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Vol 62, No 1 (2019)
- Year: 2019
- Articles: 6
- URL: https://journals.rcsi.science/0735-2727/issue/view/10937
Article
Distributed Clutter-Map Constant False Alarm Rate Detection Using Fuzzy Fusion Rules
Abstract
The performance of distributed adaptive clutter map constant false alarm rate (CMAP-CFAR) detection system using fuzzy fusion rules with homogeneous and non-homogeneous background is considered in this paper. We assume that the sensors are identical and the target is fluctuating according to Swerling I model embedded in a white Gaussian noise with unknown variance. Each detector computes the value of the membership function to the false alarm space from the previous samples of the cell under test and transmits it to the fusion center. These values are combined according to fuzzy fusion rules to produce a global membership function to the false alarm space. The obtained results showed that the best performance was obtained while using the “algebraic product” fuzzy rule and the probability of detection increases significantly with the number of detectors.
1-5
Efficiency Estimation of Discrete Algorithms for Adaptation of Weight Coefficients in Space-Time Processing of Radar Signals
Abstract
A comparative analysis of the efficiency of adaptive spatial filters with different methods of classified training sample formation under conditions of simultaneous exposure to active noise and passive interference is carried out. Based on the proposed methodology, analytical calculations of the changes in interchannel phase shifts for discrete algorithms for the adaptation of the weight coefficients of the spatial filter in various modes of operation of the 36D6 radar are carried out. It is shown that interchannel phase desynchronization/error arise at pause intervals in the adaptation of weight coefficients during antenna system scanning. The magnitude of these desynchronizations depends on the angular velocity of the antenna system rotation and on the repetition period of the radar pulses. An estimation of the suppression coefficient realized at the end of the pause in the adaptation of the weight coefficients taking into account the interchannel phase desynchronization is carried out. The recommendations on the choice of the formation method of the classified training sample under the conditions of the combined interferences are considered taking into account the losses that arise in case of discrete adaptation of the weight coefficients of the spatial filter.
6-11
Remote Identification of Liquids in a Dielectric Container Using Millimeter Waves. 3. Angular Scanning
Abstract
The use of radiometric and quasi-optical principles enables obtaining remote thermal portraits of the studied liquids in a closed dielectric container for distances from few centimeters to several meters. Microwave angular polarization radiometric scanning was used for the first time, and allows to remotely obtaining authentic thermal portraits for liquids that are similar in their physicochemical properties. It was experimentally shown that objects that have nearly indistinguishable thermal portraits (water-alcohol solutions, diesel fuels) in case of linear scanning, reveal signatures that make it easy to identify them and also to distinguish the dielectric containers for liquids in case of angular scanning. The method of angular radiometric scanning enabled obtaining the components of transmitted, absorbed and reflected waves for the authentication of liquids based on their thermal portraits in one measurement cycle. The broadband noise electromagnetic wave generated by the illumination source carries the information about the liquid and the container. The use of angular scanning reduced the time for obtaining useful information to 14 s or 4 times compared with linear scanning. The results of the study of hazardous liquids are presented on the example of combustible liquids: refined petroleum products (solvents, diesel fuels) and aqueous-alcoholic solutions in containers with dielectric constant - = 2–16. It was experimentally shown that a microwave radiometric thermal portrait carries information about the number of molecules with a weak hydrogen bond in aqueous-alcoholic solutions. The proposed method for remote identification of liquids in a closed dielectric package is safe and environmentally friendly, since the required level of the illuminating noise radiation does not exceed the value of 20 dB/kT0.
12-22
Fingers Movements Control System Based on Artificial Neural Network Model
Abstract
Surface electromyographic (sEMG) signal is used in the various fields of applications where the need exists to measure the activity of body muscles, such as brain-computer interfaces, game industry, medical engineering, and other practical spheres. Even more, the use of sEMG signal in the field of active prosthesis industry has become traditional for many years. However, despite the fact that the question of using it in the field of fingers prostheses is still open, in general, the sEMG signal required multichannel measuring devices or massive, voluminous equipment for precise recognition of hands or fingers movement. That is decreasing the possible portability and convenience of prostheses and as a consequence is increasing their final price. In this paper we propose a method of organizing the controlling and measuring unit of the prosthetic device based on artificial neural network (ANN) model and one-channel microcontroller based sEMG measuring system. The proposed ANN model works with only 4 input time-domain features of sEMG signal and provides an accuracy of 95.52% for classification of 6 different types of finger movements that makes it a good solution for next implementation in the system of prosthetic fingers or wrist devices.
23-33
Parametric Spectral Analysis of Noisy Signals with Unimodal Spectrum
Abstract
The article proposes a method for the coefficients reconstruction of a discrete autocorrelation function of random signals with a unimodal power spectral density to construct their parametric models. The method is based on finding the optimal values of the relative width ΔFT and the weighting factor α ∈ [0; 1] of the spectral mode, which characterizes the share of the Gaussian and resonant components in the spectrum envelope. The proposed method makes it possible to reduce by 1.5–4 times the discrepancy between the control and estimated spectra in comparison with the known approaches to parametric spectral analysis. An increase in the adequacy of spectral estimation makes it possible to reduce the length Mof the analyzed time sample by a factor of 2.3–4 times, while maintaining the accuracy of the spectral analysis achieved by other known parametric methods. Winnings are achieved by using a priori information about the spectral properties of the analyzed process.
34-41
Clutter Parameter Estimation Based on Indirect Algorithms
Abstract
Indirect algorithms for clutter parameter estimation using linear transformations of initial data have been synthesized by the maximum likelihood method. The likelihood function was introduced for the input samples transformed in accordance with the sum-difference algorithms. The estimation algorithms of the interperiod correlation and Doppler phase shift coefficients derived by solving the appropriate likelihood equations do not contain the traditional complex multiplication operation over input data. The functional block diagram of the estimator of appropriate clutter parameters that can be used in adaptive rejection filters is presented. The estimation accuracy analysis of required parameters of clutter is performed depending on the size of training sample and correlation properties of clutter. The comparison of simulation and calculation results for indirect and direct algorithms revealed their complete match and confirmed the asymptotic efficiency of resultant estimates and the equivalence of indirect and direct algorithms.
42-50