Where is this project going?

[Terry]

It seems that there are 2 schools of thought on this project...


1. Build the side scan from scratch-- using low cost transducers, build the electronics and writing a program for a PC to show the data.


2. Use transducers with a pre-existing bottom machine -- like Dan Fauntains page suggests.


Personally I like the first option, but I would like to see other peoples thoughts on this matter.


As far as the fish design, everybody has their own idea. What do you think of keeping this forum dedicated to transducers, electronics and programming. The fish design is the last part of this project. It may be wise to follow a path instead of trying to do everything at once.


We may want to attack this step by step. For instance...


1. Choose transducers


2. Build DSP


3. Choose cable


4. Top side programming


5. Fish Design


6. Smoke test.


Just an idea. Any input would be appreciated.

[Jan]

I am also for your first option.


I thought that perhaps 3 project could run at the same time.


This would save time, but needs a lot of control.


This might work at the office but not here.


So I dropped the fish as anyone has his own ideas about that.


I am working on my fish design at times when I am stuck with sonar problems. (and a new powersupply as my 20 year old homebuild one died a horrible death not long ago)


Since your list is line for line the same as mine (perhaps we are twin brothers... will ask my mum) I have nothing to add.


At the moment we are looking for the transducers.


Good transducers are the key to a good sonar.


Without them we will never be able to build a reasonable sonar.


At the moment we are braintorming about transducers.


Hence that ideas fly around a bit, but that is not bad.


Transducers:


So far I have been thinking about the next possibilities


1) Buy new transducers at $5000.00 an array.


(This is for me not an option)


2) Buy secondhand tranducers


(will have to see if that is possible and


affordable)


3) Upgrade normal depthsounder transducers to a level


good enough for sidescan


(That's why I looked for acoustic lenses)


4) Using deptsounder transducers in a different array.


(Using overlapping cones to double lite a small


area)


5) Having piezo elements cut and make own transducers


(The cost would be about $100 when i understood


the firm's webpage)


6) My latest train of thought is to mimic a radar


system.


(Having a narrow beam transducer scanning small


areas. I got this idea after I found that a 8°


cone lites up real small areas)


7) .... Hopefully someone else has some ideas.


As you see, we still have some thinking to do, but thats why we have the forum.


I think we need a discussion on transducers.


Lets see what the others say.


Regards Jan

[Patrick Duffy]

Terry,


I think most people on the list would agree with you. However, I only have about 6 weeks left to identify some wrecks before I have to pull my boat out of the water for the winter. Due to the limited time frame and since I already began this project prior to the list I will continue with it.


In the meantime, I'll participate where I can and let you know how my sidescan goes. There will always be someone who wants an inexpensive unit.


I'll also be more than happy to build a better unit if it can be made for a reasonable cost.


I think everyone has already agreed that we should focus on the transducer first. Personally, I hope that Sture gives us a hand here so we do not have to reinvent the wheel.


Patrick


Patrick

[Patrick Duffy]

Jan,


> 1) Buy new transducers at $5000.00 an array.


> (This is for me not an option)


I agree. This is not an option when you can purchase a whole new unit for $12,500.


> 2) Buy secondhand tranducers


> (will have to see if that is possible and


> affordable)


Interesting thought. But, I have never seen any used ones for sale.


5) Having piezo elements cut and make own transducers


(The cost would be about $100 when i understood


the firm's webpage)


Is that the cost of a single element? Also, I think most arrays use four transducers. If that is true, you will have $800 into the transducers alone.


Patrick

[Jan]

Patrick,


They mentioned $100 for a slice on piezo material.


The offer to cut it in the sizes we need.


I do not know what they ask for cutting, not much I think.


So the price of the array depends on how many elements we can get out of 1 slice.


Regards Jan.

[Tod Patterson (CT)]

The manufacture I spoke with said they supply the rectangle piezo elements for a fish and it used 2 hundred elements @ $4 a peace . The size was 1.4x.13x.1"


Regards,

[Jan]

Tod,


I suppose you mean that the price will be $800 per transducer ?


Regards, Jan

[Patrick]

Todd,


What else is in the array? Is it just a bunch of piezo elements?


Patrick

[Tod]

That price is from one source that make ceramic elements. Theirs others that make injection molded elements that mite have even better resolution but cost a lot more because of tooling. The ceramic elements are easy to make in a large sheet, than cut into what ever size you want for a certain frequency. The ones I spoke of (1.4x.13x.1") are arranged in several arcs to focus the beam. I think maybe we could do just one arc of 25 elements or so. To make the array, you first make a mold for the element support (backside), this has the arc. Than you pour potting compound into the mold. Than load cork around the bottom and sides where the elements go, this is so the element can expand and contract freely to make the wave. Than the elements are loaded into the cure compound and pot the front.


Regards,


Tod

[Tod]

That should of read,than cut into what ever size you want for a certain beam angle not frequency.


I caught my mistake to late.


Regards,


Tod

[bob]

Would you mind sharing details on who you spoke to, or looked up on the web?


I find myself in the 'build a good transducer' camp.


I'll bet we can do this cheaply, we just need to figure out how to get it done!


Thanks,


-Bob

[Tod]

Bob


They don’t make the transducer, they just make the piezo elements. And they’re not able to disclose the details of the design since all piezo elements are custom designed for other companies.


Tod

[bob]

Ah well....


Do they say what the material is?


Does anyone know if there is one ceramic that is usually used, or are there a million different kinds?


Perhaps the answer is somewhere in the middle, or the composition is a trade secret too?


-Bob

[Tod]

bob


see piezo elements


Tod