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Networking IT

Can You Build a Fiber Test Kit On a Budget? 53

An anonymous reader writes "Have any Slashdot readers hacked together cheap test kits for fiber optic cable? More and more IT infrastructure is using multimode and single mode fiber optic cabling. Commercial test equipment is extremely expensive, running the gamut from a few hundred dollars for a basic light source, to tens of thousands for an OTDR. What equipment do you consider essential to your fiber kit? Is there a way to save costs when it comes to fiber test equipment? It is worth it to do so?"
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Can You Build a Fiber Test Kit On a Budget?

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  • Just get.... (Score:4, Informative)

    by b96miata ( 620163 ) on Tuesday August 19, 2008 @10:19AM (#24658149)
    Two Media converters. If you can run ethernet over it, it's good.
    • Re:Just get.... (Score:5, Informative)

      by juiceboxfan ( 990017 ) on Tuesday August 19, 2008 @10:58AM (#24658783)

      Two Media converters. If you can run ethernet over it, it's good.

      That's true but only to a certain extent.
      It is possible that 1Gig ethernet will work fine on a cable that will not work or has a high error rate at 10Gig.

      You also will not be able to determine if a long run of single mode fiber has a multi mode patch in the middle of it (OTDR is the only thing that might give you that info).
      An Optical Power Meter [wikipedia.org] is your best investment [google.com]. That along with a good cleaning kit will give you the best results. A lot of "bad" fibers can be traced back to dirty connectors. _Always_ clean the fiber before plugging it into an interface - it is much easier to clean the fiber than it is to clean interface optics that have been contaminated by a dirty connector end.

      Beyond that if this is for in-house work just plan on using your fastest interface as a tester during downtime - setup the interface to expect loopback and put a short loopback patch at the far end. Run data through the cable and check for errors.

      Or as the parent said get a couple of cheap O/E converters for field work - not as good as a fast interface but better than a power meter alone.

    • Re:Just get.... (Score:5, Interesting)

      by rudeboy1 ( 516023 ) on Tuesday August 19, 2008 @11:25AM (#24659179)

      I friggin love this site. And here's about as cheap as you're gonna get. Though it won't exactly test your landlines.
      http://www.electronickits.com/kit/complete/fibe/ck1500.htm [electronickits.com]

    • hold one end to your eye, shine a flashlight in the other.

    • Re: (Score:3, Informative)

      by mbeckman ( 645148 )

      Two Media converters. If you can run ethernet over it, it's good.

      Alas, this can give you very misleading results. Ethernet is such an error-tolerant protocol that you can "run it" over even a very poor fiber link. You'll get rotten performance, but most people won't notice right away, and won't know how to isolate the problem to the fiber link even if they do notice.

      One particularly insidious performance degradation occurs when only one fiber in a send-receive pair has high power loss: random spanning-tree packet storms that can take down an entire network. Even pros h

  • by Anonymous Coward

    If your budget is $1 million, no problem. If your budge is $5, problem.

    • If he had a million-dollar budget, I don't think he'd be asking.

    • Re: (Score:2, Funny)

      by Anonymous Coward

      Even at $5, you have options. You can use you eyes up to 2 times to perform a rudimentary check of the light source.

  • by Anonymous Coward on Tuesday August 19, 2008 @10:26AM (#24658267)

    Depends on what you need to do.

    There are many different tests you can do on fiber. A basic college course will teach you that.

    Do you just want to know if the fiber is not "broken"? a LED and a phototransister can do that.

    Want to know if the fiber is the correct mode, optimized for the wavelength of the led, or can support multimode and run parametric tests on the fiber, gee, that gets more expensive.

    Its the same for the DIY ethernet cable testers too.

    Want to test continuity? a 5$ multimeter will do that.

    Want to determine if the cable meets spec? You need better equipment.

    Better Equipment GENERALLY equals better [test] results. [ yes, a lot can depend on the skill of the tech operating said equipment too].

    • Re: (Score:3, Insightful)

      And that means a Fluke with full fiber gear.

    • There is tons of this stuff for sale cheap on Ebay.

      If your maintenance budget is only $50, though, maybe you should have stuck with Cat-V. The equipment for terminating and connecting fiver is much more expensive than for UTP, and considerable skill is required to do it right.

  • Nick one.

  • Heh (Score:3, Informative)

    by Xtense ( 1075847 ) <xtense@NOspAM.o2.pl> on Tuesday August 19, 2008 @10:33AM (#24658383) Homepage

    Try a flashlight!

