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Related Experiment Video

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Quasi-light Storage for Optical Data Packets
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Outdoor atmospheric optical two-way time transfer with serial time code.

Junwei Ren1, Dong Hou1, Ze Li1

  • 1School of Automation Engineering, University of Electronic Science and Technology of China, Chengdu 611731, China.

The Review of Scientific Instruments
|July 10, 2021
PubMed
Summary
This summary is machine-generated.

This study presents an optical two-way time transfer method for outdoor free-space links. The technique achieves high precision, outperforming GPS-based methods for short-distance atmospheric time synchronization.

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Area of Science:

  • Optical physics
  • Metrology
  • Telecommunications

Background:

  • Accurate time transfer is crucial for various scientific and technological applications.
  • Existing methods like GPS-based time transfer have limitations in certain environments.
  • Free-space optical links offer potential for high-bandwidth, secure data transmission.

Purpose of the Study:

  • To demonstrate an optical two-way time transfer scheme in an outdoor free-space link.
  • To evaluate the performance and precision of this novel time transfer method.
  • To compare the proposed method with existing Global Positioning System (GPS)-based time transfer.

Main Methods:

  • Implementation of a complex programmable logic device-based serial time coder/decoder.
  • Transmission of a 100 Hz signal with time information over a 120-m outdoor atmospheric link.
  • Measurement of time drift, time deviation, and frequency instability to assess signal quality.

Main Results:

  • Achieved a root-mean-square time drift of approximately 81 ps over 11 hours.
  • Measured time deviation of 70 ps at 1-s averaging time, improving to 10 ps at 100-s averaging time.
  • Demonstrated fractional frequency instability on the order of 1.4 × 10⁻¹⁰ at 1 s and 3.0 × 10⁻¹⁵ at 10,000 s.

Conclusions:

  • The optical two-way time transfer scheme is effective for outdoor free-space links.
  • The method exhibits superior time deviation and frequency instability compared to GPS-based methods.
  • This technique is suitable for high-precision, short-distance time transfer applications in atmospheric conditions.