allows implementation with a different number of transmitting and receiving antennas.

Cross-linked poly(vinyl alcohol) nanofibers as drug carrier of clindamycin

Given the importance of nanofibers in the field of pharmaceutical sciences and drug delivery applications, this study aimed to use poly(vinyl alcohol) (PVA) nanofibers as drug carriers for clindamycin. First, PVA solution was electrospun without drug to obtain electrospinning optimum condition of reference carrier. Then, 8% PVA solution containing 2% clindamycin was electrospun under optimum conditions at 20 kV voltage, 10 cm for nozzle-to-collector distance and an injection rate of 1 mL/h. In order to control drug release and improve the surface wet ability, the prepared polymeric nanofibers were cross-linked by glutaraldehyde. The prepared mats of nanofibers were characterized using scanning electron microscopy, atomic force microscopy, Fourier transform infrared and contact angle analysis. The in vitro drug release from nanofibers into the phosphate-buffered saline solution was measured by high-performance liquid chromatography at a wavelength of 210 nm. The in vitro drug release showed that cross-linked nanofibers had a lower drug release rate in a longer time.

Highly coke-resistant ordered mesoporous Ni/SiC with large surface areas in CO2 reforming of CH4

An ordered mesoporous SiC (SiC-OM) material with high specific surface area (345 m2/g) and narrow pore distribution was prepared by a nanocasting method, and a commercial SiC (49 m2/g, SiC-C) was used as a reference carrier. The Ni/SiC-C and Ni/SiC-OM catalysts were prepared by an incipient wetness impregnation method, and tested in the CO2 reforming of CH4 (CRM). The textural properties of fresh and used catalysts were characterized by means of ICP, BET, XRD, H2-TPR, XPS, HRTEM, TG, and Raman. The results suggested the average carbon deposition rate over the Ni/SiC-OM decreased one order of magnitude compared with the Ni/SiC-C during 50 h of CRM reaction due to the strong interaction between Ni species and SiC-OM support and confinement effect of rigid mesoporous skeleton.

Diffusion-based single-shot diffraction tomography.

Holographic microscopy is a powerful technique for noninvasive label-free biomedical imaging. Most holographic methods utilize reference light and/or multiple measurements to observe both the amplitude and phase of a light wave passing through a specimen. However, such fundamental requirements degrade the spatial resolution due to the use of a reference carrier, cause difficulties for real-time imaging of dynamic biological events, and make the optical setups bulky. Here, we realized reference-free, single-shot holographic tomography by just inserting a diffuser into the optical path in a conventional microscope setup to generate randomly structured illumination. A three-dimensional complex amplitude field was reconstructed from a single scattered intensity image by means of sparsity-constrained multislice phase retrieval.

Конструкции с приименным генитивом качества как средство аксиологического маркирования

Constructions with adnominal evaluative genitive are considered as a specific way of encoding the axiological scores on the morphosyntactic level. The linguo-axiological approach to the study of this construction indicates the novelty and relevance of the study. Constructions of type “N nom. + N gen.” in which the position of subject is taken by the noun man or anthroponymic nouns are selected as the main object of study. It is proved that the coding of axiological evaluation in the framework of this syntactic model is based on the implementation of two main types of possessiveness: possession and belonging. The dependence of the character and intensity of evaluation on the semantic-syntactic structure of the combination is established. Inverted constructions like man of honor in which the characteristic property acquires the status of an inalienable value, and the subject itself acts as its reference carrier are described as having the greatest axiological potential. The authors claim that positive attitude in converses determines their functioning in the role of prescriptive linguistic concepts or ideologemes. It is noted that the smaller axiological potential within the estimative polarity is inherent in constructions with a figurative meaning of possessiveness, in which the assessment of a person occurs by indicating his belonging to the place, time or occupation ( man of the era , man of the year , man of show business ).

Analysis Predicted Location of Harmonic Distortion in RF Upconverter Structure

A new mathematical analysis to predict the magnitude size of the distortion products from the signal up-conversion process output is presented. The signal up-conversion process converts the digital baseband from the analog baseband into a radio frequency signal. When the signal baseband involves frequency offsetting then occurring a number of distortion products which can reduce the dynamic range so it is difficult to meet the spectrum mask requirements within the operating band. This paper will focus on methods of new mathematical analysis using a continuous frequency range and only applies to a single side band tone, with constant amplitude into any value of frequency offsets. The novel contribution to the analysis starts at generating the gate signal and convolution of the gate signal into the reference carrier signal. The results show very close between the simulation results and the calculation of the predicted location of the distortions.

Comparison between adaptive and adjustment procedures for binaural loudness balancing

Binaural loudness balancing is performed in research and clinical practice when fitting bilateral hearing devices, and is particularly important for bimodal listeners, who have a bilateral combination of a hearing aid and a cochlear implant. In this study, two psychophysical binaural loudness balancing procedures were compared. Two experiments were carried out. In the first experiment, the effect of procedure (adaptive or adjustment) on the balanced loudness levels was investigated using noise band stimuli, of which some had a frequency shift to simulate bimodal hearing. In the second experiment, the adjustment procedure was extended. The effect of the starting level of the adjustment procedure was investigated and the two procedures were again compared for different reference levels and carrier frequencies. Fourteen normal hearing volunteers participated in the first experiment, and 38 in the second experiment. Although the final averaged loudness balanced levels of both procedures were similar, the adjustment procedure yielded smaller standard deviations across four test sessions. The results of experiment 2 demonstrated that in order to avoid bias, the adjustment procedure should be conducted twice, once starting from below and once from above the expected balanced loudness level.

