GHz Sampling Research Articles

The observation of avalanche-like transport during confinement power degradation in Heliotron J

In this study, we observe avalanche-like electron thermal transport in Heliotron J under plasma conditions that exhibit power degradation to the central electron cyclotron heating (ECH). The newly installed GHz sampling electron cyclotron emission diagnostic allows for the observation of the long-distance radial propagation of electron temperature fluctuations. We find that the electron temperature fluctuations are associated with avalanches, because the Te fluctuations (i) propagate from the core to the edge with a speed comparable to the diamagnetic drift velocity, (ii) exhibit a 1/f power-law scaling in the frequency spectrum and a Hurst exponent close to 1, and (iii) dominate in the ECH deposition location and spread to the edge as the heating power increases. Furthermore, the electron heat avalanches can spread to the scrape off layer region when they are enhanced, i.e., the Te fluctuations correlate with the Dα emission, which also has a frequency spectrum that scales with a 1/f power law.

Impact of the Detection Channels Added by Fengyun Satellite MWHS-II at 183 GHz on Global Numerical Weather Prediction

Fine spectral detection can basically solve the problem of low vertical resolution at the 183 GHz water-vapor absorption line, and it is expected to become one of the main methods for next-generation geostationary and polar-orbiting satellites. Here, using data from Microwave Humidity Sounder II (MWHS-II) onboard the Chinese Fengyun 3D (FY-3D) satellite in the Global/Regional Assimilation and Prediction System (GRAPES) Four-Dimensional Variational (4D-Var) system of the China Meteorological Administration (CMA), we explore the assimilation application of the water-vapor absorption line at 183.31 ± 1 GHz, 183.31 ± 3 GHz and 183.31 ± 7 GHz, as well as 183.31 ± 1.8 GHz and 183.31 ± 4.5 GHz, two added channels, to assess the impact of adding the 183.31 ± 1.8 GHz and 183.31 ± 4.5 GHz sampling channels on data assimilation and numerical weather prediction. Our findings reveal a significant increase in the specific-humidity increment, which in the middle–upper troposphere is numerically much larger than in the lower troposphere. Specifically, the assimilation of 183.31 ± 1.8 GHz observations, positioned near the center of the water-vapor absorption line, results in a pronounced adjustment compared with the 183.31 ± 4.5 GHz observations. And under the strong constraint of the numerical model, the Root Mean Square Error (RMSE) of the wind field diminishes more significantly (by an average of 2–4%) after assimilating the water-vapor observations at greater heights.

A Bi-Objective Simulation Facility for Speed and Range Calibration of 24 GHz and 77 GHz Automotive Millimeter-Wave Radars for Environmental Perception

Automotive millimeter-wave radars are widely used to measure kinematic parameters of surrounding objects in the environmental perception of automated vehicles and typically operate in frequency bands of around 24 GHz and 77 GHz. The 24 GHz and 77 GHz automotive millimeter-wave radars are similar in their speed and range measurement principles; however, they are distinct in their accuracies when measuring the above kinematic parameters because of the different carrier frequencies and bandwidths. In order to evaluate the kinematic parameter measurement performances of automotive millimeter-wave radars for environmental perception, this paper proposes a calibration method and establishes a bi-objective simulation facility for the speed and range calibration of 24 GHz and 77 GHz automotive millimeter-wave radars. The feasibility of the proposed calibration method and the accuracy of the established bi-objective simulation facility are verified by the results obtained via experiments conducted on two 24 GHz and 77 GHz millimeter-wave radar samples. According to the speed and range calibration results of the two millimeter-wave radar samples, the 77 GHz millimeter-wave radar sample possesses superior speed measurement accuracy compared with the 24 GHz sample. Additionally, the range measurement errors of the 77 GHz millimeter-wave radar sample are much smaller than those of the 24 GHz sample. This indicates that the 77 GHz millimeter-wave radar sample is more accurate and reliable than the 24 GHz sample. Finally, the 77 GHz millimeter-wave radar sample was tested for its speed and range resolving ability. The results confirm that the bi-objective simulation facility can satisfy the calibration requirements of speed resolution up to 0.01 m/s and range resolution up to 0.1 m. The proposed calibration method and the established simulation facility can easily satisfy the speed, range and resolution calibration requirements of 24 GHz and 77 GHz millimeter-wave radars with high precision and wide range, and can achieve more economical, comprehensive and traceable performance testing on both 24 GHz and 77 GHz automotive millimeter-wave radars for environmental perception.

