Pulse Jitter Research Articles

High precision low jitter pulse generator implemented with FPGA transceiver

Precisely controlled digital pulse plays a crucial role in various cutting-edge testing applications. This paper introduces an innovative approach to digital pulse generation utilizing an FPGA transceiver, with the AMD evaluation board ZCU102 serving as a demonstrative platform. In the normal mode, the transmitter generates a serial bit stream, enabling the generation of single or repeated pulses with configurable width and period. In the high precision mode, an internal dedicated phase interpolator enhances the configuration step size for width and period by up to 64 times, providing finer phase shift capability. The demonstration system operates at a line rate of 10Gbps, achieving a resolution of 100ps in normal mode and 1.5625ps in high precision mode. This paper details the design methodology, presents test results for pulse width uncertainty and non-linearity, and showcases achieved period jitter and time interval error jitter as small as around 1ps.

Pulse Jitter and Single-pulse Variability in Millisecond Pulsars

Understanding the jitter noise resulting from single-pulse phase and shape variations is important for the detection of gravitational waves using pulsar timing arrays. We present measurements of the jitter noise and single-pulse variability of 12 millisecond pulsars that are part of the International Pulsar Timing Array sample using the Five-hundred-meter Aperture Spherical radio Telescope. We find that the levels of jitter noise can vary dramatically among pulsars. A moderate correlation with a correlation coefficient of 0.57 between jitter noise and pulse width is detected. To mitigate jitter noise, we perform matrix template matching using all four Stokes parameters. Our results reveal a reduction in jitter noise ranging from 6.7% to 39.6%. By performing longitude-resolved fluctuation spectrum analysis, we identify periodic intensity modulations in 10 pulsars. In PSR J0030+0451, we detect single pulses with energies more than 10 times the average pulse energy, suggesting the presence of giant pulses. We also observe a periodic mode-changing phenomenon in PSR J0030+0451. We examine the achievable timing precision by selecting a subset of pulses with a specific range of peak intensity, but no significant improvement in timing precision is achievable.

Sub-50 fs temporal resolution in an FEL-optical laser pump-probe experiment at FLASH2.

High temporal resolution is essential for ultra-fast pump-probe experiments. Arrival time jitter and drift measurements, as well as their control, become critical especially when combining XUV or X-ray free-electron lasers (FELs) with optical lasers due to the large scale of such facilities and their distinct pulse generation processes. This paper presents the application of a laser pulse arrival time monitor that actively corrects the arrival time of an optical laser relative to the FEL's main optical clock. Combined with post-analysis single pulse jitter correction this new approach improves the temporal resolution for pump-probe experiments significantly. Benchmark measurements on photo-ionization of xenon atoms performed at FLASH beamline FL26, demonstrate a sub-50 fs FWHM overall temporal resolution.

An insight into chromatic behaviour of jitter in pulsars and its modelling: a case study of PSR J0437−4715

ABSTRACT Pulse-to-pulse profile shape variations introduce correlations in pulsar times of arrival across radio frequency measured at the same observational epoch. This leads to a broad-band noise in excess of radiometer noise, which is termed as pulse jitter noise. The presence of jitter noise limits the achievable timing precision and decreases the sensitivity of pulsar timing data sets to signals of interest such as nanohertz-frequency gravitational waves. Current white noise models used in pulsar timing analyses attempt to account for this, assuming complete correlation of uncertainties through the arrival times collected in a unique observation and no frequency dependence of jitter (which corresponds to a rank-one covariance matrix). However, previous studies show that the brightest millisecond pulsar at decimetre wavelengths, PSR J0437−4715, shows decorrelation and frequency dependence of jitter noise. Here, we present a detailed study of the decorrelation of jitter noise in PSR J0437−4715 and implement a new technique to model it. We show that the rate of decorrelation due to jitter can be expressed as a power law in frequency. We analyse the covariance matrix associated with the jitter noise process and find that a higher rank approximation is essential to account for the decorrelation and to account for frequency dependence of jitter noise. We show that the use of this novel method significantly improves the estimation of other chromatic noise parameters such as dispersion measure variations. However, we find no significant improvement in errors and estimation of other timing model parameters suggesting that current methods are not biased for other parameters, for this pulsar due to this misspecification. We show that pulse energy variations show a similar decorrelation to the jitter noise, indicating a common origin for both observables.

