"Salomon Fringe" wrote in message
...
Calif Bill wrote:

To get very close, you would have to have two transducers. Actually
one transmitter and one receiver. The ringing in the transmitter is
one of the major timing restrictions. You have to wait until the
electronic eddy currents dampen out before you can look for a received
signal. And the new units have more power and higher frequencies so
you get better definition, but the ringing is worse, so you have the
2-3' of not readable water below the transducer.

Thanks for this explanation. Looking at the price of simple depth-only
low-power transducers (what you would need for a listen-only xducer) I
am left wondering why there are no dual transducer solutions around.

One could use a transducer optimized for low ringing but that would
require more electrical drive to get same acoustic power most likely.
(low Q, as the geeks say)

I presume that there is not consumer demand for a depth finder capable of
reading less than the 2 feet or less that the current consumer models do.
Mount the transducer off the transom near the surface of the water?