The quality of an interferogram, which is limited by various phase noise, will greatly affect the further processes of InSAR, such as phase unwrapping. Interferometric SAR (InSAR) geophysical measurements’, such as height or displacement, phase filtering is therefore an essential step. In this work, an improved Goldstein interferogram filter is proposed to suppress the phase noise while preserving the fringe edges. First, the proposed adaptive filter step, performed before frequency estimation, is employed to improve the estimation accuracy. Subsequently, to preserve the fringe characteristics, the estimated fringe frequency in each fixed filtering patch is removed from the original noisy phase. Then, the residual phase is smoothed based on the modified Goldstein filter with its parameter alpha dependent on both the coherence map and the residual phase frequency. Finally, the filtered residual phase and the removed fringe frequency are combined to generate the filtered interferogram, with the loss of signal minimized while reducing the noise level. The effectiveness of the proposed method is verified by experimental results based on both simulated and real data.

Various jamming techniques have been developed to prevent interferometric synthetic aperture radar from effective detection and observation. In this paper, a thorough analysis of the jamming effects on correlation and interferometric phase is provided. To derive the jamming result, a general signal model for the interference is first presented and the corresponding imaging results are produced through the range-Doppler algorithm. Then, the impacts of the interference on correlation are analyzed. The non-center located jammer decreases the correlation seriously due to the low correlation of the interference. However, the center located jammer clearly increases the correlation when the input jamming-to-signal ratio is large enough. Finally, the jammed interferometric phases for different jammer positions are discussed. It shows that the non-center located jammer results in large phase errors, while for the center located jammer, the interferometric phase approaches a constant. The effects of interference are demonstrated by simulated data based on the TerraSAR system.

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Deceptive jamming against synthetic aperture radar (SAR) can create false targets or deceptive scenes in the image effectively. Based on the difference in interferometric phase between the target and deceptive jamming signals, a novel method for detecting deceptive jamming using cross-track interferometry is proposed, where the echoes with deceptive jamming are received by two SAR antennas simultaneously and the false targets are identified through SAR interferometry. Since the derived false phase is close to a constant in interferogram, it is extracted through phase filtering and frequency detection. Finally, the false targets in the SAR image are obtained according to the detected false part in the interferogram. The effectiveness of the proposed method is validated by simulation results based on the TanDEM-X system.

Two-dimensional (2D) materials with simultaneous magnetic semiconducting properties and negative Poisson's ratio are crucial for fabricating multifunctional electronic devices but remain limited. Herein, on the basis of first-principles calculations, we design the 2D metal−organic framework Cr(DCNQI) 2 (DCNQI = N,N′-dicyanoquinonediimine) as a notable candidate with good dynamic, thermal, and mechanical stabilities. Interestingly, 2D Cr(DCNQI) 2 harbors an unusual in-plane negative Poisson's ratio with a maximum absolute value of 0.85, which is fairly large and scarce in reported auxetic materials. Due to the strong d−p direct exchange magnetic interaction between Cr cations and DCNQI anions, 2D Cr(DCNQI) 2 exhibits intrinsic ferrimagnetism with a relatively high Curie temperature of 217 K. Also, it possesses significant out-of-plane magnetic anisotropy (0.60 meV/Cr). In addition, 2D Cr(DCNQI) 2 behaves as an intrinsic bipolar magnetic semiconductor with a moderate direct band gap of 0.95 eV and small carrier effective masses. Electrical doping induces the transformation of 2D Cr(DCNQI) 2 into a half-metal with controllable spin polarization.