Modris Greitans

Learn More
The instantaneous frequency of a chirp-like signal varies with time. The sampling density of a signal should preferably correspond to its local bandwidth. The paper discusses the level-crossing sampling principle, which provides the capability for performing such an analog-to-digital conversion. The properties of level-crossing sampling are considered. As(More)
This paper combines the results of our previous experiments concerning acquisition of the images of the human palm in infrared and visible light, the extraction of features from images as well as our current results on biometric data hashing with the advanced biohashing algorithm. We first describe the properties of the complex 2D matched filtering for(More)
Accurate extraction of previously defined objects from noisy images is still a challenge for most image processing systems. There is a trade-off between the unwanted and useful amount of extracted information. From quality aspect, the matched filtering approach is preferable, as it significantly reduces the amount of unwanted information; however, the(More)
The paper discusses an original approach to speech processing. Traditionally it is organized using uniform sampling with a fixed sampling rate, which is followed by encoding to reduce amount of data for transmission. The proposed approach is based on event-driven digital-to-analog conversion that produces data with low redundancy and allows the compression(More)
The paper presents an improved version of Asynchronous Sigma-Delta Modulator (ASDM) in order to reduce its power consumption for time-encoding of analog signals. The proposed method is called Amplitude Adaptive ASDM (AA-ASDM) since time-varying envelope of the signal is used in the feedback loop of ASDM to reduce the switching rate of the output trigger.(More)
We propose a hybrid architecture of wired and wireless sensors for smart fabric with applications including body dynamics and shape monitoring and patient rehabilitation. Our system is capable of acquiring data from up to 200 on-body sensors with 50Hz sampling rate using conventional low-cost hardware. The sensing and data processing is done in real time(More)
The paper describes the processing of non-stationary signals, which takes the advantages offered by the use of signal-dependent techniques in sampling and analysis procedures. The level-crossing approach is exploited for signal sampling, whereby the local sampling density provides information about the local maximum spectral frequency of the signal. The(More)