Showing 7 results for Radar
M. R. Moniri, M. M. Nayebi, A. Sheikhi,
Volume 4, Issue 4 (12-2008)
Abstract
A detector for the case of a radar target with known Doppler and unknown
complex amplitude in complex Gaussian noise with unknown parameters has been derived.
The detector assumes that the noise is an Auto-Regressive (AR) process with Gaussian
autocorrelation function which is a suitable model for ground clutter in most scenarios
involving airborne radars. The detector estimates the unknown parameters by Maximum
Likelihood (ML) estimation for the use in the Generalized Likelihood Ratio Test (GLRT).
By computer simulations, it has been shown that for large data records, this detector is
Constant False Alarm Rate (CFAR) with respect to AR model driving noise variance. Also,
measurements show the detector excellent performance in a practical setting. The detector’s
performance in various simulated and actual conditions and the result of comparison with
Kelly’s GLR and AR-GLR detectors are also presented.
M. Alaee, M. Sepahvand, R. Amiri, M. Firoozmand,
Volume 6, Issue 3 (9-2010)
Abstract
In order to detect targets upon sea surface or near it, marine radars should be
capable of distinguishing signals of target reflections from the sea clutter. Our proposed
method in this paper relates to detection of dissimilar marine targets in an inhomogeneous
environment with clutter and non-stationary noises, and is based on adaptive thresholding
determination methods. The variance and the mean values of the noise level have been
estimated in this paper, based on non-stationary, statistical methods and thresholding has
been carried out using the suggested two-pole recursive filter. Making the rate of false
alarm constant, the concerned threshold resolves the hypothesis of existence or absence of
the target signal. Performance of the mentioned algorithm has been compared with the
well-known conventional method as CA-CFAR in terms of decreasing the losses and
increasing calculation speed. The algorithm provided for detection of signal has been
implemented as a part of signal-processing algorithms of some practical marine radar. The
results obtained from the algorithm performance in a real environment indicate appropriate
workability of this method in heterogeneous environment and non-stationary interference.
A. Merline, S. J. Thiruvengadam,
Volume 7, Issue 2 (6-2011)
Abstract
The role of waveform design is central to effective radar resource management for state-of-the art radar systems. The waveform shape employed by any radar system has always been a key factor in determining the performance and application. The design of radar waveform to minimize mean square error (MSE) in estimating the target impulse response is based on power allocation using waterfilling. This paper shows the effect of various power control strategies in the MMSE performance of the waveform design. We find that the truncated power control strategy exhibits a good MMSE performance. The performance improvement results from the fact that with the truncated power control no power is wasted in poor quality modes.
H. Khoshbin, S. M. Sajjadi,
Volume 8, Issue 4 (12-2012)
Abstract
Abstract: This paper proposes a novel scheme for multi-static passive radar processing, based on soft-input soft-output processing and Bayesian sparse estimation. In this scheme, each receiver estimates the probability of target presence based on its received signal and the prior information received from a central processor. The resulting posterior target probabilities are transmitted to the central processor, where they are combined, to be sent back to the receiver nodes or used for decision making. The performance of this iterative Bayesian algorithm comes close to the optimal multi-input multi-output (MIMO) radar joint processing, although its complexity and throughput are much less than MIMO radar. Also, this architecture provides a tradeoff between bandwidth and performance of the system. The Bayesian target detection algorithm utilized in the receivers is an iterative sparse estimation algorithm named Approximate Message Passing (AMP), adapted to SISO processing for passive radar. This algorithm is similar to the state of the art greedy sparse estimation algorithms, but its performance is asymptotically equivalent to the more complex l1-optimization. AMP is rewritten in this paper in a new form, which could be used with MMSE initial filtering with reduced computational complexity. Simulations show that if the proposed architecture and algorithm are used in conjunction with LMMSE initial estimation, results comparable to jointly processed basis pursuit denoising are achieved. Moreover, unlike CoSaMP, this algorithm does not rely on an initial estimate of the number of targets.
A. Abdolali, M. M Salary,
Volume 10, Issue 3 (9-2014)
Abstract
The proposed theorem in this paper is indicative of a kind of duality in the propagation of waves in the dual media of and in the spherical structures. Independent of wave frequency, the number of layers, their thickness, and the type of polarization, this theorem holds true in case of any change in any of these conditions.
Theorem: Consider a plane wave incident on a multilayered spherical structure. The core of structure may be PEC, metamaterial or dielectric. If we apply the interchange or for the constituting materials of the spherical structure and the surrounding medium the radar cross section of the structure will not change in any direction.
S. A. Karimi, S. Mirzakuchaki,
Volume 17, Issue 4 (12-2021)
Abstract
Various methods have been proposed to detect the attention and perception of an operator during tasks such as radar monitoring. Due to the high accuracy of electroencephalographic signals, it is utilized for systems based on brain signal. The event-related potential (ERP) technique has been widely used for testing theories of perception and attention. Brain-computer Interface (BCI) provides the communication link between the human’s brain and an external device. In this article, we propose a method to investigate the attention of operators of very sensitive monitoring devices, in particular, the operators of navy ships’ radars in detecting fighter aircrafts. Using a Visual Stimuli, which was shown to the subjects prior to the test, the protocol utilized in this paper yielded a very high accuracy (up to 87%), which makes it a robust method to use in such conditions. Linear LDA and non-linear SVM classifiers were utilized in processing the output signal. Although several P300 systems have been used to detect attention using pattern recognition techniques, the novelty of this study is that attention detection is used for the first time for a radar operator which resulted in acceptable accuracy.
A. Chaabane, M. Guerroui,
Volume 17, Issue 4 (12-2021)
Abstract
A new design of a Coplanar Waveguide-Fed (CPW) Ultra Wideband (UWB) Rhombus-shaped antenna for Ground Penetrating Radar (GPR) applications is designed and discussed in this work. The antenna has a simple design which is composed by a rhombus-shaped patch and a modified ground plane. The working bandwidth is improved by removing the metal from the upper part of the ground plane surrounding the patch and by introducing a corrugation geometry in the ground plane. The proposed antenna was designed on a low-cost FR4-substrate having a compact size of 0.2721λ0×0.2093λ0×0.0157λ0 at 3.14 GHz. All the simulations were carried out by using the commercially software CST Microwave StudioTM. The simulated results show that the designed antenna covers an UWB extending from 3.14 GHz to 13.82 GHz (125.94%) and indicate excellent radiation performances throughout the operating bandwidth. The measured bandwidth is nearly extending between 3.95 GHz and 13.92 GHz (111.58%). Besides, the antenna bandwidth response was checked in close proximity to a mass of Concrete. The obtained results are satisfactory and assure the efficiency of the designed antenna to work as a GPR antenna.
