EOG Artifacts Reduction from EEG Based on Deep Network and Recursive Least Squares Adaptive Filter

2016 ◽  
pp. 412-421
Author(s):  
Banghua Yang ◽  
Kaiwen Duan ◽  
Tao Zhang ◽  
Yonghuai Zhang
Keyword(s):  
Least Squares ◽  
Adaptive Filter ◽  
Recursive Least Squares ◽  
Deep Network ◽  
Artifacts Reduction

Laser Beam Jitter Control Using Recursive-Least-Squares Adaptive Filters

2011 ◽  
Vol 133 (4) ◽  
Author(s):  
Hyungjoo Yoon ◽  
Brett E. Bateman ◽  
Brij N. Agrawal
Keyword(s):  
Laser Beam ◽  
Least Squares ◽  
Adaptive Filter ◽  
Adaptive Filters ◽  
Reference Signal ◽  
Notch Filter ◽  
Recursive Least Squares ◽  
Control Techniques ◽  
Filter Methods ◽  
The Difference

The primary focus of this research is to develop and implement control schemes for combined broadband and narrowband disturbances to optical beams. The laser beam jitter control testbed developed at the Naval Postgraduate School is used for development of advanced jitter control techniques. First, we propose a least quadratic Gaussian feedback controller with integrator for cases when only the error signal (the difference between the desired and the actual beam positions) is available. An anti-notch filter is also utilized to attenuate a vibrational disturbance with a known frequency. Next, we develop feedforward adaptive filter methods for cases when a reference signal, which is highly correlated with the jitter disturbance, is available. A filtered-X recursive least-squares algorithm with an integrated bias estimator is proposed to deal with a constant bias disturbance. Finally, experimental results are provided to validate and compare the performance of the developed control techniques. The designed adaptive filter has a simple structure but shows good jitter rejection performance, thanks to the use of a reference signal.

Combined adaptive antenna array and adaptive channel equalizer, based on multichannel fast recursive least squares algorithms

Antennas ◽  
2021 ◽  
Author(s):  
V. I. Djigan
Keyword(s):  
Least Squares ◽  
Antenna Array ◽  
Radiation Pattern ◽  
Adaptive Filter ◽  
Output Signal ◽  
Directional Antennas ◽  
Recursive Least Squares ◽  
Adaptive Antenna ◽  
Adaptive Antenna Array ◽  
Array Output

An adaptive antenna array (AAA) is a sort of directional antennas, which is able to suppress the signals of the interference sources. The AAA works well if there is no multipath propagation of the information signal. A device, which removes the multipath effects, is an adaptive equalizer. However, the independent AAA and equalizer do not work well if the interferences and multipath exist simultaneously. The purpose of this paper is to present a new efficient solution of the task by using of the AAA, whose weights are shared with the weights of the fractionally-spaced feed-forward (FF) part of the equalizer. The array output signal is combined with that of the feed-backward (FB) part of the equalizer. The array and such distributed equalizer operate as an indivisible adaptive filter, providing good performance and ability to receive the multipath information signals in the presence of the signals of the external interference sources. Because the FF part of the equalizer operates at the up-sampled rate, which is a few times higher than the information symbols rate, but the FB filter operates at the symbol rate, the computationally efficient fast recursive least squares (RLS) algorithms cannot be used directly in the considered adaptive unit. To solve this problem, it is proposed to use polyphase representation of the FF part of the equalizer. In this case, the architecture of the adaptive unit is viewed as a multichannel adaptive filter with unequal number of weights in channels. The paper presents the architecture of the adaptive unit and the details of its equalizer part. The mathematical description of a multichannel fast adaptive filtering algorithm, called stabilized fast a posteriori sequential technique (FAEST), fitted for the weights calculation of the considered unit is also presented. The verification of the proposed adaptive unit has been carried out via simulation, using a linear array with sixteen omnidirectional antennas, which operates in the conditions of –30 dB signal-to-interference ratio (SIR), 10…30 dB signal-to-noise ratio (SNR), receives the phase shift keying (8-PSK) desired signal, passed through a two-rays communication channel with about –65 dB gaps in the channel amplitude-frequency response. In the steady-state, the proposed adaptive unit demonstrates about –100 dB radiation pattern gaps towards the interference sources and the transient response with less than 500 symbols duration. The simulation demonstrates the ability of the proposed unit simultaneously to steer the main lobe of antenna array radiation pattern towards the desired signal source without a priori search of its angular location and to remove the signals of the external interferences and intersymbol interference in the array output signal. Due to these properties, the proposed AAA/equalizer can be used in equipment of modern mobile communication systems.

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