| 82,7 → 82,7 |
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| \secc Bandwidth |
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| Historically, the parameter of bandwidth in radioastronomical receiver used to be within the kilohertz range. Small bandwidth was acceptable because observations were processed directly by listening or by paper chart intensity recorder. Chart recorder integrated energy of signal over defined small bandwidth which was suitable for detecting the intensity variance of microwave background. No wideband transmitters existed in that era (except for TV transmitters) and tuning to other neighbouring frequency was easy as they were mostly vacant. Parallel observations from several places were unnecessary as well because the electromagnetic conditions were nearly same at all locations. |
| Historically, the parameter of bandwidth in radioastronomical receiver used to be within the kilohertz range. Small bandwidth was acceptable because observations were processed directly by listening or by paper chart intensity recorder. Chart recorder integrated energy of signal over defined small bandwidth which was suitable for detecting the intensity variance of microwave background. No wide-band transmitters existed in that era (except for TV transmitters) and tuning to other neighbouring frequency was easy as they were mostly vacant. Parallel observations from several places were unnecessary as well because the electromagnetic conditions were nearly same at all locations. |
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| 92,19 → 92,20 |
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| Only few digitalization systems dedicated for radioastronomy currently exists. Currently existing systems uses either custom design of whole receiver or they are constructed from commercially available components. Open-source principle attempts are very rare in radioastronomy field. |
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| \secc Coustom digitalization system |
| \secc Custom digitalization system |
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| Coustom designs usually uses non-recurring engineering for development specific solution for observation project thus costs of this instruments are very high if developed instrument are not reproduced many times. |
| Custom designs usually uses non-recurring engineering for development specific solution for observation project thus costs of this instruments are very high if developed instrument are not reproduced many times. Typical instrument developed in one piece with leads to enormous founding resources draws is Arecibo ALFA survey multi beam feed Array. |
| Another opposite example for custom receiver and digitalization unit design is LOFAR system developed by Astron in Netherlands. \url{http://arxiv.org/abs/1305.3550} |
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| The system requires proper handling of huge amounts of data. |
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| Professional astronomers use proprietary digitalization units \url{http://arxiv.org/abs/1305.3550} or by multichannel sound cadrd on amateur levels \url{http://fringes.org/} |
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| ASTRON ADCs |
| http://www.astron.nl/other/desp/competences_DesApp.htm |
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| 122,5 → 123,10 |
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| Mudular radioastronomy hardware: https://casper.berkeley.edu/papers/200509URSI.pdf |
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| In opposite of professional astronomers which uses proprietary digitalization units, amateur radioastronomers currently uses multichannel sound cards \url{http://fringes.org/} |
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| It is evident that current radioastronomy lacks of proper hardware which could be used on both communities professionals and amateurs. In addition open-source hardware |
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