scholarly journals A Synchronization Acquisition Method for the Dual-Sequence-Frequency-Hopping Communication System Based on Software Defined Radio at Low SNR

2021 ◽  
pp. 235-247
Author(s):  
Xiaolu Zhang ◽  
◽  
Houde Quan ◽  
Huixian Sun ◽  
Peizhang Cui ◽  
...  
Keyword(s):  
Communication System ◽  
Software Defined Radio ◽  
Signal To Noise Ratio ◽  
Frequency Hopping ◽  
Detection Time ◽  
Low Snr ◽  
Information And Communication ◽  
Time Accumulation ◽  
Acquisition Method ◽  
Dual Sequence

The Dual-Sequence-Frequency-Hopping (DSFH) communication system based on software defined radio (SDR) system belongs to the field of information and communication security of software engineering. At very low signal-to-noise ratio (SNR), which is lower than -10dB, the DSFH fails to synchronize. Synchronization acquisition method via a combined multi-signal detection (SAMCMD) is proposed. The feature of a short sequence of frequency hopping (FH) frequency point is utilized to express the information of the time of date (TOD), and the time accumulation of several FH signals is used to extend the detection time. This method can not only be appropriate for DSFH but also greatly improve the synchronization performance at low SNR. Explain the principle and structure of the SAMCMD. And obtain the performance of this method of the SDR synchronization acquisition. The conclusions are as below: 1) the longer detection time is, the better the anti-jamming performance of SAMCMD is; 2) SAMCMD can gain about 22.5dB-24dB when the SNR is -20dB and the acquisition probability requirement is 96.31% due to the extension of the detection time, compared with the traditional FH synchronization acquisition method.

scholarly journals A Blind Parameter Estimation Method of Frequency Hopping Signal with Low SNR

2021 ◽  
Vol 15 ◽  
pp. 248-253
Author(s):  
Zengke Wang ◽  
Yi Li ◽  
Wei Xu
Keyword(s):  
Parameter Estimation ◽  
Simulation Experiment ◽  
Signal To Noise Ratio ◽  
Estimation Method ◽  
Frequency Hopping ◽  
Cross Term ◽  
Low Snr ◽  
Parameter Estimation Method ◽  
Estimate Frequency ◽  
Blind Parameter Estimation

In order to effectively estimate the parameters of the frequency hopping signals under low signal-to-noise ratio (SNR), a blind parameter estimation method based on the modified discrete time Wigner-Ville distribution (MDTWVD) is proposed. We choose a low order Chebyshev polynomial as the kernel function for reducing the cross-term. Then, the parameters of the frequency hopping signals are finally obtained from the MDTWVD. The simulation experiment results show that the method used in this paper can effectively and accurately estimate frequency hopping signals parameters, especially under low SNR condition compared with other estimating methods.

scholarly journals Precise Loran-C Signal Acquisition Based on Envelope Delay Correlation Method

Sensors ◽  
2020 ◽  
Vol 20 (8) ◽  
pp. 2329 ◽  
Author(s):  
Wenhe Yan ◽  
Kunjuan Zhao ◽  
Shifeng Li ◽  
Xinghui Wang ◽  
Yu Hua
Keyword(s):  
Signal To Noise Ratio ◽  
Correlation Method ◽  
Satellite System ◽  
Signal Acquisition ◽  
Test Results ◽  
Low Snr ◽  
Global Navigation Satellite ◽  
Suppress Noise ◽  
Acquisition Method ◽  
Selection Of

The Loran-C system is an internationally standardized positioning, navigation, and timing service system. It is the most important backup and supplement for the global navigation satellite system (GNSS). However, the existing Loran-C signal acquisition methods are easily affected by noise and cross-rate interference (CRI). Therefore, this article proposes an envelope delay correlation acquisition method that, when combined with linear digital averaging (LDA) technology, can effectively suppress noise and CRI. The selection of key parameters and the performance of the acquisition method are analyzed through a simulation. When the signal-to-noise ratio (SNR) is −16 dB, the acquisition probability is more than 90% and the acquisition error is less than 1 μs. When the signal-to-interference ratio (SIR) of the CRI is −5 dB, the CRI can also be suppressed and the acquisition error is less than 5 μs. These results show that our acquisition method is accurate. The performance of the method is also verified by actual signals emitted by a Loran-C system. These test results show that our method can reliably detect Loran-C pulse group signals over distances up to 1500 km, even at low SNR. This will enable the modern Loran-C system to be a more reliable backup for the GNSS system.

scholarly journals Performance Analysis of a Six-Port Receiver in a WCDMA Communication System including a Multipath Fading Channel

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
A. O. Olopade ◽  
M. Helaoui
Keyword(s):  
Communication System ◽  
Software Defined Radio ◽  
Communication Systems ◽  
Signal To Noise Ratio ◽  
Multipath Fading ◽  
Multipath Channel ◽  
Multipath Fading Channel ◽  
Calibration Algorithm ◽  
Receiver Performance ◽  
Calibration Techniques

Third generation communication systems require receivers with wide bandwidth of operation to support high transmission rates and are also reconfigurable to support various communication standards with different frequency bands. An ideal software defined radio (SDR) will be the absolute answer to this requirement but it is not achievable with the current level of technology. This paper proposes the use of a six-port receiver (SPR) front-end (FE) in a WCDMA communication system. A WCDMA end-to-end physical layer MATLAB demo which includes a multipath channel distortion block is used to determine the viability of the six-port based receiver. The WCDMA signal after passing through a multipath channel is received using a constructed SPR FE. The baseband signal is then calibrated and corrected in MATLAB. The six-port receiver performance is measured in terms of bit error rate (BER). The signal-to-noise ratio (SNR) of the transmittedIQdata is varied and the BER profile of the communication system is plotted. The effect of the multipath fading on the receiver performance and the accuracy of the calibration algorithm are obtained by comparing two different measured BER curves for different calibration techniques to the simulated BER curve of an ideal receiver.

