Mainlobe jamming suppression via improved BSS method for rotated array radar

This study deals with the problem of mainlobe jamming suppression for rotated array radar.The interference becomes spatially nonstationary while the radar array rotates,which causes the mismatch between the weight and the snapshots and thus the loss of target signal to noise ratio(SNR)of pulse compression.In this paper,we explore the spatial divergence of interference sources and consider the rotated array radar anti-mainlobe jamming problem as a generalized rotated array mixed signal(RAMS)model firstly.Then the corresponding algorithm improved blind source separation(BSS)using the frequency domain of robust principal component analysis(FDRPCA-BSS)is proposed based on the established rotating model.It can eliminate the influence of the rotating parts and address the problem of loss of SNR.Finally,the measured peakto-average power ratio(PAPR)of each separated channel is performed to identify the target echo channel among the separated channels.Simulation results show that the proposed method is practically feasible and can suppress the mainlobe jamming with lower loss of SNR.

Ship recognition based on HRRP via multi-scale sparse preserving method

In order to extract the richer feature information of ship targets from sea clutter, and address the high dimensional data problem, a method termed as multi-scale fusion kernel sparse preserving projection(MSFKSPP) based on the maximum margin criterion(MMC) is proposed for recognizing the class of ship targets utilizing the high-resolution range profile(HRRP). Multi-scale fusion is introduced to capture the local and detailed information in small-scale features, and the global and contour information in large-scale features, offering help to extract the edge information from sea clutter and further improving the target recognition accuracy. The proposed method can maximally preserve the multi-scale fusion sparse of data and maximize the class separability in the reduced dimensionality by reproducing kernel Hilbert space. Experimental results on the measured radar data show that the proposed method can effectively extract the features of ship target from sea clutter, further reduce the feature dimensionality, and improve target recognition performance.

Optimization of LSTM Ship Trajectory Prediction Based on Hybrid Genetic Algorithm

Accurate prediction of the movement trajectory of sea surface targets holds significant importance in achieving an advantageous position in the sea battle field.This prediction plays a crucial role in ensuring security defense and confrontation,and is essential for effective deployment of military strategy.Accurately predicting the trajectory of sea surface targets using AIS(Automatic Identification System)information is crucial for security defense and confrontation,and holds significant importance for military strategy deployment.In response to the problem of insufficient accuracy in ship trajectory prediction,this study proposes a hybrid genetic algorithm to optimize the Long Short-Term Memory(LSTM)algorithm.The HGA-LSTM algorithm is proposed for ship trajectory prediction.It can converge faster and obtain better parameter solutions,thereby improving the effectiveness of ship trajectory prediction.Compared to traditional LSTM and GA-LSTM algorithms,experimental results demonstrate that this algorithm outperforms them in both single-step and multi-step prediction.

FPGA-based high resolution DPWM control circuit

Two improved structures of high resolution digital pulse width modulator(DPWM) control circuit are proposed. Embedded digital clock manager(DCM) blocks and digital programmable delay circuits are employed as the basic resources to construct the field-programmable gate array(FPGA)-based DPWM implementations. Detailed schemes are illustrated and the circuits have been successfully implemented on the Artix-7 FPGA device developed by Xilinx. Experimental results show that when the basic clock operates at the frequency of 200 MHz, the resolutions of the two approaches can reach 625 ps and 500 ps, respectively. Besides,the presented schemes possess other merits including flexible resolution, strong versatility and relatively good stability.

Cause–Effect Relationship between Meso-γ-Scale Rotation and Extreme Short-Term Precipitation:Observational Analyses at Minute and Sub-Kilometer Scales

The cause–effect relationship between meso-γ-scale rotation and extreme short-term precipitation events remains elusive in mesoscale meteorological research.We aimed to elucidate this relationship by analyzing a rainstorm over the Pearl River Delta during the nocturnal hours of 15 May 2017 based on 6-min radar observations and 1-min rain gauge data.This rainstorm had a maximum hourly rainfall of 100.1 mm,with 26 stations recording hourly rainfall>60 mm h^(−1) in 5 h.Extreme heavy precipitation was produced in association with a convergence zone along the southern side of a synoptic low-level shear line,where southwesterly warm,humid airflows with precipitable water of>60 mm,little convection inhibition(<10 J kg^(−1)),and a low lifting condensation level(about 300 m)dominated.A meso-γ-scale vortex was quantitatively identified during the hour with the largest number of gauges observing extreme hourly rainfall.The vortex had a mean diameter of 6.1 km and a peak intensity of 3.1×10^(−3) s^(−1) during its lifetime of 54 min.The vortex initialized and remained inside the region of extreme rain rates(radar-retrieved rain rates>100 mm h^(−1)),reached its peak intensity after the peak of the collocated 6-min rainfall accumulation,and then weakened rapidly after the extreme rainfall region moved away.The radar-retrieved liquid water path was about five to seven times the ice water path and the specific differential phase(Kdp)below 0°C increased sharply downward during the lifetime of the vortex,suggesting the presence of active warm rain microphysical processes.These results indicate that the release of the latent heat of condensation induced by extreme rainfall could have contributed to the formation of the vortex in an environment with a weak 0–1-km vertical wind shear(about 4–5 m s^(−1))through enhanced lowlevel convergence,although the strengthening of low-level updrafts by rotational dynamic effects and short-term rainfall cannot be ruled out.