Standard digital correlators, which rely on the acquisition of signals and their processing, are intrinsically limited by the clock jitter of the analog-to-digital converters, and by the processing capabilities in rea...
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ISBN:
(纸本)9781510670310;9781510670303
Standard digital correlators, which rely on the acquisition of signals and their processing, are intrinsically limited by the clock jitter of the analog-to-digital converters, and by the processing capabilities in real time of digital electronics. Here, we demonstrate a novel analog correlator architecture based on a simple photonic platform, suitable for wideband RF signal processing. The system gives access in real time to the entire correlation function of two signals by computing the cross correlation coefficients for 200 values of their relative delay simultaneously. The time-delay step can be adjusted from a few ns down to a few ps, enabling us to process signals with MHz to multi-GHz bandwidth. The system, based on a frequency shifting loop, can find applications in radar, electronic warfare, imaging, and radio-astronomy.
So far, the instantaneous bandwidth of conventional digital real-time spectrum analyzers is limited to a few GHz, a limitation set by the clock jitter of the analog-to-digital converters, and by the processing capabil...
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ISBN:
(纸本)9781510670310;9781510670303
So far, the instantaneous bandwidth of conventional digital real-time spectrum analyzers is limited to a few GHz, a limitation set by the clock jitter of the analog-to-digital converters, and by the processing capabilities in real time of digital electronics. Here, we propose a simple analog architecture of RF spectrum analyzer based on photonic frequency- shifting loops. It utilizes only compact commercial telecom components, a single CW laser, and slow electronic resources (10 MSa/s). The probability of intercept is 100%, the instantaneous bandwidth reaches 16 GHz, and the spectral and temporal resolutions are respectively equal to 160 MHz and 50 mu s.
The editorial introduces JMI Issue 3 Volume 11, looks ahead to SPIE Medical Imaging, and highlights the journal’s policy on conference article submission.
The editorial introduces JMI Issue 3 Volume 11, looks ahead to SPIE Medical Imaging, and highlights the journal’s policy on conference article submission.
image forgery techniques pose a significant challenge in the digital era, particularly when it comes to detecting copy-move forgery, which is crucial for ensuring the credibility of digital evidence. This paper introd...
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ISBN:
(纸本)9798331541859;9798331541842
image forgery techniques pose a significant challenge in the digital era, particularly when it comes to detecting copy-move forgery, which is crucial for ensuring the credibility of digital evidence. This paper introduces an innovative algorithm that uses the image quality assessment metric and sharpness estimation extracted from images to uncover tampering artifacts, such as irregular tampered boundaries and discrepancies in noise patterns between original and manipulated areas. Additionally, the paper utilizes the XGBoost model to effectively distinguish between original and tampered regions, enhancing the accuracy of forgery detection. The proposed approach is evaluated on the MICC-F2000 dataset, consisting of 2000 images, with 1300 original and 700 forged ones. The experimental results, achieving an impressive accuracy of 97.50%, underscore the potential merits of our approach in advancing the domain of image forgery detection.
High spatial resolutions and wide swaths are pursued goals for spaceborne Synthetic Aperture Radar (SAR). However, these requirements are conflicting constraints on the design of traditional spaceborne SAR systems. Th...
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ISBN:
(纸本)9798350350920
High spatial resolutions and wide swaths are pursued goals for spaceborne Synthetic Aperture Radar (SAR). However, these requirements are conflicting constraints on the design of traditional spaceborne SAR systems. The innovation of combining a reflector with a digital feed array offers a promising avenue to achieve high-resolution wide-swath (HRWS) imaging. Against this backdrop, this paper analyses the Scan-On-Receive (SCORE) mode and establishes the receive echo signal model of the reflector with an elevation digital feed array. To address the complexities of digital beamforming data processing within this model and compensate for the reduced echo gain from terrain height changes, this paper proposes an optimized digital beamforming (DBF) method based on the Minimum Variance Distortionless Response (MVDR) criterion. The method introduces a pivotal elevation angle correction step prior to the digital beamforming process, coupled with the incorporation of Polynomial Curve Fitting to reduce computational demands. The efficacy of the proposed method is demonstrated through simulations with both point and distributed targets.
