355 research outputs found
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
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
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
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
Low-cost photoplethysmograph solutions using the Raspberry Pi
Photoplethysmography is a prevalent, non-invasive heart monitoring method. In
this paper an implementation of photoplethysmography on the Raspberry Pi is
presented. Two modulation techniques are discussed, which make possible to
measure these signals by the Raspberry Pi, using an external sound card as A/D
converter. Furthermore, it is shown, how can digital signal processing improve
signal quality. The presented methods can be used in low-cost cardiac function
monitoring, in telemedicine applications and in education as well, since cheap
and current hardware are used. Full documentation and open-source software for
the measurement available:
http://www.noise.inf.u-szeged.hu/Instruments/raspberryplet/Comment: 14th IEEE International Symposium on Computational Intelligence and
Informatics (CINTI 2013), November 19-21, 2013, Budapest, Hungar
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