Time-Resolved Photoluminescence in GeSn Film by New Infrared Streak Camera Attachment Based on a Broadband Light Upconversion

GeSn coatings on commercial Si substrates have gained increased interest for application in infrared detectors and lasers. The characterization of these materials is crucial for their quality assessment and in describing device performance for commercialization. The time-resolved photoluminescence is an efficient method for contactless, time-resolved characterization of GeSn optoelectronic properties. For this purpose, in this work, we developed an infrared streak camera attachment based on the broadband upconversion of infrared photoluminescence by using powerful nanosecond 1064 nm pulses. The attachment achieved picosecond time resolution, being limited by the laser pulse duration, jitter, and temporal resolution of the streak camera. The spectral range for time-resolved photoluminescence in the 1100–2400 nm interval was obtained, outperforming the range of commercial infrared InGaAs streak cameras. The developed setup was applied for excitation-dependent time-resolved photoluminescence decay measurements in a GeSn and compared to the conventional upconversion technique with the optically delayed picosecond gate pulses. The new setup provided 2D spectro-temporal images for analysis. The photoluminescence decay times in the 30–80 ps range were obtained in the GeSn layer depending on the excitation pulse energy and spectral emission wavelength. Carrier thermalization was observed as a redshift of the photoluminescence spectra with time.

On the Effects of PRBS Non-Idealities in Signal Reconstruction from AICs

The paper presents a sensitivity analysis of the non-idealities introduced by the Pseudo Random Binary Sequence (PRBS) on two modulation-based architectures of Analog-to-Information Converters (AICs), namely the Random Demodulator and the Modulated Wideband Converter. In particular, the effects of both PRBS pulse shape and jitter are contemplated. The emerging findings from this analysis can guide the design process of AICs, so that the jitter effect can be brought below acceptable levels for a given target application. The analysis is carried out firstly by characterizing the PRBS pulse shape, and then by including the calibration data in the behavioral models of the two architectures. The reconstructed signal is thus evaluated for different values of random and deterministic jitter, in terms of Spurious Free Dynamic Range and Signal to Noise And Distortion Ratio. The results highlight a different behavior of the two architectures due to the different reconstruction models they adopt. Mainly, the identification phase of the measurement matrix proves to be able to compensate the jitter effect when jitter is correlated with the PRBS sequence.

Active Gate Driving Technique for Series Connecting SiC MOSFETs in the Presence of Gate Pulse Delay Mismatch

In this article, series connection of SiC MOSFETs has been attempted with the help of an active gate driving (AGD) technique. The gate currents of SiC MOSFETs are actively controlled in such a way that several devices can switch fast (within 50 ns) even in the presence of a moderate amount of gate pulse delay mismatch and jitter in the gate pulse. This enables the AGD’s to share the gate pulse signal information among each other. Such a feature can reduce the cost of the net solution by reducing the number of optical cables required for the gate pulse transmission. In addition to this, the AGD is designed in such a way that fast switching can be achieved even in the presence of moderate parasitic inductance in the layout. The proposed AGD technique is experimentally verified in a double pulse test setup with two and four switching devices in series using 32 A, 1 kV CREE SiC MOSFETs. The experimental results show turn- <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on</small> and turn- <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">off</small> switching times of 45 and 34 ns, respectively, at 35 A load current. The AGD has also shown 47% reduction in the turn- <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">off</small> switching losses compared to the passive gate driving technique.

A 1.35-kV/500-kHz Sub-Nanosecond Pulser With High Time Base Stability

In many fields, e.g., ground-penetrating radar and ultra-wideband radiation, a high-pulse-repetition-frequency (PRF) and high-time-base-stability sub-nanosecond pulser is required, and its output waveform should be close to a gaussian pulse. In this article, the transistorized pulser is studied and optimized to improve its output parameters. The printed circuit board circuit parameters of the pulser are first optimized, which is beneficial for the amplitude and the rise time. To improve the time base stability, the collector voltage ramp triggering mode is adopted to replace the conventional base triggering mode for the pulser. For higher PRF, the pulser with the capacitance–transistor parallel structure is immersed in the fluorinert liquid. Moreover, the deficit-charge method is adopted, and small charging capacitances are used in the last few stages to weaken the oscillation in the pulse falling edge. From experimental results, the amplitude of the optimized pulser is 1.35 kV, its rise time is reduced from about 200 to 135 ps, the maximum PRF is improved from 250 to 500 kHz, the pulse jitter is reduced to 22 ps, and the pulse drift is reduced from hundreds of ps/min to 47 ps/min. Meanwhile, the oscillation in its falling edge is greatly suppressed.