    • Re: (Score:3, Informative)

      Bad moderator! No cookie! The parent is NOT offtopic. A flashlight works for a basic transmission test. I was a fiber optic technician in a former life and after terminating the ends with connectors we would shine a maglite on one end and turn out the lights on the other and if we saw the "light at the end of the tunnel" we'd call it good. If you want to get fancy you're going to need an optical time domain reflectometer. Probably not the cheapest thing.
      • by Tmack ( 593755 )
        "Do not look into fiber with remaining eye"


        • My eyes are fine. There was nothing dangerous about looking at the maglite beam from the other end of the fiber. This wasn't some kind of fancy magnified light that attached to the connector - it was just a regular flashlight that we held up to the end. But, we also use a cheap laser pointer for longer runs - here the guy on the "dumb" end of the test in the dark (often me) would just hold them up and look for the glowing red end of the fiber without looking down the tube. We'd only order out the OTDR a
  • by Khakionion ( 544166 ) on Tuesday August 19, 2008 @10:37AM (#24658441)
    "running the gambit" I don't think it means what you think it means.
  • Please, for god's sake editors, do some editing.

    It's "running the GAMUT," which means "the full range or compass of something; a range from one extreme to the other"

    GAMBIT, on the other hand, means:
    1. Chess. an opening in which a player seeks to obtain some advantage by sacrificing a pawn or piece.
    2. any maneuver by which one seeks to gain an advantage.
    3. a remark made to open or redirect a conversation.

    But I could see how they could be confused, they both start with a G and have vowels *rolling eyes*

    • I thought it was running the Gumbo... If we're following the 'starts with G and has vowels' rule than that'd work perfectly.
      • by unitron ( 5733 )

        I thought it was running the Gumbo...

        Nah, any halfway decent gumbo will be too thick to run.

        Although I suppose gumbo could be used in a different kind of "fiber" test. :-)

    • That begs the question of how long it will be before a large number of repliess along the lines of "languages evolve" "if people use it to mean that then that's what it means" or "so what, I understood it" will arrive.
      • Re: (Score:1, Interesting)

        by Anonymous Coward

        languages evolve

        "Begs the question" was a terrible translation of petitio principii in the first place, and the language never meant what people asserts it means. A proper translation from Latin would be "seeking the principles", which actually DOES describe the fallacy wherein assuming X (your principle) you make a long winded argument that eventually proves X (seeking it), which has nothing at all to do with "begging" or a "question" in the first place.

        I hope people continue to use "begs the question" in

      • Hasn't "language evolves" come to mean "I can't wait until the ignorant take over the world?"

        Oh, wait.

    • Ah, but it is correct. "Running the gambit" would mean, essentially, "playing the game". The commercial test equipment manufacturers are maneuvering price points and feature sets in order to gain the advantage of making a sale. So, they are "running the gambit", ie. playing the marketing game.

      Okay, I can't keep a straight face anymore. It is gamut, not gambit. But I held it together pretty good there, for a while.
    • by HTH NE1 ( 675604 )

      Please, for god's sake editors, do some editing.

      Ostensibly they are quoting the anonymous user. Which is most proper: to correct such mistakes in quotations, to call them out with "[sic]", or let them stand?

      For my part, I tagged with typoinsummary, runningthegamut, and !gambit.

  • by Barsteward ( 969998 ) on Tuesday August 19, 2008 @10:58AM (#24658779)
    http://www.weetabix.co.uk/ [weetabix.co.uk]
  • Confucius say "cheapest way to test fiber is to eat cow pie."

  • by caffiend666 ( 598633 ) on Tuesday August 19, 2008 @11:34AM (#24659333) Homepage

    Had to answer this question once ourselves. Never got to the implementation phase, but the plan was to have one or two high-end test sets, and build the others out of the prototypes for the equipment we were building, and Lucent OptiStar NICs on Linux systems. IE, each protype would test the next, and we would have racks full of 1U Linux Boxen with Lucen OC-12 NICs. Can't find out of Lucent or Alcatel-Lucent is still making those things, but you can find used/refurbed OptiStar (?) SONET IP Nics for Linux (PCI) fairely cheaply. No idea if they work, but as low as $60 bucks. New, they were $10k to $6k. Searching for Optistar on Ebay or Google returns a lot of info. Or, searching for SONET PCI NIC. Or, just FIBER PCI NIC. You can probably set up a laptop with Gig-E, if you just want connection tests, regardless of which protocol you're going to use. Honestly, eBay/Amazon are your friends here. At times, you can find million-dollar test sets for $100 bucks (Adtech, Omniber, Cerjac...) Most are left-overs from when startups fail. Also depends on what you're testing.

