scholarly journals Improve channel signal quality using adaptive filters

2020 ◽  
Vol XXIII (1) ◽  
pp. 90-96
Author(s):  
Ana-Maria Travediu
Keyword(s):  
Adaptive Filters ◽  
Reference Signal ◽  
Wide Band ◽  
Training Sequence ◽  
Adaptive Equalization ◽  
Signal Quality ◽  
Linear Filter ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Useful Signal

A channel can be modelled by trying to calculate the physical processes which modify the transmitted signal. In this article we simulated the adaptive equalization of some communication channels. A system of data transmission in the basic band will be considered in order to illustrate the principle of adaptive equalization. In such a system, the data sequence is applied, upon emission, to a formation filter( low pass filter), with the purpose of limiting the occupied bandwidth. A relatively wide band noise is also introduced on the communication channel. The transmission channel can also be modelled as a linear filter, this is represented by the distortion filter. We used another filter to avoid the distortion introduced by the channel, with the role of equalizer. This should compensate for the distortion introduced by the channel. The channel transfer function is not generally known, and in addition, it may vary slowly over time. Therefore, the need for this filter appears to be adaptive. In order to perform the adaptation initially, a training sequence, known at the reception, can be transmitted first and the output of the filter is compared with a locally generated reference signal, but identical to the one emitted. After this initial adaptation phase, the transmitter transmits the information symbols, the useful signal, thus the application can be used to improve the signal quality of maritime communications channels.

scholarly journals An efficient wide-band signal detection and extraction method

2021 ◽  
Vol 336 ◽  
pp. 04011
Author(s):  
Qian Cheng ◽  
Kexian Gong ◽  
Min Zhang ◽  
Xiaoyan Liu
Keyword(s):  
Computational Complexity ◽  
Signal Detection ◽  
Filter Bank ◽  
Wide Band ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Channelized Receiver ◽  
Multi Phase ◽  
Receiver Model ◽  
Band Signal

Aiming at the influence of time-varying and frequency-varying of noise on the signal detection performance in the short wave wide-band channel and the large amount of computation in the channelized receiver model of the traditional low pass filter bank, a cross-channel reconfigurable multi-phase high-efficiency channelization method based on morphological processing is proposed in this paper .Firstly, The wide-band signal is coarsely filtered by the multi-phase structure of the uniform filter bank which is determined by the protection interval between signals, and then the bandwidth and position of the signal are determined by improved morphological operation and threshold decision of the power spectrum. Finally, the sub-band signals across the channel are combined to complete the approximate reconstruction of the sub-signals. Compared with the computational complexity of traditional channelized receiver model, the results show that this method has lower computational complexity. The simulation results show that the method can achieve the approximate constant false alarm rate(CFAR) under the colored noise environment, and has higher detection capability under different signal-to-noise ratios(SNR).

scholarly journals Wide Band Stop Response Using Interdigital Capacitor/CSRR DGS in Elliptical Microstrip Low-Pass Filter

2020 ◽  
Vol 19 (4) ◽  
pp. 495-509
Author(s):  
Dristi Singhal ◽  
Shreyanshi Singh ◽  
Vipul Kaushal ◽  
Amit Birwal ◽  
Kamlesh Patel
Keyword(s):  
Wide Band ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Interdigital Capacitor ◽  
Low Pass

ECG Signal Processing

2013 ◽  
Vol 749 ◽  
pp. 394-400
Author(s):  
Lukas Smolarik ◽  
Dusan Mudroncik ◽  
Lubos Ondriga
Keyword(s):  
Notch Filter ◽  
Electric Activity ◽  
Infinite Impulse Response ◽  
Measured Signal ◽  
Point System ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Ecg Signals ◽  
Useful Signal ◽  
Contact Sensing

