Preamble-based joint frame and frequency synchronization for OFDM — WMAN systems

2011 ◽  
Author(s):  
Pushpa Kotipalli
Keyword(s):  
Frequency Synchronization

scholarly journals Frequency synchronization detection method based on adaptive frequency standard tracking

Open Physics ◽  
2021 ◽  
Vol 19 (1) ◽  
pp. 434-438
Author(s):  
Xin Geng ◽  
Baoqiang Du ◽  
Jianwei Zhang ◽  
Erlin Tian
Keyword(s):  
Detection Method ◽  
Wide Band ◽  
Frequency Standard ◽  
Frequency Measurement ◽  
Measurement Range ◽  
Period Change ◽  
Measured Signal ◽  
Frequency Synchronization ◽  
Measured Frequency ◽  
Field Programmable

Abstract In order to achieve wide-band high-resolution frequency measurement, a frequency synchronization detection method based on adaptive frequency standard tracking is proposed based on the quantized phase processing. First, the nominal value of the measured frequency signal was obtained from the rough frequency measurement module. Then, the field programmable gate array generated the nominal value of the measured frequency. After that, the direct comparison between the tracking frequency and the measured signal was carried out. Finally, the group quantized processing module gave the final result according to the phase full-period change time. Experimental results showed that the method has a wide frequency measurement range and high accuracy and can obtain frequency stability of the order of 10−13/s.

Enhanced frequency synchronization for concurrent aeroelastic and base vibratory energy harvesting using a softening nonlinear galloping energy harvester

2021 ◽  
pp. 1045389X2110263
Author(s):  
Shun Chen ◽  
David Eager ◽  
Liya Zhao
Keyword(s):  
Energy Harvesting ◽  
Electromechanical Coupling ◽  
Energy Harvester ◽  
Poor Performance ◽  
Effective Bandwidth ◽  
Frequency Synchronization ◽  
Periodic Oscillations ◽  
Energy Harvesters ◽  
Paper Form ◽  
Excited Oscillation

This paper proposes a softening nonlinear aeroelastic galloping energy harvester for enhanced energy harvesting from concurrent wind flow and base vibration. Traditional linear aeroelastic energy harvesters have poor performance with quasi-periodic oscillations when the base vibration frequency deviates from the aeroelastic frequency. The softening nonlinearity in the proposed harvester alters the self-excited galloping frequency and simultaneously extends the large-amplitude base-excited oscillation to a wider frequency range, achieving frequency synchronization over a remarkably broadened bandwidth with periodic oscillations for efficient energy conversion from dual sources. A fully coupled aero-electro-mechanical model is built and validated with measurements on a devised prototype. At a wind speed of 5.5 m/s and base acceleration of 0.1 g, the proposed harvester improves the performance by widening the effective bandwidth by 300% compared to the linear counterpart without sacrificing the voltage level. The influences of nonlinearity configuration, excitation magnitude, and electromechanical coupling strength on the mechanical and electrical behavior are examined. The results of this paper form a baseline for future efficiency enhancement of energy harvesting from concurrent wind and base vibration utilizing monostable stiffness nonlinearities.

scholarly journals High-Frequency Synchronization Improves Firing Rate Contrast and Information Transmission Efficiency in E/I Neuronal Networks

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Fang Han ◽  
Zhijie Wang ◽  
Hong Fan ◽  
Yaopeng Zhang
Keyword(s):  
Information Transmission ◽  
Firing Rate ◽  
Contrast Enhancement ◽  
High Frequency ◽  
Functional Role ◽  
Neuronal Networks ◽  
Time Window ◽  
Frequency Synchronization ◽  
Neuronal System ◽  
Information Encoding

High-frequency synchronization has been found in many real neural systems and is confirmed by excitatory/inhibitory (E/I) network models. However, the functional role played by it remains elusive. In this paper, it is found that high-frequency synchronization in E/I neuronal networks could improve the firing rate contrast of the whole network, no matter if the network is fully connected or randomly connected, with noise or without noise. It is also found that the global firing rate contrast enhancement can prevent the number of spikes of the neurons measured within the limited time window from being confused by noise, thereby enhancing the information encoding efficiency (quantified by entropy theory here) of the neuronal system. The mechanism of firing rate contrast enhancement is also investigated. Our work implies a possible functional role in information transmission of high-frequency synchronization in neuronal systems.

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