There are various scenarios where using a Single Beam Echo Sounder (SBES) either instead of, or in conjunction with, the Multibeam System, can have significant advantages. Single beam is suited to shallow waters such as lagoons and lakes where the use of multibeam would have no benefit. In addition to this, the SBES is an independent system to the Multibeam System, therefore by comparing results from both systems it can be an excellent quality control tool.
It is also very useful for defining seagrass areas and measuring the height, position and density of these vegetations. This can be advantageous for environmental requirements with subsequent surveys revealing the growth or degradation over time. See also Seagrass mapping
The single beam echo sounder produces an echogram of the sea floor at a point directly below the transducer. The major benefit of a system that outputs and records the digital echogram is the ability to post process the data. This can help identify the seabed features and determine whether the echo sounder has picked up the actual seabed or another feature such as seagrass or aeration in the water column.
Our single beam system is comprised of a dual frequency transducer. The two frequencies are made up of a high frequency and low (typically 200kHz & 33kHz). The high frequency will generate a first return on the signal and depict the seabed, sea grass, rock etc. The low frequency has some penetrating properties, for example in areas of silt, it can penetrate the material to the harder layers below.
We also incorporate RTK GNSS into the system to achieve centimetre positioning. The GNSS also out puts data at a rate of 20Hz and is capable of compensating for heave in the vessel due to various sea states. Therefore our system is capable of removing all heave artefacts which aids in delivering accurate data.
The types of outputs that can be produced using single bean include:
- Seagrass plans
- Pre/post dredge data