Single Beam Data Enhancements

Hughes Clarke and CHS

(Chair Funding)

Whilst swath sonar systems are increasingly being implemented by the world’s hydrographic agencies, it has remained clear that there are specific environments in which the single beam and sidescan survey model will remain the dominant tool. Areas include, water depths less than ~8m and areas of high potential grounding hazard.

We have examined the new potential now being offered from a subset of single beam sonar manufacturers that is evident in full digital waveform logging. Using a Knudsen 320 B/P system we have developed unique new software to extract the full echo envelope data for a variety of purposes:

• Improved bottom detection
• Analysis of water column echo information (as an aid to physical oceanographic studies)
• Analysis of subbottom echo for shallow geophysical surveys.

These tools are particularly significant for our major sponsor, the CHS. The CHS continues to operate dual frequency Knudsen 320M’s in all regions. Whilst the current mode of operation does not retain the echo envelope information (except in paper hard copy), all the existing hardware is capable of retaining this information.

Now that digital processing is sufficiently fast, it is possible to incorporate this new information into the standard processing stream. Whilst the tools allow improved confidence in bottom detection (the prime aim of hydrography) it also allows the user to deliver environmental information concurrently. With the increasing shift of inshore surveys from strictly hydrographic to coastal zone management issues, the ability to retain this information with no extra hardware cost is an important factor.