How To Test Your Fiber Optic Cables With Cheap Tester

hey friends Derek from Tech connection here with another video and this time we're going to talk about how to test fiber cables with our Optical power meter so in a previous video I talked a little bit about this knockoff tester you can get versus a very expensive fluke tester and with this one uh it's got a function which you no doubt noticed when you were shopping to test fiber optic cables and a lot of people have contacted me including some of my own employees have asked how in the heck does this thing work it's not immediately obvious how this thing is supposed to function so let me walk you through it in order to do the testing with this you'll need to run down to your local Cable store and pick up a couple different kinds of adapters these are single mode you'll also need them for multi-mode if you're looking to test both kinds of fibers here at our shop we run all kinds so we'll do mostly single mode when we're going between buildings or when we're going from one floor to another floor we'll do multi-mode when we're going within the cabinet uh we'll do multi-mode when we're going within the same cabinet so if you're going from one server to a switch or between two iSCSI Sands or something like that it's very common to use the high-end multi-mode to link those systems together but it's not very common to drag multi-mode say a thousand feet and try to link up at 10 gigs or 40 gigs in that manner it's far more appropriate to use the single mode for that so in my office I carry adapters for both kinds it's a little bit cumbersome to have so many adapters you buy the ones you need of course don't uh don't let me stop you so I've got one SC to LC one scsc and then I've got my cable under test so I've got a length of cable that I want to check is this a good cable or not that's where this little fella comes in and I need one more piece in order for this to work I need an SFP and a switch or because I don't have one of those I'm going to use a media converter so I've got a very simple media converter that takes an SFP as if D slots inside here and then it is transmitting light always we'll take our tester down to the optical power meter mode and press ok and here we're going to see a couple of things one of them is the frequency of light that we're testing so this device can test multi-mode and single mode and in those situations there's more than one frequency that you might potentially be checking so you can cycle through them from 850 nanometers 1300 nanometers 1310 which one do you use well if you break out your SFP and you look very closely on the label most sfps tell you exactly what they're transmitting at and you set the power meter to match that if you don't see anything which is sometimes the case you're going to go on to Google and you're going to look it up there's a standard there's a spreadsheet that you can get it's got everything under one big listing I usually just look it up Case by case I don't try to keep that on hand or anything but you could stick it in your toolbox if you're using this a lot let me show you the single mode SFP and how it looks so I slot it into my media converter and then I'm going to take my patch cord and I'm going to plug it in to the transmit port on my media converter always keep these dust covers handy you're going to need them again in a moment never let your fiber get dirty so if you plug the sfps transmit into your power meter you'll see here that there is in fact light being received and there's a number being shown as reference it's not super important what that reference number is at the time that you first are testing what you're looking to do right now is you're trying to get a clean signal between your tester and your source so if your source is an SFP or a switch or a router or something with a transmitter in it that you can plug into you want to read the light level as close to the source as possible and that becomes your reference so on this particular tester once I see that I've got something you're going to arrow down and select reference and then you're going to hold the OK button for just a moment you'll see then that there is a reference number that shows now your tester is essentially calibrated to the light level in the best case scenario then you're going to walk your light level to the other end of this cable that you want to test so I've got a hundred feet here but if it was going say a kilometer you're going to walk this thing all the way to the other end before you head out patch in the cable you want to test you want the situation to be that the source is transmitting all the way along the route that you want to check so at the other end I've got an sc connector I'm going to go ahead and remove my dust cover and I'm going to attach a coupler to that that way I can use this small patch cord at the other end that small patch cord I'm plugging into my power meter now you're going to see on your display that there's a new number the reference number never changes because that's best case scenario the number that's showing now is the difference of Light Between the source as it was originally tested and the source as it is now after going through this long hundred feet how much light made it to the other end they give you a measurement of how much loss there was so on this test I'm showing about 0.75 DB loss that's a real good number so what numbers are we looking for what do these numbers mean in terms of DB loss are we doing well are we doing bad do I need to clean this your most common uh source of any kind of loss is going to be dirt on the connectors so you want to keep a cleaner handy in case you need to wipe these down anytime you've got a connector like this which you might have at a bulkhead at each side so if you've got one building where you've broken out into a sort of wall mounted patch panel and you've got an sc or LC connector there and then the cable runs underneath the ground goes to another building and then you've got another bulkhead there and there's an LC or an sc connector and on both ends you patch in with a short cord so you should be looking at .75 or thereabouts in terms of DB loss for a total amount of 1.5 across the entire permanent link for single mode if you can keep total DB loss under two you should have no problem doing 10 gigs easily whenever you're going between buildings even at far distances of more than a mile now after you've tested your cable you've only tested one of the fibers you'd want to have your partner help you out by going back to the source taking this patch cord and many people don't know this but these actually open up and split you would reverse them so that you put the other fiber on the transmit then at the far end you move your coupler to the other side and you test again it's real easy to have a clean pass on transmit but a fail on receipt so you have to test both of these fibers fully once you finish testing this end of the cable it's good practice to reverse the light source and the tester to the opposite ends of the cable and test again just to be sure that your cable is functional in both directions after you've recorded all measurements return the dust covers so that nothing changes between the time that you've tested it and the time that the user needs to use this then okay so you finished doing all your testing and you recorded all your numbers nothing is above 2.0 loss so you're fairly confident that these are good cables but how can you be sure does this prove anything or not so what this proves when you do this test is that that frequency of light is received at both ends of the cable safely however it's not a for sure thing that your link will work it's a good indicator that it probably will and that the cable is probably just fine but you can't be perfectly sure without running a certification test which is unfortunately a much more expensive machine the inside plant installer will probably come after you run a tier one certification on it after the fact and that will actually test does this do 10 gigs are we losing any data in Transmission in transit are we getting bit error rates re-transmits is there high reflectance at a certain connector Etc so this first part this is just sort of laying the groundwork that your trunk is good but there's a lot more that can go on at the connector at the switch uh at the bends then you have to pay more a little bit more attention to so this isn't the end-all be-all but it's a really good start as you take more fiber jobs and you get a little bit better at your craft it's well worth investing in at least a knockoff tier one tester doesn't have to be amazing or anything you can eventually get that big fluke that you've got your eye on I'm Derek from Tech connection and thanks for watching this video

Channel: TCI Productions

Views: 24,771

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Id: WMcNmCeBwLc

Length: 9min 48sec (588 seconds)

Published: Mon May 29 2023