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A new narrowband signal detection method called subspace detection (SD) [1] was proposed recently for achieving improved detection performance in shallow ocean. The SD method requires the knowledge of mode functions and modal wavenumbers of the ocean channel. In this paper we present three new methods of narrowband signal detection in a partially known ocean using an array of acoustic vector sensors...
A specified probability of false alarm can be obtained for the FFT summation detector by setting the detection threshold as the product of the channel noise floor and the normalized detection threshold Tn. The channel noise floor is often adaptively estimated from the FFT filter bank output and Tn is mostly computed by solving a non-linear equation, which can be reliably accomplished when, L, the...
A simple measurement to analyze the signal detector's performance is desirable. Although, receiver operating characteristic (ROC) curve has long been used for characterizing system performance, area under the ROC curve (AUC) measurement provides meaningful insights of the system performance. Signal detector's performance can be characterized simply by average AUC, since average AUC varies from 0.5...
Opportunistic Dynamic Spectrum Access (DSA) systems are emerging as a key to enable the Department of Defense (DoD) to meet its technology requirements for access to the electromagnetic spectrum. One of the main goals of DSA is to protect incumbent spectrum users from interference that could be caused by DSA emitters. One of the ways to accomplish this is through spectrum sensing as means to enable...
This paper presents an efficient and reconfigurable MIMO detector design solution targeting on the emerging LTEA downlink. The detector supports signal detection of multiple MIMO modes which are spatial-multiplexing (SM), spatial-diversity (SD), and space-division-multiple-access (SDMA). Cost-reduction is achieved by algorithm and architecture co-design where low-complexity, near-maximum-likelihood...
This paper considers the problem of weak signal detection in the presence of navigation data bits for Global Navigation Satellite System (GNSS) receivers. Typically, a set of partial coherent integration outputs are non-coherently accumulated to combat the effects of model uncertainties such as the presence of navigation data-bits and/or frequency uncertainty, resulting in a sub-optimal test statistic...
Multiwavelets have recently been used for analysis of transient oscillations. Here we use them for transient oscillation detection by incorporating them into two existing Morlet-based self-normalizing detectors, one that operates on a single time series and another on two correlated time series. The Morlet-based detectors are effective in detecting weak, transient oscillations, especially in strong...
Technologies such as cognitive radio, interference coordination and spectrum sharing are promising to provide higher spectrum efficiency and throughput, and spectrum sensing is usually the first step. Generally, an intentionally emitted signal shows directionality at receiver in many cases. Intuitively, if we find the feature that characterizes the directionality of received signal, we can use this...
This paper compares different detection methods of radio broadcast frequencies to reduce dynamic PSD. It starts with spectrum analyzer-based measurements on the power lines to get experience with the ingress caused by the radio stations. Then a short wave radio detector algorithm is presented. Detailed analyses are made using this detector in conjunction with hundred thousands of PLC channels of devolos...
This paper presents the digital signal processor design for constant-false-alarm-rate (CFAR) signal detection in a frequency-modulated-continuous-waveform (FMCW) radar system. It is capable of identifying the beat signal from the spectrum so as to calculate the distance between the radar and the ground. The proposed CFAR signal detection design is an enhancement of the basic AND-CFAR architecture,...
Neural networks can easily fall into a local extremum and have slow convergence rate. Quantum Genetic Algorithm (QGA) has features of small population size and fast convergence. Based on the investigation of QGA, we propose a novel neural network model, Radial Basis Function (RBF) networks optimized by Quantum Genetic Algorithm (QGA-RBF model). Then we investigate the performance of the proposed QGA-RBF...
Sonar watermarking is defined by the secure embedding of a low power authentication code in selected components of a cover signal. The components to be watermarked are the selected time-frequency cells of the sonar pulse. In the past, watermark detection has been implemented as a step separate from sonar detection. From a practical standpoint, sonar detection must precede watermark detection. In this...
This paper examines the implementation of the Singular Value Decomposition (SVD) method to detect the presence of wireless signal. The method is used to find the maximum and minimum eigenvalues. We simulated the algorithm using common digital signal in wireless communication namely rectangular pulse shape, raised cosine and root-raised cosine to test the performance of the signal detector. The SVD-based...
In cognitive radio (CR) networks, spectrum sensing has to be performed in a reliable manner in challenging environments that arise due to propagation channels which undergo multi-path fading and non-Gaussian noise at CRs. Most existing literature on spectrum sensing has focused on impairments introduced by additive white Gaussian noise (AWGN). However, this assumption fails to model the behavior of...
In this paper, a new detection method which combines the semi-definite programming relaxation (SDR) with the sphere decoding (SD) is proposed for 256-QAM multiple-input multiple-output (MIMO) system. In this method, the SDR algorithms are engaged to obtain a primary result. Then, a hyper-sphere is constructed which is centered at the received signal and has its radius equals to the Euclidean distance...
We discuss the main principles of signal detection and signal processing algorithms employed by the 24 GHz frequency modulation continuous wave (FMCW) radar sensor systems under closing vehicle detection (CVD). This research deals with designing the detection and signal processing algorithm for FMCW radar sensor based on the generalized approach to target return signal detection and processing in...
Optimum signal detectors are investigated based on the underwater ambient noise collected in South China Sea in the winter of 2006. The statistics of underwater ambient noise has been firstly analyzed, and the results lead to a conclusion that the generalized Gaussian process is very suitable for ambient noise statistically modeling. Thereafter, the optimum detectors have been deduced for line spectrum...
It is known that, energy detector for spectrum sensing in cognitive system is simple in implementation, fast, and standards independent. However, it is known that energy detector suffers from its dependency over the noise level of detected signal. Different techniques have been proposed in order to combat that dependency. Among those techniques: antenna diversity, collaborative sensing, and double...
Reliable spectrum sensing is the key requirement for secondary users to opportunistically utilize the spectrum in the absence of primary users. To increase the secondary user's throughput and efficiency, it has to be able to detect the needed white band out of all possible bands in the shortest possible time. To speed up the spectrum sensing process and to minimize the power consumption overhead,...
Since Multiple Input Multiple Output (MIMO) transmission has become more and more popular for current and future mobile communication systems, MIMO detection is a big issue. Linear detection algorithms are less complex and well understood but their BER performance is limited. ML detectors achieve the optimum result but have exponential computational complexity. Hence, iterative tree-search algorithms...
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