A Blanket Deception Jamming Rejection Approach Based on Jamming Sample Recognition

Synthetic aperture radar (SAR) has been involved in military applications such as high resolution imaging, battle field surveillance, and moving target detection. Recently noise and deception jamming signal are introduced to counter SAR sensor, thus these jamming techniques can be used to protect ground targets or objects of high interest. In this paper, a comparative study of the performance of the deceptive and the noise jamming on a SAR focused image, with and without jamming, is performed. Two evaluations craterous, structural similarity index measure (SSIM), and correlation coefficient (CC) are used to measure the previous jamming techniques effect on a real SAR focused image (object of high interest). The computer based simulation results, reveal that for the same CC, the power required by the deceptive jamming is reduced by three order of magnitude compared with the power required by conventional noise jamming, mean while for the same SSIM the required power is reduced by nearly two order of magnitude.

Electronic jamming is the key technology of electronic countermeasure, for which models and simulations are studied on noise jamming, deception jamming, and chaff jamming. In the noise jamming, the simulation analysis of radio frequency noise jamming is conducted and the theoretical models of other forms of noise jamming are built. The simulation analysis of range-gate pull off (RGPO) is carried out in the deception jamming. In addition, theoretical modeling and simulation analysis of chaff jamming are carried out with the Monte Carlo method. Simulation results show that the models are correct and can be used to simulate the statistical characteristics of chaff jamming. With the development and wide application of electronic technology, radar, communication, navigation, and IFF signals constitute a complex electromagnetic environment. It is a must to study electronic jamming technology in the complex electromagnetic environment, which will play an indispensable role in the construction of information team and victory in the countermeasure of information technology.

Electronic jamming is the key technology of electronic warfare, for which models and simulation are studied on noise jamming deception jamming and chaff jamming. In the noise jamming, the simulation analysis of radio frequency noise jamming is conducted and the theoretical models of other forms of noise jamming are built. The simulation analysis of RGPO is carried out in the deception jamming. In addition, theoretical modeling and simulation analysis of chaff jamming are carried out with the Monte Carlo method. Simulation results show that the models are correct and can be used to simulate the statistical characteristics of chaff jamming.

An electronic counter-countermeasure (ECCM) signal processor for space-based radar (SBR) is described. An adaptive nulling block using auxiliary antennas cancels jammers. The weights on the auxiliary channels are computed using the normal equations. Adaptive nulling is combined with displaced phase center antenna (DPCA) processing to jointly cancel both jamming and clutter. Nulling is followed by sidelobe blanking, which detects and removes pulse jammers. The processor is implemented on commercial DSP hardware, and runs at SBR real-time rates. >

It is evident that noise jamming is one of the several active jamming techniques employed against tracking radars and missile seekers. The noise jamming mainly aims at completely masking the desired radar signal by the externally injected noise signal. Of several parameters to be considered for the analysis of noise jamming problem, the noise jammer power is one of the most critical parameter. In this paper, emphasis is given for estimation and quantitative analyses of the effectiveness of break-lock in a missile borne phase locked loop (PLL) based monopulse radar receiver using external noise signal. The analyses involve estimating the jamming signal power required to break-lock as a function of radar echo signal power through computer simulation and experimental measurements. The simulation plots representing the receiver PLL output are presented for selected echo signal powers from -14 dBm to -2 dBm. The simulation results are compared and verified with experimental results and it is established that these results are close approximate within 2 dB. It is noted that the measured values of jamming signal power at break-lock using HMC702LP6CE, HMC703LP4E and HMC830LP6GE PLL synthesizers are -19.5 dBm, -18.1 dBm and -17.6 dBm, respectively, while the simulated value is -18.8 dBm for a typical radar echo signal power of -10 dBm. The fairly good and consistent agreement between these results validates the simulation data.

During the rapid development of synthetic aperture radar (SAR), jamming techniques against SAR have aroused intensive study interests in the field of electronic counter measures (ECM). In this paper, we compare the jammer's transmitter power required by coherent deceptive jamming against SAR and by incoherent noise jamming against SAR. It is pointed out that, in order to yield same jamming-to-signal ratio (JSR) in SAR image domain, the ratio of the transmitter power of incoherent noise jamming to that of coherent deceptive jamming should be the average pulse compression gain (APCG), rather than, the pulse compression gain (PCG) in SAR image formation processing, which is different from the opinion of some literatures. Theoretical analyses are verified by simulation results.

