Stay Accurate: The Ins and Outs of Cable Certifier Calibration

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As I said in the beginning , those testers are pretty expensive little testers , but you don't just buy them and then just don't have to ever worry about them again .

There are some things that you're going to have to do to make sure that that tester is functioning correctly , testing correctly , so that way you can get the warranty from the manufacturers and you can meet the customer's requirements in their RFQ or RFP . One of the things that you need to get done is calibration .

There's a lot of confusion about testing , testing , calibration . I've gotten several questions over the last few weeks and I've been compiling them Just waiting for the opportunity to bring on a subject matter expert . Hmm , do I know any ? Hmm , i might know one . Hold on Steve Giles from AEM . I consider him a subject matter expert , steve .

How you doing my friend ? All right , chuck .

I forwarded the opportunity to teach a class for some Graybar people inside and outside salespeople , just to kind of get them up speed on structured cabling , and one of the tips that I told them was you know , if you sell a certifier to a contractor , in your outlook or whatever email program you're using , just set yourself a reminder in 11 months to send that

that contractor reminder to calibrate their tester , because , trust me , they're going to forget . But that's only one of the many , one of the many problems out there . So , before we get into these whole , all these tester questions , since you haven't been on the show in a few months , why don't you go ahead and give us the the introduction ?

Who is Steve Cowles ?

Chuck It's not with me , it's weird , but yeah , i've been in the test and measurement industry since 99 and you know , heavily involved in certification and copper and fiber and DSL and outside plant stuff and run the full gamut of that Been on board with AEM for last four years .

It was just four years last month And you know we've got a multifunction cable certifier So it does more than just certify the cable . You , if you've ever tuned in , i've got a tech talk video cast that I do every couple weeks and we talk about the products and applications and you know different things . So that's me .

Back in I call it the olden days , back in the 1990s , when we were doing cable certification , those testers use mechanical relays And you might remember the testers going click , click , click , click , click , click . So mechanical relays . Certainly there was much more chance for something to get out of whack on those .

Everything now is solid state , so there's not a mechanical issue but it's , you know , over time , depending on what the instrument's been exposed to . You know the condition of your adapters and everything else .

It's good to get it calibrated just because you want to make sure it's performing at its utmost , because you're measuring to tolerances specified by the standards , and if your accuracy drifts a little bit because it's out of calibration , then your measurement may not be all that accurate .

You may be masking bad measurements or you might start failing measurements on cables that are really good . So , or when you get into those marginal areas that you may have heard of a star pass or a star fail , where the pass has a little asterisk next to it .

That asterisk is there because that measurement was compared to the pass fail threshold was within the tolerance , the accuracy level of your tester And that's , you know , prescribed by the standards .

And if your accuracy is not really that tight anymore then you may get a pass when it really should be a star pass And , in my opinion , star pass I think you've said this to Chuck if you have a star pass treated as a fail , you need to troubleshoot it , because it's all about headroom . And then the other part of that , to calibrate .

Why calibrate the manufacturers that give you an extended warranty for the cabling systems ? They are not going to accept your test results if you haven't had your tester calibrated . So it's important to make sure that you get it calibrated at the recommended interval , which is a one year interval .

You know that's it's largely driven by manufacturer and specifiers that one year And one year is a good time frame because you don't know how much you've used a tester or not used it in a year . So doing it in one year is good because when you do a calibration you're not just calibrating the instrument .

We'll talk a little bit more in detail as we go here about what that calibration entails . But but you're doing other things . You're checking the adapters , making sure they're performing properly , making sure the units in good condition , etc .

They're going to tell you that it should be calibrated within a year . And and you know that's kind of where the tester manufacturers , the cable system manufacturers , all kind of work together And there's so much experience in the testing industry over the years between us and other tester manufacturers and the cable and connectivity manufacturers .

That kind of boiled everything down and looking at what happened with testers over time And that's where we ended up settling on this one year interval And pretty much everybody's going to tell you it's a one year interval .

When you're doing testing for a large job , you're leaving your permanent link adapters in the biggest connector . That is critical is the connector where that test adapter mates with your test platform .

That has to be a very high precision connector and it's rated to a very high number of mating cycles because you're not plugging and unplugging that every time you're testing . The other thing is the electronics in there .

If you're sitting here and you're running tests , you know for a full day you know a thousand tests or whatever you've run , that isn't gonna have as much of an impact on the electronics and you know what's going on , as time may have where you start to get some drift .

