Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: New method for the time calibration of an interferometric radio antenna
  array   Digital radio antenna arrays, like LOPES (LOFAR PrototypE Station), detect
high-energy cosmic rays via the radio emission from atmospheric extensive air
showers. LOPES is an array of dipole antennas placed within and triggered by
the KASCADE-Grande experiment on site of the Karlsruhe Institute of Technology,
Germany. The antennas are digitally combined to build a radio interferometer by
forming a beam into the air shower arrival direction which allows measurements
even at low signal-to-noise ratios in individual antennas. This technique
requires a precise time calibration. A combination of several calibration steps
is used to achieve the necessary timing accuracy of about 1 ns. The group
delays of the setup are measured, the frequency dependence of these delays
(dispersion) is corrected in the subsequent data analysis, and variations of
the delays with time are monitored. We use a transmitting reference antenna, a
beacon, which continuously emits sine waves at known frequencies. Variations of
the relative delays between the antennas can be detected and corrected for at
each recorded event by measuring the phases at the beacon frequencies.

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The categories of this paper are: physics
33
The categories of this paper are: plasm-ph
1
The categories of this paper are: cs
8
The categories of this paper are: hep-ex
30
The categories of this paper are: q-alg
35
The categories of this paper are: mtrl-th
31
The categories of this paper are: ao-sci
21
The categories of this paper are: adap-org
4
The categories of this paper are: cond-mat
23
The categories of this paper are: solv-int
9
The categories of this paper are: nlin
18
The categories of this paper are: econ
17
The categories of this paper are: q-fin
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The categories of this paper are: nucl-th
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The categories of this paper are: atom-ph
15
The categories of this paper are: nucl-ex