This paper proposes a deep learning-based compound jamming cognition method to recognize, detect individual jamming elements and estimate key parameters of them. The method first uses a time-frequency distribution (TFD) to characterize jamming in multiple dimensions (time, frequency and energy) and then applies an object detection network to identify and locate jamming in the time-frequency domain. This paper summarizes the types of jamming parameters and gives corresponding methods for estimating parameters. Unlike traditional studies, this paper models jamming recognition as an object detection problem and applies a deep learning framework to find solutions. Therefore, the proposed method has better stability and robustness than conventional techniques, which solves the problem of feature selection caused by the lack of mapping relationship between jamming and features. Another advantage over conventional methods is the multi-jamming detection capability of this algorithm, which provides more information about individual elements of compound jamming. In terms of jamming parameter estimation, the proposed method makes full use of the geometric characteristics of TFDs, so it is more versatile than conventional methods based on analytical analysis. Simulations and experimental data are used to verify the effectiveness of the proposed method.

Digital radio frequency memory (DRFM)-based main-lobe interrupted sampling repeater jamming (ISRJ) can achieve the effects of both deception and suppression, which cause serious performance degradation in modern radar systems. In this paper, we propose an electronic counter-countermeasure (ECCM) scheme based on signal reconstruction and mismatched filtering (SC-MMF). The ECCM scheme consists of two steps: time-domain signal reconstruction and mismatched filter (MMF) design. First, the time-domain signal without noise is reconstructed using the provided jamming perception information. Then, an MMF corresponding to the reconstructed signal is designed to suppress ISRJ targets. The MMF design problem is formulated as a problem of minimizing the peak false target level (PFTL) and is solved with an improved alternating projection algorithm. After mismatched filtering, ISRJ targets are suppressed. Numerical simulations validate the effectiveness of the proposed method and explore the impacts of various parameters on its performance. Moreover, results obtained on measured data show that the proposed method has practical value in engineering applications.

The performance of wideband radar detectors can be further improved if the features of a target's high-resolution range profile (HRRP) are fully utilized. In this paper, a target adaptive double threshold detection method is proposed. First, the amplitude distribution parameters of the HRRP's range cells are extracted for data generation, and the detection probability is statistically calculated. The online gradient descent method is then used to adaptively adjust the second thresholds of the double threshold detector, thereby improving the detection performance with a given constant false alarm rate. The effectiveness of the proposed algorithm is verified using two sets of measured data. The proposed algorithm exhibits superior detection performance compared to traditional detection algorithms for range-spread targets.

Modern radar detection faces an increasingly complex electromagnetic environment, and strong clutter and strong jamming have severely restricted radar performance. This study proposes a robust jamming suppression method that is based on the joint generalized inner product (JGIP) method in a distributed array radar, which utilizes the characteristics of the extremely high angular resolution of the distributed array radar to effectively suppress main lobe jamming. Thus, the advantages of flexible aperture synthesis of distributed array radar are investigated to design a JGIP to detect targets in a cluttered environment. This method is not sensitive to the various nonideal factors that exist in distributed array radar engineering practice and is highly robust. Simulation and actual measured data verify the correctness and effectiveness of the proposed method.

The synthetic-wideband and pulse repetition frequency jittering radar systems are receiving increasing attention due to the relatively low construction costs and good anti-jamming performance. However, the inter-pulse random hopping of the carrier frequency and pulse repetition frequency introduces challenges to the long-time coherent integration and motion parameter estimation of the high-speed weak targets for these radar systems. A modified generalized Radon Fourier transform for weak target detection and motion parameter estimation is proposed. The proposed method can achieve full coherent integration gain for the high-speed weak target and has a good parameter estimation accuracy. After the target motion has been well compensated, the well-focused high-resolution range profile of the target can be obtained by synthetic-wideband processing. The effectiveness of the proposed method is verified by Monte Carlo simulations. In addition, experimental data collected using an X-band radar system are processed and analyzed to illustrate the practical performance of the proposed method.

A novel wideband digital array radar system is introduced in this paper. The system has an open software-based processing architecture that provides a high degree of digitization and a flexible processing mode that employs digital stretch processing and digital modulation techniques to solve the beam divergence problem caused by the wide-angle scanning of both broadband and wideband array radar. The system simultaneously realizes a large range window, a wide dynamic range, and interpulse coherence for wideband array radar. The system is applicable not only to wideband linear frequency modulated (LFM) signals but also to wideband nonlinear frequency modulated (NLFM) signals. An engineering implementation scheme is also introduced. Key techniques, including wideband waveform generation, low data rate transmission, high-precision digitally modulated time delay compensation, and high-precision system synchronization are described in detail. In addition, an X-band experimental system is constructed, and the performance of this system is verified using typical target detection experiments.