So it's you know it's better to have it as a time-based And yeah , there was some calculation in there when the one year interval was figured out .

That involved average testing , average numbers of tests , and you really can't , you can't just say , okay , let's do it every thousand tests or whatever , because one tester that ran a thousand tests may not be the same as another tester that ran a thousand tests .

You know You didn't want somebody you know calling security on you because they thought you had a you know something that was gonna explode , cause it did tick , tick , tick , tick , grrrrrrrrrrrrrrr . It's almost like the AOL modems when you used to dial in . Yeah , yeah , right .

Yeah , we're talking real old school Yeah we're showing our age , the fact that you knew what I was talking about . You thought it was funny . We're old , steve , we're old , yeah .

So you already mentioned one of the potential consequences of knock calving affecting the manufacturer warranty , because a lot of the manufacturers do require that warranty And they will also check it as well , because it shows up in the test results when the last time it was calibrated , right , what are some other consequences that might come about from somebody who

hasn't had their tester calibrated ?

But they impact all of the measurements on the tester at various frequencies And your return loss , your crosstalk , your DC resistance all these things can be impacted if your tester is not calibrated regularly . So you may have a tester that you didn't calibrate at a year and maybe at a year and a half it's still working fine , but you don't know .

And you could have it two years and it works fine , but again you don't know . It might look to you like it's working fine , but because the accuracy isn't really where it's supposed to be , all your measurements that look good , they might be good , but they might not be as good as you think . So the biggest part of this is the accuracy of the tester .

You want to make sure that all of these different test parameters that you measure there's a multitude of measurements that we do . There's literally thousands of measurements because you're doing , you look at things like return loss and crosstalk and resistance and all these things . All the RF measurements are done through the frequency range .

So if you're doing CAT 6A , you're doing everything all the way up to 500 megahertz . You get into CAT 8 , you're going to 2 gigahertz . If you're in Europe doing CAT 7 , a class FA ISO , you're at 1,000 megahertz . So when you're doing these tests there's a test that every stop along that frequency range .

And you're doing so many tests that if you're not accurate you're going to start to see some problems .

If someone buys a cable certifier And and they , the server , will tell them one was last calibrated , but they buy a certifier a Used one , not not a new one should they just go ahead and get it calibrated again ?

And and you can , you know , i would say , contact the manufacturer , the tester , ask for their input on that , see what they think . They might have you run a couple tests on it to check a couple things out , to make sure things look good , and They might tell you , yeah , you can wait until the next calibration interval .

Or they might have you run a couple tests and go , yeah , we might need to replace your permanent link adapters or your channel adapters aren't really looking good , those might need to get replaced . That's usually what can happen if you're buying a used tester .

If it's within the calibration period , calibration might be alright , but you may have to replace the test adapters .

those test heads , you know , let's say , they pull a bat , one out of the back because they're gonna start testing job and most companies Share testers . They don't issue everybody a brand new test right because they're expensive , yeah , So what ? so we tend to share testers .

So when you're breaking up a test of that another crew head or another , it was back in the warehouse . What are some of the things they should look at when they're looking at , since you mentioned those , the test heads , what are some of the things they should look at to verify that those heads test heads are still usable ?

That's going to be key permanent link adapters Obviously going to have a two meter test cord on them . That's going to be the most common when you're using with copper testing . Is that permanent link . So it's got a permanently affixed Two meter test cord that comes out of that test adapter .

Look at the area where the cord comes out of the test adapter to make sure the strain reliefs intact . You don't see that the cables damaged . Feel . And look all along that two meter cable to make sure it doesn't seem like it's been kinked at any point .

And then , especially at the , the RJ45 plug-in , examine that strain relief where the connector in the cord meet . Make sure that is in good condition . You don't see any damage to the jacket of the cable . Look at the , the tip of the connector . Look at those contacts , those eight contacts . They should be nice and bright and shiny .

If they're dull Then they probably have oxidized a little bit It might still work , okay , when , when they get a little dull . But also look for any kind of damage . You know , make sure there's you know not some kind of obvious damage . Same thing with the channel adapter , one of the most common things that happens with a channel adapter .

Remember the channel we're actually , if we're using channel adapters , we're supposed to be testing the patch cords and equipment cords that are being left behind in the system , right , a lot of people use channels and just they have the same patch cord going from from Jack to Jack .

