Question for Electronics guys

Fla._Deadheader · February 16, 2003, 04:50:41 AM

Hi. Need some assistance. I have access to a side scan sonar unit, that I can use to find submerged logs. This would make my life MUCH easier. Problem is, it doesn't work properly. It has a converter on the circuit board that converts the analog signal to be sent to the computer by way of fibre optic cable. When you look at the end of the fibre optic cable, in the dark, you can see the red light emitting from it. You used to be able to see it in the dim daylight.
  There is NO schematic available, it came from England, and the people over there want $2500.00 to upgrade the unit.
  Without the schematic, is there ANY way to get this to work??
   How about if the converter is by-passed and a regular cable is used?? The signal leaves the board on a thin cable and goes to the converter. I assume that the fibre optics is used so the signal does not have to be boosted ??? Thanks for ANY assistance, good or bad. :

Den Socling · February 16, 2003, 06:26:54 AM

I don't know enough to give you much help but I can tell you a little. The analog signal goes through a digital to analog converter. Only after it is digital can the computer read it. The computer doesn't care about the fibre optics. What you need is compatibility. The computer has to know where to look and what interface format is used. I think you are going to need some technical guidance from the company or somebody who has experience with your unit.

Did the computer come with the sonar unit? It would have the software and maybe all you need is to fix the fibre optics.

Fla._Deadheader · February 16, 2003, 07:20:29 AM

It's not a modern day computer. It is a box with a mother and daughter board. No software. It simply reads the info and displays it on a screen. Whatever software it may have, was loaded at the factory.
The guys in England keep saying "send it back". It isn't mine and I Don'T want to spend the $3500.00 for the upgrade.

J_T · February 16, 2003, 07:40:09 AM

Do you have a buddy at the phone co that knows fiber opiis 0r a trade school that teaches electronics??? Just a thought.

Kevin · February 16, 2003, 08:53:20 AM

I hope you're reflecting that light onto an object and not looking at it with the naked eye.

Fla._Deadheader · February 16, 2003, 09:50:25 AM

There's no trade school around here. I had a REAL bad experience with an Electronics Engineer ?? and heastate to deal with them again. I really need a hands-on tech, that KNOWS what he or she is doing.
I haven't looked at the light. This other guy does it all the time.??

DanG · February 16, 2003, 06:50:28 PM

HAROLD! Do not look into the bizness end of a fiber-optic cable! If you just must look, put it real close to your eye. Inside, you will see a little warning sign that reads, "Do NOT look in here with remaining eye!"

I work with fiber optics on a daily basis. The innards of the F/O multiplexers do not lend themselves well to repair in the average home shop. The process of converting an electrical digital signal to an optical digital signal is complex. Converting it back is just as bad. It ain't likely that they went to all that trouble, unless it was necessary. I seriously doubt if an attempt to bypass it would be successful, and you would probably render the device unrepairable.
I guess you're just gonna have to send Ed down there to have a look. :-/

Fla._Deadheader · February 16, 2003, 07:08:33 PM

Hey DanG. Never gave you a thought about F/O. Reckon you could figger a way to check this thing out?? I could haul it to ya !! :

DanG · February 16, 2003, 07:17:26 PM

'Bout the most I could do would be to put a light meter on it, to see if the levels are ok. Even that would be iffy, since we don't have the specs, giving the correct levels and the format. Another problem might be the connectors that they might have used. The telephone industry has their own types of connectors, and I may not have an adaptor to fit yours.

Shoot me a pic of this thang, showing the fiber connections, and we'll see if anything looks familiar.

Fla._Deadheader · February 16, 2003, 08:14:13 PM

We have put a number of ends on this cable. Usually they work. Problem is, this guy thinks he can do anything, and never lets anyone else have a go at helping. If something doesn't work, he figgers it's beyond repair. The last time I talked to him, he said it wouldn't work. I asked him if he used the "gel" that we bought, that you put in the coupling to make a good path for the light??, and did that help? He had forgotten about it and when he put some in the coupling, there was "some" light visible in the end of the connector. This , he said, was weak, and that's why the unit won't work?? The actual fibre is 1/2 the size of fine human hair. This guy THINKS he can see, but, I KNOW he has to use glasses, but, the vanity won't let him wear them?? Knowhatimean, VERN??
I don't have the unit available, but, the connector is a 916S, I believe?? I figure the ends are messed up, but, he says he sanded them down to a mirror finish, so they HAVE to be good. Do the ends touch or how close do they have to be inside the coupling, to each other, in order for the light to conduct properly ??

Kevin · February 17, 2003, 04:15:15 AM

You don't sand fiber, that might be one of the problems, it might be scratched.
You have to break the fiber using a special tool then fuse it or use the proper connector that matches that specific fiber when making a splice.
It has to be very clean and close.

