scholarly journals Optimization of Direct Direction Finding Method with Two-Dimensional Correlative Processing of Spatial Signal

2018 ◽  
Vol 8 ◽  
pp. 46-53
Author(s):  
Vitaliy V. Tsyporenko ◽  
Valentyn G. Tsyporenko
Keyword(s):  
Main Parameter ◽  
Noise Immunity ◽  
Signal To Noise Ratio ◽  
Direction Finding ◽  
High Accuracy ◽  
Signal To Noise ◽  
High Noise ◽  
Spatial Shift ◽  
Simulation Results ◽  
Finding Method

In this article, the main parameter of the correlative-interferometric direction finding method with twodimensional correlative processing of spatial signal in the aperture of a linear antenna array (AA) is determined as the value of spatial shift within the AA aperture. The corresponding objective function is also formed. Analytical optimization of this parameter is presented and a comparative analysis of analytical calculations based on simulation results is conducted. In the simulation, a range of dependencies of the middle square deviation of estimation of direction on the value of the spatial shift for a signal-to-noise ratio of 0 dB, for minimum 3-sample and 4-sample Blackman-Harris windows of the spectral analysis, is received. The value of the middle square deviation of estimation of direction will be minimal and will equal 0.02 degrees using a minimum 3-sample Blackman-Harris window with the −67 dB level of side lobes. It offers high noise immunity and high accuracy of direction finding.

scholarly journals Hot Exoplanet Atmospheres Resolved with Transit Spectroscopy (HEARTS)

2020 ◽  
Vol 641 ◽  
pp. L7 ◽  
Author(s):  
J. V. Seidel ◽  
D. Ehrenreich ◽  
V. Bourrier ◽  
R. Allart ◽  
O. Attia ◽  
...  
Keyword(s):  
Transmission Spectrum ◽  
Signal To Noise Ratio ◽  
High Accuracy ◽  
Formation Processes ◽  
Line Broadening ◽  
Signal To Noise ◽  
High Noise ◽  
Formation And Evolution ◽  
The Impact ◽  
Neutral Sodium

Planet formation processes or evolution mechanisms are surmised to be at the origin of the hot Neptune desert. Studying exoplanets currently living within or at the edge of this desert could allow disentangling the respective roles of formation and evolution. We present the High Accuracy Radial velocity Planet Searcher (HARPS) transmission spectrum of the bloated super-Neptune WASP-166b, located at the outer rim of the Neptune desert. Neutral sodium is detected at the 3.4σ level (0.455 ± 0.135%), with a tentative indication of line broadening, which could be caused by winds blowing sodium farther into space, a possible manifestation of the bloated character of these highly irradiated worlds. We put this detection into context with previous work claiming a non-detection of sodium in the same observations and show that the high noise in the trace of the discarded stellar sodium lines was responsible for the non-detection. We highlight the impact of this low signal-to-noise ratio remnant on detections for exoplanets similar to WASP-166b.

scholarly journals Cooperative Spectrum Sensing Based on Convolutional Neural Networks

2021 ◽  
Vol 11 (10) ◽  
pp. 4440
Author(s):  
Youheng Tan ◽  
Xiaojun Jing
Keyword(s):  
Neural Networks ◽  
Spectrum Sensing ◽  
Convolutional Neural Networks ◽  
Cooperative Spectrum Sensing ◽  
Signal To Noise Ratio ◽  
Majority Voting ◽  
Signal To Noise ◽  
Hidden Terminal ◽  
Simulation Results ◽  
Sensing Performance

Cooperative spectrum sensing (CSS) is an important topic due to its capacity to solve the issue of the hidden terminal. However, the sensing performance of CSS is still poor, especially in low signal-to-noise ratio (SNR) situations. In this paper, convolutional neural networks (CNN) are considered to extract the features of the observed signal and, as a consequence, improve the sensing performance. More specifically, a novel two-dimensional dataset of the received signal is established and three classical CNN (LeNet, AlexNet and VGG-16)-based CSS schemes are trained and analyzed on the proposed dataset. In addition, sensing performance comparisons are made between the proposed CNN-based CSS schemes and the AND, OR, majority voting-based CSS schemes. The simulation results state that the sensing accuracy of the proposed schemes is greatly improved and the network depth helps with this.

