[AusNOG] 700Mbps over copper pair...over 400 metres

[Charles n wyble]

So as someone very interested in outside plant, I found your post most informative.  Thank you for taking the time to write such a detailed response.

You mentioned you wish folks would do more research. What are good sources of information on outside plant? I am always looking for more info. I'm an avid reader of all the specs from broadband forum. Have read some books on dsl. Hang out on the nog lists. Through those methods I have learned quite a bit.

"Tim McCullagh" <technical at halenet.com.au> wrote:

>
>----- Original Message ----- 
>From: "Kai" <vk6ksj at westnet.com.au>
>
>>
>> I'm guessing that was tested on "perfect copper" at 400 metres,
>> and not the stuff that's sitting in the pits and up the columns around 
>> Aus,
>
>I would hazard a guess that it would have been tested on a test bed similar 
>to what is installed in Australia.  Much of the copper in AU is in good 
>condition.  It is some of the design, install and maintenance practices that 
>cause the problems.  I have tested cable at new, 15 years of age and 25 
>years of age and the cable generally doesn't deteriorate.  It is the ingress 
>of water into joints, and where external factors have damaged the cable at 
>the time of installation or some time after which are not repaired 
>correctly, that causes most of the problems.  The same install issues that 
>affect Cat5 /6 installs also affect cat 3 cables and it is such issues that 
>generally cause the faults in later years.  In fact in aerial cable 
>installations, we found that the replacement of joints on cable at 25 years 
>of age took the fault performance of the cable back to new cable rates, 
>except where the cable had either fire, bird or mechanical damage pre 
>existing.  This put the perfect copper rubbish to bed many years ago.
>
>The idea of new cable being different to old cable because of age is 
>misguided, and shows a lack of technical understanding.
>
>> dealing with constant temperature and humidity variations,
>
>Again this shows a lack of technical understanding, buried cables have a 
>reasonably narrow temperature range.  The ground is an insulator and narrows 
>the temperature range variation.
>
>Humidity unless the cable is aerial cable and is install in the old aerial 
>cable boxes, then humidity should have no influence what so ever.  The 
>copper is insulated inside an external sheath.  What happens is the joints 
>either by design or poor maintenance practices may fill with water or 
>condensation.  You need to either fix the seal or replace the joint not all 
>the copper to fix this.  Or it may be due to third part damage that wasn't 
>repaired correctly. We have all seen the plastic bags on temporary joints. 
>The question is, "is it the copper or the bloody idiot that damaged it that 
>we should be blaming?"
>
>> at various stages of decay
>
>Only if it is not maintained properly
>
>>and after being repatched and respliced a few hundred times.
>
>Copper is not patched and spliced.  Copper is jumpered and soldered or uses 
>insulation displacement methods in climatically controlled environements 
>like exchanges, pillars and cabinets.
>
>As for resplicing, copper is jointed using connectors which displace the 
>insulation that also have a sealing grease. They are never reused, they are 
>replaced.
>
>My apologise in advance for any offence caused, but lists such as this one 
>would be of more useful if posters either took the time to research what 
>they say or limited their posts to things they do know about.  The first 2 
>paragraphs of this post were good and of interest, it is a pity the last 
>paragragh was written.  We all need to remember that some people who read 
>the posts may not be able to distinguish between the good stuff and the 
>crap. Then we hear people repeat the rubbish time and time again because 
>they saw it on a technical list and thought it to be fact, until it becomes 
>accepted as fact.  Once it becomes accepted as fact then it is difficult to 
>undo.
>
>regards
>
>Tim 
>
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--
from the desk of Charles wyble
ceo & president known element enterprises
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