[RFI] white noise starting at 3780 and up

[Larry Benko]

Jim and others,

I believe the problem has much to do with the cable from the DLSAM to 
the customer which over the years has been upgraded to be "data" 
compliant.  I think this means more twists per inch and different twist 
patterns between the various pairs in the cable. There is no getting 
this cable changed easily.  I believe this is a major contributor to why 
some areas have less uplink VDSL2 interference.  We were able to follow 
the VDSL2 uplink interference along these cables back to the DSLAM with 
the levels decreasing as we got further away from the subscriber (cable 
loss).

I would be willing to bet that when the initial VDSL2 tests were being 
done the link between the DSLAM and the customer was not done with 50 
year old cable but I have no solid evidence of this.

Larry, W0QE


On 7/16/2017 11:22 AM, Jim Brown wrote:
> On 7/16/2017 6:52 AM, David Robbins wrote:
>> And complaining to AT&T about something that might be their problem 
>> and that
>> their techs have no idea how to find or fix won't help.
>
> Although I haven't experienced this problem, W0IVJ and W0QE have 
> documented it quite well. I strongly suspect that it is a simple "Pin 
> One Problem" in the defective equipment (probably the DSL or cable 
> modem, but also in the CATV or DSL distro system). If so, it can 
> probably be suppressed a lot by ferrite chokes on cables connected to 
> the defective equipment. Chokes should be wound using the guidelines 
> in my "Choke Cookbook" for the frequencies where the noise is heard. 
> It's part of k9yc.com/RFI-Ham.pdf
>
> 73, Jim K9YC
>
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