Kitz Forum

Broadband Related => Broadband Technology => Topic started by: supercooper on September 01, 2008, 01:38:55 PM

Title: Copper line test
Post by: supercooper on September 01, 2008, 01:38:55 PM
Hi Chaps :)

I have a question for you today, how does a Copper line test work and what exactely does it do?

On many occasions when raising faults with BT they run this test before proceeding with the fault i have raised.

Oh by the way very soon i will have the ability to conduct whoosh testing and other tests, its a bit of a grey area at the moment but my managment have told me its going to happen :) :) :) Cant wait!!!

Hopefully i can post some interesting and usefull info when i get more things to play with so we all have a better insight on ADSL testing incuding myself of course :P

Thanks, Chris
Title: Re: Copper line test
Post by: Ezzer on September 01, 2008, 05:19:20 PM
The line test is the tests always done to check for any conditions on the line which may effect PSTN or normal telephony. Any conditions shown here is typicaly going to have an effect on DSL (although you can have a fault on the line which completely disrupts PSTN but has absolutely no effect on DSL). If any conditions are found on this test then on a DSL fault we tackle this fault before looking deeply into the DSL.

The automated test will run the same tests we do manualy with our 9083,mole,megger or the hawk (which does the job of the previous 3 in one unit) when we're working in the network.

The test will disconect the pstn an look out to the network. 1st thing it looks for is any ac voltages which shouldn't be there such as mains or 450v or higher. This isn't as uncommon as you might think. I've come across 240v before, either due to a faulty kit like a fax machine but could be any mains using item plugged into the telephony. I've also come across situations where some numpty has wired the mains on to their telephony. Just because it's a pair of telephone wires never assume ther's no more than the typical 50,95,or 140v dc to be found there.

The next thing is to check for "battery" current from another telephone line leaking on to your pair. Or "earth" current leaking from your pair to some other conducting path.

Next "Loop" or short curcuit from infinity to a few ohms. although it should see the capacitor in the nte which causes a "kick" to the needle when using a 9083 as you see the needle jump distinctly when switching polaritys with a little button we have. a smaller kick would indicate no nte on the end, but with experience you get an approximation of how far the pair are getting.

Then for any smaller dc voltages comming back. typicaly off bits os equipment plugged in not working as they should.

Then M-ohm resistance for the overall insulation quality of the pair, and to see if you get a different kick which comes via the surge protector in the nte.

Then the system would check to see if can see a nte-elite (not many of these around, you can reconise them as they're much deeper then an normal nte as they had a bit of electronics within them so a tester could remotely instruct the nte to disonnect the customers internal wiring so see if thats where the fault was, or put a full loop on the line in order to get an acurate reading for the location of an earth of batt' contact. Idea was great for various reasons never went beyond a trial period). The sytem would also look for dacs remote unit, isdn, home highway,redcare equipment.

And also do an acurate line distance measurement.

The woosh test (nice to see your getting it, was taken off us in openreach as ofcom deamed it to be a wholesale product only.  >:()
Is the dsl version of a test in that it shows the stats which you look at on a router but with an awfull lot more info, and you can play with the info to get a better picture of whats happening to a connection. The alternate we use in openreach is the apts on our laptops in conjunction with a usb modem in sync on the line. The advantage we've got is were able to intercede anywhere on the network and get a comparative test.

Ta-daaa#  ;D

Incidentaly if you've got.had an old binatone style phone, the one where the handset has the key pad and when in its holder you see 3 small holes at the top for the ringer. If a copper line test was run than in the space of a minute you hear some odd random chirps as the ringer was sensitive to the test voltages/switching done when the test was running. I've often had people mention they wondered why that phone did that occasionaly
Title: Re: Copper line test
Post by: supercooper on September 02, 2008, 11:10:52 AM
Hi Ezzer,

Wow that was very detailed and informative :)

Thank you very much for taking the time to explain in depth on Copper line testing. 

I cant believe that offcom would take away testing tools from you (whoosh test) that seems a rather silly thing to do :(

Thanks again for your time.

Chris
Title: Re: Copper line test
Post by: kitz on September 02, 2008, 11:32:24 AM
>> I cant believe that offcom would take away testing tools from you (whoosh test) that seems a rather silly thing to do Sad

It does doesnt it.   I believe though its because the WOOSH test is a BT designed test which checks details on the BT dslam.
Because LLU providers dont have their own equivalent tests, OFCOM deemed it unfair and said that BT would be at an advantage if BT Openreach engineers used it as a diagnostic.
:crazy:
Title: Re: Copper line test
Post by: Ezzer on September 02, 2008, 02:32:39 PM
The contracictory thing here is Openreach was formed as part of a means of treating all service providers in the same fair manner (which we always did, besides we all still unofficialy refer to the end user as the customer and it's them we have in mind while doing our jobs).

It was handy in keeping an eye on several dsl lines for which we could be working on that day. of course officialy we work on one dsl fault at a time. But if I have two or more from the same exchange then I check the dsl from the idf for one after the other including under load.
Title: Re: Copper line test
Post by: kitz on September 03, 2008, 10:52:20 AM
Quote
The contracictory thing here is Openreach was formed as part of a means of treating all service providers in the same fair manner (which we always did, besides we all still unofficialy refer to the end user as the customer and it's them we have in mind while doing our jobs).

Indeed.

Quote
It was handy in keeping an eye on several dsl lines for which we could be working on that day. of course officialy we work on one dsl fault at a time.

I totally agree Ezzer.

But what ofcom deemed unfair was that BTw made a tool available to you that helped you do a job better with better diagnostics for the BTw lines.  But because the LLU providers havent got this sort of tool then they ruled that you cant use it. 

Stupid isnt it