Design and Performance of a Ferrite Transmission Line Sharpener for Trigger Generator Used in FLTD

Tens of thousands of gas switches in fast linear transformer driver (FLTD) need to be switched ON synchronously, which requires gas switch triggers with fast rise time and low jitter. At present, the pulse rise time of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\sim 100$ </tex-math></inline-formula> -kV gas switch trigger is often sharpened by a gas switch. Although the gas switch sharpener can reduce pulse rise time, it is difficult to control the pulse jitter because of the dispersion of gas discharge. Using a ferrite nonlinear transmission line to steepen pulse rise time has been widely used in high-power microwave fields. In this article, a ferrite transmission line is proposed to replace the gas switch sharpener. By establishing the simulation model of the ferrite transmission line, the effects of pulse amplitude, transmission line length, and structural parameters on the sharpening rise time are analyzed. An experimental platform was established to test the sharpening performance of two different structural ferrite transmission lines. The test results show that the ferrite transmission lines can reduce the trigger pulse rise time from 124 ns to less than 16 ns, and the jitter of the whole trigger device is less than 2.5 ns, which can be used to replace the gas switch sharpener.

A modularized high-power ultra-wideband radiation system based on the space-synthesis method.

In this paper, a high-power ultra-wideband radiation system, composed of multiply radiation modules, is developed based on the space-synthesis method. The radiation module mainly consists of a transistorized pulser, a 2 × 2 combined antenna array, and a power divider. To improve the out parameters [the amplitude, the pulse repetition frequency (PRF), and the rise time] of the transistorized pulser based on the Marx circuit, the influence of the traveling wave process on the output pulse must be concerned. Based on the theoretical analysis, the printed circuit board circuit parameters and the circuit structure of the pulser are optimized. To improve the power synthesis efficiency, the pulse jitter characteristic of the pulser is improved by replacing the conventional base triggering mode with the collector voltage ramp triggering mode for the first-stage avalanche transistor in the pulser. The previous optimized antenna array is utilized in this radiation system, which has a better radiation performance in the prescribed aperture area. In addition, based on the gradient microstrip structure, the power divider integrated with the pulser is designed, which has the advantages of wide bandwidth, low loss, and light weight. Experimental results show that the peak effective potential rEp of the radiation system of 20 radiation modules is 221.8 kV, the maximum PRF could reach 10 kHz, and the half-power radiation angles of its radiation field are about 5° in both the E plane and the H plane. More radiation modules could be integrated into the system to achieve a higher electric field in the future.

Deep ToA Mask Based Recursive Radar Pulse Deinterleaving

In a complex electromagnetic environment, multiple radar signals of various modes are densely interleaved. In this environment, radar parameters overlap seriously and change continuously over time. Traditional radar pulse deinterleaving algorithms face severe challenges such as parameters missing, pulse jitter, and the increasing number of electronic countermeasure devices. In this paper, we propose a recursive deinterleaving algorithm based on blind signal separation and deep learning to cope with such a situation. The Recursive Deinterleaving Network (RDN) of Deep ToA Mask (DTM) maps the ToA train to a suitable feature space first. ToA coefficient masks of each radar emitter are estimated with the local and global context information of the radar pulse feature. Then the RDN sorts out several radar pulse trains recursively with the help of dual-path attention. It also predicts the number of emitters with nearly 100&#x0025; accuracy and handles the unknown Pulse Repetition Interval (PRI) situation. More accurate pulse deinterleaving results can be obtained if the DTM utilizes more radar parameters through proper pre-processing fine-tuning and post-processing re-clustering. The processing steps of the DTM are introduced in detail. The simulation shows it can achieve 97&#x0025; sorting accuracy for multi-pulse interleaved radar train with jitter PRI and pulse missing. The DTM algorithm can also deal with the interleaved radar signals of different PRI modulations by re-clustering with noisy PDW information. On the premise of knowing the modulation type or PRI information, the pulse train deinterleaving accuracy of multi-modulation emitters is higher.

Experimental studies on the X-ray single-pulse jitter at the SSRF

At the Shanghai Synchrotron Radiation Facility (SSRF), ultrafast experiments require picosecond temporal resolution. Thus, understanding the jitter of a single X-ray pulse is important. In this study, a timing synchronization control system that combines a timing system, optical fiber network, and X-ray streak camera detection system were employed to accurately acquire the temporal characteristics of a single X-ray pulse at a low photon intensity(103 photons/pulse). Experimental results showed that the intensity of a single X-ray pulse is distributed as a Gaussian curve in the longitudinal direction, and the pulse jitter broadens to approximately 5 ps, which is sufficient for ultrafast temporal resolution research at the SSRF.