From BEYONDPLANCK to COSMOGLOBE: Preliminary WMAP Q-band analysis

We present the first application of the COSMOGLOBE analysis framework by analyzing nine-year WMAP time-ordered observations that uses similar machinery to that of BEYONDPLANCK for the Planck Low Frequency Instrument (LFI). We analyzed only the Q-band (41 GHz) data and report on the low-level analysis process based on uncalibrated time-ordered data to calibrated maps. Most of the existing BEYONDPLANCK pipeline may be reused for WMAP analysis with minimal changes to the existing codebase. The main modification is the implementation of the same preconditioned biconjugate gradient mapmaker used by the WMAP team. Producing a single WMAP Q1-band sample requires 22 CPU-hrs, which is slightly more than the cost of a Planck 44 GHz sample of 17 CPU-hrs; this demonstrates that a full end-to-end Bayesian processing of the WMAP data is computationally feasible. In general, our recovered maps are very similar to the maps released by the WMAP team, although with two notable differences. In terms of temperature, we find a ∼2 μK quadrupole difference that most likely is caused by different gain modeling, while in polarization we find a distinct 2.5 μK signal that has been previously referred to as poorly measured modes by the WMAP team. In the COSMOGLOBE processing, this pattern arises from temperature-to-polarization leakage from the coupling between the CMB Solar dipole, transmission imbalance, and sidelobes. No traces of this pattern are found in either the frequency map or TOD residual map, suggesting that the current processing has succeeded in modeling these poorly measured modes within the assumed parametric model by using Planck information to break the sky-synchronous degeneracies inherent in the WMAP scanning strategy.

GHz sample excitation at the ALBA-PEEM

We describe a setup that is used for high-frequency electrical sample excitation in a cathode lens electron microscope with the sample stage at high voltage as used in many synchrotron light sources. Electrical signals are transmitted by dedicated high-frequency components to the printed circuit board supporting the sample. Sub-miniature push-on connectors (SMP) are used to realize the connection in the ultra-high vacuum chamber, bypassing the standard feedthrough. A bandwidth up to 4 GHz with -6 dB attenuation was measured at the sample position, which allows to apply sub-nanosecond pulses. We describe different electronic sample excitation schemes and demonstrate a spatial resolution of 56 nm employing the new setup.

Polarized laser target detection system for smoky environment based on full-waveform decomposition and multiscale convolutional neural networks with attention

To overcome the problem that the smoky environment affects the laser detection performance and generates false alarm, this paper proposes a polarization pulse laser target detection method based on the difference of the polarization information between the target and the smoke, combining full waveform decomposition and Multiple Scale-Attention convolutional neural network with Focal loss function (MSAFCNN). Optimal parameters of the algorithm are obtained by studying the recognition accuracy of the algorithm with different sampling rates and the number of convolution kernels. The polarization pulse laser detection platform is built and the target detection experiments under five different scenarios using infrared lasers are conducted. The polarization echo signals of the smoke and the targets are collected and the recognition accuracy of the proposed algorithm is calculated. The ablation experiments are carried out and MSAFCNN is compared with several advanced algorithms. The experimental results show that the proposed algorithm has the highest recognition accuracy (99.085% ± 0.249%) compared with other algorithms. According to the ablation experiment, the recognition accuracy can be improved by 1.381% using MSAFCNN. The recognition experiments with different sampling rates and numbers of convolutional kernels are performed, and the accuracy of the proposed algorithm can reach 99.348% ± 0.178% at 1 GHz sampling rate and 98.910% ± 0.297% at 500 MHz sampling rate. The optimal number of convolutional kernels is 16, and the number of the algorithm parameters is only 125.273 KB, which provides the feasibility for the subsequent implementation of the algorithm in hardware.

