Waveform Generator Research Articles

Enhancing power quality in wireless DC power supplies through active power filtering: A computer simulation approach

This paper presents a computer simulation model for a high-power factor wireless DC power supply system, integrating an active power filter (APF) at the rectifier stage on the transmitter side using a rectifier boost technique. The APF, employing a MOSFET switch regulated by active pulse width modulation (APWM) within a current control loop, addresses pulsating and distorted AC supply currents caused by non-linear loads. A robust closed-loop control mechanism, including a subtractor circuit, proportional-integral (PI) controller, and comparator, ensures the generation of a continuous sinusoidal waveform synchronized with the supply voltage. The model utilizes a high-frequency inverter to convert DC to AC, which is then wirelessly transmitted via wireless power transfer (WPT) technology and converted back to DC by a high-frequency rectifier. MATLAB/Simulink simulation results show a significant reduction in total harmonic distortion (THD) of the AC supply current, complying with IEEE 519 standards. Selected results are presented to verify the proposed method's effectiveness in reducing harmonic distortions and enhancing power quality. This study highlights the advantages of WPT in scenarios where traditional wired connections are impractical and underscores the potential of this system for real-world applications, particularly in developing high-power factor wireless DC power supply systems.

Feedback switching control of a walking piezoelectric actuator for trajectory tracking

Abstract This paper proposes a feedback switching control (FSC) scheme for a Walking Piezoelectric Actuator (WPA) to track a time-varying trajectory. A WPA has two feet with each foot integrated with a clamp and shear Piezoelectric Stack Actuators (PSAs). The first foot pushes the stage translator a step forward when clamped while the second foot is reset and retracted; subsequently, ‘foot switching’ occurs; as a result, the second foot is clamped to push the translator to make a next step forward and the first foot is reset and retracted. To make sure that the translator is always controlled in closed-loop no matter which foot is clamped, the FSC scheme is proposed. It consists of a clamping waveform generator which converts the trajectory into control signals for the clamp PSAs of the two feet and a feedback controller which provides control signals for the two shear PSAs of the feet. Experimental results show that the proposed control scheme achieves a tracking error of 0.028 µm for a constant velocity trajectory, which is a 75% reduction compared to the 0.113 µm of waveform-based control with ILC compensation in literature.

Design of a High-Voltage Arbitrary Waveform Generator Using a Modular Cascaded H-Bridge Topology

As the integration of renewable energy sources into the grid increases, the insulation systems of grid components such as transformers and switchgear encounter significant challenges due to the transients and harmonics generated by power-electronic-based converters. A test generator capable of replicating these component stresses is essential to accurately evaluate these insulation systems under real-grid conditions. This paper proposes a modular cascaded H-bridge-based high-voltage arbitrary waveform generator, prototyped with three stages to generate customized waveforms (triangular, sawtooth, pulse, and complex) up to 8 kV. The H-bridge modules are designed using Si MOSFETs with a maximum blocking voltage of 4.5 kV. The input to the HV H-bridge module is provided by a 10 kV medium-frequency transformer, whose design is described with a focus on the insulation system and winding configuration. This transformer is driven by a zero-voltage switching driver. This arbitrary waveform generator excels in several aspects, including a straightforward design procedure, compact size, high voltage capability, ease of integration, and cost.

A PAPR correction scheme for LoRa self‐jamming waveforms

AbstractA LoRa self‐jamming scheme that enables secure and covert communications by adding jamming symbols when transmitting is proposed. The scheme has been validated in simulations. The work is continued by evaluating the scheme on real‐world software defined radio (SDR) equipment. Experiments immediately showed that a demodulation is impossible as the received signal is highly distorted. This comes from the fact that adding symbols at transmission actually generates high peak‐to‐average power ratio (PAPR) preventing proper waveform generation by the equipment's hardware. This paper presents a PAPR correction scheme that modifies the waveform. The properties of this modified waveform are analysed and the performances are assessed in simulations with realistic time and frequency synchronization assumption. For the ideal 0 dB PAPR corrected output, the SER performances are close to that of a legacy LoRa communication, while preserving the physical layer security capabilities of the self‐jamming scheme. It is finally shown that our PAPR correction scheme effectively recovers the self‐jamming properties on SDR devices.

