Knowledge Base

For land surveyors, the process used in hydrography to collect the coordinate position and elevation data underwater might be unfamiliar. However, using an RTK-enabled system it is easy to collect data that will fit seamlessly into separately collected land survey datasets using the same RTK GNSS receivers / base station.

The CEE ECHO™ is designed to take in NMEA0183 format position from a GNSS / GPS receiver and merge the position data with echo sounder data simultaneously being recorded. The combined data stream is output to an acquisition software package.

The CEESCOPE™ and CEE-ECHO™ output a high definition echogram, a view of the sonar echo envelope from the entire water column. That is not just a depth sounding value from each ping. The echogram output offers substantial benefits for surveys conducted in areas with sub-aquatic vegetation.

A dual frequency echo sounder is usually used for surveys where the bottom may be poorly defined, or when sediment resuspension is occurring, such as during dredging. In addition, collecting a digital echogram using the CEESCOPE™ or CEE ECHO™ helps provide a detailed view of the bottom and sub-bottom to allow proper identification of the hard and soft bottom surfaces.

An unusual challenge was presented: use the dual frequency CEESCOPE™ to locate a 30m structure that had vanished – presumably sunk. The data processing in HYPACK® described in this article illustrates some general concepts relating to single beam echo sounder data and transducer properties.