stressed my optical cable too much?

Discussion in 'Beginners, General Questions' started by Fred G, Nov 9, 2003.

  1. Fred G

    Fred G Agent

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    Using cable ties to keep everything neat, I folded my optical cable and tied it at the center, leaving a figure 8 shape. However after learning that optical cables shouldn't be bent due to loss of signal, I am wondering if I have permanently damaged the cable, or if I can gain optimal performance if I simply undo the tie?

    I have never heard any distortion or problems form the cable thus far, but from what I've read I could be loosing information.

    Is the degree of bending even detrimental?
     
  2. Chu Gai

    Chu Gai Lead Actor

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  3. Matt`G

    Matt`G Agent

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    Bend radius is the key. As long as the fiber isn't bent too tightly you'll be fine. I believe the IEEE standard for fiber optic cable for networking use is something like 1.2", or 10 times the diameter of the cable, whichever is larger. If it were me, I'd make sure a baseball could fit inside the bend of each side of the figure 8. Seems like a decent amount of bend to me!

    You could still suffer dropouts without actually severing the cable, I'm pretty sure. Fiber optic cable transmission relies on a lotta light reflection and minimal refraction. The cable itself is designed to resist refraction. It's been a while since I've had a physics course, but too tight of a bend will cause the light to strike the exterior of the fiber at too strong of an angle, causing too much light to be refracted. It would cause signal degredation, which I assume would lead to dropouts.
     
  4. Fred G

    Fred G Agent

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    Thanks for those responses.


    So would these kinds of dropouts be permanent, or could it be resolved by returning the cable to its original position?


    Basically I have heard that optic cables are made out of some type of glass, or perhaps just the really high-end optic cables. And I know the nature of glass is to break, so once chipped, or broken, even undoing the tie would not help a damaged cable.

    However I have one of the toslink radio shack cables so I don’t think it’s made out of glass.

    So should I replace the cable I have been using all-together, or should I just undo the original figure 8.

    “I'd make sure a baseball could fit inside the bend of each side of the figure 8. Seems like a decent amount of bend to me!”

    That’s an interesting way of putting it. The way I had it I’d say a golf ball could barely fit through.

    On 2nd thought a picture is worth 1000 words.

    [​IMG]

    With this amount of bending should I

    a) leave the cable alone, it is fine the way it is.

    b) the cable is bent beyond redemption, buy a new one

    c) undo the tie and make a larger, "tennis-ball" like figure 8
     
  5. Matt`G

    Matt`G Agent

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    Fred,

    That cable doesn't look too bad. As long as the cable isn't kinked, there is not really a reason to throw it out. If I suspected degregation of signal, I might go ahead and redo the cable's arrangement.

    I found an optical tos-link cable I had still in packaging, so I snapped a shot of it to show the "out of the box" wrap, which I assume is well within the bend requirements of the cable. It's a rather large image, so see it here: http://www.accordingtomatt.com/misc/...tical_link.jpg

    I'm not sure how easy it is to tell from my crappy photography, but I could fit that golf-ball size wiffle ball through the bend almost perfectly. Judging by that, I probably wouldn't worry much about yours.

    Matt
     
  6. Fred G

    Fred G Agent

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    Thanks Matt. I'll stick with the original configuration.
     
  7. Chu Gai

    Chu Gai Lead Actor

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    a) looks OK to me.

    b) no, but if this is going to eat at you then a few dollars might buy you peace of mind. it seems that what you really want is a nice short cable to keep things tidy. For an interesting twist on fiber optic cables, take a look at the offerings from lifatec.com where they offer metal jacketed cables, armor jacketed if you will, that you can walk on.

    c) if it makes you feel better, sure.

    most consumer toslink is made from plastic fibers which work fine for modest distances. then general opinion of the AES is that plastic toslink is suitable for lengths up to 5 meters in professional applications.
     
  8. WillieM

    WillieM Stunt Coordinator

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    I may be mistaken but since we are taling about a digital signal here ANY appreciable loss of data would be very noticeable. If you aren't noticing a problem, the isn't one.
     
  9. JohnnyG

    JohnnyG Screenwriter

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    When you bend clear plastic, what happens? It's turns a white-ish color, right? Same issue for optical cables.
     
  10. Johnny Ayala

    Johnny Ayala Stunt Coordinator

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    I have mine pretty much the way you are using yours, and haven't seen or heard any problems. [​IMG]
     
  11. Geoff L

    Geoff L Screenwriter

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    I belive your over thinking a possible problem to be,,, that dose not seem to be.

    No problem so far.? (Drop outs=none), means most likely NO optic cable problem.. [​IMG]

    Open the drink of your choice and enjoy a good Movie or CD! [​IMG]

    Never hurts to ask and you certainly have received copious amounts of information on your problem that (dosn't seem to be). [​IMG]

    Regards
    Geoff
     
  12. HienD

    HienD Stunt Coordinator

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    I don't think you cable is damaged. With the amount of bends in the cable, You might experience higher levels of jitter that could affect sound quality. But wether you can here the difference is another story.
     

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