Recent Submissions

Now showing 1 - 5 of 36
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    Automatic Detection of Aerial Vehicle in Cloudy Environment by Using Wavelet Enhancement Technique
    (Společnost pro radioelektronické inženýrství, 2017-12) Pakfiliz, Ahmet G.
    Automatic target detection of surface to air surveillance and tracking systems in video applications is an important issue, because it is the first step for track initiation and continuity. Target detection can be readily overcome for clear sky conditions, but it may be a complicated problem for cloudy sky conditions. In order to fulfill automatic target detection by using conventional image processing techniques may be a hard problem in cloudy sky conditions and improper light affects. The difficulty comes from the clutter rates stem from clouds, and the target may get lost in the clutters that occupies in the whole frame area. In order to increase the detection possibility background clutters should be eliminated by using image processing techniques frame by frame. In this work a novel approach is proposed to detect air vehicles in every kind of cloudy sky conditions. For this purpose a wavelet based image enhancement algorithm is implemented to the video frames, then conventional techniques are used. These conventional techniques are the reciprocal pixel intensity measurement data usage, Sobel operator and thresholding processes for edge detection. The proposed algorithm gives outstanding results for flying object detection in different sky conditions.
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    Signals of Autodyne Sensors with Sinusoidal Frequency Modulation
    (Společnost pro radioelektronické inženýrství, 2017-12) Noskov, Vladislav Ya.; Ignatkov, Kirill A.; Chupahin, Andrey P.; Vasilyev, Aleksandr S.; Ermak, Gennadiy P.; Smolskiy, Sergey M.
    Research results of signal formation features of the autodyne sensor (AS) with sinusoidal frequency modulation (FM) are presented. Expressions for low frequency information signals are given and their numerical analysis is performed for cases when signal period is substantially longer than reflected radiation delay time as well as for the case when this inequality is not fulfilled. It is proved that at a small distance to the reflected object when feedback parameter value is commensurable with 1, the distortions of FM AS signals are typically caused by reflected radiation phase incursion irregularities. When distance grows the distortion level becomes significantly smaller due to delay phenomenon of reflected radiation. Experimental research results are obtained on the example of the autodyne oscillator based on the 8-mm wavelength range Gunn diode with varicap-based FM.
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    Overlapping White Blood Cells Detection Based on Watershed Transform and Circle Fitting
    (Společnost pro radioelektronické inženýrství, 2017-12) Sukhia, Komal Nain; Riaz, M. Mohsin; Ghafoor, Abdul; Iltaf, Naima
    White blood cell (WBC) count and segmentation is considered to be important step to diagnose diseases like leukemia, malaria etc. Automatic analysis of blood smear images will help hematologists to detect WBCs efficiently and effectively as compared to manual analysis which is quite time consuming. Therefore, an automatic white blood cells detection technique for complex blood smear images is proposed. The proposed scheme uses segmentation and edge map extraction for the separation of overlapped WBCs and further parametric circle approximation is used which is capable of detecting both separated and overlapped white blood cells. Simulation results compared with the existing techniques verify the accuracy and robustness of the proposed scheme.
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    Signal Subspace Speech Enhancement with Oblique Projection and Normalization
    (Společnost pro radioelektronické inženýrství, 2017-12) Surendran, Sudeep; Kumar, T. Kishore
    In this paper, a subspace speech enhancement method handling colored noise using oblique projection is proposed. Perceptual features and variance normalization are used to reduce residual noise and improve speech intelligibility of the output. Initially, additive noise is removed from the noisy speech by removing the orthogonal noise subspace from the noisy speech subspace to obtain the speech subspace. Then, the oblique projection of the noise subspace on the speech subspace along the additive noise subspace is used to determine the colored noise that remains. The enhanced clean speech signal is estimated using Spectral Domain Constrained Estimator, incorporating the masking property of the auditory system and the variance of the colored noise. To avoid the occurrence of any abrupt spikes in the output, variance normalization is performed by adaptively changing the control parameter of the gain matrix. The spectrogram, objective measures and subjective intelligibility test show superior performance of the proposed method over other existing speech enhancement methods.
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    Micro-Diversity Analysis of Error Probability and Channel Capacity over Hoyt-Gamma Fading
    (Společnost pro radioelektronické inženýrství, 2017-12) Kumar, Sandeep; Soni, Sanjay Kumar; Jain, Priyanka
    In wireless communication system, various parameters such as average symbol/bit error probability (ASEP/ABEP), outage probability and average channel capacity, etc. are studied for its performance analysis. In this paper, the performance of L-Hoyt/Gamma (HG) composite fading channel with Maximum Ratio Combining (MRC) employing micro-diversity is analyzed. Closed-form expressions for distribution function, moments, outage probability and channel capacity are derived in terms of hypergeometric functions. Further, the expressions of ASEP/ABEP for all formats of coherent and non-coherent modulation techniques involving Q-functions and Marcum Q-function are derived over the composite fading channel. Monte-Carlo simulations are performed to validate our analytical results. The analytical results produced here can be useful in several wireless applications where multipath and shadowing are characterized by Hoyt/Gamma distribution.