Rapid measurement of jitter time of MCP gating pulse in framing camera

A measurement system of exposure time is introduced. The jitter time MCP gating pulse is rapidly measured using an array of fiber bundle(AFB) and pulse-dilation framing camera. The research results show that the AFB is early or delay synchronized with MCP gating pulse by the pulse jitter result in the variation of position of maximum intensity of the dramatic imaging of the AFB. According to the variation of position, while the MCP gating pulse has a width of 200 ps and amplitude of −1.75 kV, the left and right jitter time of gating pulse are 61 ps and 73 ps, respectively. The measurement method provide a conveniently diagnosis to estimate jitter time of MCP gating pulse.

Absolute phase marking technology and fiber-optic remote coherent phase transmission.

Fiber-optic time and frequency synchronization technology demonstrates ultra-high synchronization performance and has been gradually applied in various fields. Based on frequency synchronization, this study addressed the problems of period ambiguity and initial phase uncertainty of the phase signal to realize the coherent transmission of the phase. An absolute phase marking technology was developed based on high-speed digital logic with zero-crossing detection and an optimized control strategy. It can realize picosecond-level absolute phase marking and provide a picosecond-level ultra-low peak-to-peak jitter pulse marking signal to eliminate phase period ambiguity and determine initial phase and transmission delay. Thus, by combining the high-precision phase measurement capability of the synchronized frequency signal and long-distance ambiguity elimination capability of the pulse-per-second signal, a high-precision remote coherent phase transmission over an optical fiber is realized. After frequency synchronization, the peak-to-peak jitter between the local and remote phase-marking signals can be only 3.3 ps within 10,000 s measurement time. The uncertainty of the coherent phase transmission is 2.577 ps. This technology can significantly improve the phase coherence of fiber-optic time and frequency transmission and provide a new approach to achieve peak-to-peak picosecond-level reference phase marking and high-precision fiber-optic remote coherent phase transmission. This demonstrates broad application prospects in coherence fields such as radar networking.

A Single-pulse Study of PSR J1022+1001 Using the FAST Radio Telescope

Abstract Using the Five-hundred-meter Aperture Spherical radio Telescope (FAST), we have recorded ∼105 single pulses from PSR J1022+1001. We studied the polarization properties, their energy distribution, and their times of arrival. This is only possible with the high sensitivity available using FAST. There is no indication that PSR J1022+1001 exhibits giant pulse, nulling, or traditional mode changing phenomena. The energy in the leading and trailing components of the integrated profile is shown to be correlated. The degree of both linear and circular polarization increases with the pulse flux density for individual pulses. Our data indicates that pulse jitter leads to an excess noise in the timing residuals of 67 ns when scaled to one hour, which is consistent with Liu et al. We have unsuccessfully trialed various methods to improve timing precision through the selection of specific single pulses. Our work demonstrates that FAST can detect individual pulses from pulsars that are observed in order to detect and study gravitational waves. This capability enables detailed studies, and parameterization, of the noise processes that affect the sensitivity of a pulsar timing array.

High energy (0.8 J) mechanically Q-switched 2.94 μm Er:YAG laser.

We report a flashlamp pumped mechanically Q-switched (MQS) 2.94 μm Er:YAG laser based on a spinning mirror with a highest output energy of 805 mJ at a pulse duration of 61 ns and 13 MW of peak power at 1 Hz repetition rate. This record output energy was achieved with the use of 300 mm long MQS Er:YAG laser cavity consisting of a 70% output coupler, 7 × 120 mm AR coated Er(50%):YAG crystal, and 4200 rad/s angular speed of the spinning mirror. The pulse jitter was also measured by using optical triggering and was smaller than 10 ns for 150 ns Q-switched pulses, which could be applicable to many laser applications where precise synchronization of pulses is required.

Measurements of pulse jitter and single-pulse variability in millisecond pulsars using MeerKAT

ABSTRACT Using the state-of-the-art SKA precursor, the MeerKAT radio telescope, we explore the limits to precision pulsar timing of millisecond pulsars achievable due to pulse stochasticity (jitter). We report new jitter measurements in 15 of the 29 pulsars in our sample and find that the levels of jitter can vary dramatically between them. For some, like the 2.2 ms pulsar PSR J2241−5236, we measure an implied jitter of just ∼4 ns h−1, while others, like the 3.9 ms PSR J0636−3044, are limited to ∼100 ns h−1. While it is well known that jitter plays a central role to limiting the precision measurements of arrival times for high signal-to-noise ratio observations, its role in the measurement of dispersion measure (DM) has not been reported, particularly in broad-band observations. Using the exceptional sensitivity of MeerKAT, we explored this on the bright millisecond pulsar PSR J0437−4715 by exploring the DM of literally every pulse. We found that the derived single-pulse DMs vary by typically 0.0085 cm−3 pc from the mean, and that the best DM estimate is limited by the differential pulse jitter across the band. We postulate that all millisecond pulsars will have their own limit on DM precision which can only be overcome with longer integrations. Using high-time resolution filterbank data of 9 μs, we also present a statistical analysis of single-pulse phenomenology. Finally, we discuss optimization strategies for the MeerKAT pulsar timing program and its role in the context of the International Pulsar Timing Array.