But what can happen in the field is if somebody makes their own patch cord which we Tell everybody don't do that and it's not a good termination and you plug it into a channel adapter , it can push the pins up . Or somebody accidentally plugs an RJ 11 into that RJ 45 port , it can damn it happens is damaged , mm-hmm .

So look at those pins to make sure that they look good , they don't look damaged . Now You may see in some cases pins that they're not all gonna be the exact same level and that's by design . The manufacturers design them that way and you work for a connector manufacturer , so you know this , chuck . Yeah , where it's to help avoid crosstalk .

So you're not all gonna be in the same design , but they're . They're . They have specific tolerances and they give a little bit when you plug that , plug into that jack . So if you see any damage on those pins , that's a sure sign . Or if the connectors loose , you know , i've seen that happen , where I don't know what they're doing .

I don't know if they're taking a Hammer and a chisel and trying to , you know , drive the connector in . But I've seen those . They get treated rough .

Yeah , right , yeah , in Florida . You know , i know my , my pickup truck , if it sits out , you know I usually park it in the shade . But if the , the primo parking space in Florida is the shaded spot , not the closest spot , that's right .

You're getting to , because it can get extremely hot inside that vehicle and in the north , you know , if wintertime it gets cold . Yeah , and I'm assuming those elements probably affect the performance of a tester , do they not ?

And if you , if you do store it in in an environment that exceeds those Limits , then you probably need to make sure you're going to leave extra time to allow that tester to cool down or warm up or whatever , but especially heat . You can really cause some damage to equipment if you leave it for an extended period in in really high heat .

There's just a personal opinion . I'm always leery about buying used electronics . You know , electronics are one of those things I want to buy brand new . You know , if I'm buying like a , if I'm buying like a shovel or something for the farm , i don't care if it's old news , but something electronic . Why are they selling it ? Yeah , what kind of conditions .

You , that was a left-in-air truck in the summertime and and then you know , now It's kind of worked a little bit and sometimes it's like somebody selling that that test for you know , use test You're not may not tell you that information .

You're gonna leave your laptop in there when it's , you know , a hundred and two degrees in the shade here in Central Florida , which means it's a hundred and forty or hundred and fifty in your car . Yeah , would you leave your laptop sit there for hours on end ?

So you mentioned the parameters when doing the , the calibration . What are some of the performance metrics that are looked at during a calibration cycle ?

Now , when you get a calibration done , you'll see a calibration certificate And I'll scroll down through this and just show you some of these parameters . So there's a few different Things that are looked at and we use these calibration artifacts and they'll they'll actually test the unit and then make subtle corrections and adjustments to fine-tune the unit .

And then they do a verification to make sure everything is functioning properties properly . So Directivity , so this , this really , you know , when you're transmitting a signal Into a terminator , you know into into one of these terminator , essentially one of these artifacts The terminator should absorb all the signal .

So you shouldn't really see any reflected signal , no return loss . You shouldn't see any signal coming back . If you do , that means that you've got some leakage In your , your transmission there . So So directivity is measured Source match .

You know , ideally the , the tester is going to match the impedance of the system And what should happen is when you're testing with a main and remote , as we do in certification . The remote unit should absorb that , that energy from that signal should absorb that signal at that far end .

None of that should get reflected back from the tester Because if it does , then it's going to mask your real return loss measurements . So if you're actually getting return loss as an effect of your remote on your tester , it's going to skew your return loss measurements . So so that's why we do the source match , the tracking .

So with tracking there's two extremes . We're looking at in cable here in open , which is going to be Infinite resistance , and a short which should be close to zero at the tester . So these , when they're they're compared together , should balance out right around zero . Then you've got your source , a Return loss , your source load return loss here .

So what this is , when you do get a signal coming back , a reflected signal , and And part of the calibration artifacts will intentionally reflect a signal back and when it comes back it should be absorbed Into that source tester . And again this this goes back into the whole return loss thing .

So when you're measuring return loss on a cable , there's a reflection and you get signal coming back if you're your source , your tester on the main end , or if it's the signal coming from the remote as a transmit . If it doesn't absorb that reflected signal It will bounce it back out on to the cable .

And now you're actually Injecting a reflected signal back into the cable and it's going to cause problems with your crosstalk and your return loss measurements . So that's why we do that part of the calibration . The output signal balance and the , the , the common mode rejection , are going to be the next two down here .

