Josip Job

A Possibility of Applying Differential Digital Holography in Manufacturing Process

This paper presents a method for detecting the small changes in image patterns applied on ceramic tiles using differential digital holography. Holograms are constructed from tile images using composition of spherical waves. One hologram is created from ceramic tile with correct pattern and the other hologram is created from tile with small error in pattern. The two holograms are subtracted and resulting hologram is observed. Next step in the process is creating image from subtracted holograms. The results show that for small change in the tile pattern there is a great alteration in the hologram and reconstructed image. The experiment is repeated with different tile errors in patterns

Method for Bandwidth Efficiency Increasing of M-ary PPM Transmitted-Reference UWB Communication Systems

One of the main drawbacks of conventional transmitted reference (TR) ultra-wideband systems is the fact that time delay between the reference and the data pulse has to be at least equal to channel delay spread, in order to avoid inter-pulse interference (IPI). This requirement drastically limits the achievable data rate of conventional TR systems based on M-ary pulse position modulation (PPM). In this paper, the new method for M-ary TR PPM scheme bandwidth efficiency increasing is proposed. In the proposed method the orthogonal codes are used such that only the pulses which can cause IPI are coded. Usage of such type of coding allows the reduction of time delay between the reference and the data pulse, whereas IPI is avoided. The proposed method achieves higher bandwidth efficiency than the conventional TR PPM method for the similar BEP performance level. Furthermore, the results show that an additional increase in bandwidth efficiency can be achieved by using higher modulation levels. Additionally, the analysis on tradeoffs between the BEP performance, bandwidth reduction and system costs is given in this paper.

Ultra-wideband transmitter based on integral pulse frequency modulator

The paper presents a novel short-range wireless sensor node architecture, based on Integral Pulse Frequency Modulator (IPFM) and Ultra-Wideband (UWB) pulse generator. Due to the lack of internal clock signal source and multi user implementation without application of a microprocessor, the architecture is simple and energy efficient. Multi-user coding is performed using delay elements, where each user has unique delay time value. The output of the IPFM is fed to the delay element. Delayed and original signal from the IPFM are feeding UWB pulse generator. The paper presents the transmitter architecture and measurements of the transmitter signals in time and frequency domain.

The receiver circuit for ultra-wideband integral pulse frequency modulated wireless sensor

The paper presents the novel receiver architecture for the short-range wireless sensor communication, based on Integral Pulse Frequency Modulator (IPFM) and Ultra-Wideband (UWB) pulse generator. UWB IPFM wireless sensor transmits ultra-wideband pulse pairs with information contained in the distance between consecutive pulse pairs. Multi-user coding is performed using delay elements, where each user has unique delay time. At the receiver input Low Noise Amplifier (LNA) amplifies UWB pulses and detect each pulse. Since the narrow pulses cannot be processed with digital signal processor, class C amplifier with integrated pulse stretcher is used at the output of the LNA. The amplified and stretched pulses are fed to the comparator which is followed by FPGA for digital signal processing and demodulation. The paper presents the architecture of the receiver that is implemented in discrete type laboratory prototype. Measurement results of the signals at each stage are presented for IPFM-based transmitter.

Chaos-Based transmitted-reference ultra-wideband communications

ABSTRACT Transmitted-reference (TR) ultra-wideband (UWB) communication systems have gained increasing popularity for the usage in the low data rate application, due to its non-coherent receiver structure. In conventional TR system, non-coherency at the receiver is achieved by sending reference pulses prior to the data-bearing pulses. Then, at the receiver side, reference pulses are used as template signals for correlation with data-bearing pulses. Therefore, the orthogonality between reference and data pulses is obtained in time division multiple access (TDMA) fashion. However, the implementation of a wideband delay line is very difficult in the current low power integrated circuits. In this paper, a TR method called Chaos-Based TR (CB-TR) is proposed. In the proposed method, chaotic sequences are used to separate the reference and data pulses. Such approach exploits the benefits of chaotic signals, such as non-periodicity, easy-to-generate, impulse-like autocorrelation value and low cross-correlation value. Furthermore, in order to decrease the influence of some negative properties of conventional chaotic maps, a modified chaotic generator (MCS) is proposed. Simulation results over the IEEE 802.15.4a channel model show comparable bit error rate performance to other TR methods.

Prediction of Euroleague Games based on Supervised Classification Algorithm k-Nearest Neighbours

Machine learning becomes one of the top fields in world of ICT (Information and communications technology). In the last few decades machine learning has taken a big boost in sports. Sport fans are using machine learning in sport betting and sport managers are using it for player selection, performance evaluation and even in outcome prediction. This paper gives basketball outcome prediction algorithms using k-nearest neighbours (k-nn). Few methods of preparing data calculated with different k and time period for k-nn algorithm will be presented and closely explained. Feature selection will also be discussed and results based on feature selection will be presented.