Envirtech - Directional Wave Sensor and Processing Payload
The system core consists of a state of the art IMU (Inertial Measurement Unit) . It is a solid state, MEMS, electronic device that measures the buoy hull dynamic parameters using a combination of 3D accelerometers, gyroscopes, and magnetometers. A Digital Signal Processor (DSP) provides real-time 3D orientation, acceleration, rate of turn and earth-magnetic field data. Once calculated the attitude and heading data, a microprocessor unit processes them to obtain a geographically oriented displacement file (HNE file). In the HNE file each sample consists of Heave, Displacement North/South and Displacement East/West measured in millimetres. Once transmitted to a shore station, data can be further processed by a zero-crossing analysis and a Fast Fourier Transform to obtain the directional sea wave statistics as well as the directional energy spectra. The local Non-Volatile Ram can store all collected data for some years, depending on the data acquisition rate.
The unit is composed of following main parts:
- The sensor pack containing the IMU sensors and 3D magnetic compass
- The micro-controller. It consists of a low power consumption RISC processor, embedding a LINUX operating system able to manage serial lines I/O.
- Local data processing software to format an HNE file (Heave, Displ. N/S, Displ. E/W)
- DC Power supply
- As option, a multi Analog/Digital I/O interface to manage local sensors
- As option, a multi-channel multi-satellite GNSS receiver for iSSH measurement
- As option, a Radio Frequency modem. Its configuration depends on the user choice at order time.
- Available Radio Frequency Bands are : VHF, UHF, GPRS/EDGE, Inmarsat mini-C, Iridium, W-LAN
- Software for remote data decoding, post-processing and user presentation of wave statistical data (Hm0, Hmax, Tp, Tm, Dp, Dm etc.) and directional energy spectra.