Transducers (again!)

[bob]

It seems to me that the _really_ technically challenging issue is to obtain an effective transducer array, which will have a very narrow horizontal beam and a wide vertical one.


This isn't to say that other parts of the design won't take a lot of time and effort, on many people's part, only that the transducers are central to getting good images.


Also, we can always start with a simple design and add features later, but until we get good transducers the results won't be as good as we (or me at least) want them to be.


One idea that has not been discussed yet is the fabrication of transducers. Does anyone think we (or they) can design and model a transducer? There are packages out there to do this, but I am not sure about how hard they are to use. Also, they can be expensive in their own right!


If we are able to design transducers, I saw one link (below) that sells piezoelectric materials. (I am sure there are more.. This was only an example.)


Maybe this problem has a simpler solution. perhaps we could place material that acts as an 'acoustic lens' over cheap circular transducers to create a more optimal beam.. Again, I imagine there are others out there with ideas on this... We just need to find them!

[bob]

Re: Transducers (again!)

I guess the link didn't show up. Here it is again:


http://www.piezo.com/ssas4.html

[Patrick Duffy]

Re: Transducers (again!)

Bob,


No doubt about the transducers. They are the heart of the unit and we have nothing without them.


My "fish" will be put to the test on August 14th. I'll take it over a known wreck and see how it performs. If it meets the test, I'll take it to two other known areas where I'm told a couple of wrecks are located and post the results.


Patrick


>


>It seems to me that the _really_ technically challenging issue is to obtain an effective transducer array, which will have a very narrow horizontal beam and a wide vertical one.


>This isn't to say that other parts of the design won't take a lot of time and effort, on many people's part, only that the transducers are central to getting good images.


>Also, we can always start with a simple design and add features later, but until we get good transducers the results won't be as good as we (or me at least) want them to be.


>One idea that has not been discussed yet is the fabrication of transducers. Does anyone think we (or they) can design and model a transducer? There are packages out there to do this, but I am not sure about how hard they are to use. Also, they can be expensive in their own right!


>If we are able to design transducers, I saw one link (below) that sells piezoelectric materials. (I am sure there are more.. This was only an example.)


>Maybe this problem has a simpler solution. perhaps we could place material that acts as an 'acoustic lens' over cheap circular transducers to create a more optimal beam.. Again, I imagine there are others out there with ideas on this... We just need to find them!

[bob]

Re: Transducers (again!)

Please let me know how the test turns out. If you get great performance, then great, we're all set!


One idea I had to see how your transducers were performing was to tow the fish past a single vertical structure. (A piling out by itself would be ideal, but that might not be good for navigaition!)


The point would be to see when it showed up on the scan and how long it lasted. This would be one way of determining the horizontal beam width, and any side lobes that may be present.


I scuba dive, and at the quarry where I did my checkout dives, they have a series of platforms, not unlike diving platforms in lakes, but held at a known depth below the water.


Perhaps you could do something similar to create a target. You could make a beer keg mooring, but purposely make the chain too short, so it sat a known distance below the surface.


Also, you could reduce the bouyancy of the keg by filling it partway, so it sank more easily (But use water, not beer; it would be a terrible waste!)


Also, be sure to put a flag or something on it that does float!


Maybe others have ideas about what to use for a test target...


In the meantime, I will look into designing a transducer. I'll let everyone know how it works out, or at this point I should say IF it works out!


-Bob

[Charles]

Re: Transducers (again!)

If you haven't looked at Sture's site, he has built his own transducer. He removed a commercially built transducer on his fish and put his on. This left a fish with a homemade transducer and a commercial transducer. The images are incredible. You don't know which one is which judging by the pictures. He also has pictures of the homemade transducer. Maybe he will help point us in the right direction.


Charles


>


>It seems to me that the _really_ technically challenging issue is to obtain an effective transducer array, which will have a very narrow horizontal beam and a wide vertical one.


>This isn't to say that other parts of the design won't take a lot of time and effort, on many people's part, only that the transducers are central to getting good images.


>Also, we can always start with a simple design and add features later, but until we get good transducers the results won't be as good as we (or me at least) want them to be.


>One idea that has not been discussed yet is the fabrication of transducers. Does anyone think we (or they) can design and model a transducer? There are packages out there to do this, but I am not sure about how hard they are to use. Also, they can be expensive in their own right!


>If we are able to design transducers, I saw one link (below) that sells piezoelectric materials. (I am sure there are more.. This was only an example.)


>Maybe this problem has a simpler solution. perhaps we could place material that acts as an 'acoustic lens' over cheap circular transducers to create a more optimal beam.. Again, I imagine there are others out there with ideas on this... We just need to find them!