Linas Svilainis

Learn More
The technique is suggested for a kind of pulse-width-modulation LED dimming in LED video displays. The significant increase of the gray levels number and image refresh frequency can be achieved when the large number of LEDs is controlled serially. The need for a large number of grayscale levels and high refresh rate is explained. The controlling data flow(More)
Some factors influence on light emitting diode (LED) far-field pattern (FFP) approximation performance is analyzed. The mean square root intensity error, mis correlation factor and half power and peak angles variance have been suggested for performance evaluation. The polynomial order, range and the noise influence have been analyzed. The best function(More)
The ultrasonic transducer excitation circuits have been investigated. The system structure is presented where excitation circuit is planned to be used. The possible excitation solutions are presented and discussed. The result of impedance measurement of ultrasonic transducer has been used to derive the Butterworth-Van Dyke electrical model.Then this model(More)
An overview of the electronics used to drive the light emitting diodes (LEDs) displays is presented. The common problems and the solutions are given. The driver technologies overview indicates the remaining challenges: the high current distribution and the LED dimming range. New driver topology suggested could solve the mentioned shortcomings.
Versatile system for ultrasound equipment parameters measurement is presented. The system is based on single direct digital synthesis (DDS) generator which is used for excitation and dual simultaneous sampling analog-to-digit (ADC) conversion channels. System is dedicated for ultrasound equipment frequency domain parameters measurement: transduction AC(More)
LED PWM dimming application for large scale LED video displays is analyzed. The need for short light pulse duration is outlined. PWM dimming with short driving pulses is investigated experimentally. The LED response time skew introduces the nonlinearity for PWM dimming. For LED response time skew estimation, a method is suggested that has been successfully(More)
The universal acquisition system is presented. System is dedicated for multiple frequency domain parameters measurement: transfer, insertion loss, AC response, harmonic distortion, noise and electrical impedance. The primary application was the ultrasonic equipment AC parameters evaluation. Operation range is 20 kHz to 30 MHz. System is targeted for(More)
Practical aspects of design and application radio frequency (RF) transformers in an ultrasonic system excitation channel are analysed. Design steps are discussed for those willing to design their own transformer an for excitation channel. Investigation has been carried out on what generator parameters can be obtained if instead of a purely active output(More)
Sun and ambient light is a serious problem for outdoor LED video displays. Shading the front-face surface by louvers implementation is used in majority of LED displays, but louvers influence the LED directivity. The analytical method is developed for image visibility estimation. The louver geometry and position are taken into account. LED FFP goniometry is(More)