Design and Implementation of Key Technologies of Carrier Synchronization in Wireless Communication System

2014 ◽  
Vol 602-605 ◽  
pp. 3329-3332
Author(s):  
Guo Qing Dang ◽  
Xiao Yan Cheng
Keyword(s):  
Wireless Communication ◽  
Communication System ◽  
Signal To Noise Ratio ◽  
Low Complexity ◽  
Carrier Synchronization ◽  
Signal To Noise ◽  
Wireless Communication System ◽  
Low Snr ◽  
Noise Ratio ◽  
The One

Noise multiple and user interference are the two important influencing factors that carrier synchronization technology in the wireless communication system faces. On the one hand, the phase locked loop and data aided carrier synchronization device is faced with poor estimation precision and slow convergence speed. On the other hand frequency offset and channel estimation problem need to be solved in multi-input multi-output (MIMO) communication system collaboration under the condition of dry low signal to noise ratio. So research of carrier synchronization algorithm of low complexity, high precision in view of the low SNR and multi-user communication system is becoming an important issue. 1. Carrier synchronization technology in wireless communication system of low signal-to-noise ratio and multiuser

Modal frequencies of bridges from GNSS (GPS) monitoring data: Experimental, statistical evidence

2021 ◽  
Vol 17 (1-2) ◽  
pp. 3-14
Author(s):  
Stathis C. Stiros ◽  
F. Moschas ◽  
P. Triantafyllidis
Keyword(s):  
Signal To Noise Ratio ◽  
Vertical Axis ◽  
Bridge Monitoring ◽  
Low Snr ◽  
True Value ◽  
Gps Satellites ◽  
Wide Range ◽  
Spectral Peaks ◽  
Monitoring Survey ◽  
True Frequency

GNSS technology (known especially for GPS satellites) for measurement of deflections has proved very efficient and useful in bridge structural monitoring, even for short stiff bridges, especially after the advent of 100 Hz GNSS sensors. Mode computation from dynamic deflections has been proposed as one of the applications of this technology. Apart from formal modal analyses with GNSS input, and from spectral analysis of controlled free attenuating oscillations, it has been argued that simple spectra of deflections can define more than one modal frequencies. To test this scenario, we analyzed 21 controlled excitation events from a certain bridge monitoring survey, focusing on lateral and vertical deflections, recorded both by GNSS and an accelerometer. These events contain a transient and a following oscillation, and they are preceded and followed by intervals of quiescence and ambient vibrations. Spectra for each event, for the lateral and the vertical axis of the bridge, and for and each instrument (GNSS, accelerometer) were computed, normalized to their maximum value, and printed one over the other, in order to produce a single composite spectrum for each of the four sets. In these four sets, there was also marked the true value of modal frequency, derived from free attenuating oscillations. It was found that for high SNR (signal-to-noise ratio) deflections, spectral peaks in both acceleration and displacement spectra differ by up to 0.3 Hz from the true value. For low SNR, defections spectra do not match the true frequency, but acceleration spectra provide a low-precision estimate of the true frequency. This is because various excitation effects (traffic, wind etc.) contribute with numerous peaks in a wide range of frequencies. Reliable estimates of modal frequencies can hence be derived from deflections spectra only if excitation frequencies (mostly traffic and wind) can be filtered along with most measurement noise, on the basis of additional data.

scholarly journals Convolution Network with Custom Loss Function for the Denoising of Low SNR Raman Spectra

Sensors ◽  
2021 ◽  
Vol 21 (14) ◽  
pp. 4623
Author(s):  
Sinead Barton ◽  
Salaheddin Alakkari ◽  
Kevin O’Dwyer ◽  
Tomas Ward ◽  
Bryan Hennelly
Keyword(s):  
Raman Spectra ◽  
Loss Function ◽  
Signal To Noise Ratio ◽  
Biomedical Science ◽  
Clinical Tool ◽  
Signal To Noise ◽  
Low Snr ◽  
Low Intensity ◽  
Spectral Peaks ◽  
Noise Ratio

Raman spectroscopy is a powerful diagnostic tool in biomedical science, whereby different disease groups can be classified based on subtle differences in the cell or tissue spectra. A key component in the classification of Raman spectra is the application of multi-variate statistical models. However, Raman scattering is a weak process, resulting in a trade-off between acquisition times and signal-to-noise ratios, which has limited its more widespread adoption as a clinical tool. Typically denoising is applied to the Raman spectrum from a biological sample to improve the signal-to-noise ratio before application of statistical modeling. A popular method for performing this is Savitsky–Golay filtering. Such an algorithm is difficult to tailor so that it can strike a balance between denoising and excessive smoothing of spectral peaks, the characteristics of which are critically important for classification purposes. In this paper, we demonstrate how Convolutional Neural Networks may be enhanced with a non-standard loss function in order to improve the overall signal-to-noise ratio of spectra while limiting corruption of the spectral peaks. Simulated Raman spectra and experimental data are used to train and evaluate the performance of the algorithm in terms of the signal to noise ratio and peak fidelity. The proposed method is demonstrated to effectively smooth noise while preserving spectral features in low intensity spectra which is advantageous when compared with Savitzky–Golay filtering. For low intensity spectra the proposed algorithm was shown to improve the signal to noise ratios by up to 100% in terms of both local and overall signal to noise ratios, indicating that this method would be most suitable for low light or high throughput applications.

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).

Sign in / Sign up

Export Citation Format

Share Document