fiber optic cable 1

[shaw]

Sources of potential damage or interference in fiber optic cable, does RFI or what is it? Improperly polished cable ends, imprecise connector/sensor alignment or excessive cable bending.

 

[SRFlanigan]

Fiber Optic is not susceptible to either RFI or EMI, which why it is the cable of choice, costly that it is.

Don’t have any input regarding the polished ends, but mis-alignment would affect it’s integrity, I believe.

Steve
Home: SRFlanigan@home.com
Work: Steve@regionalinternetmedia.com

DILBERT FOR PRESIDENT!

 

[wybnormal]

polished ends do have an impact on the loss of a fiber run. THink about the paint on your car.. scratches in th esurface makes it dull and not very nice. Remembering that paint works by reflecting light , you can see that the scratches diffuse the light, making the returned light weaker and more scattered.

The fiber end is the same. Scratches diffuse the light and scatter it which causes what we call "loss" The better the polish, the less loss.. I have seen *magic* gells that purport to help this loss by filling in the scratches and providing a briage across the ends that is optically clear.

MikeS "Diplomacy; the art of saying 'nice doggie' till you can find a rock" Wynn Catlin

 

[2ffat]

We've always had a policy of hiring "professionals" to terminate our FO cables. They will put a device on the fiber to measure transmission loss. I've seen one of these guys re-terminiate the ends of a cable run 5 times before he was satisfied with the results (turned out to be a batch of bad epoxy). Once they are properly terminated, you should make certain that the terminations (ends) stay covered until you put them in use. Using MikeS' example, dust can cause paint damage on a car's shine can also damage the FO's terminations.

The ony other problems we've had with FO is mishandling and cutting. FO is spun glass similar to fiber glass. Like you've said, they can't take sharp jerks or creases in them like wire can. You usually get these when you install it. Again a "professional" can help as can the type of jacket around the FO cable. After they've been installed, pretty much the only thing you have to worry about is someone cutting them, e.g., backhoes, welding equipment, saws, anything workpeople will use to "repair" wherever you;ve run your cables. But the same is true for copper cables.

Oh, and FO won't rust. Some friendly advice, match the cable jacket to where you are going to put FO. If you are going to run the FO in the ground, don't use the same jacket that you would through the walls. If the FO has to support it's own weight, for example, going from one pole to another pole in the air, you've need a jacket that has a supporting metal cable though it.

We've used FO in our mill and between our building for over 10 years now. They've lasted better than the phone lines have. With a careful look at what type you need for your situation and proper installation, FO will last years.

Sorry, I didn't mean to go on so long. ;-)
James P. Cottingham

I am the Unknown lead by the Unknowing.
I have done so much with so little
for so long that I am now qualified
to do anything with nothing.

 

[kcottrcdd]

The most common cause of loss in fiber optic cables is with improperly terminated connectors and excessive bending of the fiber. Connectors should be installed by professionals that have the proper tools and knowledge for the particular type of connector that is being installed. Believe it or not - A common cause of signal loss with fiber optic cable is due to wire ties that are installed too tightly. Although, the cable may not be damaged, A wire tie that is too tight will cause a "micro bend" that decreases the amount of light that can pass. This point of loss can be detected with a special Optical Visual Fault Locator. The wire ties can be cut and the signal will return to normal.

Keith

 

[mercenary]

...and extending what kcottrcdd said- this is why we never use wire ties on fiber, ever. Your installer/tech might think the tie is fine, but fine for one is loose for another, and so on... use velcro instead if you need to secure a fiber patch or cable. Also, a good rule of thumb for fiber bend radius is 20:1. 20 times the width of the cable should be your minimum bend radius.

 

[wybnormal]

Amen.. I wont use zip ties on copper.. much less fiber. Or D rings for that matter. The cables on the bottom of the bundle end up crushed over time and gives you a headache finding out why you have errors.

MikeS
"Diplomacy; the art of saying 'nice doggie' till you can find a rock" Wynn Catlin

 

[msoderlund]

just to add to Mercenary, All fiber should be ran in innerduct to protect from the knowing and the unknowing.