So These are kind of related and they're both related to our TCL measurements , which is our measurement of the cable And how resistant it is to noise interference . So the output signal balance you know we're looking at . Think about the pair . You got a positive and a negative signal going out . They need to be perfectly balanced .

So they're in phase , the same intensity that you know , the same Same magnitude on the plus and the minus . So they balance out to zero . So your , your transmitter , needs to be able to send that perfectly balanced signal . The other part of this , the common mode rejection , has to do with that balance signal coming back to you Going into a cable .

There are going to be things that that will change the signals that's coming back and you need to be able to measure those . So if your tester can't be within a certain tolerance of being close to zero on the measured signal , you're going to have problems seeing those issues on the cable .

So these two are really tied in together and that's that same plus and minus balance signal on both sides of the pair . The last two you see here , and these are on all of your calibration certificates when you and you get these back from having the tester calibrated , the residual next .

So this is , this is a measurement of , This is a measurement of the easiest way to explain it is internal leakage or internal crosstalk on your test equipment . All pieces of equipment are going to have this . But you need to be within a certain tolerance and you'll see limit lines , all these red limit lines you see on here .

Just like you went on a regular cable test , you have a limit line , so you need to make sure that you don't exceed the threshold there . And then the last one is a really important one random noise floor . So this is essentially the smallest measurable noise level of the equipment when you're not transmitting a signal into that cable .

So it's , you know , it's really goes to the sensitivity and tying into how , how much , how , how you can see the subtle issues with a cable when you're doing a certification test . The other things that don't show up in these graphs are our DC part of this . So that's the DC resistance measurement .

So that is also tested as part of the calibration to make sure that we're falling within .

On the test it's actually above the limit line , but on the people seem to have an easier way of , or easier understanding when you put the limit line low , like this on the printed report . If it were to exceed that limit line , it would fail the calibration , it wouldn't pass .

So you know DC resistance is going to fail it and then any of these parameters will fail it as well . And you know , if a , if a calibration fails , then you have to go back to square one to figure out why it failed and determine if it's an issue with the tester . Was it something you were doing during the calibration ? maybe you need to recalibrate ?

So it's . You know it's a . It's a whole series of a . Calibration like this typically takes about 90 minutes to two hours , depending .

You have to do a set reference between the units , other parts of the calibration service , including updating the firmware , physically inspecting everything , make sure nothing looks like it's damaged . And then after the calibration , we do something with the permanent Lincoln channel adapters , called a cat 6a verification baseline test . Where it's .

It's like plugging the units into each other with a permanent Lincoln one and a channel in the other And running a certification test . But it's to a much tighter standard than what you do for install cabling and it's designed to look at those test adapters to make sure that they're functioning properly .

There was one of the contacts had actually been damaged And in that case it was an instant where somebody had actually dropped it off . A 20-foot scissor lift .

So what happens is if you have a test adapter in there and you drop it from that high of a height , depending on where it lands , what part of the tester hits the ground , different things can happen . In this case it must have hit directly on the adapter and transferred that energy through the connector to the board and caused a problem .

But it was interesting because there's other things on the board that were actually shifted . Yeah , the impact was so heavy , we saw components that had shifted out of place , So it takes a pretty significant amount of force to do that .

So let me ask you this So you said it's usually done by the manufacturer or a calibrated house . Is there any cost associated from a test owner's perspective to get their tester calibrated ?

We have something called extended care and you can get it for either a one year or a three year version , and what it does is it includes the calibration , but it also protects you against damage . So if you do drop that tester off , a 20 feet .

Does it cover being dropped from 20 feet from a little lift And that customer had our extended care program and they got their repair free of charge And in that case I think we actually just replaced the entire board , which is like getting a whole new tester . So yeah , so you know , consult with your manufacturer of your test equipment .

We offer that and you know our program . It covers those kind of damages . It covers the calibration cost And realistically I don't know if the others are doing it this way , but the way ours is it works out to be about the same cost as calibrating annually And if you do the three year you get a little extra discount .

So you come out ahead of the game but you get the additional protection . And that also gives you a free replacement once a year of your permanent Lincoln channel adapters as part of that . So you know , if the channel adapters and permanent link adapters aren't performing , they need to be replaced .

You don't have to buy new ones once a year , you can replace them . So I recommend , whether you're using our tester or one of our competitors , to check into that coverage program to see if you can get on board , and typically manufacturers are going to offer that when you buy the product They might give you a window .