The rapid development of Synthetic Aperture Radar Ground Moving Target Indication (SAR-GMTI) is threatening ground moving targets. The key against it is the efficient jamming technology. This paper introduces SAR-GMTI at first. Then, RF noise jamming, noise AM jamming, noise FM jamming and noise convolution jamming are also introduced and analyzed. Finally this paper illustrates the jamming effect by computer simulation which contains velocity estimation and detection probability. The results show that under the proper JSR condition, the active noise jamming can jam SAR-GMTI effectively, and under the same JSR condition, noise convolution jamming has a more efficient jamming effect than those non-coherent jamming obviously.

Modern electronic technology is developing rapidly, traditional passive jamming is not effective when facing the Ka-band radar seeker using pulse compression technology. This paper introduces two kinds of active coherent methods including intensive deception jamming (IDJ) and smart noise jamming (SNJ) against the Ka-band radar seeker. These methods can work in the radar frequency band, covering the original echo signal from the time domain and frequency domain to deceive the non-cooperative radar. In addition, the MATLAB R2018a simulations verify the effectiveness of the jamming to the 35.75Ghz linear frequency modulation (LFM) radar signal. Finally, the paper designs the digital radio frequency memory (DRFM) hardware platform. Results show the effectiveness of these two jamming methods by the upper computer.

Radar jamming waveform design is a vital part of radar jamming. Over seven to eight decades of evolution, the field has transitioned from noise signal design to coherent jamming signal design, resulting in a multitude of complex jamming styles capable of achieving deceptive jamming, suppressive jamming, and smart noise jamming, which combines both deception and suppression. For the first time, this article establishes a general formula for unifying jamming waveform design. Building upon this foundation, we systematically categorize jamming techniques, and provide an in-depth summary of the corresponding principles and conduct comparative analysis of their effectiveness against different targets. Finally, we look forward in terms of future research directions in jamming waveform design, including quantifiable jamming effect evaluation indicators, combined jamming styles, and intelligent jamming waveform generation methods to address the continuous advancement of radar technology and the complexity and variability of the electromagnetic environment. In order to fill the gap in the literature by summarizing the current state of the field and highlighting key challenges and opportunities, this review provides a comprehensive overview of radar jamming waveform design, categorizes and compares different jamming techniques, and identifies future research directions.

By weighing the similarity of features before and after jamming, a novel evaluation method of jamming effect on ISAR based on the similarity of features is presented in the paper. This method can reflect the impact on the target features caused by jamming, consequently, the jamming effect can be evaluated by the similarity of features. It can not only be computed easily, but also has the merit of unitary. Furthermore, Two typical noise barrage jamming modes, radio frequency (RF) noise jamming and noise frequency modulation (FM) jamming are employed in computer simulation of interference with ISAR, The results indicate the validity and feasibility of the proposed method.

This letter presents a novel technique for optimizing the performance of a phased-multi-in multi-out (MIMO) radar in the presence of strong jamming effects. The proposed technique not only overcomes the noise jamming but also counters the effects of deception jamming. Two orthogonal waveforms beam-formed by coherent operation of two sub-arrays are used to leverage the advantages of both the MIMO and phased-radar simultaneously. The heart of the idea lies with its coherent receive operation where matched filtering and Karhunen–Loeve transform is applied for separating the signals. We make use of the MUltiple SIgnal Classification (MUSIC) algorithm for angle estimation; thereafter the signal-to-noise-plus-jamming ratio is maximized by solving a convex optimization problem. The output shows remarkable results with an excellent peak to sidelobe ratio of more than 40 dB.