Development of a Digitising Data Acquisition Pipeline for Next Generation Pulsed Muon Spectrometers

The next generation of muon spin spectrometers at the ISIS pulsed source are being developed to make efficient use of the increased source intensity. They will provide a transformational improvement in counting rates: ‘Super-MuSR’ will be the first of these instruments, capable of counting at ≈1 G·event·hr−1. Key to delivering this capability is the development of highly pixelated, high density detector arrays that cover an appreciable solid angle, with each detector element optimised for counting at very high data rates. A series of ‘firsts’ are planned to optimise individual element count rate capability, where analogue waveforms recorded from SiPMs are fully digitised and processed using digital signal processing (DSP) methods at either software or firmware level. Full raw-signal digitisation will be achieved using the Xilinx Zynq® UltraScale+TM series of ‘system on a chip’ operating with ADCs capable of 1 GHz sampling, data handling using event streaming technology, and DSP to provide novel data correction techniques. We will discuss our concept and present preliminary results. Our prototype digitising data acquisition system, which is key to implementing a ‘digital data pipeline’ (DDP) is presented.

Устройства и методы измерения параметров RFTES-болометра

Several new approaches to the measurement of intrinsic noise and dynamic characteristics of superconducting bolometers based on the RFTES technology are demonstrated. The developed methods were tested with an experimental 550–750 GHz sample at reading frequency of ~1.5 GHz at a temperature of 400 mK. The absorption of thin-film resistive coatings on sapphire and quartz substrates was studied, and the emissivity of the experimental heat source was estimated as ~14%. A shot noise source based on Al/AlOx/Al tunnel junction was developed, and the noise temperature of the 1.35–1.6 GHz buffer amplifier referred to the detector output was determined as ~20 K. The response time of RFTES with a hafnium film sized 6 µm × 2 µm × 0.08 µm was evaluated as ~3 µs via microwave heat modulation at the second resonance at ~4.2 GHz; the dynamic range at a modulation frequency of 10 kHz was more than 23 dB. The data obtained made it possible to determine the RFTES sensitivity as 1∙10-17 W/√Hz ± 30%, that coincided with the theoretical value up to the measurement error.

An 18.1 mW 50 MHz-BW 76.4 dB-SNDR CTSDM With PVT-Robust VCO Quantizer and Latency-Free Background-Calibrated DAC

This paper presents a continuous-time sigma-delta modulator (CTSDM) with a voltage-controlled-oscillator-based (VCO-based) integrating quantizer. A background replica-based calibration technique is proposed to alleviate the impact of the process, voltage supply, and temperature (PVT) variations on the tuning characteristic and current consumption of the VCO-based quantizer. Matching between the replica VCO and the main VCO in the proposed calibration is not needed. A latency-free background calibration technique is also proposed to eliminate the distortions caused by the DAC mismatch. The prototype VCO-based CTSDM is fabricated in a 40 nm CMOS and achieves SNDR/SFDR/DR of 76.4 dB/91.7 dBc/79.6 dB, respectively, within a 50 MHz bandwidth (BW) at 1.6 GHz sampling frequency. The measured SNDR varies within ±1 dB over a temperature range of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0\sim 80~^{\circ }\text{C}$ </tex-math></inline-formula> and a voltage supply variation of ±10%, across different tested samples. The power consumption is 18.1 mW, achieving a Schreier Figure of Merit (FoMS) of 170.8 dB.

