SBP29

SBP29 provides sub-bottom profiling as an optional extension to the EM 124 or EM 304 multibeam echo sounder systems. It applies a dedicated SBP29 array for transmitting narrow beam sub-bottom signals in the frequency range fro 2 to 9 kHz. The echoes are received using the EM 124 or EM 304 receiver unit. The array geometry is the same as used by the EM multibeam echo sounders, providing narrow beam footprints.  Due to the TX/RX geometry – the mills-cross geometry - the SBP29 sometimes is referred to as a multibeam sediment profiler. A fan of receiving beams is formed across-track, and the system can observe up to 21 beams across for every ping. In addition, the TX beam can be cyclically tilted along-track from ping to ping. This gives the SBP29 some quite unique features – especially when it comes to slope robustness.

The SBP29 comes in 3-, 6- and 12-degree configuration, where 3, 6, and 12 refers to the transmit beam width. The 3-degree system is the largest, with 96 transmit transducer elements.

SBP29 is a system that operates on its primary low frequency from 2 to 9 kHz. It has high source level, 228 dB at 4 kHz for the 3deg version

Sloping seabed and sloping subsurface features may result in loss of sub-bottom return signals, especially with very narrow beams. Stearing the beam to normal incident to the seabed slope is one option that most sub-bottom profiler systems provides. But the sub-seabed sediments may have a different slope than the seabed, where this methodology will not work that well. Wide beams are more robust to slopes than very narrow beams, but narrow beams provides better signal-to-backscatter ratio, and thus clearer sediment imaging.

SBP29 with its multiple beams across for each ping, and with its option for cycling the transmit beam provides additional unique slope robustness. SBP29 can be configurd to give several narrow beam echograms with different TX/RX pointing angles, increasing the likelihood of normal incident to all slope directions in the sub-surface layers.  In addition, the beam width can be cyclically changed between each ping, allowing for both narrow and wide beam data. 

The composite echogram is a unique SBP29 features that helps you pick the best from each of the many available. The composite echogram is one single echogram consisting of individual traces picked from all available observations with the best signal-to-noise ratio.