Sub-bottom profiler, Extension
The SBP 120/300 is an optional extension to the highly acclaimed EM 122/302 multibeam echo sounders.
Option to the EM 122 multibeam echo sounder
The operating principle of this SBP is to the same as that of a multibeam echo sounder, but the signal frequency is lower in order to penetrate the sea floor. Transmission is made by a dedicated projector array, normally of the same length as the multibeam projector and mounted parallel to this. The SBP 120/300 shares receiver array with the EM.
The SBP 120/300 Sub bottom profiler has a much narrower beam width than a conventional sub bottom profiler with correspondingly lesser smearing. It thus provides deeper penetration into the bottom, and higher angular resolution. Compared to the other class of narrow beam SBPs: the parametric sediment profilers, a significantly higher source level can be produced by the large transmitter array of the SBP 120. This enables better penetration into the sediments.
Stabilised for ships attidude
The transmit beam and the receiver beams are stabilised for pitch and roll, respectively.
Several simultaneous beams
The receiver beam former have access to the digitized individual hydrophone signals of the receiver array. This is utilized to generate several beams per ping providing the SBP 120 with the unique feature of being a true multibeam sub bottom profiler.
Integration with EM 120/300
The sub bottom profiler is tightly integrated with the EM 122/302 multibeam echo sounder:
- It makes use of the same receiver array and preamplifier as the EM. The EMs preamplifier is filtering the received signals into a high frequency channel used by the EM and a low frequency (2-8 kHz) channel that is used by the SBP.
- It uses the water depth measured by the EM for automatic setting of the observation window.
- If the bottom is sloping, the EM can estimate the local slope angles and inform the SBP 120, so that the beams can be directed perpendicularly to the bottom, in order to get the best resolution and contrast
- Pinging can be synchronized so that interference is minimized. For deeper waters SBP 120/300 can transmit several pings for each multibeam ping, without affecting the operation or ping rate of the EM.