An Improved Acquisition Method for High-Order BOC-Modulated Signals Based on Fractal Geometry

2013 ◽  
Vol 846-847 ◽  
pp. 1185-1188 ◽  
Author(s):  
Hua Bing Wu ◽  
Jun Liang Liu ◽  
Yuan Zhang ◽  
Yong Hui Hu
Keyword(s):  
Fractal Geometry ◽  
Output Signal ◽  
Signal To Noise Ratio ◽  
High Order ◽  
Main Peak ◽  
Signal To Noise ◽  
Binary Offset Carrier ◽  
Simulation Results ◽  
Modulated Signals ◽  
Acquisition Method

This paper proposes an improved acquisition method for high-order binary-offset-carrier (BOC) modulated signals based on fractal geometry. We introduced the principle of our acquisition method, and outlined its framework. We increase the main peak to side peaks ratio in the BOC autocorrelation function (ACF), with a simple fractal geometry transform. The proposed scheme is applicable to both generic high-order sine-and cosine-phased BOC-modulated signals. Simulation results show that the proposed method increases output signal to noise ratio (SNR).

A High Accuracy Direction-Finding Method of 2-D Multi-Beams

2012 ◽  
Vol 229-231 ◽  
pp. 1577-1581
Author(s):  
Zhi Gang Wang ◽  
Fang Wang
Keyword(s):  
Direction Finding ◽  
Surface Fitting ◽  
High Accuracy ◽  
Simulation Experiments ◽  
Factors Influencing ◽  
Main Factors ◽  
Finding Method ◽  
Specific Influence

In order to acquire a kind of high accuracy multi-beams direction-finding method, this paper proposes a sort of 2-D multi-beams direction-finding method based on surface fitting. Three main factors influencing direction-finding accuracy are summarized in this paper, and the specific influence of these three factors to direction finding accuracy are analyzed by simulation experiments. The result of simulation experiments analysis shows that this method has higher steadiness and better direction-finding accuracy.

Highly Accurate Frequency Interpolation of Apodized FFT Magnitude-Mode Spectra

1998 ◽  
Vol 52 (1) ◽  
pp. 134-138 ◽  
Author(s):  
Yutaka Goto
Keyword(s):  
Simple Formula ◽  
Previous Investigation ◽  
Signal To Noise Ratio ◽  
Damping Ratio ◽  
Frequency Error ◽  
Signal To Noise ◽  
Window Functions ◽  
Optimal Values ◽  
Simulation Results ◽  
True Frequency

“Generalized” interpolation (called GIα here) of fast Fourier transform (FFT) spectra apodized by a family of sinα ( X) windows has previously been proposed. The GIα gives the highly accurate interpolated frequency by calculating the simple formula of frequency determination with the use of two squared ratios between three magnitudes nearest to the peak maximum on the apodized FFT spectrum. Although the value of window parameter α, limited to integer values, has been used for the GIα, we show in the present paper that the GIα with a real α value also gives an extremely good estimate of the true frequency from the sinα ( X)-apodized spectra. Thus, we intend to apply the GIα with the optimal values of α to FFT spectra apodized by any other window functions that are often used in Fourier spectroscopy. Simulation results show that the GIα is easier and more accurate than the KCe interpolation, which uses a family of interpolating functions [ KCe(ω) = ( aω2 + bω + c)e] proposed by Keefe and Comisarow. Finally, in the presence of noise we examine effects of damping and windowing on the frequency interpolation of FFT spectra. Because damping and windowing reduce the signal-to-noise ratio (SNR), we define anew the relative SNR by the ratio of the SNR of the apodized spectrum of a damped sinusoid to the SNR of the unapodized spectrum of an undamped sinusoid. Numerical calculation shows that the relative SNR varies, owing to damping rather than windowing. In fact, the observed frequency error roughly increases as the damping ratio increases for any window functions, as is expected from our previous investigation that the frequency error based upon the GIα is inversely proportional to the SNR. However, no obvious differences between the various window functions are observed in the presence of noise.

Digital Modulation Recognition in Different Environments

2014 ◽  
Vol 1049-1050 ◽  
pp. 2084-2087 ◽  
Author(s):  
Rong Li
Keyword(s):  
Gaussian Noise ◽  
Signal To Noise Ratio ◽  
Automatic Recognition ◽  
Modulation Recognition ◽  
Signal To Noise ◽  
Digital Modulation ◽  
Multipath Interference ◽  
Modulation Signal ◽  
Simulation Results ◽  
Recognition Success

For the using of multi-modulation, the precondition of receiving and demodulating signal is to determine the type of the modulation, so automatic recognition of modulation signal has significant influence on the analysis of the signals. In this paper, digital modulation recognition is studied respectively in different environment of White Gaussian Noise (WGN), stationary interference and multipath interference. The simulation results show that the recognition success rate is the highest in stationary interference environment and the lowest in multipath interference environment with the same signal to noise ratio (SNR).

scholarly journals Superposition Coded Modulation Based Faster-Than-Nyquist Signaling

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Shuangyang Li ◽  
Baoming Bai ◽  
Jing Zhou ◽  
Qingli He ◽  
Qian Li
Keyword(s):  
Bit Error Rate ◽  
Spectral Efficiency ◽  
Detection Method ◽  
Signal To Noise Ratio ◽  
Coded Modulation ◽  
Signal To Noise ◽  
Data Rates ◽  
Orthogonal Signaling ◽  
Simulation Results ◽  
Constrained Capacity

