GHz Sampling Rate Research Articles

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.

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.

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.

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.

A High‐linearity Input‐Buffer with high output common‐mode stability for 10bit 3.2GSs ADC

A high-linearity input-buffer with high output common-mode stability for 10-bit 3.2 GS/s ADC is proposed in this Letter. The buffer is mainly composed of a source follower for strong driving ability. To enhance its linearity, a feed forward signal path from input to output is proposed. A replica buffer-based common-mode feedback is designed to achieve high output common-mode stabilisation of input-buffer. The prototype is implemented in 40 nm CMOS process. The output common-mode variation is reduced from 200 to 1 mV. Input-buffer consumes 96 mW in 3.2 GHz sampling rate and achieves 69.3 dB spur-free dynamic range at 1581 MHz input frequency.

Electron beam test of the large area Mu2e calorimeter prototype

The Mu2e calorimeter consists of 1348 pure CsI crystals coupled to two large area UV-extended Silicon Photomultipliers (SiPMs) organized in two separate annular disks. An intense R&D phase has been pursued to check if this configuration satisfies the Mu2e requirements. In May 2017, a dedicated test has been performed at the Beam Test Facility (BTF) in Frascati (Italy) where the large calorimeter prototype (Module-0) has been exposed to an electron beam in the energy range between 60 and 120 MeV. The prototype consists of 51 crystals, each one readout by two Mu2e SiPMs. We present results for timing and energy resolution both for electrons at normal incidence (0°) and at a grazing impact angle (50°) more similar to the experiment configuration. At 100 MeV, an energy resolution of 5.4% (7.4%) at normal (grazing) incidence has been achieved in good agreement with Monte Carlo expectation. In the same energy range, a time resolution of ∼ XX ps (∼ YY ps) has been measured at normal incidence with 1 GHz (250 MHz) sampling rate. Dependence of time and energy resolutions as a function of beam energy and impinging angle are also presented.

The large helical device vertical neutron camera operating in the MHz counting rate range.

In the currently performed neutral beam (NB) -heated deuterium plasma experiments, neutrons are mainly produced by a beam-plasma reaction. Therefore, time-resolved measurement of the neutron emission profile can enhance the understanding of the classical and/or anomalous transport of beam ions. To measure radial neutron emission profiles as a function of time, the vertical neutron camera (VNC) capable of operation with a counting rate in the MHz range was newly installed on the Large Helical Device (LHD). This is the world's first neutron camera for stellarator/heliotron devices. The VNC consists of a multichannel collimator, eleven fast-neutron detectors, and the digital-signal-processing-based data acquisition system (DAQ). The multichannel collimator having little cross talk was made from hematite-doped heavy concrete, which has a high shielding performance against both neutrons and gamma-rays. A stilbene crystal coupled with a photomultiplier having high-gain-stability in the high-count rate regime was utilized as a fast-neutron scintillation detector because it has a high neutron-gamma discrimination capability at high count rates. The DAQ system equipped with a field programmable logic controller was developed to obtain the waveform acquired with a 1 GHz sampling rate and the shaping parameter of each pulse simultaneously at up to 106 cps (counts per second). Neutron emission profiles were successfully obtained in the first deuterium campaign of LHD in 2017. The neutron emission profile was measured in tangentially co-injected NB-heated plasma with different magnetic axes (R ax). The neutron counts became larger in the inward-shifted configuration, which was consistent with the total neutron rate measured by the neutron flux monitor. The radial peak position of the line-integrated neutron profile which changed according to R ax showed that the VNC worked successfully as designed. The VNC demonstrated the expected performance conducive to extending energetic-particle physics studies in LHD.

Time-resolved triton burnup measurement using the scintillating fiber detector in the Large Helical Device

Time-resolved measurement of triton burnup is performed with a scintillating fiber detector system in the deuterium operation of the large helical device. The scintillating fiber detector system is composed of the detector head consisting of 109 scintillating fibers having a diameter of 1 mm and a length of 100 mm embedded in the aluminum substrate, the magnetic registrant photomultiplier tube, and the data acquisition system equipped with 1 GHz sampling rate analogies to digital converter and the field programmable gate array. The discrimination level of 150 mV was set to extract the pulse signal induced by 14 MeV neutrons according to the pulse height spectra obtained in the experiment. The decay time of 14 MeV neutron emission rate after neutral beam is turned off measured by the scintillating fiber detector. The decay time is consistent with the decay time of total neutron emission rate corresponding to the 14 MeV neutrons measured by the neutron flux monitor as expected. Evaluation of the diffusion coefficient is conducted using a simple classical slowing-down model FBURN code. It is found that the diffusion coefficient of triton is evaluated to be less than 0.2 m2 s−1.

