High resolution stopwatch for cents

A very low-cost, easy-to-make stopwatch is presented to support various experiments in mechanics. The high-resolution stopwatch is based on two photodetectors connected directly to the microphone input of the sound card. A dedicated free open-source software has been developed and made available to download. The efficiency is demonstrated by a free fall experiment

Noise properties in the ideal Kirchhoff-Law-Johnson-Noise secure communication system

In this paper we determine the noise properties needed for unconditional security for the ideal Kirchhoff-Law-Johnson-Noise (KLJN) secure key distribution system using simple statistical analysis. It has already been shown using physical laws that resistors and Johnson-like noise sources provide unconditional security. However real implementations use artificial noise generators, therefore it is a question if other kind of noise sources and resistor values could be used as well. We answer this question and in the same time we provide a theoretical basis to analyze real systems as well

Power spectral density estimation for wireless fluctuation enhanced gas sensor nodes

Fluctuation enhanced sensing (FES) is a promising method to improve the selectivity and sensitivity of semiconductor and nanotechnology gas sensors. Most measurement setups include high cost signal conditioning and data acquisition units as well as intensive data processing. However, there are attempts to reduce the cost and energy consumption of the hardware and to find efficient processing methods for low cost wireless solutions. In our paper we propose highly efficient signal processing methods to analyze the power spectral density of fluctuations. These support the development of ultra-low-power intelligent fluctuation enhanced wireless sensor nodes while several further applications are also possible

What kind of noise guarantees security for the Kirchhoff-Loop-Johnson-Noise key exchange?

This article is a supplement to our recent one about the analysis of the noise properties in the Kirchhoff-Law-Johnson-Noise (KLJN) secure key exchange system [Gingl and Mingesz, PLOS ONE 9 (2014) e96109, doi:10.1371/journal.pone.0096109]. Here we use purely mathematical statistical derivations to prove that only normal distribution with special scaling can guarantee security. Our results are in agreement with earlier physical assumptions [Kish, Phys. Lett. A 352 (2006) 178-182, doi: 10.1016/j.physleta.2005.11.062]. Furthermore, we have carried out numerical simulations to show that the communication is clearly unsecure for improper selection of the noise properties. Protection against attacks using time and correlation analysis is not considered in this paper

Spectra for the product of Gaussian noises

Products of Gaussian noises often emerge as the result of non-linear detection techniques or as a parasitic effect, and their proper handling is important in many practical applications, including in fluctuation-enhanced sensing, indoor air or environmental quality monitoring, etc. We use Rice's random phase oscillator formalism to calculate the power density spectra variance for the product of two Gaussian band-limited white noises with zero-mean and the same bandwidth W. The ensuing noise spectrum is found to decrease linearly from zero frequency to 2W, and it is zero for frequencies greater than 2W. Analogous calculations performed for the square of a single Gaussian noise confirm earlier results. The spectrum at non-zero frequencies, and the variance of the square of a noise, is amplified by a factor two as a consequence of correlation effects between frequency products. Our analytic results is corroborated by computer simulations.Comment: submitted for publicatio

Efficient Sound Card Based Experimention At Different Levels Of Natural Science Education

Sound cards, which count as standard equipment in today's computers, can be turned into measurement tools, making experimentation very efficient and cheap. The chief difficulties to overcome are the lack of proper hardware interfacing and processing software. Sound-card experimentation becomes really viable only if we demonstrate how to connect different sensors to the sound card and provide suitable open-source software to support the experiments. In our talk, we shall present a few applications of sound cards in measurements: photogates, stopwatches and an example of temperature measurement and registration. We also provide the software for these applications.Comment: MPTL-HSCI 2011 Joint conference, 15-17 September 2011, Ljubljana, Sloveni

Interdiszciplináris fluktuáció és zajproblémák technológiai alkalmazásokkal: nanostrukturák, sztochasztikus rezonancia, szenzorok és más releváns alkalmazások = Interdisciplinary scientific problems of noise and fluctuations with technological applications: nanostructures, stochastic resonance, sensors and other relevant applications

A kutatások során numerikus szimulációkkal és mérésekkel is megmutattuk, hogy a sztochasztikus rezonancia segítségével jelentős jel/zaj viszony erősítés érhető el igen általános feltételek és bemenő jelek esetére. Az 1/f zaj időbeli szerkezetének vizsgálatához DSP alapú jelgenerátort fejlesztettünk ki, és empirikus formulát adtunk meg a zaj szintmetszési statisztikájának leírására. Neurokardiológiai kutatási erdeményeink közé tartozik a vérnyomásjelek spektrális analízisének új, artefaktumokra sokkal kevésbé érzékeny módszerének bevezetése és DSP alapú mérőműszerek kifejlesztése. Félvezető polimerek termikus és elektromos tulajdonságainak kutatásába, nanotechnológiai alapú kémiai szenzorok vizsgálatába is bekapcsolódtunk. Digitális műszereket fejlesztettünk ki impulzuslézerek késleltetésének sztochasztikus szabályozására és egy AFM mérőműszer precízebb vezérléséhez is. A virtuális méréstechnikában szerzett jártasságunkra alapozva szakmódszertani kutatásként demonstrációs kísérleteket fejlesztettünk ki. A kutatási eredmények publikációi: 3 könyv illetve konferenciakiadvány szerkesztése; 6 nemzetközi és 2 hazai meghívott előadás, 8 nemzetközi és 1 hazai cikk, 10 nemzetközi és 1 hazai konferenciaelőadás. | On the basis of numerical simulations and measurements we have shown that high signal-to-noise ratio gain can be obtained in systems showing stochastic resonance for quite general conditions and various signals. The time structure of 1/f type noises has been explored by universal DSP based noise generator developed by our group. We have introduced an empirical expression for the level-crossing statistics of 1/f noises. We have shown a new method for the spectral analysis of blood pressure which is much more straightforward and insensitive to artifacts than the commonly used resampling method. DSP based instruments supporting neurocardiological data acquisition have also been developed. We have started collaborations for the research of the thermal and electrical properties of semiconductor polymers, and nanotechnology-based chemical sensors. We have developed intelligent instruments for the stochastic control of laser pulse delays and a more precise control of an atomic force microscope (AFM). We have also developed demonstration experiments based on virtual instrumentation technology. Our results have been shown to the public in numerous publications: we have edited 3 books and conference proceedings, presented 6 international and 2 domestic invited talks, published 8 international and 1 domestic papers, presented 10 international and 1 domestic regular conference talks