A structure of faster-than-Nyquist (FTN) signaling combined with superposition coded modulation (SCM) is considered. The so-called FTN-SCM structure is able to achieve the constrained capacity of FTN signaling and only requires a low detection complexity. By deriving a new observation model suitable for FTN-SCM, we offer the power allocation based on a proper detection method. Simulation results show that, at any given spectral efficiency, the bit error rate (BER) curve of FTN-SCM lies clearly outside the minimum signal-to-noise ratio (SNR) boundary of orthogonal signaling with a larger alphabet. The achieved data rates are also close to the maximum data rates of the certain shaping pulse.

scholarly journals An Algorithm for Automatic Recogniton of Digital QAM Modulations

2019 ◽  
Vol 25 (3) ◽  
pp. 36-41
Author(s):  
Alexandru-Daniel Luţă ◽  
Paul Bechet
Keyword(s):  
Lower Order ◽  
Signal To Noise Ratio ◽  
Recognition Rate ◽  
Automatic Recognition ◽  
Signal To Noise ◽  
Small Influence ◽  
Qam Modulation ◽  
Digital Modulations ◽  
Simulation Results ◽  
Noise Ratio

Abstract This paper proposes a new Matlab-developed algorithm for automatic recognition of digital modulations using the constellation of states. Using this technique the automatic distinction between four digital modulation schemes (8-QAM, 16-QAM, 32-QAM and 64-QAM) was made. It has been seen that the efficiency of the algorithm is influenced by the type of modulation, the value of the signal-to-noise ratio and the number of samples. In the case of an AWGN noise channel the simulation results indicated that the value of SNR (signal-to-noise ratio) has a small influence on the recognition rate for lower-order QAM (8-QAM and 16-QAM). The length of the signal may change essentially the recognition rate of this algorithm especially for modulations with a high number of bits per symbol. Consequently, for the 64-QAM modulation in a case of 25dB signal-to-noise ratio the recognition rate is doubled if the sample rate is incresed from 5400 to 80640.

scholarly journals Joint use of frequency-time division and antinoise coding in radio communication systems with FHSS

2021 ◽  
Vol 9 (4) ◽  
pp. 77-84
Author(s):  
A. A. Paramonov ◽  
Van Zung Hoang
Keyword(s):  
Data Transmission ◽  
Communication Systems ◽  
Error Probability ◽  
Noise Immunity ◽  
Signal To Noise Ratio ◽  
Frequency Division ◽  
Radio Communication ◽  
Signal To Noise ◽  
Noise Ratio ◽  
Time Division

In the context of continuous improvement of radio prospecting and active radio jamming technics along with introduction of automated active countermeasures systems (ACS), the frequency-hopping spread spectrum (FHSS) radio communication systems (RCS) are widely used in order to improve reliability and noise immunity of data transmission. The noise immunity of the RCS affected by unintentional or deliberate interference can be significantly perfected by the combined use of frequency-time division and antinoise coding. This paper explores the case when the interference created by an ACS system with a limited transmitter power covers a part of the RCS frequency range. The receiver gets input mix of the wanted signal, the receiver noise, and probably a deliberate interference also considered as a noise. The article analyzes the noise immunity of signals reception with FHSS in the low-speed radio systems with joint use of frequency-time division of information subsymbols and noise combating codes when the deliberate interference destructively impacts a part of the RCS working band. Dependence of the bit error probability on the signal-to-noise ratio is calculated for the joint use of frequency division of information subsymbols and noise combating codes. It is shown that due to effective use of the frequency-energy resource of a radio line, considering the use of correction codes, a quite high noise immunity of RCS under the influence of deliberate interference can be assured. The indicated dependences of the error probability on the signal-to-noise ratio confirm that the reliability of data transmission can be significantly increased by the proper combination of signal spectrum spreading, applying of correction codes, and frequency division of subsymbols followed by their weight processing.

scholarly journals Physical layer synchronization algorithms for signal-code sequence increasing noise immunity of dvb-s2x standard vl-snr mode

2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
L. A. Antiufrieva ◽  
◽  
K. K. Iansitov ◽  
A. V. Dvorkovich
Keyword(s):  
Noise Immunity ◽  
Signal To Noise Ratio ◽  
Physical Layer ◽  
Code Sequence ◽  
Signal To Noise ◽  
Synchronization System ◽  
Noise Ratio ◽  
Signal Operating

The work is devoted to expanding the noise immunity of the DVB-S2X standard and the VL-SNR mode physical layer synchronization algorithms. The article proposes a signal-code sequence that increases the noise immunity of the signal, operating down to −11 dB signal-to-noise ratio, and a synchronization system for it.

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