Multi-channel physical random number generation based on two orthogonally mutually coupled 1550 nm vertical-cavity surface-emitting lasers

Physical random number, which is non-reproducible and non-periodical, has attracted much attention due to its potential applications in various fields such as secure communication, statistical analysis, and numerical simulation. Recently, fast physical random number generators based on optical chaotic entropy sources have been demonstrated to reach a rate of up to several hundreds of Gbit/s. Although many efforts have been made to optimize the schemeis of chaotic-based random number generation, most of them are based on distributed feedback semiconductor lasers and can only generate single-channel physical random number. After taking into account the costs and technological applications, the multi-channel physical random number generation technique needs developing. On the other hand, vertical-cavity surface-emitting lasers (VCSELs) can simultaneously emit two orthogonally polarized components under appropriate parameter conditions, and then each polarized component can be used as an entropy source for generating random number. As a result, VCSEL-based chaotic entropy sources may be suitable for multi-channel random number generation. In this work, a scheme for achieving multi-channel physical random number is proposed. Also the influence of the coupling parameters on the performance of the randomness of final bit sequences is investigated. For such a scheme, two orthogonally mutually coupled VCSELs are used to supply four-channel chaotic signals with a comparable output power and weak time-delay signature (TDS). The four-channel chaotic signals, which serve as chaotic entropy, are quantized by 8-bit analog-to-digital converters (ADCs) with 20 GHz sampling rate, and then the m least significant bit (m-LSB) post-processing method is adopted for generating final four-channel random bit sequences. Firstly, based on the spin-flip mode of VCSELs, the influences of coupling strength and frequency detuning on the dynamics of two orthogonally mutually coupled 1550 nm VCSELs are analyzed. Next, the optimized parameter regions for generating four-channel chaotic signals with comparable output power and weak TDS are preliminarily determined. For a given optimized value of coupling strength and different frequency detunings within the optimized parameter regions, the generated four-channel chaotic signals are taken as the entropy sources for obtaining final bit sequence by quantizing the 8-bit ADC and m-LSB post-processing. Finally, the randomness of the four final bit sequences is tested by NIST SP 800-22 statistical test suite, and the regions of preferred coupling parameters for simultaneously generating four-channel random numbers are determined.

Improvement in data processing of Thomson scattering diagnostic on HL-2A tokamak

There are two types of digitizers to acquire the values of Thomson scattering signals in HL-2A tokamak. One is charge-sensitive analogue-to-digital converters (Q-ADCs) which simply integrates the signal over a gate interval, and the other is transient recorders with 12 bits resolution and 1 GHz sampling rate at each channel. Because the Thomson scattering diagnostic is prone to electrical noisy environment, in which Q-switched Nd:YAG lasers and polychromators are located closely to the HL-2A device, the high speed transient digitizers are found helpful to reduce noise overlapped in Thomson scattering signals. After triggered by the front of TTL pulse generated by laser light, data acquisition is fulfilled from −250 ns to 250 ns, so that the temporal evolution of Thomson scattering signals is obtained. A Gaussian function is utilized to fit the pulse shape of the digitized scattering signal by nonlinear least square methods. By pulse fitting and data processing, the influence of background perturbations is substantially reduced.

Prototype of Data Acquisition Systems for ITER Divertor Thomson Scattering Diagnostic

Thomson scattering diagnostic is the most reliable and widely used method to measure electron temperature and density profiles of magnetically confined plasma. The prototype of data acquisition system for ITER divertor zone Thomson scattering diagnostic has been recently developed at the Budker Institute of Nuclear Physics (Novosibirsk, Russia). The small power (∼10−8W) and short duration (∼3–5 ns) are the main technical problems of the diagnostic. For detection and recording such low level signals the prototype of uniquely designed complex data acquisition system was developed. This system consists of 48 photodetector modules with 0–200MHz bandwidth, 48 simultaneously sampling ADC modules and synchronization subsystem. The photodetector modules are based on avalanche photodiodes and extremely low noise transimpedance preamplifiers. ADC modules include fast analog to digital convertors and digital units based on the Field-Programmable Gate Array for data processing and storage. The synchronization subsystem is used to form triggering pulses and to organize the simultaneously mode of ADC modules operation. Features of the system allow detection and recording short duration (3–5 ns) scattered pulses with 2GHz sampling rate and 10-bit total resolution in oscilloscope mode. At present, the system is tested on GLOBUS tokamak (St. Petersburg, Russia).

