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Re: LF: Any ADSL2 BBand router / RF proof ?

To: <[email protected]>
Subject: Re: LF: Any ADSL2 BBand router / RF proof ?
From: "Dave Brown" <[email protected]>
Date: Mon, 29 Nov 2010 22:50:54 +1300
References: <[email protected]> <25671BC19A084642B38CBC31639E7633@lindavideo>
Reply-to: [email protected]
Sender: [email protected]

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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