Boris Simak

Improvement of handover prediction in mobile WiMAX by using two thresholds

One of the most important challenges in mobile wireless networks is to provide full mobility together with minimum degradation of quality of service. This can be ensured by handover prediction. Handover prediction means a determination of the next station that will serve a mobile station. This paper proposes a prediction technique based on monitoring the signal quality between the mobile station and all base stations in its neighborhood. The proposed technique utilizes two different thresholds for selection of the most likely target base station. Further, the potential improvement of the prediction efficiency via techniques originally proposed for minimizing the number of redundant handovers is analyzed. The efficiency of the proposed prediction technique is evaluated and compared with other prediction techniques based on channel characteristics in scenarios according to IEEE 802.16m. The proposed technique achieves a prediction hit rate of up to 93%.

Equiripple FIR triple narrow band filters

A novel design method for the digital optimal equiripple FIR triple narrow bandpass and triple narrow bandstop (notch) filters is presented. The filters are optimal in the Chebyshev sense. An example demonstrates the design procedure.

Very long band-pass FIR filters on the eight-core DSP TMS320C6678

Implementation of high performance linear phase FIR filters is presented. The filters are implemented on a high performance eight-core digital signal processor TMS320C6678. Selected aspects of the filter implementation are discussed.

Low-Complexity Voice Activity Detector Using Periodicity and Energy Ratio

An alternative low-complexity method to identify voice and silence regions in a speech signal is introduced in this paper. Its performance, limitations, and some other voice classification techniques which deal with energy estimation are presented as well. The proposed algorithm uses periodicity measure, high-frequency to low-frequency signal energy ratio, and total voiceband signal energy to provide voice/silence classification. According to the experiments results the algorithm is less susceptible to variable acoustic environment. Furthermore, it is possible to use this voice detection scheme for very low-energy speech, which in turn makes the detection more robust in situations where a poor-quality microphone is used or where the microphone recording level is low.

Fast and Robust Analytical Design of Equiripple Comb FIR Filters for Communication Purposes

A novel analytical design method for highly selective digital optimal equiripple comb FIR filters is presented. The equiripple comb FIR filters are optimal in the Chebyshev sense. The number of notch bands, the width of the notch bands and the attenuation in the passbands can be independently specified. The degree formula and the differential equation for the generating polynomial of the filter is presented. Based on the differential equation, a fast simple algebraic recursive procedure for the evaluation of the impulse response of the filter is described. Its arithmetic robustness outperforms by far the known analytical design method. Highly selective equiripple comb FIR filters with thousands of coefficients can be designed. One example demonstrates the efficiency of the filter design.

Implementation of Morse decoder on the TMS320C6748 DSP development kit

This paper presents a real-time implementation of a Morse code decoder based on the TMS320C6748 digital signal processor. The hardware platform is the TMS320C6748 DSP development kit LCDK. The decoder processes a noisy audio signal, detects Morse signals, selects the strongest one, extracts its dots and dashes, decodes the Morse code and displays the decoded symbols on the VGA monitor in real-time.

Pitch Detection Algorithms and Voiced/Unvoiced Classification for Noisy Speech

This paper describes pitch tracking techniques, which combine voiced/unvoiced classification and pitch estimation based on cepstral analysis, time autocorrelation, spectro-temporal autocorrelation (STA) and average magnitude difference function (AMDF). Pre- and post processing techniques improving performance of pitch detection algorithms (PDAs) are also presented. PDAs have been evaluated by telephone speech signals, corrupted by additive noise, in order to provide comparison and demonstrate their performance and robustness. Speech signals used for evaluation were taken from the Czech telephone speech database consisted of 5 male and 5 female speakers.

Degree of Equiripple Narrow Bandpass FIR Filter

This brief presents the degree equation of an equiripple narrow bandpass finite-impulse response filter, which follows from the filter approximation rather than from empirical data. The degree equation relates the filter specification and the corresponding filter degree. It completes the closed-form filter design, and it is useful in numerical design procedures as well. Two examples demonstrate its functionality and usefulness.

Education in real-time digital signal processing using digital signal processors

An advanced education in the real-time digital signal processing is presented. A practical training based on implementation of algorithms on digital signal processors is emphasized. Three laboratory tasks are presented. The long-year experience is summarized. Several recommendations are presented.

Fifth type of comb FIR filters

An extension of the design of digital equiripple comb FIR filters is presented. We introduce the fifth type of comb FIR filter which complements the existing four standard types. The design runs from the filter specifications through the degree formula to the impulse response coefficients, which are evaluated by an efficient recursive algorithm. One example is included.