Search

In recent years, the rapid development of deep learning technology has brought new opportunities for specific emitter identification and has greatly improved the performance of radar emitter identification. The most specific emitter identification methods, based on deep learning, have focused more on studying network structures and data preprocessing. However, the data selection and utilization have a significant impact on the emitter recognition efficiency, and the method to adaptively determine the two parameters by a specific recognition model has yet to be studied. This paper proposes a knowledge graph-driven convolutional neural network (KG-1D-CNN) to solve this problem. The relationship network between radar data is modeled via the knowledge graph and uses 1D-CNN as the metric kernel to measure these relationships in the knowledge graph construction process. In the recognition process, a precise dataset is constructed based on the knowledge graph according to the task requirement. The network is designed to recognize target emitter individuals from easy to difficult by the precise dataset. In the experiments, most algorithms achieved good recognition results in the high SNR case (10–15 dB), while only the proposed method could achieve more than a 90% recognition rate in the low SNR case (0–5 dB). The experimental results demonstrate the efficacy of the proposed method.

A novel orthogonal frequency-division multiplexing (OFDM) multiple-input multiple-output (MIMO) radar is proposed in this paper in a scenario of coexisting with a communication system. For the purpose of avoiding interference to communication while maintaining MIMO radar's capabilities, such as measuring signal's direction of departure (DOD), a collocated antenna array is divided into several overlapped subarrays. Mutually OFDM waveforms exploiting an orthogonal space-time block code are transmitted through these subarrays to obtain waveform diversity, which can be separated at the radar receiver. A MUSIC-like DOD estimation algorithm and the Cramer–Rao bound of DOD are proposed for overlapped subarrays’ configuration in order to evaluate performance of the beamforming strategy. The beamformer is designed using an optimization technique at cost of maximizing the input SNR of radar while keeping communication rate constant. Due to nonconvexity of the optimization problem, a two-step optimization algorithm is proposed. Simulation experiments validate theoretical analysis of the proposed precoding radar. Experiments also show robustness of the precoding scheme and the ability of balancing the input SNR of radar and the communication rate.

In modern warfare, the role of airborne early warning aircraft is becoming more and more significant. The airborne early warning radar can accurately detect moving targets in a chaotic environment. Its suppression of strong clutter and jamming by radar is mainly through space-time adaptive processing (STAP) technology to achieve. The STAP algorithm uses the two domains of time and space to perform two-dimensional joint processing on the echo data, adaptively forming a notch that matches the clutter and jamming, and its excellent jamming suppression capability increases the difficulty of radar countermeasures. In this case, it is very necessary to conduct a comprehensive jamming study about the technology. At present, relevant jamming methods at home and abroad are still in the preliminary research stage. In this paper, we take genetic algorithm as an example, and a new distributed jamming method for STAP radar based on improved penalty-based boundary intersection decomposition multiobjective evolutionary algorithm (MOEA/D-PBI) is introduced in the many-to-many confrontation. Through simulation experiments, the optimized distributed jamming scheme is compared with the distributed jamming scheme before optimization, verifying the feasibility of the method proposed in this paper, which simplifies the problem of jamming resource allocation and realizes a fast search for the optimal allocation strategy, and complete real-time jamming decision-making on the battlefield.

In this paper, a joint communication interference integration signal waveform is proposed to satisfy the need of electronic system integration in civil and military uses, and mitigate the tension of spectrum resource. We design the system structure of the integrated signal model and propose the communication receiving processing flow of the integrated system. We utilize the dense false-target jamming style to raise the constant false alarm rate detection threshold via the delay superposition of multiple groups of frequency modulation (FM) slope mismatch jamming signals, which can play a role in protecting our target from being detected. Furthermore, linear frequency modulation (LFM) signals with different FM slopes and Doppler frequencies are obtained via the modulation mapping of communication data; thus, a single LFM signal can carrynbit data. Through correlation processing and frequency detection, code sequence information can be obtained to achieve communication function. The simulation results show that the integrated signal has the effect of shielding and jamming the pulse compression radar. Moreover, the system has a better bit error rate and a high communication rate, which can ensure that the communication task of sending accurate instructions is completed while implementing effective interference.

With the rapid development of radar and communication industry, radar communication integration system based on OFDM system is emerging in many fields. The current research focuses on the accuracy of communication transmission, radar signal design and processing. In this paper, an integrated OFDM radar communication system based on symmetrical triangulation velocity measurement is proposed to solve the problems related to the communication subsystem. In the low-speed scenario of ground to air mode, the system can achieve high resolution by transmitting triangular wave signals and OFDM signals with large bandwidth at intervals. This paper attempts to analyze the sensitivity of OFDM signal to doppler frequency and the accuracy of symmetrical triangular wave velocity measurement, and uses the results of triangular wave velocity measurement to calibrate the OFDM signal, so as to reduce the bit error rate of communication subsystem.

With the development of science and requirement, Integration of Communication and Radar with properties of more functions, lower buck and safety is becoming a trend and draws more attention of researchers. Current researches are focusing on communication or radar respectively or just focusing on signal generation. This paper proposes a solution of integrated system for SAR radar communication based on OFDM techniques in high speed scenario. The receiver can reconstruct the reference signal which is adopted for radar pulse compression procedure by communication system directly. In high speed scenario, channel response changes fast, comb type pilots and channel estimation are added to equalize the channel response to reduce bit-error-rate in communication system. Finally, the simulation are used to validate the performance of the proposed algorithm.

