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Hello Dan, I have build a
digital intercom in the past (when I was in collage), but it wasn’t
designed to transmit underwater by a sonar system, that can be arranged, I mean
I should have the schematics somewhere and it can be easily modificated, the
question for those who knows physics is……in order not to make a
hole in to the hull I was thinking to put the sonic transducer inside the cabin
attached to the hull wall, does anyone know if this will distortion the sound
waves coming out of the cabin in to the water?, if it does, will the distortion
be great enough to make impossible to rebuild the data string on the surface? Please
let me know what you think. De: For a quick up date on my sub
"Persistence." I revamped my thruster controls to what they should have
been in the first place. I had relatively light relays controlling the
motors. After many hours of use they started sticking, both on and
off. Pretty scary when you're spinning around in a marina next
to docked hundred thousand dollar boats. I was going to switch to
solid state but decided to stick with mechanical relays, only use heavier
ones. It's fine now. I've been diving the sub in relatively shallow water for a
year. Finally, I'm going to do a deep water test. It's time to get
out-a-da baby pool and in-ta-da the big pond. In a week and a
half we're supposed to take Persistence up to Seneca Lake in New York State and
do an unmanned deep water test. It's going to be weighted thirty pounds
positive to go to Ah yes, Underwater communication! I have a
request of you electronic types. I have been researching several methods of communication
between my sub and the surface. There are three methods I came
up with. One is to have a radio transceiver, VHF or CB type, in the
sub and a coax cable to the surface with an antenna on a float. It's relatively cheap but there is the drawback of the cable
dangling in the water to get caught in a thruster. Also, I've been
told that after running through Method two is almost the same as method one except with an
intercom in the sub and a twisted pair of very small wires going to the
surface. The unit is also cheap and it has the
advantage of very small wires going to a surface float so Now for the big bucks! The proper way to do it is to
have an acoustic type underwater telephone. I have tried to transmit from
the sub with a walkie talkie and it's good until you get about two feet
deep. The radio frequency electrical signal gets absorbed into the
water and that's the end of the contact. An acoustic telephone uses high
frequency sound waves instead of electromagnetic waves as a carrier.
Since sound transmits through water quite well, they work fine. I know there are commercial systems out there to be
purchased, but for a personal sub, they're way high in price. I was
wondering if anyone knows of a system for communicating that might be in a
P-sub price range or, is there anyone out there that has the know how
to design a system that can be built by someone with a little bit of
electronic knowledge and a soldering iron. Captain Kittredge had an acoustic system designed and
they built a few of them. I understand they worked reasonably well but
that was thirty years ago. With the advances in electronics, most of the
components he used could probably be replaced with a few IC's. Does anyone know of a reasonable priced system out there or,
is anyone knowledgeable in this area and willing to take on the challenge of
designing something. I'll do the building but I just don't know what to
build. Thanks for listening, Dan H. |