Homebuilt

[Ronnie_B]

Hi, my name is Ronnie, new to post in this forum but I've been a active reader earlier. My divemaster some years ago here in Sweden was a "sonar business partner" of Sture. So since then I have had plans to make my own sonar. But the same time we got kids and then no more time for hobbies. Now the kids are getting older and i start to have some time for my self again. So now my dreams of a home built sonar is back on track.

I tried to update my self on this forum but it seams like those who started this Forum already built their sonars and after them it seams like there isn't that much about homebuilt sonars anymore. Or did I just miss it?

If there is some homebuilding threads I missed hopefully someone can post some links?

Also all of Stures old links are cleaned out of pictures and attached files.

So back to my dreams/plans...
1. Transducers. Anyone who like to share their knowledge? Where to buy, what to buy and how to make them?
2. High voltage, Voltage, Current, Effect on the transducers?
3. Software, some example code? Maybe someone like to share their old beta versions, just some code to show how the sampled signal is decoded into a picture?

It would be nice to make a basic "Build your own Sidescan Handbook". It will not be a perfect sonar described but atleast a working product that anyone can improve to reach higher performances.

One last question, when you are using transducers from fishfinders, how do you connect them? Are they "just" transducers or they are intelligent units with serial communication to the main unit?

Many questions. Hope there will be some answers.

[Rickard]

Homebuilders are rare

Hello Ronnie!

Nice to see someone else who still has the ambition to build his own sonar equipment. You are right, the activity in this subject is decaying and it's a long time since I saw someone presenting something in Sture's spirit. The reason, I think, for this is the appearence of relatively cheap sonar systems on the market. Ten years ago people were forced to make things themselves because of the costs for commercial systems. But Burton's systems and Humminbird's sideimaging fishfinders and perhaps also the Sportscan, the Starfish and the DeepVision (a Sture design?) revolutionised this area by presenting very competent systems for reasonable prices. Building one's own system is an acheivement but it takes time, can fail and the cost will probably be as high as for a ready-made system. I think the best systems available today, if you consider what you get for the money, are the Humminbird SI units. People who are interested in amatuer sonar technology have moved to the forums where these units are discussed. Nobody builds their own head units anymore (as far as I'm aware of) but there are people who develop software and new applications for the HB systems. The HB SI units were developed for fishermen but they are also very popular among wreck-hunters and divers. These systems are simpler than Sture's since the transducers are just encapsulated piezos with no electronics inside. Thus, there is a limit as to the length of the cable between transducer and head unit. Still, they can be used for scanning down to about 50 m. Perhaps you already know of all this but here you have the link to the presently "best" forum:
http://www.xumba.scholleco.com/index.php

I have some material on experiments with fishfinder arrays and some other applications in both the Geotech forum and Humminbird's forum.

Regards,
Rickard

[Unregistered]

Ronnie,

I tink Rickard summed it up pretty well. Why kill your self to make one, when you can buy them now for under $2k. The Humminbird units are very impressive for the price and they are getting better all the time.

Good Luck,

RGecy

[Rickard]

Still many things to DIY

Ronnie,

Don't get downhearted because of our replies. There is still room for home-made add-ons to the commercial systems. One thing is improving beamform and this has to be done by making your own transducer. The Humminbird transducers (I have Humminbird in mind in the following) have beam widths in the medium range, 1 - 1.5 degrees, achieved by high frequencies in rather short arrays. Making a longer array, around 300-400 mm, would enhance horisontal resolution significantly. Also, range would be better because of higher energy concentration in the main beam. This would be at the cost of a several meters long nearfield with constant, rather wide beam. But long range performance would be much better than with the present arrays. The result would be as good as in Sture's high resolution arrays. Material for the array could be supplied from slaughtered sideimaging transducers.

The existing arrays are not shaded, which means sidelobes are not well suppressed, causing some blurr in the image. This could be a challange for someone, to accomplish physical shading of an array. This could be done using PVDF cut to appropriate shape. The problem remains how to design a transmitter that match the shaded PVDF receiver. (PVDF doesn't work well in transmitters).

