MLABlibrarysvnkaklikMLAB_E8magsvn

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/dokumenty/skolni/diplomka/description.tex
1,4 → 1,4
\chap Trial design implementation
\chap Trial version of the receiver, design and implementation
The whole design of radioastronomy receiver digitalization unit is constructed to be used in a wide range of applications and tasks related to digitalization of signal from radioastronomy receivers. A good illustrating problem for its use is a signal digitalisation from multiple antenna arrays.

/dokumenty/skolni/diplomka/diplomka.tex
39,7 → 39,13
.
}
\abstractCZ {
Aktuální radioastronomická pozorovnání jsou dnes z důvodu existence rušení a potřeby získat velké úhlové rozlišení realizována jako multi anténní přijímací systémy. Takto konstruovaná zařízení mají ale značné nároky kvalitu zpracování signálu z více kanálů. V této práci je navržena možná realizace digitalizační části takového přijímače. Popsaná realizace je optimalizována na vysoký dynamický rozsah vstupních signálů a dobrou fázovou stabilitu, což jsou nejvýznamnější parametry pro použítí ve více anténních systémech. Konstrukce je koncipována jako open-source hardware řešení, které má zatím jedinnečné parametry v oblasti přístrojů určených pro amatérskou i profesionální radioastronomii.
Dnešní radioastronomická pozorovnání jsou kvůli rušení a potřebě získat velké úhlové rozlišení realizována jako víceanténní přijímací systémy. Takto konstruovaná zařízení mají ale značné nároky 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.
V diplomové práci jsem navrhl a realizoval zkušební verzi zařízení. Experimentoval jsem s ním. Ze zkušeností vyplývají doporučení pro opakovanou realizaci přijímačů, kterou chceme v amatérské síti pro sledování meteorů mnohonásobně zopakovat.
%Aktuální radioastronomická pozorovnání jsou dnes z důvodu existence rušení a potřeby získat velké úhlové rozlišení realizována jako multi anténní přijímací systémy. Takto konstruovaná zařízení mají ale značné nároky kvalitu zpracování signálu z více kanálů. V této práci je navržena možná realizace digitalizační části takového přijímače. Popsaná realizace je optimalizována na vysoký dynamický rozsah vstupních signálů a dobrou fázovou stabilitu, což jsou nejvýznamnější parametry pro použítí ve více anténních systémech. Konstrukce je koncipována jako open-source hardware řešení, které má zatím jedinnečné parametry v oblasti přístrojů určených pro amatérskou i profesionální radioastronomii.
} % If your language is Slovak use \abstractSK instead \abstractCZ
\keywordsEN { ADC interface, radioastronomy, signal digitalisation

/dokumenty/skolni/diplomka/introduction.tex
4,15 → 4,15
From a radioastronomer's point of view, it is important that radioastronomy focuses its interest primarily on natural signals originating in the surrounding universe. It does not pay much attention to the man-made signals created by our civilisation.
However, it is due to these artificial signals, that the current radioastronomy faces a disturbing problem. The problem arises from the fact, that there are so many terrestrial transmitters currently active and all of them are sources of a dense signal mixture which can cause trouble not only to radioastronomers.
However, it is due to these artificial signals, that the current radioastronomy faces a disturbance issue. The issue arises from the fact, that there are so many terrestrial transmitters currently active. All of them are sources of a dense signal mixture which can cause trouble not only to radioastronomers.
As a consequence, there already exist effort to control the radiofrequency spectrum. As result of attempts to control the radiofrequency spectrum, the frequency allocation table was created \cite[radio-astronomy-frequency]. Radio-frequency allocation table table contains special bands allocated to radioastronomy use. However, for many reasons these bands are not clean enough to be used directly in radioastronomy observations. As a result, we cannot work in the same way as had the radioastronomers in the very beginnings of radioastronomy. Many experiments, namely Cosmic microwave background detection or pulsar detection, cannot be nowadays realised in their original forms with satisfactory results.
As a consequence, there already exists an effort to control the radiofrequency spectrum. As result of attempts to control the radiofrequency spectrum, the frequency allocation table was created \cite[radio-astronomy-frequency]. The radio-frequency allocation table contains special bands allocated to radioastronomy use. However, for many reasons these bands are not clean enough to be used in radioastronomy observations directly. As a result, we cannot work in the same way as did the radioastronomers in the very beginnings of radioastronomy do. Many experiments, namely Cosmic microwave background detection or pulsar detection, cannot be realised nowadays in their original forms with satisfactory results.
Supporting evidence of such effect is RadioJOVE project. NASA engineers who originally created the RadioJOVE project had a great idea. The RadioJOVE project brought an opportunity for creating a publicly available, cheap radioastronomy receiver. However, they used an old-fashioned construction design which, on one hand, can operate in unoccupied harsh environments like deserts, but on the other it simply did not meet the criteria that would make it possible to be used in modern civilisation, as we know it in Europe \cite[radio-jove].
Supporting evidence of such an effect is RadioJOVE project. NASA engineers who originally created the RadioJOVE project had a great idea. The RadioJOVE project brought an opportunity for creating a publicly available, cheap radioastronomy receiver. However, they used an old-fashioned construction design which, on one hand, can operate in unoccupied harsh environments like deserts, but on the other hand it simply did not meet the criteria that would make it possible to be used in modern civilisation, as we know it in Europe \cite[radio-jove].
The source of its dysfunction is a presence of strong radiofrequency interferences. These interferences are orders of magnitude stronger than Jupiter decametric emissions, whose detection was the main aim of the RadioJOVE project.
From what we have already seen in the light pollution mitigation pursuit, there is only a small chance to radically improve the situation in radiofrequency spectrum.
From what we have already seen in the light pollution mitigation pursuit, there is only a small chance to improve the situation in radiofrequency spectrum radically.
The only way to overcome this problem is to search for new methods of radioastronomy observations. New methods which allows us to work without completely clear radiofrequency bands and which allow us to see the surrounding universe even despite the existence of man-made radiofrequency interference mixture. One solution is to use already known natural radio frequency signals parameters. Natural signals usually have different signal properties than local interference. Natural objects do not have problems with transmission in bandwidths of tens of megahertz in sub 100 MHz bands. These objects are usually far away and the same signal could be received at almost half of the Earth globe without any significant differences. On the other hand, it is obvious that signals with such parameters have some drawbacks, namely in the reception power. The reception power of radioastronomical object is $1 \cdot 10^9$ smaller than signal power received from a typical broadband radio transmitter.
The only way to overcome this problem is to search for new methods of radioastronomy observations, new methods which allows us to work without completely clear radiofrequency bands and which allow us to see the surrounding universe even despite the existence of man-made radiofrequency interference mixture. One solution is to use already known natural radio frequency signals parameters. Natural signals usually have different signal properties than local interference. Natural objects do not have problems with transmission in bandwidths of tens of megahertz in sub 100 MHz bands. These objects are usually far away and the same signal could be received at almost half of the Earth globe without any significant differences. On the other hand, it is obvious that signals with such parameters have some drawbacks, namely in the reception power. The reception power of radioastronomical object is $1 \cdot 10^9$ smaller than signal power received from a typical broadband radio transmitter.
From the above mentioned facts concerning the natural radio signals we can conclude that modern requirements imposed on a radioastronomy receiver are completely different from the requirements existing back in the history. Radioastronomy is no longer limited by an access to electronic components, today it is rather limited by the everywhere presence of electronic.