Operation Manual
FarSounder, Inc.
F31552 (Rev. 2.6.1)
Page 51 of 56
Figure B.2. Reflections from a medium angle.
Figure B.3. Reflections from a shallow angle.
In reality, the situation is actually quite a bit more complicated as the sound waves reflect no only off the
sea floor but also off the sea surface - sometimes more than once! (see figure B.4) This type of bouncing
is called multipath propagation.
Figure B.4. Multi-path reflections.
Differing levels of sophistication enable various navigation sonar products to extract back-scatter reflections
from the sea floor at differing minimum echo levels. This directly defines the water depth limit at which a
particular sonar can produce bottom maps ahead of the vessel. As range increases, the angle at which
the incoming sound wave hits the sea floor becomes shallower. At some angle, not enough energy is
reflected back to the receiver to allow for sea bottom detection and mapping. The FarSounder-500 and
FarSounder-1000 products are specified as 8 water depth sonars. This means they can map the sea floor
out to a range equal to 8 times the depth below the transducer. Depending on the actual local propagation
conditions and the sea floor composition, this range may be longer or slightly shorter.
One of the most impressive features of FarSounder's technology is its shallow water capability. Though
FarSounder's products are specified as 8 Water Depth systems, 10+ Water Depth performance can