I think there is a potential for developing the towfish technology. Many people have experimentet with longer cables to get deeper but the results are varying and some testings are never reported. There has been talk about constructing an amplifier for the transducer end but I haven't seen any such device yet. So there you have a mission, design something that can survive the 1000 Volt output from the instrument and amplify the millivolt signal from the transducer and send the amplified signal up to the instrument without killing it.

You asked about how fishfinder tranducers are connected. I assume you have seen my testings in my efforts to solve the old problem of optimal spacings between unequally spaced fishfinder transducers? I used four transducers starting with wide spacings and ended up with cutting the transducer walls to bring the piezos close enought together to get an optimal array. In all configurations I used parallell connection to the instrument. No electronics involved. In theory, a combination of serial and parallel connection is optimal but I never tested that. I will (when time allows me to) modify the array to a "big gun" with superior range for overview scanning under ice. Then I will connect the array to the 200 kHz channel as I have already done with the cork shaded version.

Hope this gives some input!

Annars, eftersom vi är landsmän får du gärna kontakta mig direkt på modersmålet när du har lust!

Bästa hälsningar (Best regards)
Rickard

[Ronnie_B]

Just a DIY unit...

Hi, thanks for all your replies.

As I understand most of the people here are trying to get the "perfect" picture and then I also understand it's better to buy a ready made unit.

For me, I'm more like a DIY freak. I'm not that keen on getting the perfect picture. I apprechiate more to make my own sidescan sonar than buying one, even if I will just reach low-quality results. Since I'm not a professional I just want to make a unit by myself. It's like most the homemade PVC ROV's on Internet, quite useless toys, but still plenty of fun for those making them.

So for me I'd like to make a simple sonar just for fun. Just to learn how they are working. Just to feel satisified and happy if I will be able to find a big rock on the bottom.

So the kin dof help I'm hoping for is to get some help with is just the basics...
How to wire a Fishfinder transducer, some simple sampling software for the transducer data from a AD-input to show how the Sonar-picture is built-up.


/Ronnie

PS. Tack Rickard för inläggen.

[ciuccacci]

maybe this can help

http://cgi.ebay.it/Klystron-radar-F1...3A1|240%3A1318

[Glennk]

So the kin dof help I'm hoping for is to get some help with is just the basics...
How to wire a Fishfinder transducer, some simple sampling software for the transducer data from a AD-input to show how the Sonar-picture is built-up.

Hi, I'm in a hurry now, but I'll feed you with some info after this weekend.
Got lots of schematics and plans, even down to component lists for 100 and 500Khz sidescans.

Since you live in Sweeden, you have the option to seek assistance with some of the guys that worked with Sture.

I'll get back to you after the weekend!

Regards,
Glenn

[laland]

DIY SONAR

Ronnie,

if you read german, then maybe you should consider the following book, written by Gerhard Aretz, a naval sonar professional:

http://www.buchhandel.de/detailansic...-3-86582-393-9

Some of the illustrations (schematics) in this book are a bit hard to read, but replacement for those can be downloaded here:

ftp://ftp.artematrix.org/g_aretz/

And the book suffer somewhat from inadequate proof-reading of formulas, but I still think it's a very interesting book. The final chapter discusses the details of a homebuilt Side Scan Sonar project... and it would be nice to discuss these matters with another DIY'er.

Besides, you could try to get hold of this book, ie. "Fundamentals of Sonar" by J. W. Horton. A very nice reference book, now available on eBay:

http://cgi.ebay.com/Fundamentals-of-Sonar-Second-edition-J-W-Horton-Ver_W0QQitemZ120399634907QQcmdZViewItemQQptZLH_Def aultDomain_0?hash=item120399634907&_trksid=p3286.c 0.m14&_trkparms=72%3A1205|66%3A2|65%3A12|39%3A1|24 0%3A1318|301%3A1|293%3A1|294%3A50

I guess many will consider this latter book to be rather outdated, however, I believe the opposite is also true: the general character of a discipline is perhaps, better exemplified in its first phases of development.

Jens