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What is doppler center?

Center frequency

Synthetic aperture radar

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The Doppler centroid refers to a crucial parameter in radar systems, particularly in Doppler scatterometers and synthetic aperture radar (SAR). In Doppler scatterometers, the Doppler centroid estimation is essential for ocean current field estimation, with methods like the average cross-correlation coefficient (ACCC) and Doppler spectrum-based estimations being utilized for accuracy enhancement . Similarly, in SAR processing, Doppler centroid estimation aids in motion parameter determination, azimuth matching function construction, and target localization, with techniques like phase center tracking and evaluation functions being employed for accuracy improvement . Additionally, methods like frequency shift iteration are used to estimate the Doppler spectrum center frequency in radar systems, ensuring precise measurements for applications such as Doppler wave observation radars .

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Patent Doppler spectrum center frequency estimation method based on frequency shift iteration Chen Zezong, Chen Xi, Jianbo Zhong, Zhao Chen, Zhang Longgang - Show less +4 more 20 Jan 2016 3 Citations	Doppler center refers to the estimated center frequency of a Doppler spectrum, crucial for accurate ocean wave parameter measurements using Doppler wave observation radar with improved estimation precision.
Patent Doppler spectrum center frequency estimation method based on frequency shift iteration 陈泽宗, 陈曦, 钟建波, 赵晨, 张龙刚 - Show less +4 more 10 Nov 2015	The Doppler center refers to the estimated center frequency of a Doppler spectrum, crucial for accurate ocean wave parameter measurements using Doppler wave observation radar.
Proceedings Article•DOI Doppler centroid estimation of Doppler scatterometer based on deramping Bing Chen, Xiaonan Yao, Xiaoqing Wang, Chen Wang - Show less +3 more 14 Dec 2022	The Doppler centroid is estimated using deramping in Doppler scatterometers to improve accuracy by aligning targets' frequencies, enhancing estimation precision by 26.15% compared to the ACCC method.
Proceedings Article•DOI Doppler centroid estimation of Doppler scatterometer based on deramping 14 Dec 2022	The Doppler centroid is estimated in Doppler scatterometers using deramping to improve accuracy by moving target frequencies closer to zero, reducing Doppler ambiguity caused by azimuth scanning.
Proceedings Article•DOI A Doppler Centroid Estimator for Synthetic Aperture Radar Based on Phase Center Point Tracking Iingzeng Wang, Junjie Wu, Wei Pu, Wenchao Li, Jianyu Yang - Show less +4 more 22 Jul 2018 1 Citations	Doppler centroid is crucial in SAR for motion parameter estimation, azimuth function construction, and target localization. The paper proposes a Doppler centroid estimator based on phase center tracking for SAR.

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How to simulate doppler effect in computational electromagnetic?4 answersTo simulate the Doppler effect in computational electromagnetics, various methods and techniques have been proposed. One approach involves using a hybrid iterative method with acceleration techniques to analyze the Doppler spectrum of moving targets above a time-evolving sea surface, considering electromagnetic scattering from both the surface and targets, and accounting for mutual EM coupling effects through an iterative process. Another method focuses on the acoustic Doppler effect in the time domain, utilizing transmission line matrix modeling to observe frequency changes caused by motion of either the source or receiver in electromagnetic and acoustic waves. Additionally, simulations using finite difference time domain analysis have been conducted to study Doppler reflectometry, examining effects of electromagnetic wave characteristics, target properties, and plasma uniformity on Doppler shift and velocity calculations.

How would the Doppler effect be used to measure the flow rate of a river?5 answersThe Doppler effect can be used to measure the flow rate of a river by analyzing the frequency shift of sound waves reflected off the moving water. This can be achieved using various techniques and devices. For example, Li et al. proposed a method based on adaptive Gaussian weighted integral (AGWI) to extract the Doppler frequency from weak non-stationary coherent signals, allowing for high-precision measurement of water flow velocity. Ling et al. developed a Doppler flow rate direction identifying device that utilizes ultrasonic waves and mixing signals to accurately measure flow rate and direction. Zhang et al. introduced a ship type buoy type ultrasonic Doppler flow rate measuring device that operates under river water, providing stable current surveying and reliable data. Che et al. designed a natural river bank-mounted Doppler device that allows for easy installation and avoids losing hydrological data during water level fluctuations. Ge et al. presented a processing circuit adapted to sound wave Doppler measurement of flow rate, offering high integration and low power consumption.

What Doppler ?3 answersDoppler is a scalable recommendation engine that provides right-sized Azure SQL Platform-as-a-Service (PaaS) recommendations for migrating SQL estates from on-premises to the cloud. It uses a novel price-performance methodology based on low-level resource statistics to rank relevant cloud targets and guide migration customers towards the optimal target. Doppler is also a serverless toolkit designed to trace serverless data processing systems with minimal performance and cost overhead, providing a deep understanding of query execution dynamics in distributed cloud-based databases. Additionally, Doppler imaging is an established ultrasonographic method that uses the Doppler effect to evaluate blood flow non-invasively. Doppler methods in ultrasonography offer functional information through blood circulation analysis, complementing B-mode ultrasonography's ability to determine anatomical morphology.

Doppler effect in highspeed trains train5 answersThe Doppler effect in high-speed trains can have a negative impact on communication capacity. One proposed solution is to use a moving relay, such as a vehicle on a nearby road, to mitigate this effect. By selecting a relay that is moving in the same or similar direction as the train, the relative speed between the train and the base station can be reduced, thus reducing the impact of the Doppler effect on communication capacity. Additionally, the handover performance on high-speed trains can be affected by the Doppler frequency spread, which is related to the speed of the train. The impact of the Doppler effect on mobile networks, including high-speed rail networks, has been analyzed, and methods and algorithms for overcoming this effect have been discussed. A test platform using dual-Doppler channel emulators has been proposed for real-time simulation of the Doppler effect in high-speed railway transit WLAN systems.

What is doppler beaming in Black holes?5 answersDoppler beaming in black holes refers to the phenomenon where the rotation of the black hole causes a modulation in the emitted radiation. This effect is observed in various astrophysical systems, including eclipsing binaries and supermassive binary black holes. In eclipsing binaries, the rotational Doppler beaming can exceed the orbital effect, leading to changes in the observed light curves during eclipse ingress and egress. In the case of supermassive binary black holes, the Doppler-boost effect can modulate the continuum radiation from the accretion disk associated with the secondary component, resulting in periodicity in the emitted light. The Doppler beaming effect can be significant when the orbital orientation is close to edge-on. Understanding the properties and profiles of the emitted radiation in these systems is important for studying black hole dynamics and accretion processes.

Doppler effect for speed estimation5 answersThe Doppler effect is used for speed estimation in various applications. It can be used to detect the occurrence of Doppler spectrum components from moving scatterers and estimate their speed. A speedometer and speed measuring method utilizing the Doppler effect can detect Doppler frequency with high responsiveness and accurately show the moving direction of a measuring object. Another Doppler speed meter can increase the Doppler frequency even when the frequency of the transmission signal is low, allowing for high-definition speed detection. A Doppler effect speed measurement device using light waves can derive the ground speed of a vehicle from the frequency of the radiated and reflected waves. The Doppler effect is also utilized in GPS receivers to measure vehicle speed more accurately than dashboard speedometers.

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