Characterisation and synchronisation of a netted software defined radio radar

AbstractThe present work intends to characterise the combination of two netted software defined radios (SDR) and different radio frequency (RF) front‐ends installed in them, together with a two‐stratum time dissemination and synchronisation system. A modified implementation of the Network Time Protocol is used as coarse event synchronisation for either SDR back‐end. The White rabbit light embedded node implementation of the commonly known white rabbit synchronisation system (IEEE 1588 PTP‐2019) or arbitrary wave form generators are used as fine time dissemination system for either SDR. The resulting netted transceiver system is intended to compose a demonstrator for proof‐of‐concept experiments. The findings presented in this article show that the chosen combination of hardware and software is suitable for radar applications operating within L‐, S‐ and C‐bands. A channel coherency throughout the network with a relative modified Allan deviation of less than 80 fs for averaging intervals of 1 s, a phase noise better than −118 dBc/Hz at 10 Hz frequency offset and a fractional frequency lower than was measured. Within a single transceiver node, a fractional frequency lower than and phase noise of −124 dBc/Hz at 10 Hz frequency offset were measured as well. Multistatic radar systems exploit wide spatial diversity to enhance target detection and tracking, albeit with increased complexity when compared to a monostatic configuration. To exploit these benefits, all participating transceiver nodes within the netted radar need to synchronise to a common time base . The achieved synchronisation level increases the accuracy with which the chain of timed events at the transmitter and at the receiver side occur, intending to maximise the signal‐to‐noise ratio available at the receiver. The Universal software radio peripheral model X310 with two different daughterboard models as RF front‐end was used as SDR on either radar node. A network combining data and synchronisation purposes allowed the radar nodes under test to operate synchronously. The two‐stratum synchronisation system used glass fibres between 2 m and 5 km of length or coaxial cables with 2 m in length for network traffic, time and frequency dissemination purposes. The multiple RF front‐ends were stimulated by means of arbitrary waveform generators with calibrated traceability. Up‐chirp and sinusoid waveforms were used as stimuli for measuring the offset of either channel with regards of to ultimately estimate the achievable coherency limits of the system under test. Both analogue and digital evaluation methods were considered.

Experimental study of polyurethane rubber with half-sine waveform generator

Abstract Impact mechanics environmental testing technology is booming. Polyurethane rubber, as a typical semi-sinusoidal waveform generator, is particularly important to understand its stiffness performance. This paper presents an experimental investigation utilizing a pneumatic impact testing machine to evaluate the performance of polyurethane rubber waveform generators, varying in both hardness and height. By recording their compression under varying impact pressures, as well as the rebound height of the table and the corresponding velocity changes, we observed that the data generated by the 60mm thick waveform generator exhibited greater regularity. Notably, these data adhered to the principle that increased hardness correlates with decreased compression and reduced rebound height of the table. Additionally, we successfully designed an initial prototype of a rebound collision acceleration amplifier, which, under an impact pressure of merely 0.038MPa, achieved an impressive impact acceleration of nearly 2700g, accompanied by a smoother half-sine waveform curve.

SiGe high-frequency pulse-width modulation for low-noise applications

This paper details the first-known experimental observation of pulse-width modulation at 100 MHz using silicon-germanium HBT technology. By performing pulse-width modulation (PWM) at a higher frequency, undesired harmonic-components—which are interpreted as noise—are likewise raised to higher frequencies. In doing so, the noise generated by the PWM controller can be raised to frequencies at which it is no longer relevant. Noise-free operation is guaranteed below the operating frequency of the PWM controller, so long as the semiconductor technology supports high-frequency waveform generation. Such capability is readily provided by modern silicon-germanium HBT technology. The paper also provides an integrated-circuit design with additional flexibility for the end user, with simulated performance results.

