A large common mode choke on the incoming line, just down stream
towards the modem from the ETP (=NTE over there I guess) and again at
the input to the modem did it for me. Using a single ADSL filter at
the ETP and connecting the modem at that point, as opposed to the DIY
'filter per CPE outlet ' setup with the modem fed from a unknown
configuration of extension wiring, will give better performance as
well.
73
Dave, ZL3FJ
----- Original Message -----
From: "Ken" <[email protected]>
To: <[email protected]>
Sent: Monday, November 29, 2010 9:13 AM
Subject: Re: LF: Any ADSL2 BBand router / RF proof ?
Hello Everyone.
I think you will find that with your line length from the serving
exchange (7km)? the S/N ratio will be poor, a minimum of 10dB is
required, my copper connection is about 2.7km which is considered to
be approaching the limit, although the tests at the customer NTE
showed that 3Mbt/s.should have been possible. At these line lengths
any rf will swamp the DSL signal. I have discussed this problem at
length several time with the people I worked with at Adastral Park (
commonly known as BT Labs), both DSL and EMC, the problem is
compounded if a) you have a long length of overhead drop wire, b) the
number and configuration of any internal extensions, and c) the
position of the router with respect to the incomming NTE (master
socket). If the dropwire is long, the induced common mode interference
will be transformed into differential mode before it reaches the
router, any internal extension wiring will increase attenuation,
especially if it is a 'star configuration.
The router should be as close as possible to the incoming NTE. A
spectral analysis of my line revealed that there were no DSL carriers
above 500kHz, hence not being able to use 500kHz, if the router shuts
down because a corrupted incoming signal, it will start a
're-training' sequence with the DSLAM in the serving exchange, however
if either the line or the router is changed, the exchange equipment
will then go though a process of determining the best possible data
speed of the new configuration, thia can take up to ten days, if
during this time any of the speedtest sites are used different data
rates will be loged.
I changed my 1st generation BT Homehub router for an older BT Voyager
2500, which improved the situation with the HF bands but not at
500kHz, even with high value common mode chokes on everything in
sight. The problem was finally solved by changing over to BT Infinity
Fibre To The Cabinet (FTTC) with copper line length of 400m giving
data speeds of 14Mbt/s.
I hope some of this is both of use and interest you all.
73
Ken
M0KHW
----- Original Message -----
From: M0FMT
To: [email protected]
Sent: Friday, November 26, 2010 10:08 AM
Subject: Re: LF: Any ADSL2 BBand router / RF proof ?
Hi Again Graham and LF
Hmmmmm OK looks like you are in better shape than me. A local
station who has difficulty with his ADSL has put Ferrite clamp on
filters on all leads in and out of the Modem including the power
supply lead. He claims (and I have no reason to doubt him) that this
has solved his problems. The modem is the new BT Black Box one. I have
one of those although much more reliable and faster it still suffers
from my description below. The issue I have appears not to be Modem
related but exchange based.
I talk to Larry regularly on 4m so next time, if I remember, I
will get the details of his solution Viz ferrite type and where on the
lines he is fitting them and forward it to you. It may help.
As before good luck with your efforts; what ever success you
get please publish it. Ken M0KHW Luton has an ADSL problem too so
several people would be interested I am sure.
73 es GL petefmt
I support www.NotSpotTelecom.Com your community Telco / ISP.
--- On Fri, 26/11/10, Graham <[email protected]> wrote:
From: Graham <[email protected]>
Subject: Re: LF: Any ADSL2 BBand router / RF proof ?