  • I would use ... (Score:1, Interesting)

    by Anonymous Coward

    I used to build fibre optic cables and every cable that didnt have glowing bits when you pushed a laser down them seemed to test perfectly. So I would use a 5mW green laser and if any bits on the cable glow you know that cable is broken.

  • Really, the cheapest solution is a simple power meter, some cable-cleaning swabs, and a nice long spool of pre-terminated spare cable.

    There are full-fledged cable certification devices out there, and you cannot afford one, nor do you need one.

    Yes, there are a lot of problems that can happen with a cable that won't be caught with a power meter, but those problems can be prevented by only using factory-terminated cables from a quality supplier.


  • by mbeckman ( 645148 ) on Tuesday August 19, 2008 @11:52AM (#24659591)
    The primary tools you need are a fiberscope for visual connector inspection and a power meter with laser source, a set of laser goggles (if you plan to work on single-mode or long-haul multimode fiber), an assortment of fiber patch cables, and a mini-maglite with fiber adapter (for simple continuity tests).

    You can get these used on eBay all day long for a few hundred dollars for the entire set (search terms: "fiber test*" "fiber patch*" "fiber splice*"). You may have to watch a few days for a bargain, but I'm constantly amazed at how often high-quality fiber test gear goes for a song on eBay. Purchase only name-brand gear, such as Fluke, Noyes, Microtest, TestUM, etc. (You can learn the name brands by looking at new-equipment listings at places like CDW).

    There are many tutorials on the web showing how to use these tools, most from equipment vendors themselves, and some are even high quality video presentations. A useful starting point is http://fiberu.com/ [fiberu.com] (although it's become less useful since Fluke took it over).

    The mini-maglite will instantly identify any fiber -- the light will be clearly visible at the far end of even a thousand-foot run. If high-power IR lasers are in use on the network, be careful to be wearing fiber goggles whenever looking at fiber ends, even at your own white light. You can't tell when a fiber is energized with high-power IR, since it's invisible.

    The power meter lets you measure the light loss through a fiber path, which when correctly interpreted will give you performance information. Get one that reads tenths of a microwatt, and that also directly displays dB loss from a reference signal. If you know the installed fiber specifications (you can read these off the fiber jacket), you can compute the available bandwidth based on fiber length.

    The fiberscope reveals otherwise-invisible defects in a connector so that you don't spend hours trying to make an unworkable connection work. Again, be sure you're wearing laser goggles if you don't have both ends of a fiber in your hands. Magnifying harmful IR radiation is very dangerous.

    For routine work you don't need an OTDR. Besides measuring the length of a fiber, an OTDR will locate defects along a fiber span so you can locate and repair them. If you're not repairing cable, or splicing it, an OTDR is overkill. Fiber installers have such gear, and they'll be happy to use theirs on your network for a fee when you need that capability.

  • by ak_hepcat ( 468765 ) <{leif} {at} {denali.net}> on Tuesday August 19, 2008 @01:22PM (#24661069) Homepage Journal

    There's a really cheap "laser" detector that nearly every tech carries, although you may have forgotten it.

    It's that camera on your cell-phone.

    Yup, in a pinch, you'll see a nice little purple dot appear on your screen if you've got IR coming down the fiber. Works well enough to identify active cables.

    You can also pick up a mag-lite->fiber adapter that'll shine visible down the line fairly cheap.

  • by Anonymous Coward

    Im active duty, and in my shop we use a LS/PM model TS-4358 made by EXFO AMERICA. For an OTDR we use an ACTURNA MTS 5000 measurses 850nm and 1300nm wavelengths. The machines are simple to use but have many options.

    Multimode fiber reels that I repair come in 500m lengths. I use my led Maglight for simple testing of it passing light or not. So easy a caveman can do it.

    Im sure the civilian market has higher standards of min dB loss then the military.

  • I remember when I was a kid I had a lego spaceship that had fiber optics on it.
    They didn't do anything but they sure looked cool!

    Wait, what were we talking about?
  • As some pointed out.. what is defined as 'Cheap'? And also what level of work are you doing?

    If you're just a cable/server/network guy (like me) then you really just need a cleaner and something basic to check for breaks.. (see comments about mag-lites; etc). I mostly deal with pre-made patch MM/SM.
    A decent DB tester on 1300/850 is helpful too just so you can check for light-loss assuming your optics don't tell you (some do).

    If you are a 'Fibre Guy', or make your own SM/MM; then you'll want to look at things

When a fellow says, "It ain't the money but the principle of the thing," it's the money. -- Kim Hubbard