Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Picosecond-precision optical time transfer in free space using flexible
  binary offset carrier modulation   Free-space optical time transfer that features high precision and flexibility
will act a crucial role in near-future ground-to-satellite/inter-satellite
clock networks and outdoor timing services. Here we propose a free-space
optical flexible-binary-offset-carrier-modulated (FlexBOC-modulated) time
transfer method. The utilized FlexBOC modulation could yield a comparative
precision, although its occupied bandwidth is tremendously reduced by at least
97.5% compared to optical binary phase modulation. Meanwhile, the adoption of
optical techniques eliminates the multi-path effect that is major limit in the
current microwave satellite time transfer system. What's more, the time
interval measurement avoids a continuous link that may be routinely broken by
physical obstructions. For verification, a time transfer experiment with our
home-built system between two sites separated by a 30-m free-space path outside
the laboratory was conducted. Over a 15 h period, the time deviation is 2.3 ps
in a 1-s averaging time, and averages down to 1.0 ps until ~60 s. The
fractional frequency instability exhibits 4.0E-12 at a gate time of 1 s, and
approaches to 2.6E10-15 at 10000 s.

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The categories of this paper are: adap-org
10
The categories of this paper are: q-bio
37
The categories of this paper are: supr-con
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The categories of this paper are: chao-dyn
13
The categories of this paper are: quant-ph
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The categories of this paper are: atom-ph
5
The categories of this paper are: gr-qc
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The categories of this paper are: dg-ga
12
The categories of this paper are: nucl-th
16
The categories of this paper are: stat
2
The categories of this paper are: math
36
The categories of this paper are: cmp-lg
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The categories of this paper are: nucl-ex
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The categories of this paper are: patt-sol
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The categories of this paper are: funct-an
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The categories of this paper are: comp-gas