This study considers the problem of deception electronic counter‐countermeasure (ECCM) in distributed multiple‐radar architectures. To discriminate deception targets from the detected targets, a two‐block detection/discrimination ECCM scheme is proposed. The first block is devoted to the detection task, which is achieved by the non‐coherent accumulation detector. If a target is declared, the second block is performed to discriminate between radar targets and deception jamming, exploiting the difference that the jamming signal vectors always exist in a rank one subspace and that the target signal vectors randomly distribute in the whole space. The target discriminator in the Neyman–Pearson sense is developed based on the generalised likelihood ratio test in classical linear models. Furthermore, the analytical expression for the probability of correctly discriminating radar targets is derived. An iteratively censored procedure is established to estimate the jamming subspace in real time. Finally, simulation results verify the feasibility of the new discriminator, and its performance due to the spatial correlation of radar targets, the signal‐to‐noise ratio, and the geometric spread are covered.

This study investigates the target detection problem of multistatic radar in the presence of deception jamming. A detection algorithm based on non-coherent integration is presented to determine whether a target exists in each probed spatial resolution cell (SRC). This algorithm can suppress the jamming to some extent because the spatial divergence of the jamming signal inhibits the effective energy accumulation for detection. However, a jamming signal influences more SRCs than a target. Given that the power of deception jamming is usually larger than that of the target, the global statistics of the SRCs can still exceed the detection threshold with a certain probability, which leads to many false targets. Therefore, a discriminator is presented to distinguish the jamming signals from the target echoes and noises. Subsequently, a joint target detection and deception jamming suppression method that can simultaneously detect targets and suppress the jamming is derived to eliminate the interference in the relative SRCs. Simulation results show that the proposed algorithm can suppress the deception jamming while accurately detecting multiple targets.

Jamming recognition is an essential step in radar detection and anti-jamming in the complex electromagnetic environment. When radars detect an unknown type of jamming that does not occur in the training set, the existing radar jamming recognition algorithms fail to correctly recognize it. However, these algorithms can only recognize this type of jamming as one that already exists in our jamming library. To address this issue, we present two models for radar jamming open set recognition (OSR) that can accurately classify known jamming and distinguish unknown jamming in the case of small samples. The OSR model based on the confidence score can distinguish known jamming from unknown jamming by assessing the reliability of the sample output probability distribution and setting thresholds. Meanwhile, the OSR model based on OpenMax can output the probability of jamming belonging to not only all known classes but also unknown classes. Experimental results show that the two OSR models exhibit high recognition accuracy for known and unknown jamming and play a vital role in sensing complex jamming environments.

Near space is the key to integrating “sky” and “space” into the future. A synthetic aperture radar (SAR) that works in this area would initiate a technological revolution for remote sensing applications. This study mainly focused on ground moving target imaging (GMTIm) for a near-space hypersonic vehicle-borne SAR (NS-HSV-SAR) with squint angle. The range history, parameter coupling, and Doppler ambiguity of the squint-looking NS-HSV-SAR are more complicated than traditional side-looking airborne or space-borne SARs. Thus, a precise range model is presented on the basis of phase error analyses. Then, all potential distributions of echo’s azimuth spectrum are derived, and a GMTIm method is proposed on the basis of a detailed analysis of the echo characteristics. The proposed method consists of three steps. Firstly, a prior information-based pre-processing function was created to decrease the Doppler ambiguity and range migration effects. Secondly, a blur matched keystone transform was developed to correct the residual range walk migration. Thirdly, a time-saving chirp Fourier transform was investigated for azimuth focusing. Implementation considerations, including the curvilinear trajectory of the NS-HSV-SAR, multiple moving target imaging, and applicability and limitation of the method, are discussed. Finally, simulation results are presented to validate the effectiveness of the proposed method.

In this paper, we investigate an approach for embedding communication symbols into radar waveform, while holding constant envelope with spectral containment. To achieve this approach, a new frequency modulation (FM) scheme is proposed, where the proposed FM is the addition of communication frequency modulation term (CFMT) and the base radar FM. For communication information modulation, the CFMT is designed to be a linear combination of multiple sub-FM terms and the information-bearing communication symbols are carried out by the coefficients of different sub-FM terms. This technique is based on these sub-FM terms comprising of the CFMT mathematically orthogonal to each other in the inner product domain. In addition, in order to mitigate the interference caused by the radar FM on the demodulation procedure, the CFMT is designed mathematically orthogonal to the radar FM. Therefore, the resulting FM of emission is actually a group of orthogonal FM terms. Besides, a weighted coefficient is introduced to make a tradeoff between the degrees of range sidelobe modulation (RSM) and the communication bit error rate (BER) performance. The performance of the designed radar-embedded communication waveform, including ambiguity function, spectral, weighted coefficient design and the demodulation procedure is analyzed. The results show that a satisfactory communication BER performance can be achieved without sacrificing the radar performance.

Owing to the exponentially increasing spectrum demand for commercial communication, radar and communication are increasingly encouraged to share spectrum. One approach is to incorporate information bearing communication sequences into radar waveforms. However, the varying radar/communication waveforms in a coherent processing interval lead to a range sidelobe modulation (RSM) that cause a loss of coherence when the Doppler processing operation is applied, thus leading to reduced target visibility. In this study, a new approach of embedding communication into radar waveform is proposed. Based on the scheme of constant envelope orthogonal frequency division multiplexing phase modulation (CE‐OFDM‐PM) and the orthogonality among trigonometric function, information bearing sequences are implemented using CE‐OFDM‐PM signal and then phase attached to a radar modulation term with a weighted coefficient. Also, the radar modulation term is synthesised by multiple sinusoidal functions where the coefficients of each sinusoidal modulation function are generated using random variables to achieve a thumbtack‐like ambiguity function. The weighted coefficient of a communication modulation term provides a direct control of the degree of RSM. Theoretic analysis and simulation results show that a satisfactory communication bit error rate performance can be achieved without sacrificing the radar performance.