<div><span>Snow as a major part of the cryosphere is an important component of Earth’s hydrological cycle and energy balance. Understanding the microstructural, macrophysical, thermal and optical properties of the snowpack is essential for integration into numerical models and there is a great need for accurate snow data at different spatial and temporal resolutions to address the challenges of changing snow conditions.</span></div><div><span>Physical snow properties are currently determined by traditional ground-based measurements as well as remote sensing, over a range of temporal and spatial scales, following considerable developments in instrument technology over recent years. </span></div><div><span>Data assimilation (DA)</span><span> methods are widely used</span> <span>to combine data from different observations</span><span> with numerical model using uncertainties </span><span>of observed and modeled variables  to produce an optimal estimate. DA provides a reliable improvement of the initial states of the numerical model and a benefit for hydrological and snow model forecasts. </span></div><div> </div><div><span>European efforts to harmonize approaches for validation, and methodologies of snow measurement practices, instrumentation, algorithms and data assimilation techniques were coordinated by the European Cooperation in Science and Technology (COST) Action ES1404 “HarmoSnow”, entitled, “A European network for a harmonized monitoring of snow for the benefit of climate change scenarios, hydrology and numerical weather prediction” (2014-2018) .</span></div><div><span>One of the key objectives of the action was “Advance the application of snow DA in numerical weather prediction (NWP) and hydrological models, and show its benefit for weather and hydrological forecasting as well as other applications.” </span></div><div><span>One key result from COST HarmoSnow is a better knowledge about the diversity of usage of snow observations in DA, forcing, monitoring, validation, or verification within NWP, hydrology, snow and climate models. The main parts of this knowledge are retrieved from a COST HarmoSnow survey exploring the common practices on the use of snow observations in different modeling environments. We will show results from the survey and their implications towards standardized and improved usage of snow observations in various data assimilation applications.</span></div>

Transponder landing system (TLS) was a transponder based precise approach landing system. This paper introduced a spatial smoothness technique based on MUSIC algorithm replaced the traditional phase interferometer angle measurement algorithm of TLS, then designed the antenna arrays according to the new algorithm and compared the feasibility, validity, resolving power and precision of the designed arrays to the ULA with same array elements by computer simulation. It effectively validated the usability and reliability of the designed arrays.

Traditional phase measurement profilometry adopts divergent illumination to obtain the height distribution of a measured object accurately. However, the mapping relation between reference plane coordinates and phase distribution must be calculated before measurement. Data are then stored in a computer in the form of a data sheet for standby applications. This study improved the distribution of projected fringes and deducted the phase-height mapping algorithm when the two pupils of the projection and imaging systems are of unequal heights and when the projection and imaging axes are on different planes. With the algorithm, calculating the mapping relation between reference plane coordinates and phase distribution prior to measurement is unnecessary. Thus, the measurement process is simplified, and the construction of an experimental system is made easy. Computer simulation and experimental results confirm the effectiveness of the method.

We examine and model the patterns of velocities and turbulence from flow‐following measurements along a tidally influenced river, collected from the heavily sediment‐laden Kaipara River, New Zealand, using Lagrangian ‘Floc Drifter’ platforms released at different locations and times. Numerical modeling was undertaken in Delft3D with the k−ϵ turbulence closure scheme. While model calibration using Eulerian measurements was classified as excellent, results explored in a Lagrangian framework revealed deficiencies in model performance. Generally, the model reproduced flow speeds and patterns of dissipation rates of turbulent kinetic energy ϵ of the right order of magnitude, but did not always correctly reproduce the observed ϵ, particularly around abrupt meander bends. These discrepancies were attributed partly to errors in velocity predictions, but also indicated that other processes (omitted or not accurately represented in our model) such as wind‐driven mixing and secondary flow strongly influenced turbulence dynamics. Predicted ϵ were relatively consistent across different tidal phases and days, suggesting the bathymetry and geometry of the river were the greatest control on the along‐river structure of turbulence. The vertical and cross‐sectional distributions of turbulent quantities (ϵ, k and ν) displayed larger variations vertically than longitudinally and agree with previous studies. Results show that flow‐following measurements offer a stringent validation for numerical modeling of hydrodynamics over large (riverine) spatial scales at a temporal and spatial resolution not possible with traditional Eulerian measurements. Ultimately, robust numerical predictions of velocities and turbulence are critical to accurately model and predict the dispersal and fate of fine‐sediments in aquatic environments.