50 lines
2.6 KiB
TeX
50 lines
2.6 KiB
TeX
% vim: fdm=marker fmr=<<<,>>>
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\documentclass[../thesis.tex]{subfiles}
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\graphicspath{
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{.}
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{../../figures/}
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{../../../figures/}
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}
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\begin{document}
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\chapter{Conclusion}
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\label{sec:conclusion}
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%<<<
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Using radio antennas to detect \glspl{UHECR} has received much attention recently.
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The \acrlong{Auger} is currently being upgraded to \gls{AugerPrime} incorporating radio and scintillation detectors together with the already existing water-Cherenkov and fluorescence detectors.
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Other experiments, such as \gls{GRAND}, envision to rely only on radio measurements of an \gls{EAS}.
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\\
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% Timing not enough
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Time information in such large observatories is typically distributed using \glspl{GNSS}, reaching up to $10\ns$ accuracy under very good conditions.
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For analysis using radio interferometry to be competitive, this timing accuracy needs to be improved towards the $1\ns$ mark.
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\\
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%>>>
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% Beacon introduction %<<<
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A viable method to obtain this timing accuracy is to incorporate a beacon transmitter into the array.
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This (narrow-band) transmitter sends out a special signal that is picked up by the radio antennas in the array.
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With relatively simple techniques, the timing accuracy can be improved to below $1\ns$.
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Thus, at a relatively low cost, the (relative) timing of radio arrays can be improved to enable radio interferometry.
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\\
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%>>>
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% Passive Beacon %<<<
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In some circumstances, an external transmitter can be used as a beacon.
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For example, in \gls{Auger}, a public TV broadcaster emits its signal at $f = 62.75\MHz$.
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With the source location and the frequency known, time delays can be calculated and this signal can be used to account for timing errors smaller than $T = 1/f \sim 16\ns$.
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Unfortunately, with the \gls{GNSS} timing accuracy estimated in the same order of magnitude and the signal being periodic, the synchronisation of the antennas can be off by an integer amount of periods $T$.
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\\
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% >>>
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% Combined sine beacon + air shower %<<<
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Recording an air shower, in addition to such a narrow-band beacon, might provide a method to determine the correct beacon period.
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Radio interferometric analysis of the air shower depends on the coherence of the received signals.
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Any synchronicity problems in the radio antennas decrease the coherence and thus the power mapping used to derive properties of the air shower.
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With a limited set of periods to test, this power can be maximised while simultaneously inferring the correct beacon period.
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\\
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The developed method to synchronise can be directly tested at \gls{Auger}, both with data from \gls{AERA} and the upcoming radio detectors from AugerPrime.
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% >>>
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\end{document}
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