For an experimental project I would like to classify the seabed (sediment detection) at close range (1 to 4 meters) using acoustic. For this I am looking at single beam echosounders.
I’m not familiar with seabed classification, so it’s difficult to provide advice here without additional information. What kind of spatial resolution do you want/need (both horizontally and vertically), and what’s involved in the detection/classification process?
If you have precise positioning estimates for the sensor then you could potentially use overlapping data from neighbouring profiles to get a higher horizontal resolution / directional data. Beyond that I suppose I would theoretically expect there to be more information to be extracted from a sensor that can perform frequency sweeps / chirps instead of using a fixed frequency, but it’s also quite possible that a fixed frequency profile is sufficient for your needs (I don’t know enough about the signals and classification materials involved to make a meaningful estimate at this point).
It’s not clear what your concern is here. Note that if you’re pointing a wide beam at a flat surface then only a small portion of the beam’s contact area will end up being reflected back towards the sonar for detection, and that proportion reduces with increased separation distance between the sensor and the surface being measured.
