scholarly journals Analog Beamforming and Digital Beamforming on Receive for Range Ambiguity Suppression in Spaceborne SAR

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Pingping Huang ◽  
Wei Xu
Keyword(s):  
Signal To Noise Ratio ◽  
Pulse Repetition Frequency ◽  
Synthetic Aperture ◽  
Signal To Noise ◽  
Digital Beamforming ◽  
Imaging Geometry ◽  
Range Ambiguity ◽  
Special Cases ◽  
Simulation Results ◽  
Receive Antenna

For future spaceborne synthetic aperture radar (SAR) missions, digital beamforming (DBF) on receive in elevation to form a sharp high receive beam will be adopted to improve the signal to noise ratio (SNR) level and suppress range ambiguities. However, in some special cases, range ambiguities may be received by grating lobes with the high receive beam gain, and range ambiguities would not be well suppressed and even may be increased. In this paper, a new receiving approach based on analog beamforming (ABF) and DBF is proposed. According to the spaceborne SAR imaging geometry and the selected pulse repetition frequency (PRF), the antenna patterns of all subapertures of the whole receive antenna in elevation are adjusted by ABF at first. Afterwards, signals from all subapertures in elevation are combined by a real time DBF processor onboard. Since grating lobes could be suppressed by the antenna pattern of the subapertures via ABF, range ambiguities would be well suppressed even if ambiguities are received by grating lobes. Simulation results validate the proposed approach.

A Novel Registration Algorithm for Pol-InSAR Images Based on the RVOG Model

2012 ◽  
Vol 198-199 ◽  
pp. 1475-1480
Author(s):  
Sha Sha Wu ◽  
Dao Wei Yan ◽  
Zheng Lu ◽  
Ming Ming Bian
Keyword(s):  
Image Registration ◽  
Signal To Noise Ratio ◽  
Synthetic Aperture ◽  
Interferometric Synthetic Aperture Radar ◽  
Estimation Result ◽  
Coordinate Plane ◽  
Signal To Noise ◽  
Registration Algorithm ◽  
Forested Areas ◽  
Simulation Results

In the processing of the polarimetric interferometric synthetic aperture radar (Pol-InSAR), the image registration is a key procedure. If the error of image registration occurs, the signal-to-noise ratio (SNR) of the interferometric image will be lowered and the precision of the height estimation will be decreased. Numerous registration algorithms have been proposed to solve the above-mentioned problem. However, in forested areas, the effect of volume scattering is significant. This property yields the fact that the characteristic of phase and frequency in the interferometric image is not obvious, leading to the worse performance of conventional registration algorithms. In this paper, a novel registration algorithm based on the random volume over ground (RVOG) model is presented. The method employs the fact that the coherence coefficients of the same pixel are displayed as a beeline in the complex coordinate plane for forested scenes. The image offset which yields the best linearity of coherence coefficients will be treated as the final estimation result. Simulation results verify that this method is able to provide the image registration estimation in the pixel and sub-pixel levels.

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).

Research on the Signal-to-Noise Ratio in Sliding Spotlight Mode Down-Looking Synthetic Aperture Imaging Ladar

2016 ◽  
Vol 36 (8) ◽  
pp. 0828001
Author(s):  
张宁 Zhang Ning ◽  
卢智勇 Lu Zhiyong ◽  
孙建锋 Sun Jianfeng ◽  
周煜 Zhou Yu ◽  
栾竹 Luan Zhu ◽  
...  
Keyword(s):  
Signal To Noise Ratio ◽  
Synthetic Aperture ◽  
Signal To Noise ◽  
Synthetic Aperture Imaging ◽  
Noise Ratio

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.

scholarly journals Graphics and statistics for cardiology: designing effective tables for presentation and publication

Heart ◽  
2017 ◽  
Vol 104 (3) ◽  
pp. 192-200 ◽  
Author(s):  
Maarten Boers
Keyword(s):  
Signal To Noise Ratio ◽  
Safety Monitoring ◽  
Clear Understanding ◽  
Signal To Noise ◽  
Clear Vision ◽  
Special Cases ◽  
Scientific Report ◽  
Flow Diagrams ◽  
Meta Analyses ◽  
Clinical Study Reports

Research is of little use if its results are not effectively communicated. Data visualised in tables (and graphs) are key components in any scientific report, but their design leaves much to be desired. This article focuses on table design, following two general principles: clear vision and clear understanding. Clear vision is achieved by maximising the signal to noise ratio. In a table, the signal is the data in the form of numbers, and the noise is the support structure necessary to interpret the numbers. Clear understanding is achieved when the story in the data is told effectively, through organisation of the data and use of text. These principles are illustrated by original and improved tables from recent publications. Two special cases are discussed separately: tables produced by the pharmaceutical industry (in clinical study reports and reports to data safety monitoring boards), and study flow diagrams as proposed by the Consolidated Standards of Reporting Trials and Preferred Reporting Items for Systematic Reviews and Meta-Analyses initiatives.

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).

Improvement of the signal-to-noise ratio in static-mode down-looking synthetic aperture imaging ladar

2015 ◽  
Author(s):  
Zhiyong Lu ◽  
Jianfeng Sun ◽  
Ning Zhang ◽  
Yu Zhou ◽  
Guangyu Cai ◽  
...  
Keyword(s):  
Signal To Noise Ratio ◽  
Synthetic Aperture ◽  
Signal To Noise ◽  
Synthetic Aperture Imaging ◽  
Static Mode ◽  
Noise Ratio

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 Signal Processing for Digital Beamforming FMCW SAR

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Qin Xin ◽  
Zhihong Jiang ◽  
Pu Cheng ◽  
Mi He
Keyword(s):  
Signal Processing ◽  
Continuous Wave ◽  
Single Channel ◽  
Pulse Repetition Frequency ◽  
Sampling Frequency ◽  
Synthetic Aperture ◽  
Signal Model ◽  
Digital Beamforming ◽  
Processing Gain ◽  
Detailed Imaging

According to the limitations of single channel Frequency Modulation Continuous Wave (FMCW) Synthetic Aperture Radar (SAR), Digital Beamforming (DBF) technology is introduced to improve system performance. Combined with multiple receive apertures, DBF FMCW SAR can obtain high resolution in low pulse repetition frequency, which can increase the processing gain and decrease the sampling frequency. The received signal model of DBF FMCW SAR is derived. The continuous antenna motion which is the main characteristic of FMCW SAR received signal is taken into account in the whole signal processing. The detailed imaging diagram of DBF FMCW SAR is given. A reference system is also demonstrated in the paper by comparing with a single channel FMCW SAR. The validity of the presented diagram is demonstrated with a point target simulation results.

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