Drifting Buoys

• This drifting buoy uses Globalstar satellite communications, low-orbit satellites that cover areas other than the polar regions.
• Compared to drifting buoys using other satellite communication systems, it is inexpensive, and a one-year communication contract is included in the main unit price.
• With standard batteries, approximately 1,200 communications, equivalent to about 50 days, can be performed every 60 minutes transmission, making it ideal for short-term observations.
• The appearance and specifications of the product are subject to change without notice.
• For more information, please feel free to contact us.

• Iridium satellite communication range covers the entire earth, and it is possible to change the transmission interval remotely by two-way communication.
• In the case of lead-acid battery type, the communication period is 3~4 months (in the case of hourly transmission).
• In the case of a solar cell type, it is possible to operate annually (in the case of hourly transmission setting) for long-term drifting.
• For more information, please feel free to contact us.

• With a diameter of 800 mm and a weight of 35 kg, this drifting buoy is small in size and lightweight that can observe waves with high accuracy with a single positioning GPS.
• This is a buoy-type wave meter developed to observe ocean wave data (wave height, wave direction, wave period, etc.).
• It achieves high accuracy comparable to conventional expensive ultrasonic and acceleration wave meters, with a wave height of 10 m and a wave direction of 5°.
• Wave data is transmitted to a PC or other device on the receiving end via LTE communication or Iridium satellite communication.
• For more information, please feel free to contact us.

System Specifications

Categories	System Specifications
Measured Items	Buoy position, significant wave height, period, wave direction, 1/10 maximum wave height, period, wave height, maximum wave height, wave period, wave direction, wave count, battery voltage (optional: water temperature)
Measurement Range	Wave height: 0–20 m (accuracy ±10 cm) Period: 3–16 seconds Wave direction: 0–359° (accuracy ±5°)
Communication	LTE communication, Iridium satellite communication, etc.
Power Source	Solar panels, rechargeable batteries, etc.

Specialties

  This product is a completely new buoy-type wave meter developed to observe ocean wave data (wave height, wave direction, wave period, etc.) using only a single positioning method GPS sensor attached to a small buoy.
  The GPS wave measurement by this single positioning method is based on the digital filter processing (Patent No. 3658595: Registered in March 258, 2005) newly developed by the Japan Aerospace Exploration Agency (JAXA), which is not DGPS or RTK/GPS and has an error margin of about 20m in general.), which is comparable to conventional ultrasonic wave gauges and acceleration wave gauges.
  Furthermore, in order to improve the wave surface tracking performance on the sea surface, a compact, lightweight, and low vibration type disk float (Patent No. 45661916, registered on August 13, 2010), developed in collaboration with Osaka Prefecture University, is employed.Wave data such as wave height, direction, and period can be obtained with high accuracy.

System Configuration

  An example system configuration is shown below.The system consists of buoys floating on the sea and a PC on the ground, and wave data is automatically transmitted via packet communication and Iridium satellite communication via the Internet and e-mail.

Measurement Accuracy

  A ground-based simulation test conducted by JAXA has confirmed that wave motion can be measured with an accuracy of 10 cm in wave height and 50° in wave direction, which is more than the specified values.
  The figure below shows the transition of significant wave height data obtained by the Kitan Strait wave buoy. It can be seen that the results are in good agreement with those of the accelerometer-type wave height meter used as reference data.
  At the time of this test, a very large typhoon No. 6 passed near the Kitan Straits on June 21, 2004, and waves with a significant wave height of about 7 m (the maximum wave height at that time was 10.1 m) could be observed without problems.
(Excerpt from a paper presented by JAXA)