Fla._Deadheader · February 17, 2003, 04:27:37 AM

We got all the info from the makers of the ends. We got a small disk with a place on top to screw the new end. You "figure 8" the end on this super fine paper and then finish with a polishing paper. Makes the end look like a mirror. The guy uses a bench microscope to look at the ends when he is finished. One time, he put one on and after several days of frustration, took the end outside, into natural light, and found the fibre to be shattered. I talked him into putting another end on, and the unit worked fine after that.
  I think that when he got finished using it , the last time it worked, a film of some sort formed on the end of the fibre. It worked fine before he shut it off, and the next time, it wouldn't show on the screen. You USED to be able to see the screen "flinch", not anymore ??
   I been trying to get my hands on it, but, he thinks he is the only one that knows how it works, so, no go !!
  Maybe I should Hijack it ?? :

Kevin · February 17, 2003, 04:42:59 AM

We break it, clean it, put it in the machine and inspect and line it up then fuse it.
Send a light through it and it has to be within the limits for that specific type of fiber.
It's cowboy simple but it has to be right to work.
The jelled connectors have made it easier.

I stand corrected
There is a polishing paper for hot melt connectors but we've never used them here.
A figure 8 motion is used when using this method.

If you can send a signal ... not the ruby but a laser signal and measure the loss you would get a good connection.
The ruby will spill over into the connector and you have to play with the alignment to get it to line up.

Noble_Ma · February 17, 2003, 05:37:55 AM

I work for in the tele-communications field for Lucent. I'm not an expert but I can make a few suggestions. We always look at the cable first for any problems. Power lever ( like DanG suggested), eye mask pattern and connector alignment are all critical. It doesn't take much for a cable to fail given it is in a working environment and could be bumped. I'm not sure how you can verify the cable is good other than replace it with a known good one? I don't think you can bypass the optics because the mating component is looking for a fiber optic signal and wouldn't be compatible with any other signal. I would see about getting another good cable and go from there.

Fla._Deadheader · February 17, 2003, 03:16:35 PM

Good ideas guys. Another cable is not an option, as, this one is armored with 2 layers of Stainless braid. It is the tow cable. I suppose a cheap alternative would be to buy a 25 foot NON-strain cable, and use it for testing?? Thanks for the feedback. Much appreciated.

Kevin · February 17, 2003, 03:24:37 PM

multi mode is pretty forgiving.

Fla._Deadheader · February 17, 2003, 03:55:57 PM

Kevin, exactly what is multi mode??

Jason_WI · February 17, 2003, 04:39:58 PM

I think the telecom fiber and the fiber that Fla_Deadheader has on the sonar are two different animals.

I believe they used fiber on the sonar unit to prevent galvonic corrosion and possibly for voltage isolation.

The telecom fiber I work with are coming out of OC192 transponders have minimum bend radiuses and definately cannot be used to tow something. Other transponders use larger fiber but the connectors just snap in and are not water proof nor rugged enough to tow something.

Another clue is the visible light. Most transponders are in the UV range of the light spectrum so you would not be able to see it so to speak. If you can't see it, it doesn't mean that it isn't working

What Fla_Deadheader has is industrial fiber with a custom shield. It is fairly low tech and not used for huge amounts of data unlike telecom fiber where an OC192 cable can pass thru more porn than one can surf in a lifetime ;D

If you can get us more part numbers or a picture of it that would help.

I used some low speed fiber to isolate an airbag discharge control unit from the monitoring equipment as it was being tested for radiated suseptibility at 30 volts per meter.

Jason

Tom · February 17, 2003, 04:41:49 PM

That's when you get Strawberry, Vanilla and Chocolate on your pie, Harold. ;D

Kevin · February 17, 2003, 05:21:43 PM

Tom,
Single mode is long distance cable and multi mode is short distance.
I don't know about the cable for the intended application in this thread though.
This is tele communications cable.
The testing should be the same, send a signal from one end and measure the loss at the other.

Tom · February 17, 2003, 05:32:23 PM

oh

Jeff · February 17, 2003, 06:55:48 PM

I am enjoying this thread. I am beginning to think ya''ll are Greaking feniouses. Wish I could understand itall.

Larry · February 17, 2003, 07:26:06 PM

Harold,
I would try to clean the end of the fiber with alcohol and put them back into the connectors then try to wiggle them around some to see if you can get data through (optimizing). Make sure that you don't nick or scrap the outside of the fiber as it has "cladding" which keeps the light from jumping out.

Fla._Deadheader · February 17, 2003, 08:05:16 PM

Thanks, Larry. We already have a very small plastic tube that goes over both ends of the connectors for an exact alignment. I think that there is a film covering the end of the connector??

DanG · February 17, 2003, 09:29:11 PM

There's no "film" there if this guy's been scraping it with sandpaper.

If that's the case, a fresh splice, using proper equipment, is the only way to restore it, no matter what the transmission level.

I've been thinking about this, and also concluded that it is probably a lot less sophisticated than telecom fiber. That seems like a plus, at first, but I doubt that our test gear would match up to it.

Jason, I have worked with a couple of O/C 192's. Their capacity is awesome. We don't use anything bigger than an O/C 48, so we don't put too many eggs in one basket.

For those of you who aren't "into" this stuff, an O/C 192 is an optical concentrator, which carries 192 DS-3's, each supporting 28 DS-1's, or T-1's. Each DS-1 carries 24 speech or data channels. When I look at the way this stuff is put together, and the awesome responsibility it bears, I am totally amazed. In fact, it's amazing that we ever talk on the phone, or send a message on the Internet.