A high speed low power low offset dynamic comparator used in SHA-less pipelined ADC

A novel fully differential high speed high resolution low offset CMOS dynamic comparator has been implemented in the SMIC 0.18 μm process used for a sample-and-hold amplifier (SHA)-less pipelined analog-to-digital converters (ADC). Based on the analysis and optimization between delay time and offset, an enhanced reset architecture with transmission gate was introduced to speed up the comparison and reset procedure. Four inputs with two cross coupled differential pairs, reconstituted bias circuit for tail current transistor and common centroid layouts make the comparator more robust against mismatch and process variations. The simulation results demonstrate that the proposed design achieves 1 mV sensitivity at 2.2 GHz sampling rate with a power consumption of 510 μW, while the mean offset voltage is equal to 10.244 mV.

Design of High-speed Sampling System in Pulse Laser Application

In measurement system by means of pulse laser, such as plasma measuring, laser ranging, the amplitude of echoed laser wave is very weak and difficult to detect by traditional analog electronic technology. A digital high speed data acquisition and processing system was designed to meet the accuracy requirement. It adopted high speed AD chip and advantage FPGA chip as core unit. Experiment results have verified this system can reach to 1GHz sample rate and can catch weak echo wave effectively and the measuring accuracy is improved markedly.

Conversion gain characterisation of optical radiofrequency signal mixing by all-optical sampling based on SOA-MZI

Using an optical network to transmit radiofrequency signals (radio over fibre) naturally leads to implementation functions, such as frequency mixing, directly in the optical layer. Proposed is an all-optical sampling method based on a SOA-MZI to frequency upconvert an electrical subcarrier at 1 GHz up to 38 GHz. The optical pulsed source used to sample the electrical subcarrier generates 21 ps-width pulses at a repetition rate of 7.8 GHz. Although the SOA-MZI bandwidth is limited to 7 GHz, frequency upconversions up to five times the 7.8 GHz sampling rate have been evaluated through the conversion gain. Its value lies between 14.4 to −20.3 dB depending on the frequency to be reached.

Design of a parallel low power flash A/D converter for the sub-sampling IR-UWB receiver

This paper presents the design of a dual-channel 4-bit analog-to-digital converter (ADC) for the sub-sampling impulse radio ultra-wideband receiver with the sampling rate of 2.112 GS/s. The ADC's specifications are optimized at the system level. Two parallel channels help to achieve high conversion speed and low power consumption. To tackle the problem of clock mismatch between the channels, a twice sampling front end is used. An improved averaging termination technique using intended asymmetric spatial filter response is proposed. This circuit is designed in a 0.13 μm CMOS technology with 1.2 V power supply. Simulation results show a 26 dB SNDR at 2.112 GHz sampling rate with 36 mW power consumption and the effective figure of merit value is 0.24 pJ/step.

Performance Evaluation of UWB Wireless Link

An Ultra wideband technology played an important role in home networks to facilitate the transmission of multimedia contents between two consumer devices using wireless USB. This paper investigated the performance of UWB Transmitter-Receiver system, based on 2-dimensional hermite modulation, in view of its practical implementation. Performance of the UWB system was evaluated here with a cost effective and simple receiver structure, for short distance communication of 4 meters, by limiting the transmitter power, to maintain the Effective Isotropic Radiated Power (EIRP) of -41.3dBm/MHz as per FCC rule for UWB radio. The performance of the said system was also analyzed for different data rates using different sampling frequencies over multipath UWB channel, with and without the use of error correcting code. Simulations were performed in MatLAb Simulink for single user, for the image transmission application, as an extension to the previous work. System BER of 10e-5 was required to receive an image with 100% accuracy at the receiver end. It was observed that over UWB channel, at 10 GHz sampling rate, with 1.5 ns pulse width and with 10dBm transmission power, an image was received accurately at symbol SNR of 35dB without ECC and that of 12dB with (8 2 5) double error correcting code, of ¼ code rate designed in earlier work. The simulation results presented in this paper support the future implementation of UWB system that is cheaper and simpler for better performance.

Digital signal processing for time of flight measurements of muons at sea level

This paper presents digital signal processing techniques for obtaining high accuracy in time of flight (TOF) measurements of muons at sea level. The Hilbert transformation of the original signal is employed as suitable time signal behavior for extracting the start time of the muon signal. Here we have used the Hilbert transformation incorporated into LabVIEW software and, as a data acquisition system, a two channel Tektronix oscilloscope running at a 2.0 GHz sample rate per channel. The muon TOF in the vertical Tupi telescope, made with two scintillator detectors separated by a distance of 3 m, is determined with an accuracy of some 1.5 ns. In this paper we report this TOF method that allows to obtain the speed, β = v / c , and consequently the rigidity (energy) of an incident particle (muon).