Electrocardiography (ECG) is a diagnostic method that allows sensing and record the electric activity of heart [. The measurement of electrical activity is used as a standard twelve-point system. At each of these leads to measure the useful signal and interference was measured. The intensity of interference depends on the artefacts (electrical lines, brum, motion artefacts, muscle, interference from the environment, etc.). For correct evaluation of measured signal there is a need to processing the measured signal to suitable form. At present, the use of electrocardiograms with sensors with contact scanning are difficult to set a time so we decided to use the principle of non-contact sensing. Such a device to measure the ECG was constructed under the project. The disadvantage of such devices is a problem with a high level of noise, which degrades a useful signal. The aim of this article is to pre-process the signals obtained from non-contact sensing. The contactless devices are powered from the network and battery. The electrodes were connected by way of Eithoven bipolar leads. Signals were pre-treated with suitable filters so that they are also appropriate for their subsequent analysis. In the filtration ECG signals was used as a method of linear (low pass filter, high pass, IIR (Infinite Impulse Response) peak, notch filter. The results of many signals clearly demonstrate removing noise in the ECG signals to the point that is also suitable for their analysis.

scholarly journals Miniaturized ultra-wideband coplanarwaveguide lowpass filter with extended stop band

2020 ◽  
Vol 19 (3) ◽  
pp. 1415
Author(s):  
Elmahjouby Sghir ◽  
Ahmed Errkik ◽  
Jamal Zbitou ◽  
Otman Oulhaj ◽  
Ahmed Lakhssassi ◽  
...  
Keyword(s):  
Stop Band ◽  
Wide Band ◽  
Ultra Wideband ◽  
Pass Filter ◽  
Entire Area ◽  
Low Pass Filter ◽  
Planar Circuits ◽  
Low Pass ◽  
Band Pass ◽  
Novel Design

<p class="Default">In this article, we propose a novel design of large rejected band of miniaturized ultra wide band (UWB) of a planar CPW low pass filter “LPF” based on the use of periodic elements of ‘e’ slots. The goal of this work is to develop a new structure of Low Pass Filter with the following criterion: Miniature, Compact and Easy for Fabrication. The Miniaturization of this structure is achieved by entering the 'e' slot  in etching area in the ground of CPW line, to save the standard gap of the adapted coplanar line. The designed coplanar LPF is a compact filter having a large band pass and extended stop band, with the possibility to associate easily with others RF and microwave planar circuits. The entire area of the proposed structure of CPW LPF is 14.3x20 mm<sup>2</sup>.</p>

scholarly journals The Investigation on L 1 Adaptive Control of the Tilt-Rotor Aircraft

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Quanlong Chen ◽  
Shanyong Zhao ◽  
Ke Lu ◽  
Senkui Lu ◽  
Chunsheng Liu ◽  
...  
Keyword(s):  
Control System ◽  
Adaptive Design ◽  
Reference Signal ◽  
Engineering Application ◽  
Adaptive Controller ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Tilt Rotor ◽  
Conversion Mode ◽  
Flight Dynamics Model

Considering the uncertainty of the flight dynamics model of the tilt-rotor aircraft in different flight modes, an L 1 adaptive controller for full flight modes control system of tilt-rotor aircraft is designed. Taking advantage of the separation of robustness and adaptive design of the L 1 adaptive controller, adaptive gain, and low-pass filter are designed to achieve the desired control performance and meet the requirements of flight quality. The simulations of XV-15 tilt-rotor aircraft in helicopter mode and airplane mode are carried out. Then, the simulation of conversion mode is further carried out. The results show that the tilt-rotor aircraft can track the reference signal well under the L 1 control system. In addition, the changes of states as well as controls in conversion mode flight are quite smooth which is very meaningful for engineering application.

Denoising Analysis on UWB Communication in Mine Tunnels

2013 ◽  
Vol 756-759 ◽  
pp. 3246-3249
Author(s):  
Hong Wei Zhang
Keyword(s):  
Wide Band ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Pulse Interference ◽  
Noise Simulation ◽  
Power Spectral ◽  
Wavelet Transform Modulus Maxima ◽  
Low Pass ◽  
Modulus Maxima ◽  
Signal Band

In the EMC interference environment of mine, we found the EMC is white noise and pulse interference. The UWB signal pulses is short and signal power spectral density distributed in wide band is very low. This article mainly proposes a de-noising method of Wavelet transform modulus maxima in signal band, focused on the traditional low-pass filter that can only remove the outside-band noise. Simulation results show that the scheme can effectively retain the signal singularity based on information to achieve obvious noise reduction

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