I had the same problem on 500 up in KL7 at home. I ended up moving
the modem to the garage where the telephone line comes out of the
ground and keeping the ADSL loaded wiring as short as possible -
then on the telephone side of the router I connected
up a pair of reasonable quality of seried ADSL filters outbound
for normal telephone wiring in the house. From 20 over noise I
cant "see it" now as the big antennae has been chocked off.
I only use wireless around the property so it wasnt an
issue.
Next job is to choke off the noise from the AC
power line coming out of the ground - its awful.
relates
to MTA Palmer Alaska solutions ADSL
Laurence KL 1
X
> From:
[email protected]> To:
[email protected]> Date: Tue, 13 Oct 2009 23:10:53
+0100
> Subject: Re: LF: MOFMT ADSL noise
>
> Dear
Pete, Paul-Henrik,
>
> M0FMT wrote:
> ....> Well
I can only conclude it is ADSL because it is just raising the
>
noise floor it is very subtle not really identifiable like say TV LTB,
it's
> a mush...>
>
> I have problems with ADSL
on 500kHz at my QTH - it sounds like "white noise"
> with no
audible distinctive features I can detect. The noise can be about
> 10 - 20dB over the band noise here over a fairly wide
bandwidth in the MF
> range. It does not seem to be a problem
at 136k, perhaps because this is in
> the guard band between
upstream and downstream ADSL signals. It is easy to
> tell if
you are experiencing noise from your own ADSL connection -
>
disconnect the incoming phone line (probably just unplugging the modem
from
> the phone socket will be enough) and there will be a
reduction in noise
> level. Unfortunately, there also seems to
be a significant level of similar
> noise here from other
sources, probably my neighbors' ADSL via the overhead
> phone
lines.
>
> I have had some success with a
noise-cancelling arrangement here, where the
> ADSL noise is
sampled using a current transformer made by passing the
>
incoming phone line through a ferrite core, and summed with the signal
from
> loop antennas via a variable phase-shifting and
gain-adjusting network,
> which is adjusted for a null in the
noise. Also, moving the loop around the
> QTH shows some
positions are better than others. Actually, life is a bit
>
more complicated at this particular QTH, since there also seems to be
> wide-band noise originating as very low-level sidebands from
the local
> broadcast stations. This requires a second
noise-cancelling network to null
> noise from that direction.
Also, it was necessary to insert a relay in
> series with the
loading coil to disconnect the TX antenna on receive,
>
otherwise this coupled more noise into the receiving antennas. But
when it
> is all adjusted properly, the overall noise level can
be reduced in
> favourable directions by about 20dB, which is
worth doing.
>
> Cheers, Jim Moritz
> 73 de M0BMU
>
>
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