Re: [PSUBS-MAILIST] Underwater Communication

[john <mongo14904@yahoo.com>]

Dan
When you are at seneca lake doing you test if you have
any problems.
Lake diver is here in ny now (elmira) and can be there
to help in less than 2-3 hr
also id love to come up when you are here and check
out "Persistence."  When are you going to be there 
heck we could bring lake diver along and have a race 
Take care 
john

--- "Dan H." <jmachine@adelphia.net> wrote:

> 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 550 feet on a line.  After sitting on the
> bottom for an hour, a second smaller line is pulled
> to release sixty pounds of weight and Persistence
> now thirty pounds negative, will come back to the
> surface......if all goes as planned.  If it doesn't,
> well, we won't think about that right now.
> 
> 
> 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 350 feet of cable there won't be much of a
> signal radiating from the antenna. Another drawback
> is coax cable is big and bulky to store on a reel on
> the back of a small sub.  
> 
> 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 350 feet of cable
> will store easily, but to communicate, a surface
> boat has to actually get to the float and plug in
> their half of the intercom.  Also, there is still
> the chance to get the wire wrapped up in a thruster.
> 
> 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.
> 
> 


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