We give 90 days typically , so you buy it now and you decide within 90 days . Yeah , i really do want to do that extended care . I'll go ahead and buy that now .

Level 2g , which is what we are , can go all the way up through cat 8.2 . And that's where the calibration comes in . If you're not calibrated and it gets out of calibration , then your accuracy comes into question And that's why it ties in And the ANSI-TIA 1152a talks about all of that .

So if you're looking for a standard to read up on the field testing specifications and what parameters need to be tested , what has to be done for calibration , you can look at that standard .

But if you start to see some strange things happening , the first thing to do one thing that you can see in the field . You might start to notice a resistance measurement where your resistance value seemed a little high . Plug your main unit into your remote . Use a permanent link in a channel adapter . Plug them into each other . Run an auto test .

See what your resistance is when they're plugged into each other . If it's anything more than a 0.5 ohm for your loop resistance , do a set reference . I think other manufacturers might call it a field calibration process , but we call it a set reference where you go into your tools and you tell it to do a set reference while they're connected together .

Once it does that , it takes about a minute and a half or two minutes tops . Then run another auto test . It should drop that down to something below 0.5 ohms . Usually it'll be like 0.1 or 0.0 . But you may get a little resistance on those over time If you've used those adapters a lot .

What happens is all that mating that plug in and disconnect is going to wear on the contacts . That's going to increase the resistance . That's where you start to see things change . If you do that set reference , it negates that additional resistance .

It kind of makes sure the two testers are communicating in the proper sequence and proper timing And then you start running testing . You're still seeing problems . You're seeing crosstalk problems , you're seeing return loss problems and you can't figure out why . That's when it might be time to look at getting calibration .

It should go typically it should go more than a year before you start to notice something . But if you do start to notice something that can't be explained by a problem with the adapter and replacing the adapter doesn't solve the problem , then it might be time for calibration . Now most testers will also notify you .

The issue with that , chuck , is that the people that usually see the message are the tech out in the field and they just X out of it And they're just cranking out to get the job done .

Now it gets back to the shop and it's that Friday afternoon and like , oh , i'll remember to tell the boss on Monday morning , and they don't tell the boss on Monday morning .

We're working on adding a reminder into our system that will trigger a message to go out and say , hey , it's been 11 months since you calibrated . It might be time Now . That's something that's not active yet , but it's something that we're looking at adding as a feature to our customers . So say , hey , it's been 11 months .

You might want to think about scheduling to get your unit in here to have it calibrated .

And you can do the same thing as a project manager or if you're the person who runs the warehouse and communication company same thing . You can go into your outlook or whatever Google calendar , whatever program you use , and you can put in there hey , 11 months from today , mommy , test or serial number , blah , blah , blah .

When a contractor sends a tester to be calibrated , is that a one day turnaround , a five day turnaround , Some days ?

But typically we let everybody know it's gonna be about two to three weeks And I do still have your tester here and I'm gonna calibrate it .

You remove the copper adapter and you plug in the OTDR adapter and it will work not only with the test pro but it will work with your network service assistant . The network service assistant is the only qualifier anywhere on the planet that you can plug an OTDR adapter into . So we've created our OTDR in this small form factor .

It's just one of our test adapters . We've got it available individually . So everybody already owns a test pro or an NSA can add the OTDR capability . We've got multi mode and a single mode version . They can order if they just wanna order an OTDR like what you've got there on your desk . We have kits that have a single handset .

It's a single test pro handset with a multi mode or with a single mode , or you can get it with both adapters . And the nice thing about that is , at some point if you wanna turn that into an optical loss test system , it just means buying another handset and the additional fiber adapters . If you wanna turn it into copper certification .

You just buy that second handset , get your permanent link and channel adapters , get a copper test license . Boom , now you've turned it into that . So it's just part of our whole scalable system where everything kind of works together . And again , this will work with both the test pro and the network service assistant .

I gotta run some fiber up there to make connection between the new podcast studio and the home , to extend the network up there . So I'm gonna have to obviously test that fiber .

Well , i appreciate you coming on today , mr Steve , especially on such short notice , but we've been talking about doing this show for , oh , i don't know , three months .

person . Just , you know it didn't happen . I was like you know what ? I just need to get this show done . Well , I'm glad you reached out . It's always good to chat with you Same here And it's always easy doing shows with you , because you answered like three of my questions before I even even asked them . Ha ha , ha , ha , ha ha ha . You read my mind .

That's great . You read my mind .