MLABlibrarysvnkaklikMLAB_E8magsvn

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/dokumenty/skolni/diplomka/description.tex
31,9 → 31,9
\sec Sampling frequency
The sampling frequency is not limited by the technical constrains in the trial version. This parameter is especially limited by the sampling frequencies of the analog-to-digital conversion chips available on the market and interface bandwidth. Combination of the required parameters -- dynamic range requiring at least 16bit and a minimum sampling frequency of 1$\ $MSPS \glos{MSPS}{Mega-Samples Per Second} leads to the need of high end ADC chips which does not support such low sampling frequencies at all. Their minimum sampling frequency is 5$\ $MSPS.
The sampling frequency has not been a limiting factor in the trial version. Generally, the sampling frequency is mostly limited by the sampling frequencies of the analog-to-digital conversion chips available on the market and by the interface bandwidth. The combination of required parameters -- dynamic range needing 16 bits at least and a minimum sampling frequency of 1 Mega-Samples Per Second (MSPS\glos{MSPS}{Mega-Samples Per Second}) -- leads to the need of the high-end ADC chips. However, they do not support such low sampling frequencies at all. Their minimum sampling frequency is 5$\ $MSPS.
We calculated a minimum data bandwidth data rate for eight receivers, 2 bytes per sample and 5$\ $MSPS as $8 \cdot 2 \cdot 5\cdot 10^6 = 80\ $MB/s. Such data rate is at the limit of the actual writing speed of classical HDD \glos{HDD}{Hard disk drive} and it is almost double the real bandwidth of USB 2.0 \glos{USB 2.0}{Universal Serial Bus version 2.0} interface. As a result of these facts we must use faster interface. Faster interface is especially needed in cases where we require faster sampling rates than ADC's minimal 5$\ $MSPS sample rate.
We calculated the minimal data bandwidth data rate for eight receivers, 2~bytes per sample and 5$\ $MSPS as $8 \cdot 2 \cdot 5\cdot 10^6 = 80\ $MB/s. Such data rate is at the limit of the actual writing speed of a classical hard disk drive (HDD\glos{HDD}{Hard disk drive}) and it is almost a double the real bandwidth of USB~2.0\glos{USB 2.0}{Universal Serial Bus version 2.0} interface. As a result of these facts, we must use a faster interface. Such a faster interface is especially needed in cases in which we require faster sampling rates than ADC's minimal 5$\ $MSPS sample rate.
The most perspective interface for use in our type of application is USB 3.0 or PCI Express interface. However, USB 3.0 is a relatively new technology without good development tools currently available. We have used PCI Express \glos{PCI Express}{Peripheral Component Interconnect Express} interface as the simplest and the most reliable solution.
\sec System scalability

/dokumenty/skolni/diplomka/diplomka.tex
37,14 → 37,14
\abstractEN {
Due to the ubiquitous presence of interference and a need for a large angular resolution, the current radioastronomical observations are carried out using multi-antenae receiver systems. Construction of such devices places great demands upon the quality of signal processing. A source of inspiration for my diploma thesis has been my own amateur radioastronomical activity in the field of meteor observations.
The thesis deals with a possible realization of a digitalization unit for a radioastronomical signal receiver. The implementation described in the thesis is optimized for a high dynamic range and good phase stability, both being the most important parameters for its application in the multi-antenae systems. Design and the instrument implementation have been created as open-source hardware solutions, so far having unique characteristics among the devices used in amateur or professional radioastronomy.
I have devised and implemented a trial version and made further experiments with it. A resulting recommendations for repeated implementations of the receivers, that we are planing to use in the amateur meteor observing networks, are based on these experiences.
Due to the ubiquitous presence of interference and a need for a large angular resolution, the current radioastronomical observations are carried out using multi-antennas receiver systems. Construction of such devices places great demands upon the quality of signal processing. A source of inspiration for my diploma thesis has been my own amateur radioastronomical activity in the field of meteor observations.
The thesis deals with a possible realization of a digitization unit for a radioastronomical signal receiver. The implementation described in the thesis is optimized for a high dynamic range and good phase stability, both being the most important parameters for its application in the multi-antennas systems. Design and the instrument implementation have been created as open-source hardware solutions, so far having unique characteristics among the devices used in amateur or professional radioastronomy.
I have devised and implemented a trial version and made further experiments with it. A resulting recommendations for repeated implementations of the receivers, that we are planing to use in the amateur meteor observing networks, are based on these experiences.
}
\abstractCZ {
Dnešní radioastronomická pozorovnání jsou kvůli rušení a potřebě získat velké úhlové rozlišení realizována jako víceanténní přijímací systémy. Takto konstruovaná zařízení mají ale značné nároky na kvalitu zpracování signálu z~více kanálů. K práci mě motivovala moje amatérská radioastronomická aktivita při sledování meteorů.
Dnešní radioastronomická pozorovnání jsou kvůli rušení a potřebě získat velké úhlové rozlišení realizována jako víceanténní přijímací systémy. Takto konstruovaná zařízení mají ale značné nároky na kvalitu zpracování signálu z~více kanálů. K práci mě motivovala moje amatérská radioastronomická aktivita při sledování meteorů.
Diplomová práce se zabývá možnou realizací digitalizační části přijímače radioastronomických signálů. Popsaná realizace je optimalizována na vysoký dynamický rozsah vstupních signálů a dobrou fázovou stabilitu, což jsou nejvýznamnější parametry pro použití ve víceanténních systémech. Návrh i konstrukce jsou koncipovány jako open-source hardwarové řešení, které má zatím jedinečné parametry v~oblasti přístrojů určených pro amatérskou i profesionální radioastronomii.