PGC-Atan Demodulation Scheme With the Carrier Phase Delay Compensation for Fiber-Optic Interferometric Sensors

Phase generated carrier (PGC) demodulation schemes are widely used in fiber-optic interferometric sensors. All known PGC schemes use carrier signals to obtain in-phase and quadrature components from the interference signal. The unwanted phase delay between the reference carrier signal and the modulation signal in the interference signal might exist. This effect might lead to the incorrect measurement of the phase signal in the PGC scheme. In this paper, the original PGC demodulation scheme with the carrier phase delay compensation based on the basic PGC-Atan scheme is presented. The proposed scheme provides the real-time carrier phase delay compensation over the all possible phase delay range from 0° to 360° without using phase adjustments of the carrier signal. Theoretical analysis and mathematical modeling of the proposed scheme and the basic PGC-Atan demodulation scheme were performed to compare their performance under the same conditions. The proposed scheme, the basic PGC-Atan demodulation scheme, and the PGC synchronous carrier restoration scheme were implemented in the FPGA-based electronic processing circuit of the single interferometric fiber Bragg grating sensor. Experimental results showed that the proposed scheme provides carrier phase delay compensation without using phase adjustments of the carrier signal.

DQPSK modulation and demodulation using SAW device

A Differential quadrature phase shift keying (DQPSK) modulator and demodulator system incorporating surface acoustic wave (SAW) device is presented. The SAW device in the modulator consists of four delay lines corresponding to different phase delays and generates phase shift keyed radio-frequency signals. In the demodulator section, another SAW device performs addition operation between two consecutive received signals to obtain the phase difference. The DQPSK demodulation is extended for the demodulation of quadrature phase shift keying signal without the requirement of locally generated reference carrier. The operation of the proposed DQPSK system using SAW along with the bit error rate (BER) performance is presented. The effect of additional phase delay in the received signal on BER is also presented. Addition operation of the received signals using SAW is also verified using simulation.

Adjacent Channel Beating With Recombined Dual-Mode Colorless FPLD for MMW-PON

By delivering a reference carrier through adjacent dense-wavelength-division-multiplexing (DWDM) channel to remotely beat with the downstream transmitted optical carrier, a full-duplex millimeter-wave DWDM passive-optical-network (MMW-DWDM-PON) is demonstrated to transmit 36- ${\text{Gb/s}}$ data over 25-km single-mode fiber (SMF) and to remotely deliver a 28-GHz MMW carrier for wireless 6- ${\text{Gb/s}}$ data transmission. Such a remotely recombined dual-mode beating scheme provides baseband 36- ${\text{Gb/s}}$ data with corresponding bit error rate (BER) of 2.7 × 10 −3, which is better than the directly dual-mode injection-locked colorless Fabry-Perot laser diode (FPLD) does because of the less fiber chromatic dispersion during 25-km SMF transmission. In a hybrid 25-km SMF-wired and 1.6-m wireless link, it successfully transmits 4- ${\text{Gb/s}}$ data to fit the forward error correcting criterion. By maintaining the free-space distance at 1.6 m, the allowable raw data rate for MMW wireless transmission can be increased up to 6 ${\text{Gb/s}}$ with BER of 1.9×10−3. For optical baseband upstream transmission, the 36- ${\text{Gb/s}}$ data is also directly encoded onto the upstream colorless FPLD injection-locked by reusing the downstream pure carrier delivered through adjacent DWDM channel, and the received data reveals a BER of 2.9 × 10 −3.

Real-time frequency estimation of complex gmsk signal of green communications devices

Parameter estimation of signals of universal software radio peripheral (USRP) devices is crucial to solve the problem of phase offsets of received signals in distributed beamforming. For systems that will utilize the closed loop feedback algorithm where the receiver needs to send the received signal strength (RSS) values periodically to the beamforming node so as to take advantage of energy conservation, the frequency and phase of these signals should be estimated before smoothening by nonlinear filters. This article presents the estimation of the frequency offsets of a Gaussian minimum shift keying (GMSK) signal from N210 USRP devices in real time by using the Radix-2 fast Fourier transform (FFT) algorithm in GNURadio. For these green communications devices, most of the needed hardware parts have been software defined, thereby reducing the supposed energy consumption. The frequency offsets from reference carrier frequencies of 900 MHz and 2.4 GHz are less than 3 kHz each before the estimation, but the average offsets are 45 Hz and 100 Hz after the estimation, respectively. The high offset value experienced with the 2.4 GHz carrier was due to consistent interference from devices on that same frequency.

Design of a Short Reference Noncoherent Chaos-Based Communication Systems

Data rate and energy efficiency decrement caused by the transmission of reference and data carrier signals in equal portions constitute the major drawback of differential chaos shift keying (DCSK) systems. To overcome this dominant drawback, a short reference DCSK system (SR-DCSK) is proposed. In SR-DCSK, the number of chaotic samples that constitute the reference signal is shortened to $R$ such that it occupies less than half of the bit duration. To build the transmitted data signal, $P$ concatenated replicas of $R$ are used to spread the data. This operation increases data rate and enhances energy efficiency without imposing extra complexity onto the system structure. The receiver uses its knowledge of the integers $R$ and $P$ to recover the data. The proposed system is analytically studied and the enhanced data rate and bit energy saving percentages are computed. Furthermore, theoretical performance for AWGN and multipath fading channels are derived and validated via simulation. In addition, optimising the length of the reference signal $R$ is exposed to detailed discussion and analysis. Finally, the application of the proposed short reference technique to the majority of transmit reference systems such as DCSK, multicarrier DCSK, and quadratic chaos shift keying enhances the overall performance of this class of chaotic modulations and is, therefore, promising.