Photonic-Assisted Modulation Format Identification for RF Signals under Low Sampling Rate

A photonic-assisted approach is proposed for modulation format identification (MFI) on radio frequency (RF) signals under low sampling rate. In this approach, a photonic-assisted interferometer (PAI) is designed for computation-free data augmentation by transforming the signal’s phase and frequency variations into modulation format-sensitive amplitude features. A fully connected neural network (FCNN) is used to implement end-to-end MFI. An experiment is conducted on the identification of amplitude-shift keying (ASK), binary phase-shift keying (BPSK), quadrature phase-shift keying (QPSK), frequency-shift keying (FSK), and linear frequency modulation (LFM) signals with signal-to-noise ratios (SNRs) from −10 to 15 dB and carrier frequencies within 5 to 10 GHz. The results show that the proposed photonic-assisted modulation format identifier (PA-MFI) achieves the identification accuracy of 82.44% at 1 GHz sampling rate, which is 10.6% higher than the accuracy of direct modulation format identification (Direct-MFI) without PAI processing.

An improved lorentz fitting algorithm for BOTDR using SVM model to capture the main peak of power cumulative average data

The Brillouin scattering signal is weak and the signal-to-noise ratio (SNR) is low in Brillouin optical time domain reflectometer (BOTDR), these result in a difficulty to improve the spatial resolution (SR) and measurement accuracy at the same time. In this paper, the denoising principle of power cumulative average (PCA) is analyzed theoretically, then an improved Lorentzian-curve fitting (ILCF) algorithm based on PCA data is proposed, in which the support vector machine (SVM) model is adopted to capture the main peak, and the Brillouin frequency shift (BFS) of double-peak spectrum is determined precisely. Furtherly, by adjusting the step of the sliding window, the precision of edge detection in the transition section is improved to 0.1-m. For the fiber under test (FUT) with a length of 12-km, 500 groups of time-domain data are processed under the probe pulse with 50 ns width and 1 GHz sampling rate. The average error of temperature accesses to 0.8 °C and the SR achieves 6.4-m simultaneously. The algorithm in this paper can reduce BFS standard deviation from 28.21 MHz to 1.27 MHz, improve the SR to the maximum limitation by the probe pulse, determine the BFS of double-peak spectrum and reduce the measurement time. Therefore, the proposed method can improve SR and measurement accuracy at the same time.

A 110 GHz Comb Generator in a 250 nm InP HBT Technology

We report a monolithic microwave integrated-circuit (MMIC) comb generator capable of producing a repetitive narrow pulse (7.1 ps pulse duration) with sharp edges (4.2 ps falling time). The circuit was designed in a 250 nm indium phosphide (InP) heterojunction bipolar transistor (HBT) technology using differential pairs. We characterized the output signal with a 110 GHz sampling oscilloscope and de-embedded the band-limited frequency spectrum of the pulse in the circuit reference plane. We measured a pulse duration of 7.1 ps and a peak amplitude of −0.333 V. In the frequency domain, the comb generator provided −48.7 dBm of output power at 110 GHz when the circuit is fed with a 1 GHz input signal.

Atmospheric Exploration of the Qinghai–Tibet Plateau during the East Asian Winter Monsoon (EAWM) from a Ground-Based Microwave Radiometer

The investigation of atmospheric characteristics is of great significance in properly exploiting air and water resources, and quantitatively estimating and nowcasting precipitation. Microwave radiometers are widely used in this field because they can operate unattended for a long time under almost all weather conditions, and obtain high-quality remote sensing data. This research focuses on the applications of ground-based microwave radiometers in retrieving meteorological characteristics of the Qinghai–Tibet Plateau (QTP) during the East Asian winter monsoon (EAWM), such as humidity and temperature structures, stability/convection indices, and cloud and precipitation retrievals. Vertical structures of atmospheric temperature, pressure, humidity, and other variables were investigated under clear-sky and snowy-sky conditions. The statistical characteristics of stability/convection indices in the QTP region, such as convective available potential energy (CAPE) and convective inhibition (CIN), were investigated, with a special focus on snowy-sky conditions. The relationship between potential cloud water resources and atmospheric and thermodynamics and instability conditions were taken into consideration. The results showed that the peak CAPEs under clear-sky and snowy-sky conditions were 1349.11 J/kg and 1165.12 J/kg, which were relatively larger than the corresponding values during the summer monsoon. CINs during the EAWM were small enough to be negligible. For quantitative precipitation forecasting (QPF), brightness temperatures at 30.0 GHz and 51.24 GHz sampling channels were sensitive to the snowfall process. Within 1 h before snowfall, the precipitable water vapour (PWV) and liquid water content (LWC) increased sharply by 0.05 cm and 0.12 mm, respectively, while the CAPE and downwards CAPE decreased by 225.60 J/kg and 180.31 J/kg, respectively. The findings of this article may be meaningful for characterizing meteorology and precipitation in the QTP and similar regions during the winter monsoon.

