Overview:
This is a hybrid solution utilizing communications aspects of Examples 2 and 3 listed above. In this situation, there is no suitable shore structure nearby for acoustic underwater modem (UWM) data communications. Alternatively, a surface buoy is placed near the bottom mounted instrument and data are transmitted between the bottom instrument and the surface buoy via UWM. In this application, an UWM is placed under a purpose-built surface buoy or a buoy of opportunity such as a Coast Guard Aid to Navigation (ATON). Data are then transmitted from the buoy to the shore station via radio modems, cell phones or Iridium phones. The AWAC is a common choice for bottom mounted directional wave and current profiling equipment.
Advantages:
- Uses bottom mounted instrument for wave and velocity measurements
- Can be deployed in nearly any location without regard for boating/fishing activity or nearby communications structure
- Efficient pre-processing of wave and velocity data for UWM transmissions
- Surface buoy is inexpensive compared to traditional wave buoys
Limitations:
- Relatively low bandwidth communications
- Requires periodic replacement of batteries
- Requires surface buoy installation
Technical considerations:
This is a hybrid solution combining the Radio Modem, GSM, or Iridium communication techniques of Example 2 with the acoustic underwater modem (UWM) techniques of Example 3. The primary difference in this system is that the surface buoy is not fixed in position or orientation compared with the pier or other offshore structure. This means that omni-directional UWM would be used on both the bottom mounted AWAC as well as the surface buoy. All other communication considerations are applicable.
An ActiveX toolbox with current and wave processing commands is supplied for real-time data conversion. These processed data are then ready for display on the users web site in real-time.
Examples:
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