To: [email protected]
Date: Friday, 26 November, 2010, 0:49
Ok Pete
This is the new router , as its in the same place as the
old one , with (now) the same filters , the PC is linked with a
short network cable , the rest of the pc's are linked by radio.
its the adsl like thats failing
The edimax router was quite robust , never had a drop
out on HF and only over 200 watts , feed , on 500 would stop the
link , this one fails with 25 watts on 160 .. the router is
off most of the day and night , only on with the pc , the new
router is faster , from 6 (old) meg to 9 med down and 500k (old)
to 890 k upload , but if it keeps dropping out with no cure
then its not much use for my usage
G,
From: M0FMT
Sent: Friday, November 26, 2010 12:26 AM
To: [email protected]
Subject: Re: LF: Any ADSL2 BBand router / RF proof ?
Hi Graham
Are you sure the problem is the router?
136, 500, 160 and to some extent 80m here are
kill the ADSL. Even at very low powers. If your ADSL is cut during
your transmissions only and resumes at the original speed directly
afterwards it may well be the router being temporarily being knocked
out. If however you line stays down for a period of time say several
hours then it is not the router. What you are doing is putting noise
(owing to RF) onto your line which is being picked up at the exchange
DSLAM. The exchange equipment (DSLAM) serving your line will reduce
data speed to ensure that a connection of sorts is maintained. This
speed can go down to below 80kb/s from which it will not recover
without technical intervention by BT Open Reach. If it goes down to
about 300/500kb/s it may well recover it's original speed over a
period of time BT quote 72 hours yes 72 hours (I think this time
period is not a technical issue but one to stall the punters off). On
a good day the recovery period can be speeded up by turning the router
off and disconnecting every thing from the line and waiting. This
makes a quiet line for the automatic recovery to work.... on a good
day!!! If you don't have enough life left to wait for BT to physically
do some thing then the best thing is to write to BT HQ in London to
the their CEO (his name and location can be found with a bit of
research) and tell him what you think of his outfit. I know from
experience he does not like receiving this kind of letter. You may
have your ISP as Joe Blogs Internet Provider dot Com but in reality it
is all provided by BT they own the final mile and the exchange ......
legal niceties to one side it is a fact.
If you get a good Broad Band data rate of say
4/8mb/s your transmissions on LF/MF will only slightly degrade your
ADSL but if like me on the end of 7.5km of copper its only 1/1.5mb/s
on a very good day, RF will wipe out your ADSL for a week or more. So
without a lot of letter writing to BT and angry phone calls your ASDL
will not return to original speed..
To maintain a usable data rate on Broad Band
here I can not use 136 or 500kc/s above a few Milli Watts at TX output
about 1 Watt on 160m 80 about 50Watts and on 60m and above 100Watts
(possibly more but not tested yet). Also the longer you stay on the
worst the speed degrades.My guess is with ADSL2 having a much wider
bandwidth the problem for Amateurs will extend further up the spectrum
than shown above.
Hope you are not in my situation....... Oh and
don't believe all this Fibre stuff. Open Reach have told me that one
reason why Fibre is not being rolled out like the Virgin setup is that
there are only a few BT people capable of working with Fibre. This is
the reason why BT is Wedded to copper wire. So we locally have
Internet breakdowns owing to Junkies and the like ripping the Copper
cables out of BT ducting to pay for drugs... Bedfordshire has had
Internet disconnections for days owing to this phenomenon. So along
with cable theft and the lack of trained staff a proper interference
free Broad Band coverage using fibre in this country is looking
particularly bleak.
Good luck!
73 es GL petefmt
I support www.NotSpotTelecom.Com your community
Telco / ISP.
--- On Thu, 25/11/10, Graham
<[email protected]> wrote:
From: Graham <[email protected]>
Subject: LF: Any ADSL2 BBand router / RF proof
?
To: [email protected]
Date: Thursday, 25 November, 2010, 22:06
Any ADSL2 BBand router / RF proof ?
Just upgraded to ADSL2 with a orange
net-gear router/wifi router, now 15 watts on 160 kills the
connection
router is in the same location as the old
edimax , which kept running with 200 watts on 500 K and 400 on
Hf
? any RF proof ADSL2 on the market >
Tnx - G..
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