Resolution-Selective and Resolution-Adaptive 2 to 8-Bit Flash ADC for High-Speed Application-Independent IC (HS-AIIC)

Application-Specific ICs (ASIC) are manufactured in bulk for a long time. In this paper, an approach to High-Speed Application-Independent IC (HS-AIIC) design is discussed. A resolution-selective (RS) and resolution-adaptive (RA) 8-bit Flash ADC are designed for use in various high-speed applications. With the choice of resolution, one can work with the trade-off between speed, power consumption, and resolution for a particular application. The proposed resolution selection algorithm can be implemented for any set of resolutions for a flash ADC design. Further, an adaptive block is added to make the ADC design adaptive in nature so that we do not have to select a particular resolution manually. The proposed design entrusts on saving manufacturing cost and increases the functionality of ADC on a single chip. Proposed resolution adaptive 8-bit flash ADC design dissipates 512[Formula: see text]mW of power with an ENOB of 7.56 bits and SNDR of 46.27[Formula: see text]dB for 1[Formula: see text]GHz sampling clock pulse.

Demonstration of Shor Encoding on a Trapped-Ion Quantum Computer

Fault-tolerant quantum error correction (QEC) is crucial for unlocking the true power of quantum computers. QEC codes use multiple physical qubits to encode a logical qubit, which is protected against errors at the physical qubit level. Here we use a trapped ion system to experimentally prepare $m$-qubit GHZ states and sample the measurement results to construct $m\times m$ logical states of the $[[m^2,1,m]]$ Shor code, up to $m=7$. The synthetic logical fidelity shows how deeper encoding can compensate for additional gate errors in state preparation for larger logical states. However, the optimal code size depends on the physical error rate and we find that $m=5$ has the best performance in our system. We further realize the direct logical encoding of the $[[9,1,3]]$ Shor code on nine qubits in a thirteen-ion chain for comparison, with $98.8(1)\%$ and $98.5(1)\%$ fidelity for state $\left\vert\pm\right\rangle_L$, respectively.

Towards Energy Efficient Mobile Wireless Receivers Above 100 GHz

Wireless communication above 100 GHz offers the potential for massive data rates and has attracted considerable attention for Beyond 5G and 6G systems. A key challenge in the receiver design in these bands is power consumption, particularly for mobile and portable devices. This paper provides a general methodology for understanding the trade-offs of power consumption and end-to-end performance of a large class of potential receivers for these frequencies. The framework is applied to the design of a fully digital 140 GHz receiver with a 2 GHz sample rate, targeted for likely 6G cellular applications. Design options are developed for key RF components including the low noise amplifier (LNA), mixer, local oscillator (LO) and analog-digital converter (ADC) in 90 nm SiGe BiCMOS. The proposed framework, combined with detailed circuit and system simulations, is then used to select among the design options for the overall optimal end-to-end performance and power tradeoff. The analysis reveals critical design choices and bottlenecks. It is shown that optimizing these critical components can enable a dramatic 70 to 80% power reduction relative to a standard baseline design enabling fully-digital 140 GHz receivers with RF power consumption less than 2 W.

