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Multichannel SAR systems have grown rapidly over the past decade due to their powerful high-resolution and wide-swath (HRWS) capabilities. Because spatially separated channels also have the potential to suppress jamming, dual-channel cancellation is a general method that is effective regardless of the type of jamming signal. In this paper, the principle of dual-channel cancellation (DCC) is introduced, and several practical problems using DCC are also discussed. Moreover, this paper emphasizes interferometric phase estimation, which is the key to DCC. If the jamming-to-signal ratio (JSR) is high, the interferometric phase can be estimated accurately from the interferometry of two channel signals, but estimation becomes rather difficult when the JSR decreases. To solve the problem of interferometric phase estimation under a low JSR, a novel interferometric phase estimation method using cosine similarity is proposed in this paper. L-band airborne dual-channel SAR is performed to investigate the applicability of the method. The results not only prove that cosine similarity is an effective method for interferometric phase estimation, but also demonstrate the potential of DCC in the SAR anti-jamming processing.
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http://dx.doi.org/10.3390/s22239356 | DOI Listing |
Rev Sci Instrum
September 2025
Institut für Physik, Universität Osnabrück, Barbarastr. 7, 49076 Osnabrück, Germany.
An interferometer used for displacement measurement is typically adjusted to the center or another appropriate point of the interferometer fringe as a working point to yield maximum detection sensitivity and linearity. The interferometer is prone to varying misalignment in the course of measurements, most noticeable due to thermal drift affecting the interferometer dimensions. We introduce an automatic correction mechanism based on a proportional/integral (PI) control loop to remove any error in the alignment of the fiber interferometer, specifically long-term drift.
View Article and Find Full Text PDFSensors (Basel)
August 2025
Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, China.
Optical interferometry provides high-precision displacement and angle measurement solutions for a wide range of cutting-edge industrial applications. One of the key factors to achieve such precision lies in highly accurate optical encoder signal processing, as well as the calibration and compensation techniques customized for specific measurement principles. Optical interferometric techniques, including laser interferometry and grating interferometry, are usually classified into homodyne and heterodyne systems according to their working principles.
View Article and Find Full Text PDFSci Adv
August 2025
Physics Department and Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat Gan 52900, Israel.
The resolution of a measurement system is fundamentally constrained by the wavelength of the used wave packet and the numerical aperture of the optical system. Overcoming these limits requires advanced interferometric techniques exploiting quantum correlations. While quantum interferometry can surpass the Heisenberg limit, it has been confined to the optical domain.
View Article and Find Full Text PDFIn this paper, we demonstrate a high-power Yb-doped fiber femtosecond laser system integrating divided-pulse amplification (DPA) with pre-chirped management amplification (PCMA). The PCM-DPA system generates 42 fs pulses with 5.1 J energy at 10.
View Article and Find Full Text PDFSensors (Basel)
August 2025
School of Electronic and Optical Engineering, Nanjing University of Science and Technology, Nanjing 210094, China.
In the field of interferometric fiber-optic sensing, the phase-shifting technique is well known as a highly efficient method for retrieving the phase signal from the interference light intensity. The rectangular-pulse binary phase modulation (RPBPM) method is a typical phase-shifting method with the advantages of high efficiency, low complexity, and easy array multiplexing. Exploring the impact of the parameters on the performance is of great significance for guiding its application in practical systems.
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