A Simple test by the Telecom contractor with the Dynatel DSP 965 would tell you if there are coils on the line. Some of the cables that have been regrouped/reconstructed so that cable that used to feed customers further out from the exchange are now feeding customers that are closer could have been loaded. The reconstruction job would cover the removal of the coils but sometimes this is not done. A looptrans on the line tests (the test that Telecom use's) the lines using the AM/FM plans that the cables are recorded on and it does not do a physical test on the line. If a job goes through and the coils are not removed the AM/FM plans are updated and the circuit is then tested as a working circuit when it is not due to the coils.

If the proper equipment is used by someone that knows what they are doing it is a easy yes or no to weather the circuit will work along with the looptrans. With a combination of the above Dynatel DSP 965 and add on unit called the FED (Far end device) (http://www.3m.com/market/telecom/access/faq/tm_965dsp.jhtml#ans13) will prove the circuit. This is what I call a physical test and yes multiple cable's coming off a line can be as bad a loading coil. Also I would like to note that if the cable pair is loaded there can be unloaded pairs in that same cable that could be used. The conductor size does have a lot to do with it but if it was 0.4 you should get some kind of connection. What I have found that does mess things up a lot is a combination of different conductor sizes 0.5 - 0.63 - 0.5
0.9 - 0. 4 .

What the problem is that the equipment that is required to do the above is very expensive and this may change with the new super patch's as the contractors have to reduce their cost to Telecom over the next 4 to 5 years. The Telecom requirement is that if your can connect with a dial-up modem at 14400 and it passes the NTS test with a good line it meets the Telephone requirements, ADSL does not come into the equation. The contractor does not have to do any more. This does not mean that ADSL will work over that line but the contractor will charge you the appropriate fee when the line may have a real fault or design problem on it that effects ADSL.

Another issue with high speed data is crosstalk. Again the standard test's that are carried out do not test for this, not at the frequency of VF or ADSL.

Not sure on the ASAM but I would be able to get some kind of connection on a DSLAM, would say 1200k down.

Dave

-----Original Message-----
From: owner-adsl@unixathome.org [mailto:owner-adsl@unixathome.org]On
Behalf Of Wayne Kampjes
Sent: Wednesday, 14 January 2004 6:30 p.m.
To: adsl@lists.unixathome.org
Subject: RE: ADSL modems on dodgy/long lines

If you do in fact have a loaded line then you are dead in the water. Loading coils are used on longer lines to give lower loss (and hence better speech quality) on the 0.3-4kHz range with the downside (for DSL but not speech) of significantly increasing the attenuation above 4k. Need to go into a bit of transmission line theory to understand how this happens. (By the way the 1st coil is a half section (3000ft) due to the impedance of the exchange equipment.)
 
Cheers
Wayne

        -----Original Message-----
        From: owner-adsl@unixathome.org on behalf of Matthew
        Sent: Wed 14/01/2004 5:32 p.m.
        To: adsl@lists.unixathome.org
        Cc:
        Subject: Re: ADSL modems on dodgy/long lines
        
        

        Ah, there's your culprit. Here's more info -
        http://www.dslreports.com/information/kb/load+coil
        
        
        ----- Original Message -----
        From: "Simon Garner" <sgarner@expio.co.nz>
        To: <adsl@lists.unixathome.org>
        Sent: Wednesday, January 14, 2004 4:58 PM
        Subject: Re: ADSL modems on dodgy/long lines
>
> I should note the house is only 4 years old - it was newly built when I
> first tried to get DSL - so I would expect the internal wiring to be
> decent enough.
>
> One thing I should probably add. When I was doing this four years ago,
> somebody from Telecom (from this list in fact) contacted me and did some
> sort of a test on the line and found there were "loading coils", which,
> he said, would prevent DSL from working. Anybody know what that means?
        
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        This message is part of the NZ ADSL mailing list.
        see http://unixathome.org/adsl/ for archives, FAQ,
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