Sensing Framework for the Internet of Actors in the Value Co-Creation Process with a Beacon-Attachable Indoor Positioning System.

To evaluate and improve the value of a service, it is important to measure not only the outcomes, but also the process of the service. Value co-creation (VCC) is not limited to outcomes, especially in interpersonal services based on interactions between actors. In this paper, a sensing framework for a VCC process in retail stores is proposed by improving an environment recognition based indoor positioning system with high positioning performance in a metal shelf environment. The conventional indoor positioning systems use radio waves; therefore, errors are caused by reflection, absorption, and interference from metal shelves. An improvement in positioning performance was achieved in the proposed method by using an IR (infrared) slit and IR light, which avoids such errors. The system was designed to recognize many and unspecified people based on the environment recognition method that the receivers had installed, in the service environment. In addition, sensor networking was also conducted by adding a function to transmit payload and identification simultaneously to the beacons that were attached to positioning objects. The effectiveness of the proposed method was verified by installing it not only in an experimental environment with ideal conditions, but posteriorly, the system was tested in real conditions, in a retail store. In our experimental setup, in a comparison with equal element numbers, positioning identification was possible within an error of 96.2 mm in a static environment in contrast to the radio wave based method where an average positioning error of approximately 648 mm was measured using the radio wave based method (Bluetooth low-energy fingerprinting technique). Moreover, when multiple beacons were used simultaneously in our system within the measurement range of one receiver, the appropriate setting of the pulse interval and jitter rate was implemented by simulation. Additionally, it was confirmed that, in a real scenario, it is possible to measure the changes in movement and positional relationships between people. This result shows the feasibility of measuring and evaluating the VCC process in retail stores, although it was difficult to measure the interaction between actors.

The Two Emission States of PSR B1534+12

Abstract We have observed PSR B1534+12 (J1537+1155), a pulsar with a neutron star companion, using the Five-hundred-meter Aperture Spherical radio Telescope. We found that this pulsar shows two distinct emission states: a weak state with a wide pulse profile and a burst state with a narrow pulse profile. The weak state is always present. We cannot, with our current data, determine whether the pulse energy of the weak state follows a normal or a log-normal distribution. The burst state energy distribution follows a power law. The amplitude of the single-pulse emission in the burst state varies significantly; the peak flux intensity of the brightest pulse is 334 times stronger than that of the average pulse. We also examined the timing precision achievable using only bright pulses, which showed no demonstrable improvement because of pulse jitter and therefore quantified the jitter noise level for this pulsar.

High power and high pulse repetition frequency transistorized pulser by time base stability improvement and power synthesis technique.

Output power of a transistorized pulser is usually limited by the power capacity of avalanche transistors. To improve the total output power, the power synthesis method is widely used, in which a single pulser with high output power and high time base stability is required. However, the time base stability tends to deteriorate as the output power increases. To improve the output power under the premise of high time base stability, from the perspective of carrier movement, the mechanisms of pulse jitter and pulse drift are investigated. It is found that the pulse jitter is caused by time dispersion of the ionization process in the collector depletion region, while the pulse drift is due to the decrement of the diffusion coefficient Dn and the electron mobility μn, which are both temperature-dependent. Based on the microscopic theoretical study, some macroscopic improvements on the time base stability are made. Some parameters of the trigger pulse and the circuit (e.g., charging capacitance) are optimized experimentally. Consequently, we achieved a pulser with an amplitude of 1.8 kV, pulse jitter of 25 ps, pulse drift of 100 ps/min at a pulse repetition frequency (PRF) of 100 kHz. Additionally, a new parameter k, the product of the highest PRF f and the peak power Ep, is defined to evaluate the output power. With almost the same time base stability, the proposed pulser has a k of 6.48 GHz W, which is improved significantly. Finally, a synthesized pulser with an amplitude of 2.5 kV and highest PRF of 100 kHz is achieved.