Linas Svilainis

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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)
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)
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)
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)
Keywords: LED dimming LED video display Pulse-width-modulation LED display electronics a b s t r a c t 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(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)
Paper is analyzing the ultrasonic preamplifiers performance comparison problem. Technique and equipment for ultrasonic preamplifier's performance evaluation and different manufacturers' products comparison has been established. Equipment used and measurement technologies applied are described and presented. Experimental results for the measured complex gain(More)
LED video display smallest module is tile. Common LEDs intensity has to be used in order to match the neighboring tiles and manage white balance. This control is established by common resistor. But large currents present on LED tile distort the common source influence on individual LED drivers. This article is presenting the research conducted in order to(More)