In the traditional model of monostatic synthetic aperture radar (SAR), the flying platform should have a uniform linear trajectory. In practice, the flight path of the SAR platform, which is highly nonlinear or curvy caused by 3-D velocity and acceleration, cannot be used in the traditional model. In this paper, a geometrical model of the monostatic SAR with general configurations is graphically illustrated by vector notation. Moreover, the gradient method is utilized to point out the effects of the motion parameters, namely, velocity vector and acceleration vector, on total bandwidth and image resolution. Based on the accurate model, a general frequency-domain algorithm, with the incorporations of pre- and postprocessing, is proposed to focus the raw data. Applicability is studied through theoretical analysis and numerical experiments. All these general analyses can be applied to different realizations of monostatic SAR mode, including spotlight SAR, sliding spotlight SAR, and Terrain Observation by Progressive Scans (TOPS) SAR.

Synthetic aperture radar (SAR) imaging is usually performed along a straight path. In practice, variations from the ideal caused by maneuvers with acceleration are inevitable. The main problem is the complex signal processing, particularly in the highly squinted spotlight mode. In this paper, acceleration model is analyzed in more details. Impacts are obtained how the acceleration influences the Doppler parameters and space-variant terms, including the SAR resolution and azimuth bandwidth. According to the special signal properties of the acceleration case, an approximation of the range history is made to avoid using the method of series reversion (MSR) to obtain an accurate spectrum. Based on the high-accurate spectrum, a spotlight algorithm with a modified two-step approach is given. Simulation results show the effectiveness of the modified algorithm.

A novel Root-MUSIC algorithm based on cross-correlation matrix is proposed to estimate the direction of arrival (DOA) and direction of departure (DOD) for the bistatic multiple-input multiple-output (MIMO) radar. In the algorithm, the cross-correlation matrix is first constructed by using the received data which are arranged according to the transmit array and the receive array, respectively. And the DOAs and DODs are estimated independently employing cross-correlation Root-MUSIC algorithms without eigendecomposition, where the null spaces are constructed with a linear operation of the cross-correlation matrices. Secondly the pair-matching of DOAs and DODs is accomplished by solving an angle estimate optimization. The effectiveness of the proposed method is verified through numerical simulations, and it is shown that the proposed method can provide more accurate angle estimation with small computational complexity than conventional eigendecomposition algorithms.

The purpose of this study was to determine the effect of aspirin plus cisplatin (CDDP) in the chemotherapy of gastric cancer. We cultured SGC7901/CDDP cells by long-term exposure of SGC7901 cells to small doses of CDDP in vitro. The cells were treated with aspirin, CDDP or aspirin plus CDDP for 24 h and cell growth was assessed by the MTT assay, the apoptotic rate by flow cytometry, the survivin mRNA expression by RT-PCR and the survivin protein expression by western blotting. The results revealed that the cell growth in the aspirin plus CDDP group was significantly inhibited. The apoptotic rate in the aspirin plus CDDP was significantly higher compared to that in the other groups. The survivin mRNA and protein expression were also significantly reduced in the aspirin plus CDDP group. Our data suggest that the combination of aspirin and CDDP exhibited a higher degree of toxicity against SGC7901/CDDP cells compared to that of aspirin or CDDP alone. Thus, the combination of aspirin plus CDDP may reduce the expression of survivin and induce the apoptosis of SGC7901/CDDP cells.

A new wavenumber domain mapping method for the highly squinted beam steering synthetic aperture radar (BS-SAR) is analysed. After the mapping operation, the two dimensional (2-D) spectrums have a broadside form which can be regarded as an equivalent broadside SAR. Furthermore, a novel 2-D two-step approach is introduced to avoid spectral aliasing and skewing caused by the beam steering and the high squint angle. With the mapping operation being incorporated into the novel two-step approach, the baseband azimuth scaling (BAS) algorithm which is only used for broadside cases can be applied for the highly squinted BS-SAR without subaperture.

This paper proposes an algorithm to process the data acquired of the targets underneath the circular center, which cannot be focused by frequency algorithms directly. Using the vector expression, the azimuth frequency modulation rate is partitioning into velocity and acceleration parts. After compensation of the acceleration parts, the circular path is corrected to a linear path and the frequency algorithms can be used to focus the data. The simulated results are covered to validate the effectiveness of the proposed algorithm.

The aim of the present study was to investigate the mechanism of SGC7901 cell resistance to cisplatin (CDDP). SGC7901/CDDP cells were established by the long-term continuous exposure of SGC7901 cells to CDDP in stepwise concentration increments. The morphologies of the SGC7901/CDDP and SGC7901 cells were observed by microscopy. The expression levels of Survivin mRNA and protein in the SGC7901/CDDP and SGC7901 cells were examined by reverse transcription polymerase chain reaction and western blotting respectively. The results revealed morphological differences between the SGC7901 and SGC7901/CDDP cells. The expression levels of Survivin mRNA and protein were significantly higher in the SGC7901/CDDP cells than in the SGC7901 cells. Therefore, high expression levels of the Survivin gene may explain SGC7901 cell resistance to CDDP.