Design of PWM-Based Digital Receiver for 5G

The next generation, 5G and 6G standards, are allocated different bands for the same standard due to the worsening shortage of available spectrum. This has led to significant research interest in digitizing the RF signal as close as possible to the antenna motivated by flexibility and high performance allowed by cognitive radio and software defined radio. In this paper, a PWM-based all digital receiver is Presented. A system level simulation of the pulse-width modulator is performed using cadence software. In addition, a high-speed two-stage dynamic CMOS-latched comparator is proposed. In addition, a high-speed ring oscillator for clock generation is given. The proposed pulse-width modulator is implemented with a target technology TSMC 65nm process. The comparator achieves sampling frequency up to 10 GHz with resolution of 10.11 bits and 13.28 bits at 1 GHz sampling clock while keeping the propagation delay less than 64 psec. for 1 mV input voltage difference. Furthermore, the oscillator achieves a 10.025GHz output frequency.

An FPGA-based Direct Sampling and Digital Processing System for Wideband and Narrowband Radar Signal

This paper designs an integrated wideband and narrowband radar signal direct sampling and digital processing system based on FPGA. The system comprises a VPX case, a main board, a direct sampling board, a fiber board. It makes direct sampling of 1.8GHz-3.0GHz echo waves, with 3.2GHz sampling rate. The wideband and narrowband echo waves share the same ADC channel. After ADC sampling, both of wideband and narrowband data are exported to a mix-free digital quadrature demodulation module in FPGA. The narrowband data will be further processed by digital frequency down conversion. The wideband data will be further processed by digital de-chirp operation, with parallel DDS structure and multi-level decimation filters. Data rate of both the wideband and narrowband data after processing is decreased obviously. The designed sampling system cut down the analog radar signal processing operation, and decreases signal distortion. Besides, it integrated the reception, sampling and processing of wideband and narrowband signal, simplified the structure of radar system.

A NAND-SPIN-Based Magnetic ADC

This brief introduces a 3-bit magnetic analog-to-digital converter (MADC) employing the NAND-SPIN based multi-bit device which has the same structure as the NAND-SPIN memory cell. By adjusting the physical shape of the heavy metal (HM) line, the all-in-one integrated NAND-SPIN device exhibits multiple switching thresholds which could quantify the input current into several states and store them into the corresponding Magnetic Tunnel Junctions (MTJs). In order to read data reliably, a read port is connected to each Spin Orbit Torque (SOT) MTJs so as to minimize Tunnel Magnetoresistance (TMR) degradation due to non-uniform heavy metal resistance. In addition, an HM size adjustment methodology is proposed to improve the conversion accuracy and switching reliability. Detailed micromagnetic simulation results show that the proposed MADC could achieve 5 GHz sampling rate with only 0.068 pJ conversion energy, and in-memory conversion for higher bit resolution while provides the benefit of nonvolatility.

Burial Depth Effect of Crack on the Lcr Wave Acoustoelastic Coefficient for Stress Measurement of Laser Cladding Coating.

In this paper, the influence of burial depth of crack on stress measurement of laser cladding coating with the critical refracted longitudinal wave (Lcr wave) was discussed based on the Lcr wave acoustoelastic effect. The regular rectangular slots with different depths that were used to simulate the burial crack in coating was based on the equivalent theory. The experimental system including an ultrasonic wave generator, digital oscilloscope (2.5 GHz sampling rate), and two Lcr wave transducers (2.5 MHz center frequency) was used to collect the Lcr wave under different tensile loads, and the Lcr wave was denoised by using wavelet analysis technology, then the fracture morphology was observed using SEM. The results show that after the denoising by wavelet analysis technology, the signal-to-noise ratio of Lcr wave becomes bigger and the mean square deviation of Lcr wave becomes smaller. When the tensile load is within the turning point load, the difference in time of flight between Lcr wave increases linearly as the tensile load increases, and the deviation of the experimental results becomes obvious as the tensile load increases. When the tensile load is the same, as the burial depth of the slot increases, the nominal Lcr wave acoustoelastic coefficient decreases and tends to be stable gradually. At last, the experimental results are discussed based on the Lcr wave acoustoelastic effect and deformation theory, and it is analyzed that the uneven deformation caused by the interface in coating, anisotropic microstructure, and the burial crack is considered as the main reason.