A time difference measurement method for digital satellite television signals based on the advanced coding of video and audio for broadcasting (AVS+), taking into account the current status of digital satellite televi...
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ISBN:
(纸本)9798350350920
A time difference measurement method for digital satellite television signals based on the advanced coding of video and audio for broadcasting (AVS+), taking into account the current status of digital satellite television in China, is proposed. By analyzing the relevant standards of AVS+ encoding, this method can be utilized for both scrambled and unscrambled television programs, while remaining compatible with the original digital satellite television signals based on Moving Picture Experts Group-2 (MPEG-2) encoding. Experimental results demonstrate that the standard deviation of time difference measurement using this method is approximately 50 ns, and the measurement bias after data fitting is less than 1 ns.
digitalimage forgery poses a security threat by manipulating personal data shared on open networks in recent years. In this study, the performance of deep learning models with residual or dense connections, with or w...
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ISBN:
(数字)9798350388961
ISBN:
(纸本)9798350388978;9798350388961
digitalimage forgery poses a security threat by manipulating personal data shared on open networks in recent years. In this study, the performance of deep learning models with residual or dense connections, with or without transfer learning, for the classification problem of multiple image manipulations with dual JPEG compression, has been investigated. Transfer learning has produced higher and more stable results at different compression rates. The average accuracy values of the proposed model with dense connections were obtained as 0.9920, 0.9953, and 0.9907 for compression quality factors of 75, 85, and 95, respectively. These values were higher compared to similar studies in the literature.
The implementation of China's higher education talent quality enhancement project integrates modern information technology, particularly digitalimageprocessing and virtual simulation technology, to promote the c...
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ISBN:
(纸本)9798350375343;9798350375336
The implementation of China's higher education talent quality enhancement project integrates modern information technology, particularly digitalimageprocessing and virtual simulation technology, to promote the cultivation of talent in universities under the "Intelligent + Education" model. This paper introduces a virtual simulation experimental system for the "digitalimageprocessing" course based on WebGL and Matlab, which centers around a 3D environment and supports online coding, real-time computation, and virtual display, facilitating task-driven online experimental learning. The system, built with a frontend using Vue, ***, and *** in conjunction with a MySQL database, enables user interaction with the 3D environment, enhancing the real-time and interactive nature of the experiments. It transforms traditional teaching methods and encourages students to engage in active and in-depth learning. The trial run of the system has demonstrated good compatibility, stability, and cross-platform capabilities.
This paper comprehensively overviews image and signal processing, including their fundamentals, advanced techniques, and applications. imageprocessing involves analyzing and manipulating digitalimages, while signal ...
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Autonomous Aerial Vehicles (AAVs) have evolved into important assets across diverse industries, owing to their remarkable versatility and adeptness in undertaking a broad spectrum of tasks. AAVs capacity for autonomou...
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ISBN:
(纸本)9798350352368
Autonomous Aerial Vehicles (AAVs) have evolved into important assets across diverse industries, owing to their remarkable versatility and adeptness in undertaking a broad spectrum of tasks. AAVs capacity for autonomous landing further enhances their utility, allowing for precise and efficient operations in various environments. This paper presents a landing area identification system for AAVs utilizing digital surface maps from onboard cameras. These maps serve as a primary reference for precise trajectory planning and obstacle avoidance during landing and photogrammetry techniques are used to refine spatial awareness, enabling dynamic adjustments. This work incorporates computer vision algorithms for the interpretation of maps and photogrammetric data, making a decision regarding altitude, approach angle, and lateral adjustments during the landing process. Validation through mathematical models demonstrates the system's effectiveness in achieving precise landings across diverse scenarios. The presented system, combining digital surface maps and photogrammetry, offers a viable solution for AAVs, improving landing accuracy in complex environments.
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