Ultra cheap head unit? Eagle 480?

[flyboypa28r]

Hi all,

Recently I built an ROV and that project is coming along well. We are now looking into towable SSS. Our budget is miniscule so I am looking for opinions and experiences. I have read pretty much all of the posts and gleaned a little information, but I need help.

Probably will be doing a thinned array of 4 transducers. Could I start with one and add more and still get decent results with just one?

I was looking around for a recording sounder with GPS that was halfway affordable and found the Eagle 480, which is about our price limit:

http://www.eaglegps.com/Products/Sonar/FishMark480.htm
http://www.eaglegps.com/Products/Com...arter480DF.htm

Has anyone attempted to use this unit?
What I would really like is a pcmcia card that does all the headend work, yep, i'm a dreamer huh?

Any help to this noob would be greatly appreciated.:confused:

[flyboypa28r]

I just realized that I submitted a link for the fishmark 480. I meant the Fishelite 480:
http://www.eaglegps.com/Products/Combo/FishElite480.htm

[ukdiver]

I brought a Fishmark 480 as a backup while I was waiting for a replacement transducer for my main Fishfinder.

I have only used it for its intended purpose and I haven't tried to use it for a SSS.

I have been very impressed with its performance, sensitivity is very good and it gives a clear noise free image. When fishing you can track individual fish leaving the bottom and moving in on the bait.

My only grip is the connectors on the cables; they are the push in type and of low quality. Not the rugged Lowrance grey connectors which I was expecting it would have.

For the money it’s a thumbs up.

[Glennk]

It lokks like the Eagle is the same unit that Lowrance offer.
They even have the same software versions.
What the unit is capable of you can read about in some other threads here in the Sidescan forum.

I have the unit, and a couple of other guys here. The unit gives great pictures!

I would recoment that you use a transducer that are tuned to the working frequency, as you then get the most out of your logging unit.
You could buy from GLB here on the forum, as he builds transducers and sell them at a nice price. These are all 200kHz.

You can take a look at his site at www.burtonelectronics.com

I can recomend this guy. Great products, great proces, and GREAT service!

regards,
Glenn

[Rickard]

Hi!

We are all dreamers, don't worry! But it so happens that our dreams actually can come true with less effort than most other dreams.

As you may have seen in my tread I have spent some time simulating beam patterns for fishfinder arrays. I have concentrated on arrays with four transducers but also tried a little with one, two and three transducers.

Whatever the number of transducers they should always be unevenly spaced. Equal spacing will result in a beam pattern that can be described as the beam pattern of a single transducer "sliced" into several sidebeams almost as strong as the main beam. I haven't tested this in practice yet but one can expect a blurred image with several ghost images. Actually, it could be better using only one transducer as this won't give ghost images.

Two transducers is a case with evenly spaced transducers as there is only one spacing. I guess one transducer is better than two in most cases.

Three transducers can give much better image than two or one, provided the two spacings are unequal. Four transducers gives even better images but the largest improvement appear in the step from two to three transducers. More than four transducers gives better images but the improvement levels off the more transducers you already have in the array.

The choice of spacings depends on size of transducer housing and number of transducers. It seems as the smallest spacing should be as small as possible in most cases (there are exceptions). Thus, the length of a transducer sets the size of the smallest spacing. Don't make any decision on total length of the array before you optimize the spacings. There are only a few good configurations for each case of number and size of transducers so you will have to accept the array lengths that result from these configurations. Note, that the solutions are independent of frequency and piezo size.

Fishfinder array construction is rather difficult but there are more to master than that. I think towfish construction is at least as tricky and a bad fish will ruin the results even if the array is good. Further, the instruments used for showing/ storing images is ment for fishfinding, not sidescanning. The instruments use various automatic settings of ping rate, signal strength, scaling and algoritms for detection of fishes. These features can be destructive (or helpful) when sidescanning. Difficulties may arise when the instrument can't find the bottom which is common when sidescanning. The effects of this may differ among fishfinders depending on their "intelligence". If the automatic processes have manual overrides this is a great benefit. Most instruments have a "secret" way of allowing manual settings that are not in the manuals. Ask, gently, the manufacturer for this secret and your control of your scanning will improve very much!

Regards,
Rickard

[Glennk]

Fishfinder array construction is rather difficult but there are more to master than that. I think towfish construction is at least as tricky and a bad fish will ruin the results even if the array is good. Further, the instruments used for showing/ storing images is ment for fishfinding, not sidescanning. The instruments use various automatic settings of ping rate, signal strength, scaling and algoritms for detection of fishes. These features can be destructive (or helpful) when sidescanning. Difficulties may arise when the instrument can't find the bottom which is common when sidescanning. The effects of this may differ among fishfinders depending on their "intelligence". If the automatic processes have manual overrides this is a great benefit. Most instruments have a "secret" way of allowing manual settings that are not in the manuals. Ask, gently, the manufacturer for this secret and your control of your scanning will improve very much!

I know that at least the Lowrance units have menu options to turn off automatic range detection, fish id, ping rate and so on. You can actually set everything manually.

I have been usint the LMS-480m unit for a while, and I can highly recomend this unit. BUT the screen is a bit small, and have only 16 shades of grey on screen. It would be adviceable to go for a bit more expensive unit with a larger screen AND color.
I am currently looking at the LCX-111hd, but I dont know if I should put the money into this unit, or just buy a complete dual scan sidescan unit later.

Glenn