Lowrance StructureScan solves cable length issue?

[Rickard]

I guess few people have had an opportunity to try the new Lowrance StructureScan sidescanning option but it seems to have a feature that should interest all those who have tried to build a towfish for their Humminbird SI units. The problem is the length of the cable. Since the HB transducers must be fed from the head unit and the weak signal generated in the transducer must make its way up to the head without help from an amplifier the result is low signal level and influence from interference in long cables. The Lowrance StructureScan system communicates with the head via an ethernet link. Thus, the StructureScan add-on module can be located far from the head (as far as an ethernet link allows for). Imagine a system where the StructureScan module and the transducer is mounted in/at a waterproof towfish. Such a towfish could be connected to a very long cable that feeds the StructureScan module and the transducer with power and provides ethernet communication with the surface. I'm not in the position to try this myself right now but it would be very interesting to hear from those who might have similar thoughts.

An interesting detail, the Humminbird and the Lowrance sidescan transducers operate at the same frequencies....

Rickard

[erikgreen]

Anyone tried this?

Really pretty cool... the Lowrance LSS-1 installation manual says in part:

"The StructureScan transducer can be mounted on a trolling motor or towfish with the purchase of a trolling motor mount accessory kit"

It's on page 10.

So, sounds it's not just possible but they actually expect some people to do this

Anyone tried one of these units yet? I'm leaning toward getting one and rigging it for a towfish, but I'm wondering:

*How's the image quality
*Can you record the sounder data and export it (or are we still stuck with the SLV file format?)

Again, this looks pretty cool.

Erik

[Rickard]

Pessimistic...

I haven't tried the Lowrance LSS-1 system but there are many screenshots posted at fishing and sidescan forums and the general impression is that the system performs very well when mounted to a boat. The transducer is a little longer than the Humminbird HDSI transducer so the horizontal resolution should be a little bit better in the Lowrance system. But this difference is probably almost impossible to see.

They suggest you can mount the sidescan transducer on a towfish. But the transducer technology seems to be the same in the Lowrance and the Humminbird solutions, namely, no electronics in the transducers, only piezos which act as transmitters and receivers. So the Lowrance LSS-1 must have about the same limitation in length of cable as Humminbird transducers have.

There is another, very critical issue, how is sidescan ping rate controled in the Lowrance system? Humminbird uses a downward element that is integrated in the same housing as the sidescan elements to control ping rate from depth info. Something similar must exist in the Lowrance system. But the LSS-1 transducer is too slim for a normal downward piezo. Lowrance uses, most likely, the downward 'broad band' channel that is connected to the head unit for control of ping rate in the sidescan channels. But, in principle, depth can be measured also with the sidescan channels so Lowrance can have their own solution to the control problem.

If the LSS-1 needs info from the 'broadband' transducer that is connected directly to the head unit, not the LSS-1, a Lowrance towfish with long cable needs two transducers, one for sidescan and another for measuring depth. This would be a clumsy arrangement indeed with two cables and a towing wire. Thus, if my guesswork is correct, I don't believe in the idea I had when I started this thread anymore. I will regain my hope if someone can tell the LSS-1 can control sidescanning independet of the rest of the system.

All this is relevant if a towfish with long cable is constructed. If the towfish shall be used with a short cable, about 30 feet or so, it doesn't matter how ping rate is controled.

I have made several assumptions about the Lowrance system since most of the critical issues have no solutions in the manuals. Any corrections are most welcome!

Kind regards
Rickard

[erikgreen]

Lowrance LSS-1 transducer cable

Well, I'm not sure exactly how the lowrance system works - I know the connection from the LSS-1 module to the HDS units is ethernet, but I'm not sure about the transducer.

I do know the wire from the LSS-1 transducer to the LSS-1 module is 9 conductor, which tells me that it's more than just transducer signals going across it. That's enough pins for power and an ethernet connection to it, or any number of other things. How sure are you that the LSS-1 transducer doesn't have communication hardware included, like maybe an ethernet chip embedded in the potting for the transducers?

I haven't tried out the HDS units yet, but my older side scan, which is based on a lowrance head unit, has the ability to set ping rate manually. I'd be surprised if this is changed in the new units, even with the side scan capability.

More info is needed, I guess. But if you can run the transducer 300 meters from the boat (ethernet limit) then I'll be buying a couple of them plus an HDS head unit and some other accessories.

I also am interested in seeing if the new SL2 file format is open or if lowrance supplies a utility or viewer that translates to XTF or yellowfin format.

Erik

[Rickard]

Well, I can't know what's inside the LSS-1 transducer, but it's size and the existance of a control box between head unit and transducer makes me beleive there is very little processing done inside the transducer. The crucial thing is: does the transducer contain a receiver that has ethernet connection, or the like, to the control box? The signal generator can be in the control box because high voltage pulses can be sent through rather long cables, but the very weak receive signals need help to make their way in a long cable.

Nine pins is a positive observation. But the Humminbird transducer cables have seven pins and only five of them are used so many pins is not a guarantee.

(Manual control of pingrate is something I miss in the Humminbird machines. There is a workaround for that, you can set max depth to something shallow and thus force a high, but unknown, pingrate. But then the 2D-view can't show the seafloor.)

I hope someone can help in the file format issue.

/Rickard

[erikgreen]

Lowrance support response

Hmm.. well, I heard back from Lowrance support on my query. I asked how long the XCDR (transducer) cable can be.

They said that the LSS-1 has a 20 foot transducer cable and a 15 foot ethernet cable included that are used to hook it up, and no custom wiring is required... sometimes I think the support people working for them barely speak english.

They also said the transducer has a "proprietary 4 pin connector", which is different from the other information I've seen. They also said that I "would have to use their transducer and no other" for the unit to work (duh).

At any rate, the fact that A) It's a separate module and B) it communicates with ethernet is enough for me to give it a try sometime soon.

If nothing else I can try opening the LSS-1 module up and repackage the electronics in a pressure hull with a couple cable glands, sort of a fat towfish. Ethernet should let me run 100 meters of cable from the head unit, so I just need to use power over ethernet or similar to run the unit underwater.

Of course, the real problem with lowrance is their lousy sonar viewer and closed/proprietary recording file format, which I've been dealing with for a while. One hopes they'll release a new sonar viewer with better features to go with the LSS-1, but if they don't I can still keep trying to get conversion software written.

I found out I still can't afford a DeepEye towfish, so I'm kinda stuck at the low end

Erik

[Rickard]

Hope you try

I haven't thought about opening the LSS1 unit and rearrange the electronics into something more compact, good idea! The present design makes it very difficult to mount it into a underwater housing. The ethernet cable between head and the LSS1 must have power wires, and if not, a small battery could be sent down with the LSS1/towfish. From my humble experience I know you don't need large batteries to feed a sonar system for hours.

I think the sidescan images from the Lowrance system generally are better than the images from the Humminbird systems. The Lowrance sidescan transducer is longer, which is good, but I also have the impression Lowrance has less problems with sidelobe interference than Humminbird has. This could indicate the Lowrance tranducers have better quality than the Humminbirds transducers have. If the Lowrance LSS1 transducer only contains piezos, and since it uses the same frequencies as Humminbird systems do, this gave me the idea to try using a Lowrance transducer with my Humminbird unit. This wouldn't help much on the cable length issue, but it could give better images than those I get now. Especially when I use a rotating transducer technique the sidelobes are very annoying with the Humminbird transducers. I have asked the Lowrance support via mail if it's possible to order only the transducer but, as you know, their support barely exists so I didn't get any answer at all. I have to wait for more input before I can try this.

Rickard