Generative adversarial networks for whispered to voiced speech conversion: a comparative study

AbstractGenerative Adversarial Networks (GANs) have demonstrated promising results as end-to-end models for whispered to voiced speech conversion. Leveraging non-autoregressive systems like GANs capable of performing conditional waveform generation eliminates the need for separate models to estimate voiced speech features, and leads to faster inference compared to autoregressive methods. This study aims to identify the optimal GAN architecture for the whispered to voiced speech conversion task by comparing six state-of-the-art models. Furthermore, we present a method for evaluating the preservation of speaker identity and local accent, using embeddings obtained from speaker- and language identification systems. Our experimental results show that building the speech conversion system based on the HiFi-GAN architecture yields the best objective evaluation scores, outperforming the baseline by $$\sim$$ ∼ 9% relative using frequency-weighted Signal-to-Noise Ratio and Log Likelihood Ratio, as well as by $$\sim$$ ∼ 29% relative using Root Mean Squared Error. In subjective tests, HiFi-GAN yielded a mean opinion score of 2.9, significantly outperforming the baseline with a score of 1.4. Furthermore, HiFi-GAN enhanced ASR performance and preserved speaker identity and accent, with correct language detection rates of up to $$\sim$$ ∼ 98%.

Magneto-acousto-electrical tomography based on frequency response compensated linearly frequency-modulated signal stimulation

Objective. In magneto-acousto-electrical tomography (MAET), linearly frequency-modulated (LFM) signal stimulation uses much lower peak voltage than the spike pulse stimulation, lengthening the operation life of the transducer. However, due to the uneven frequency responses of the transducer, the low-noise amplifier (LNA), and the bandpass filter (BPF), MAET using LFM signal stimulation suffers from longitudinal resolution loss. In this paper, frequency response compensated linearly frequency-modulated (FRC-LFM) signal stimulation is investigated to resolve the problem.Approach. The physical model of measurement of the frequency responses of the transducer and the cascading module of the detection electrodes, the LNA, and the BPF is constructed. The frequency responses are approximated by fitting a curve to the measurement data. The frequency response compensation function is set to the reciprocal of the product of the frequency responses. The digital FRC-LFM signal is generated in MATLAB and converted to analog signal through an arbitrary waveform generator. Two groups of MAET experiments are designed to confirm the performance of the FRC-LFM signal stimulation. Pure agar phantom with rectangular through-holes and agar phantom with pork tissue inclusion serve as the samples.Main results. The pulse-compressed magneto-acousto-electrical signal obtained using FRC-LFM stimulation has narrower main-lobe than that obtained using LFM excitation, although the signal to noise pulse interference ratio of the former is little lower than that of the latter, which is due to the limitation of the power amplifier. FRC-LFM also proves to be an effective method to utilize the frequency outside the working band of the transducer in MAET.Significance. The method in this study compensates for the longitudinal resolution loss due to the uneven frequency responses. Combining with high-capability power amplifier and high-performance LNA, the MAET using FRC-LFM signal stimulation can potentially achieve high longitudinal resolution and high sensitivity, advancing MAET toward the clinical application.

Real-Time Reconfigurable Radio Frequency Arbitrary-Waveform Generation via Temporal Pulse Shaping with a DPMZM and Multi-Tone Inputs

Benefitting from a large bandwidth and compact configuration, a time-domain pulse-shaping (TPS) system provides possibilities for generating broadband radio frequency (RF) arbitrary waveforms based on the Fourier transform relationship between the input–output waveform pair. However, limited by the relatively low sampling rate and bit resolution of an electronic arbitrary-waveform generator (EAWG), the diversity and fidelity of the output waveform as well as its reconfiguration rate are constrained. To remove the EAWG’s limitation and realize dynamic real-time reconfiguration of RF waveforms, we propose and demonstrate a novel approach of RF arbitrary-waveform generation based on an improved TPS system with an integrated dual parallel Mach–Zehnder modulator (DPMZM) and multi-tone inputs. By appropriately adjusting the DC bias voltages of DPMZM and the power values, as well as the center frequencies of the multi-tone inputs, any desired RF arbitrary waveform can be generated and reconfigured in real time. Proof-of-concept experiments on the generation of different user-defined waveforms with a sampling rate up to 27 GSa/s have been successfully carried out. Furthermore, the impact of modulation modes and higher-order dispersion on waveform fidelity is also discussed in detail.

Semiconductor optical amplifiers as an optical arbitrary waveform generator for high-energy laser systems

A simple and straightforward technique is presented as a novel temporally controllable front-end for nanosecond very-high energy laser systems. It is based on an original utilization of a semiconductor optical amplifier (SOA) used as an intensity modulator. The essential characteristics of the component are analyzed in order to evaluate potential limitations. Various parameters of interest for standard operation are displayed, demonstrating its usability and its effectiveness. We demonstrate arbitrary and controllable pulse temporal profiles with duration ranging from 1 nanosecond to 100 nanoseconds and a temporal precision of 1.1 ns. A high extinction ratio is also achieved ensuring a modulation contrast up to 53 dB. The SOA is then integrated into an existing operating system in an ultra-compact, reliable all-fibered system. It is used to seed a 2*200 J laser system, exhibiting excellent performance, and validating its usability under operation conditions without any detrimental effects.

