Zdenek Nemec

UWB through-wall propagation measurements

The propagation of ultra-wideband (UWB) signals is analyzed. The UWB radar output signals are formed both with transmitter and antenna. Moreover, they can be substantially affected due to electromagnetic wave propagation through walls. Experimental results and numerical simulations are analyzed and compared. The given examples show that the numerical simulations, which are very fast, could be reliable, when suitable wall parameters are used.

Computing of bistatic cross-ambiguity function on GPU

The real-time computation of cross ambiguity function (CAF) using brute force and block processing methods is a challenging task for parallel programming techniques. CAF is a key function for successful location tracking by passive radar systems. In this paper, the comparison of CAF methods computation and using a Graphics Processing Unit (GPU) are presented. The main goal of the research is to compare the computation efficiency and speed of the CAF methods on the GPU hardware with a single or multi-Core PC workstation. The results show the highest speed-up factor using GPU for all CAF methods.

A TDOA system using received signal decomposition on delayed replicas

The paper deals with a received Wi-Fi (802.11 spec, b) signal, consisting of a dominant direct-path component and of a sum of multiple reflected signals. In this paper the system based on decomposition of RF data signals to a linear combination of delayed replicas is suggested. The dominant components TDOAs could then be evaluated with a higher accuracy. It is shown, that this method may significantly enhance position estimation accuracy in indoor TDOA systems.

Real-time sound source localization

This paper deals speaker localization using received acoustic signals on microphone array. The real time localization system is based on method for a speaker speech processing and extraction of sibilant sequence. It is shown, that this method leads to good position estimation accuracy in indoor systems.

Advanced targets association based on GPU computation of PHD function

The precise and quick association of targets is one of the main challenging tasks in the signal processing field of the Multistatic Radar System (MRS). The paper deals with target association techniques based on the computation of the Probability Hypothetic Density (PHD) Function. The Computation time makes solving the PHD a very demanding task. The speedup of a newly developed algorithm depends on vectorization and parallel processing techniques. This paper describes the comparison between the original and parallel version of the target association algorithm with the full set of input data (without any knowledge about the approximation of targets direction) and the comparison with the advanced target association algorithm using additional input information about the direction of the target. All algorithms are processed in the MATLAB environment and Microsoft Visual Studio - C. The comparison also includes Central Processor Unit (CPU) and Graphics Processor Unit (GPU) version of all algorithms.

Speed-up the computing of bistatic cross-ambiguity function

Cross ambiguity function (CAF) is the key function for successful location tracking for passive radar systems. This paper describes several brute-force methods of CAF. The computation time of CAF is a challenging problem for parallel programming techniques. In this paper the CAF is computed with multi-core and cluster approach.

Multipath Propagation Effects of UWB Radars

The propagation of ultra wide band (UWB) signals is analyzed. The UWB radar output signals are formed both with transmitter and antenna. Moreover, they can be substantially affected due to electromagnetic wave propagation through walls and multipath effects. Multipath effects are analyzed and simulated numerically for various cases with several heights and distances.

Propagation over terrain considering refractivity profiles

The physical optics (PO) calculations have been utilized for numerical simulations of electromagnetic field above irregular ground. The PO approximation and numerical simulations using parabolic equation method are used for new comparison with findings of longstanding testing of microwave field and tropospheric refractivity profiles. It is demonstrated that the PO could offer reliable numerical simulations for low altitude field and diffraction field zone even for numerous three-dimensional distributions of the atmospheric refraction.

Speed-up the computing of bistatic cross-ambiguity function on different hardware configuration

Cross ambiguity function (CAF) is the key function for successful location tracking for passive radar systems. This paper describes several methods of the CAF based on block processing. The computation time of the CAF is a challenging problem for parallel programming techniques. In this paper the CAF is computed with Multi-core and Cluster approaches.

Research of harmonic spectrum of currents in traction drive with PMSM

The paper deals with the significant results of the experimental research of the harmonic spectrum of currents and induced voltages at traction drive with permanent magnet synchronous motors (PMSM). The experiments were done in a special workplace with a real traction drive for wheel vehicles. The harmonic spectrums of currents were analyzed by a specialized device on the basis of a central measuring station. The knowledge of marked subharmonic components of stator winding currents is the most significant finding of these experiments. The frequencies of these components are given by multiples of frequency of mechanical speeds. The subharmonic components also pass to the dc current at an input site of the traction inverter. This fact is particularly important from the viewpoint of legislative requirements to electromagnetic compatibility (EMC) of drive with railway interlocking devices.