Simultaneous measurement of SO2 and CO2 for sulfur content detection in marine diesel fuel using QCL absorption spectroscopy

Simultaneous measurement of CO2 and SO2 in ship exhaust gases is a common method for assessing compliance with sulfur emission standards. This study develops a new ship exhaust gas analyzer using time-division multiplexing of two quantum cascade lasers for simultaneous detection of the two gas species. A digital circuit integrated with a dual-channel waveform generator and a lock-in amplifier is developed to implement wavelength modulation spectroscopy (WMS) scheme. To enhance the measurement accuracy of SO2 with broadband absorption feature, a novel WMS approach that combines first-harmonic and normalized second-harmonic detection is introduced. A Kalman filter algorithm is employed to further refine the measurement precision. Experimental results show a 30.76% increase in detection accuracy. With a 1 s time resolution, the sensitivities of 13.4 ppb for SO2 and 9.81 ppm for CO2 are achieved. The effectiveness of the prototype for sulfur content detection is demonstrated, aiding emission management of water transport emissions.

Technical Committee 10: Recent Progress: The IEEE Technical Committee 10: The Waveform Generation, Measurement, and Analysis Committee, Update 2023

Technical Committee 10: Recent Progress: The IEEE Technical Committee 10: The Waveform Generation, Measurement, and Analysis Committee, Update 2023

Frequency linearization of voltage controlled oscillator (VCO) for 2 µs frequency modulated continuous wave (FMCW) reflectometer.

Frequency modulated continuous wave reflectometers have been widely used to measure plasma density profiles in many magnetic fusion devices. The frequency modulation (FM) time of the KSTAR reflectometer was 20 µs, that is, the FM rate was 50kHz. However, the edge density of the KSTAR tokamak fluctuates typically over the frequency range of 20-50kHz in the ELMy H-mode plasmas. Therefore, the density profile changes significantly during the FM time, causing significant distortion in the density profile measurements. The FM rate must be increased at least ten times faster than the density fluctuation frequency. A new voltage controlled oscillator (VCO) driver is designed based on the AD8067 operational amplifier to achieve a FM time of 2 µs. The VCO output frequency is linearly modulated by predistorting the tuning voltage of VCO using a 400 MSamples/s arbitrary waveform generator. The resulting output frequency of the VCO is measured by mixing the VCO output with a fixed frequency synthesizer signal and measuring the mixer intermediate frequency using a 2.5 GSamples/s digitizer. The tuning voltage is adjusted to minimize the amount by which the measured frequency deviates from the linearly modulated frequency. A simple linear adjustment proportional to the deviation does not effectively suppress the nonlinearity in FM. The response time of the VCO driver and the VCO input interface should be taken into account by solving the entire circuit equation. In this paper, the developed VCO driver circuit and the frequency linearization method are described.

Ultra-Wideband Photonic Frequency-Hopping Waveform Generator Enabled by Optical Injection Locking for Secure Terahertz Wireless Communications

Ultra-Wideband Photonic Frequency-Hopping Waveform Generator Enabled by Optical Injection Locking for Secure Terahertz Wireless Communications

Photonic Generation of Arbitrary Microwave Waveforms with Anti-Dispersion Transmission Capability

We propose and demonstrate a photonic-assisted approach for generating arbitrary microwave waveforms based on a dual-polarization dual-parallel Mach–Zehnder modulator, offering significant advantages in terms of tunability of repetition rates and anti-dispersion capability. In order to generate diverse microwave waveforms, two sinusoidal radio frequency signals with distinct frequency relationships are applied to the dual-polarization dual-parallel Mach–Zehnder modulator. By adjusting the power of the applied sinusoidal radio frequency signal, the power ratio between these orthogonal polarized optical sidebands can be changed, and thereby desired radio frequency waveforms can be obtained after photoelectric conversion. In our proof-of-concept experiment, we systematically varied the repetition rate of triangular, rectangular and sawtooth waveforms. Meanwhile, we calculated the Root Mean Square Error (RMSE) to assess the approximation error in each waveform. The RMSEs are 0.1089, 0.2182 and 0.1185 for the triangular, rectangular and sawtooth microwave waveforms with repetition rate of 8 GHz, respectively. Furthermore, after passing through 25 km single mode fiber, the optical power decreased by approximately 5.6 dB, which verifies the anti-dispersion transmission capability of our signal generator.

Photonic-assisted generation of fast switchable multi-format LFM waveforms with a tuned bandwidth for a joint radar-communication system

A photonic-assisted generation scheme of fast switchable multi-format linearly frequency modulation (LFM) waveforms with a tuned bandwidth for a joint radar-communication (JRC) system is proposed and demonstrated. In this scheme, the up-, down-, dual-chirp LFM waveforms along with zero-value are obtained to form the joint waveform for carrying two bits of information per symbol. The bandwidth of the LFM waveforms can be tuned by adjusting the parabolic signal that drives the phase modulator (PM). The joint waveform can be used not only for radar ranging but also for the wireless communication. Simulation results show the 9–11 GHz up-, down- and dual-chirp waveform as well as the zero-value signal can switch at a rate of 64 MHz. The bandwidths of the LFM waveforms are tunable. The communication rate is up to 128 Mbit/s and the radar ranging resolution can reach up to 1.875 cm. The proposed scheme has a simple structure and can get good communication and range detection performance based on a joint waveform, and is expected to be used in the multifunctional JRC system.

Silicon photonic microresonator-based high-resolution line-by-line pulse shaping

Optical pulse shaping stands as a formidable technique in ultrafast optics, radio-frequency photonics, and quantum communications. While existing systems rely on bulk optics or integrated platforms with planar waveguide sections for spatial dispersion, they face limitations in achieving finer (few- or sub-GHz) spectrum control. These methods either demand considerable space or suffer from pronounced phase errors and optical losses when assembled to achieve fine resolution. Addressing these challenges, we present a foundry-fabricated six-channel silicon photonic shaper using microresonator filter banks with inline phase control and high spectral resolution. Leveraging existing comb-based spectroscopic techniques, we devise a system to mitigate thermal crosstalk and enable the versatile use of our on-chip shaper. Our results demonstrate the shaper’s ability to phase-compensate six comb lines at tunable channel spacings of 3, 4, and 5 GHz. Specifically, at a 3 GHz channel spacing, we showcase the generation of arbitrary waveforms in the time domain. This scalable design and control scheme holds promise in meeting future demands for high-precision spectral shaping capabilities.

Photonic generation and programmable switching of variable-band chirped waveforms with immunity to power fading.

A photonic approach for generating and programmable switching variable-band chirped waveforms by using a dual-parallel Mach-Zehnder modulator (DPMZM) is proposed and experimentally demonstrated. By coupling binary switching codes with the baseband chirped signal and applying them into the RF input port of DPMZM, the variable-band chirped waveforms can be generated and fast switched. The switching speed is consistent with the input code bit rate. Moreover, by properly adjusting the bias voltages, the generated signals can be anti-dispersion transmitted over different distances. Full experimental verification on the generation and programmable switching of the chirped waveforms centered at 2.1, 6.3, and 8.4 GHz or 1.5, 4.5, and 6 GHz over 10 or 20 km standard single-mode fibers with 4 or 100 Mbps switching rates are successfully carried out. The proposed approach features compact architecture, programmable switching capability and immunity to power fading, which are significant in distributed multifunction radar networks with optical fiber-based transmission.

Joint waveform design of radar detection, wireless communication and jamming based on chaotic composite modulation

AbstractIn this letter, we address the problem of designing the joint waveform of radar detection, wireless communication and jamming. In the current most powerful filter‐bank multi‐carrier comb spectrum framework, a parameter‐agile time–frequency structure between symbols is elaborated to improve the uncertainty of waveform generation architecture. Furthermore, a novel composite modulation strategy that combines intra‐symbol chaos‐based radar frequency modulation and inter‐symbol chaos‐based phase modulation is proposed for a substantial jamming performance improvement. Simulation results verify that the proposed joint waveform produces a superior jamming performance while satisfying the requirements of radar detection and wireless communication.